However, the project involved much more than installing an electrostatic precipitator. It also included continuous particulate emission monitoring, improving the plant’s energy efficiency by recovering heat from flue gases, and collecting and conveying the separated ash.

Another major challenge was integrating large new equipment into an existing plant. This required partial demolition of the building and associated construction work.

Finally, an independent accredited laboratory had to verify the plant’s performance through emission measurements.

Who Did Dijamant Entrust with the Project?

Dijamant entrusted the engineering design and execution of the project to Marquis Commerce, Belgrade.  Working with a partner, the company delivered the complex system on a “turnkey basis”.

In other words, Marquis Commerce was responsible for the entire process: from developing the technical solution and detailed engineering designs to equipment supply, installation, and commissioning. The project documentation comprised the main civil engineering, electrical engineering, and mechanical and process engineering designs.

The contract signing received media coverage. A recording of the event by KTV television is still available on the Marquis Intelligence YouTube channel.

Sunflower Husks as Fuel

Sunflower processing generates substantial quantities of sunflower husks. At Dijamant, these husks were regarded not as waste, but as a valuable resource. This energy-rich biomass was used as fuel to generate process steam.

Boiler K5, manufactured by Minel Kotlogradnja, had a steam generation capacity of 25 t/h and could operate on either natural gas or sunflower husks. When operating on biomass, natural gas was used primarily for start-up, until stable sunflower husk combustion had been established.

Using sunflower husks made it possible to replace approximately 70% of natural gas consumption. The project presentation assumed a daily consumption of approximately 84 tonnes of sunflower husks, with an energy benefit equivalent to saving around 1,600 Nm³ of natural gas per hour.

The economic justification for using biomass as fuel was clear. The problem was particulate matter emissions.

Particulate Emissions 32 Times Above the Limit

Measurements carried out in 2003 in the flue gas duct of boiler K5 showed a total particulate matter concentration of  1,630.04 mg/Nm³, with the boiler operating at a steam generation rate of 11 t/h. The applicable emission limit at the time was 50 mg/Nm³.

The measured concentration was therefore more than 32 times the permitted limit, resulting in the shutdown of the boiler. The problem was no longer purely environmental. Shutting down the boiler also meant losing the opportunity to use biomass as a virtually free fuel in place of substantial quantities of natural gas.

The solution therefore had to meet process, environmental, and economic requirements simultaneously.

Electrostatic Precipitator at Dijamant – Price or Technical Challenge?

Several serious suppliers competed for the project. The decisive factor in selecting the supplier was not simply the equipment price, but its technical characteristics and the manufacturer’s experience. Selecting an electrostatic precipitator to clean flue gases generated by sunflower husk combustion represented a significant technical advance, extending beyond the local context.

Sunflower oil production processes differ in how the raw material is initially prepared. Most producers do not dehull sunflower seeds. As a result, sunflower husks are not separated as a distinct process by-product. Because of their low bulk density, separated sunflower husks present particular challenges in storage, conveying, and subsequent use. Boiler plants designed to burn this biomass must therefore be adapted to its specific characteristics.

This is what made the application of an electrostatic precipitator to flue gases from sunflower husk combustion particularly distinctive.

Sunflower husks cannot simply be treated as equivalent to wood or wood pellets. Their structure, moisture content, and organic constituents affect combustion and the properties of the resulting particles. The analysed sunflower husk composition included, among other constituents, approximately 3% oil.

Why Was an ESC Umwelttechnik Electrostatic Precipitator Selected?

The selected solution was supplied by the German company ESC Umwelttechnik GmbH. An important advantage was the experience of its owner, Jürgen Fischer, with biomass of similar characteristics, including rice husks. Other solutions under consideration relied more heavily on experience with woody biomass.

For a plant of this type, nominal airflow capacity and declared collection efficiency are not sufficient selection criteria. Engineers must understand the actual process that generates the flue gas. That process determines the properties of the particles and other pollutants and, consequently, the appropriate technical solution.

Marquis Commerce as Engineering Designer and System Integrator

As already noted, the project scope extended far beyond the electrostatic precipitator itself.

The proposed system included a new waste heat recovery heat exchanger, an ESC Umwelttechnik electrostatic precipitator, a flue gas particulate monitoring system, an ash discharge and conditioning system, connection to the existing induced-draft fan, new flue gas ducts, piping, thermal insulation, maintenance access provisions.

Marquis Commerce prepared the project documentation through three coordinated engineering disciplines: civil, electrical, and mechanical/process engineering.

The project was therefore not simply a matter of installing an electrostatic precipitator between the boiler and the chimney. It involved creating a new, integrated process system in which all components had to function together.

Electrostatic Precipitator from a Reliable German Manufacturer

The electrostatic precipitator installed at Dijamant in Zrenjanin was manufactured by ESC Umwelttechnik, Germany, type 400/ESC/1 × 2 × 10 × 6 × 3.0.

The unit was designed for a flue gas flow rate of 33,100 Nm³/h, equivalent to approximately 50,000 m³/h under operating conditions. The design inlet particulate concentration was 6 g/Nm³, while the guaranteed outlet concentration was a maximum of 50 mg/Nm³.

The precipitator had two sections and ten gas passages. The specified collecting electrode area was 720 m², or 960 m² of developed surface area for the sigma-profile collecting electrodes. Each section had its own high-voltage power supply unit, with a nominal high voltage of 111 kV and a rated power of 15.54 kW per unit.

How the Electrostatic Precipitator Separates Particles

Inside the electrostatic precipitator, particles are first electrically charged in the corona discharge zone. The corona discharge is generated at the discharge electrodes installed in each of the ten passages between the rows of collecting electrodes. Under the influence of the electric field, negatively charged particles migrate towards the collecting electrodes, where they are separated from the flue gas stream.

A layer of collected particulate matter gradually forms on the collecting electrodes. The accumulated material is removed by a mechanical rapping system using hammers.

SEE ALSO: FAQ 2 – Marquis Intelligence Solutions

The design of discharge electrodes has changed significantly throughout the development of electrostatic precipitators. Early designs used thin wires and, later, serrated elements. These were more susceptible to mechanical damage and operational interruptions. Modern designs use rigid discharge electrodes with pointed emission elements, providing substantially greater reliability.

During operation, positively charged particles also accumulate on the discharge electrodes. These deposits are likewise removed by rapping.

All electrodes are cleaned through periodic mechanical rapping. The cleaning process is automated, and the rapping interval and frequency can be adjusted to suit operating conditions. At the Dijamant plant, the rapping interval was set to less than five minutes.

The electrostatic precipitator was also equipped with a system for optimizing electrical energy consumption.

Waste Heat Recovery from Flue Gases

Before entering the electrostatic precipitator, the flue gases passed through a new waste heat recovery heat exchanger. The unit was designed to handle approximately 50,000 m³/h of flue gas. It reduced the flue gas temperature from approximately 240–290 °C to 130 °C. The recovered heat was used to preheat demineralized water for the steam-generating boiler plant.

This arrangement recovered part of the thermal energy contained in the flue gases. At the same time, it provided suitable operating temperatures for the electrostatic precipitator and reduced the amount of heat discharged into the atmosphere.

Removing Ash from Flue Gas Is Not the End of the Process

Flue gas cleaning does not end when particulate matter is separated from the gas stream. After separation, both the collected particles and the cleaned flue gases continue through the system, but along different paths. 

The Path of the Collected Ash

When the electrodes are rapped, the collected ash falls into the ash collection hopper. From there, a system of screw conveyors removes it from the electrostatic precipitator. The project included a dry ash screw conveyor, an ash conditioning and moistening system, a conveyor for moistened ash.

Special enclosed containers were also designed to collect the separated ash and transport it away from the factory premises.

The Path of the Cleaned Flue Gases

Measuring Residual Particulate Matter in Flue Gases

After passing through the electrostatic precipitator, the cleaned flue gases flow through the flue gas ducts, past the monitoring station, and into the chimney.

At the advanced monitoring station, particulate matter concentration is measured directly in the flowing flue gas using laser-based measurement technology. More than twenty years ago, this was exceptionally sophisticated equipment.

In Engineering, Every Detail Matters

In an electrostatic precipitator, numerous design details directly affect reliability, collection efficiency, and service life.

Dedicated Ventilation for High-Voltage Insulators

The high-voltage insulators mounted on top of the electrostatic precipitator were provided with a dedicated ventilation system. The system supplied thermally conditioned and filtered air to prevent contamination and condensation on the insulators. Such conditions could otherwise lead to the formation of electrical leakage paths along the insulator surfaces.

Rounded Internal Edges of the Precipitator and Ash Hopper

The project demonstrated how details that may initially appear insignificant can influence the final result.

The internal geometry had to be designed to avoid areas where dust could accumulate unnecessarily. For this reason, the internal edges of both the precipitator housing and the ash hopper were rounded. This reduced the risk of collected ash accumulating and adhering in corners.

Thermal Insulation and Electric Heating Elements

Insulating the large precipitator housing and ash hopper presented a particular challenge. The insulation was installed on welded insulation pins, with special attention to minimizing thermal bridges. A flexible electric heating element was also installed beneath the insulation, following a serpentine pattern across the surface.

Its purpose was to help maintain the required surface temperature and prevent unwanted condensation.

Today, such a detail may seem like a logical part of the design. Two decades ago, however, finding a domestic company willing and able to install this type of specialized insulation on the precipitator and its large ash hopper was far from straightforward.

Details such as these often determine whether equipment that performs well in the design stage will also operate reliably under actual plant conditions.

Ash Conditioning and Moistening

Moistening the collected ash was an important part of ensuring its safe removal and transport. Adding water reduced the possibility of smouldering particles remaining in the collected ash, as well as the risk of fine dust becoming airborne again during handling and transport.

At the same time, the moistened particles tended to bind together. This reduced the loose, free-flowing nature of the ash and facilitated its controlled transport and disposal.

Trial Operation and Final Commissioning

During the initial trial operation of the plant, the monitoring equipment indicated very low particulate matter concentrations. However, during the first morning inspection, a sudden deterioration in performance was observed. The readings had exceeded the measurement range of the continuous particulate emission monitoring system.

An analysis of the operating procedures, together with discussions with the boiler plant operators, identified the cause. During the night, the operators had carried out steam sootblowing unusually frequently and for extended periods, exercising additional caution while operating the new equipment.

The increased moisture content of the flue gases caused ash to adhere more strongly to the electrodes, forming deposits. These deposits reduced the effective electrode surface area and impaired the performance of the electrostatic precipitator.

The operators received more detailed operating instructions. The electrodes were thoroughly cleaned by rapping, and the automatic rapping intervals were shortened. These measures improved electrode cleaning and stabilized system operation.

Following final commissioning, guarantee performance measurements were carried out.

Guarantee Measurements Confirmed Collection Efficiency

The project results were verified by the accredited laboratory A.D. Bio-ekološki centar, Zrenjanin. On 14 June 2006, the laboratory carried out emission measurements using the prescribed methods.

The measured mean particulate matter concentrations were:

• 17 mg/Nm³
• 23 mg/Nm³
• 32 mg/Nm³

The applicable emission limit at the time was 50 mg/Nm³.

Following the guarantee measurements and further optimization during operation, particulate emissions were reduced to below 20 mg/Nm³. In other words, compared with measurements taken before the electrostatic precipitator was installed, particulate matter emissions were reduced by more than a factor of 80.

A Significant Investment with a Short Payback Period

The technological part of the investment amounted to approximately EUR 750,000. Additional construction, reconstruction, and associated works increased the total investment to approximately EUR 900,000.

The techno-economic analysis assessed the value of the energy obtained by burning sunflower husks against the cost of alternative energy sources.

Based on the official industrial natural gas price at the time, the estimated payback period for the technological part of the investment was 88 operating days.

The analysis was also verified by comparing the energy equivalent of sunflower husks with the cost of the natural gas or electricity required to produce the same amount of energy. When the broader investment scope was considered, both approaches indicated a payback period of approximately 8–9 months.

In this case, environmental protection was not simply a regulatory compliance cost. The investment enabled the plant to continue using its own energy resource.

More Than Two Decades Later

More than two decades have passed since the project was completed.

After completion and the expiry of its contractual obligations, Marquis Commerce was no longer involved in the plant’s regular operational monitoring. In the meantime, the applicable particulate emission limits have become more stringent.

According to Predrag Nenin, Quality and Environmental Manager at Dijamant, the electrostatic precipitator continues to meet the current particulate emission requirements. This may be the most important long-term confirmation of the project’s success.

The system was not designed merely to comply with the 50 mg/Nm³ limit applicable immediately after commissioning. Further optimization and the achievement of concentrations below 20 mg/Nm³ provided an additional performance margin. This margin allowed the system to remain suitable for continued operation even after regulatory requirements became stricter.

A Project That Connected Two Professional Careers

On the client’s side, the project was managed by professionals directly responsible for investment projects, maintenance, and technical implementation at Dijamant.

Momčilo Ćuk, then Director of Investments and Maintenance, played a key coordination role throughout the project.

Other key representatives of the client included Sava Dutina and Gordana Petrović, now Gordana Blagić. They were responsible for supervising the electrical and mechanical installation works on behalf of the client during the electrostatic precipitator project.

After the project was completed, Gordana joined Marquis Commerce. As a licensed engineer for design and construction works, she continued working on the engineering and implementation of ventilation, air quality, and process engineering systems.

SEE ALSO: Gordana Blagić: 20 Years at Marquis Commerce

What Does the Dijamant Electrostatic Precipitator Project Demonstrate Today?

The Dijamant project demonstrates that successful industrial flue gas cleaning depends on more than selecting the right equipment. It also depends on how well the solution is adapted to the specific fuel, plant, and actual operating conditions.

In this case, the challenge was to enable continued use of sunflower husks as fuel, address exceptionally high particulate matter emissions, and integrate the new system into an existing energy plant.

The result was an electrostatic precipitator that reduced particulate matter emissions by more than a factor of 80, while achieving a remarkably short investment payback period.

More than 20 years later, according to confirmation from the plant operator, the same electrostatic precipitator continues to meet the applicable particulate emission requirements.

The long-term durability of the achieved results may be the strongest evidence of the project’s value.

References

1. Marquis Commerce d.o.o. Main Mechanical and Process Engineering Design for Addressing Particulate Emissions from Boiler K5, Book 3, Volume 1, Dijamant AD Zrenjanin, Belgrade, January 2006.
2. A.D. Bio-ekološki centar, Zrenjanin. Laboratory Test Report No. I 424, 19 June 2006, based on emission measurements carried out on 14 June 2006 in the common flue gas duct of boilers K4 and K5, Dijamant AD Zrenjanin.
3. A.D. Bio-ekološki centar, Zrenjanin. Laboratory Test Report No. I 502, 10 July 2006, based on emission measurements carried out on 4 July 2006 in the common flue gas duct of boilers K4 and K5, Dijamant AD Zrenjanin.
4. Petrović, G.; Janaćković, V. Addressing Particulate Emissions from Boiler K5 at Dijamant AD, Zrenjanin, by Installing an Electrostatic Precipitator. 33rd Conference Air Protection ’05, Belgrade, 2005, pp. 89–94. Bibliographic record of the National Library of Serbia.
5. Petrović, G.; Ćuk, M. “Installation of an Electrostatic Precipitator to Reduce Particulate Emissions from Boiler K5 at Dijamant, Zrenjanin.47th Oil Industry Conference “Oilseed Production and Processing”, Herceg Novi, June 2006. Uljarstvo, Vol. 37, Nos. 1–2, 2006.
6. Petrović, G. “Sunflower Husks as Fuel. 48th International Conference “Oilseed Production and Processing”, Herceg Novi, 11–16 June 2007.

This article is part of the Marquis Intelligence Grande Case Study (GCS) series, which documents projects distinguished by their technical complexity, implementation scope, measurable results, or long-term significance.

Document No.: MI-GCS-001.26 – Grande Case Study: Electrostatic Precipitator at Dijamant, Zrenjanin

The post Grande Case Study: Electrostatic Precipitator at Dijamant, Zrenjanin appeared first on Marquis Intelligence.

These were not the years when the first air pollution laws were introduced. However, this period marked the beginning of a different approach. Air pollution was increasingly viewed not simply as a local problem involving smoke, soot, or individual industrial emissions, but as a public health issue requiring action by municipal, state, and national authorities.

Three Cities, Three Continents, Three Windows into Modern Air Pollution Regulation

London, New York, and Tokyo were among the most striking examples of the period. They faced different sources and levels of pollution. However, the underlying problem was similar. Large quantities of pollutants, particularly under unfavorable weather conditions, could become trapped over cities and seriously endanger public health.

Air Pollution Regulation Before 1952

The 1950s did not mark the beginning of legal air pollution control. One of the most important early examples was the British Alkali Act of 1863. The Act targeted hydrochloric acid emissions from the alkali industry of the time. It required at least 95% of the gas generated during the process to be condensed. It also introduced inspections of industrial facilities.

This legislation is important because it shows that technically defined requirements for reducing specific industrial emissions already existed in the 19th century. Various cities later introduced local regulations against smoke and soot. These generally targeted specific emission sources, particular industrial processes, or visible smoke.

What changed in the 1950s was not simply the existence of regulations. It was the way the problem itself was understood.

The Great Smog of London Changes the Perception of the Problem

From 5 to 9 December 1952, London was covered by exceptionally dense smog.

The burning of large quantities of coal, combined with emissions from industry and transport and unfavorable weather conditions, caused smoke, soot, and sulfur dioxide to accumulate in the air over the city.

The consequences could no longer be regarded simply as an inconvenience caused by smoke. Around 4,000 additional deaths were recorded during and immediately after the Great Smog. Later estimates indicated an even greater overall health impact. The UK Parliament today directly links the Great Smog with the legislative measures that followed.

SEE ALSO: The Great Smog of London (1952): Lessons from the Past

The Great Smog was not London’s first smog episode. Its scale, however, demonstrated that air pollution could have catastrophic health consequences for an entire urban population.

London’s First Legislative Response

The first significant legislative step followed less than two years after the Great Smog. The City of London (Various Powers) Act 1954 received Royal Assent on 5 July 1954, formally becoming law. The part of the Act dealing with pollution reduction prohibited smoke emissions from buildings within the City of London.

The City of London thus became the first local authority in Great Britain to prohibit smoke emissions throughout its entire territory. This was not yet a national air quality control system, but the direction was clear.

The UK Clean Air Act Changes the Approach at National Level

Exactly two years later, on 5 July 1956, the Clean Air Act 1956 received Royal Assent and became law. The UK Parliament describes it as the first Clean Air Act to apply across the United Kingdom and places it directly in the regulatory sequence that followed the Great Smog and the 1954 London legislation.

Among other measures, the Act enabled the establishment of “smoke control areas.”

It regulated dark smoke emissions and introduced measures that encouraged a transition towards fuels and combustion methods with lower emissions. This represented a significant change. Legislation was no longer focused solely on one chemical industry or an individual chimney. Urban air pollution was beginning to be addressed systematically

Smog in New York

Only one year after the Great Smog of London, New York experienced a serious air pollution episode in November 1953. A multi-day temperature inversion and stagnant air allowed pollutants to accumulate. Sulfur dioxide and smoke concentrations reached unusually high levels. A subsequent analysis of health data showed a statistically significant increase in mortality during the period associated with the event.

However, the American path towards air pollution regulation should not be linked to a single event. The catastrophic Donora smog in Pennsylvania in 1948, Los Angeles’ long-standing problems with photochemical smog, the London disaster of 1952, and other pollution episodes gradually demonstrated that the problem exceeded the capacity of individual cities to address it.

SEE ALSO: Smog Threatens Health – Is There a Way Out?

Air Pollution Enters U.S. Federal Legislation

On 14 July 1955, the United States adopted the Air Pollution Control Act of 1955. The U.S. Environmental Protection Agency (EPA) identifies it as the first federal legislation in the United States to address air pollution.

Its scope, however, should not be equated with that of the British Clean Air Act. The U.S. legislation primarily provided funding for research, data collection, the development of pollution reduction methods, and technical assistance to state and local authorities. Primary responsibility for controlling air pollution remained with state and local governments.

The EPA identifies the Clean Air Act of 1963 as the first federal legislation to establish a federal air pollution control program.

How Tokyo Initially Regulated Soot and Smoke

At almost the same time, a similar process was taking place on a third continent. During Japan’s post-war reconstruction, industrial growth brought increasingly serious pollution problems. In 1949, Tokyo became the first city in Japan to adopt the Tokyo Metropolitan Factory Pollution Prevention Ordinance, a local regulation designed to control pollution from industrial facilities. According to Japan’s Ministry of the Environment, the ordinance did not yet include quantitative standards.

By the mid-1950s, air pollution had become particularly severe.

Japan’s Ministry of the Environment states that smog caused by soot and the combustion of heating fuels frequently covered urban areas. In response, Tokyo adopted the Tokyo Metropolitan Soot Prevention Ordinance in 1955.

The ordinance introduced smoke-density control based on the Ringelmann scale. Stricter criteria applied in residential areas than in other parts of the city.

What Is the Ringelmann Scale?

The Ringelmann scale is one of the oldest methods for visually assessing the density of black smoke. An observer compares the appearance of smoke with standardized shades of grey and black. The shades are represented on a numerical scale, with higher numbers indicating darker and optically denser smoke.

The scale did not measure particle concentrations in the modern sense. However, it made it possible to replace the subjective observation of “a lot of smoke” with a more standardized criterion that could be used for regulation and enforcement.

From a Local Ordinance to Japan’s First National Law

The Tokyo ordinance was not a national law. Japan did not introduce its first national legislation controlling smoke and soot emissions until 1962. Nevertheless, the 1955 ordinance is important because it illustrates another characteristic of the development of modern air pollution regulation: the transition from a general prohibition of excessive smoke to a criterion against which emissions could be assessed.

What Connects London, New York, and Tokyo?

British, American, and Japanese regulations did not have the same legal status, scope, or regulatory mechanisms. It would therefore be inaccurate to present them as three parallel national laws adopted in three countries on three continents.

What connects them is something else. Within a very short period, it became clear on three continents that urban air pollution was more than a local smoke problem and required an organized regulatory response. It was no longer simply a matter of visible smoke, unpleasant odors, or dirty building façades. It had become a public health issue.

At the same time, elements that would later become integral parts of modern air pollution regulation began to emerge: research into health effects; monitoring; definition of permitted emission levels; controlled zones; inspections; standardized assessment methods; increasing involvement of government authorities.

For this reason, the period from 1952 to 1956 did not mark the beginning of air pollution regulation, but it represented an important turning point in the development of its modern form.

From Visible Smoke to Measurable Air Quality

Since the 1950s, both the sources of air pollution and the way we measure it have changed.

Black smoke and soot are no longer the only indicators of the problems associated with polluted air.

Modern air pollution regulation addresses both emissions from pollution sources and permissible concentrations of pollutants in ambient air. Today, authorities monitor concentrations of PM₂.₅ and PM₁₀, nitrogen dioxide, sulfur dioxide, ozone, and other pollutants. Regulations define limit and target values, measurement methods, monitoring locations, reporting obligations, and measures to be taken when air quality deteriorates.

This development continues today.

SEE ALSO: New EU Air Quality Regulations

Protecting Health as a Driver of Air Pollution Regulation

The emergence of modern outdoor air quality regulation was closely linked to the recognition of the harmful effects of air pollution on human health. Major smog episodes demonstrated how serious the consequences of exposure to high concentrations of pollutants could be.

Today, increasing attention is also being given to indoor air quality, where people spend around 90% of their time on average. The COVID-19 pandemic further highlighted the importance of ventilation in indoor spaces. However, indoor air quality involves a much broader range of pollutants and sources.

Marquis Intelligence and Air Quality Today

Today, it is no longer enough to conclude that air is clean simply because we cannot see smoke or detect an unpleasant odor. Many pollutants that affect health are invisible to the human eye. At the same time, indoor air quality depends both on outdoor air and on pollution sources within the building itself.

For this reason, when addressing indoor air quality problems, Marquis Intelligence follows the principle that the problem must first be identified. It must then be measured and confirmed, after which an appropriate technical solution can be selected. Once the solution has been implemented, the achieved results should be verified.

Depending on the problem and the building, the solution may include: ventilation; filtration; air purification; system control; air quality monitoring.

Technologies have changed significantly since the days when smoke density was assessed by comparing it with shades of grey on the Ringelmann scale. The fundamental principle, however, remains very similar: what we want to control must first be identified and measured, and the results of the implemented solution must then be verified.

This Marquis Intelligence article is part of the professional series “News from the World of Ventilation and Clean Air Standards.”
Document No.: MI-NewLegislation-008.26 – Modern Air Pollution Regulation and Smog

The post Modern Air Pollution Regulation and Smog appeared first on Marquis Intelligence.

However, bipolar air ionization is a technology, not magic. Several prerequisites must be met to achieve effective air treatment.

Prerequisites for Effective Bipolar Air Ionization in a Central Ventilation System

Bipolar air ionization can provide many benefits as part of a central ventilation system, provided that:

• the bipolar ionization system is properly designed and coordinated with the central ventilation system;
• the bipolar ionization equipment, as well as the other components of the central ventilation system, is functional and of good quality;
• the systems are properly configured, operate together as intended, and receive appropriate maintenance.

When these prerequisites are met, bipolar air ionization becomes an integral part of the system for controlled air treatment and distribution throughout the home.

Benefits of Bipolar Air Ionization in a Central Home Ventilation System

What are the main benefits of bipolar air ionization when it forms part of a properly designed central ventilation system?

1. Provides Additional Treatment of Fresh Air After Filtration

Outdoor air today is generally not clean. According to the World Health Organization, 99% of the world’s population lives in areas where air pollution levels exceed WHO guideline limits.
It is therefore particularly important to clean outdoor air in a central ventilation system before introducing it into the home. As a rule, the air first passes through filters that remove particulate pollutants.

Bipolar air ionization provides an additional level of air treatment after filtration. Positive and negative ions are introduced into the already filtered airflow before the system distributes it throughout the home.
As a result, the rooms receive not only filtered outdoor air but also air that has undergone additional bipolar ionization treatment.

2. Acts on Both Outdoor Pollution and Pollution Generated Inside the Home

This is one of the particularly important benefits of bipolar air ionization in a central ventilation system.

Outdoor air is often polluted, but pollution sources also exist inside our homes. According to the U.S. Environmental Protection Agency (EPA), concentrations of some pollutants indoors are often two to five times higher than typical outdoor concentrations.

At the same time, we spend about 90% of our time indoors. The Healthy Buildings Program at the Harvard T.H. Chan School of Public Health states that we spend around 65% of our lives in our homes.

This makes one feature of bipolar air ionization in a central ventilation system particularly important: its effect is not limited to the outdoor air passing through the system.

Cooking, cleaning, people, pets, furniture, finishing materials, and products we use every day can generate particles, odors, volatile organic compounds, and microbiological contaminants.
The system distributes positive and negative ions throughout the rooms together with the treated air. They can therefore also act on pollutants generated inside the home.

3. Reduces the Number of the Smallest Airborne Particles

One important application of bipolar air ionization is the reduction of very small particles.

Ions charge airborne particles and can promote their agglomeration. This creates larger particle structures that can be removed from the air more easily.

This effect is particularly important for ultra-fine particles, which have a diameter of up to 0.1 µm. Because of their small size, these particles can penetrate deep into the lungs. Some may also enter the bloodstream. Exposure to ultra-fine particles is associated with an increased risk of respiratory and cardiovascular diseases.

SEE ALSO: 11 Questions and Answers: How Do PM2.5 Particles Affect Health?

4. Can Improve Particle Filtration Efficiency

Bipolar air ionization and filtration are not two completely separate processes. In a properly designed system, they can complement each other.

Charging particles and promoting their agglomeration changes the way they behave in the air. When these ionized particles subsequently pass through a filter, the filter may capture them more effectively.

The effect depends on the system configuration, the position of the ionizer, and air circulation. Any potential improvement in filtration efficiency must therefore be evaluated as part of the complete system, rather than as an isolated characteristic of the ionizer.

5. Helps Reduce Unpleasant Odors

Unpleasant odors in the home often result from emissions of various gaseous compounds. Cooking, cleaning, and other everyday activities can generate these compounds.

Bipolar air ionization can act on certain compounds responsible for unpleasant odors, and help reduce them.

Because the system distributes the ions together with the air, their effect is not limited to the location where the ionizer is installed.

6. Can Reduce Concentrations of Volatile Organic Compounds – VOCs

Volatile organic compounds (VOCs) can originate from emissions from furniture, building and finishing materials, cleaning products, cosmetics, and other products used indoors.

Bipolar air ionization can help reduce the concentrations of certain VOCs in the air.

The effect depends on the type of compound, the technology used, the ion concentration, the contact time, and indoor conditions. For this reason, test results for a specific device should always be considered in the context of the technology and the system in which it is used.

7. Helps Reduce Airborne Allergens

Airborne allergens can enter from outdoors, but many sources also exist inside the home. Pollen, mold spores, and allergens associated with dust mites and pets are just some examples.

Many allergens travel through the air as particles of different sizes. By charging these particles and promoting their agglomeration with other particles, bipolar air ionization can help remove them from the air more effectively.

In a central ventilation system, there is an additional benefit: the system treats both the air entering from outdoors and the air containing allergens released or resuspended inside the home.

8. Acts on Microbiological Contaminants

Bipolar air ionization can act on certain microorganisms present in the air and on surfaces that come into contact with treated air. The effect depends on the type of microorganism, the technology used, the ion concentration, and exposure time.

It is therefore important to use proven equipment with documented test results and to apply it correctly within the specific system.

9. Helps Maintain the Microbiological Hygiene of the Air Distribution System

This is another specific benefit of bipolar air ionization in a central ventilation system.

The ions travel with the air through the distribution network before reaching the rooms. The treated air therefore also comes into contact with the internal surfaces of ventilation ducts and other air distribution components.

In this way, bipolar air ionization can help maintain the microbiological hygiene of the air distribution system.

Does Bipolar Air Ionization Replace Filtration?

No. Bipolar air ionization and filtration perform different functions in air treatment.

A filter captures particles from the air that pass through it. Bipolar air ionization provides additional air treatment. The ions then continue to travel with the air through the distribution network and into the rooms.

This is precisely why bipolar air ionization can also act on pollutants generated after filtration, within the air distribution system, and inside the home.

SEE ALSO: Heat Recovery Ventilation: 8 Benefits for Your Home

Is Every Bipolar Air Ionization Technology the Same?

No. Technologies differ in the way they generate ions, device design, the quantity and ratio of positive and negative ions produced, their effective range, and potential by-products. As a result, individual devices can achieve different effects in real systems.

The experience and expertise of the equipment manufacturer are therefore important. So are the knowledge and experience of the designers and installers who apply the technology. Regular maintenance of both the system and the equipment is essential for efficient and long-lasting operation.

SEE ALSO: FAQ – Marquis Intelligence: Bipolar Air Ionization

What Do Measurements Show in a Home with Central Ventilation and Bipolar Air Ionization?

The declared performance of individual devices provides a starting point. However, what matters more to the user is how the complete system performs after installation.

In an apartment of approximately 200 m² in Belgrade, Marquis Intelligence designed and implemented a central ventilation system with heat recovery, additional filtration, bipolar air ionization, and humidification.

The ionizer was installed immediately upstream of the air distribution manifold. This allows the system to distribute ionized air through the duct network and into the rooms.

After approximately 24 hours of continuous system operation with the windows closed, an independent scientific institute carried out instrumental air quality measurements. The measurements showed fewer than 50 particles/cm³ in the 0.3 to 10 µm range. Ozone, SO₂, and NO₂ were not detected during the measurements.

SEE ALSO: Mini Case Study: Verifying the Performance of a Central Ventilation System in an Apartment

This example shows why we should not assess performance based only on the characteristics of an individual device. In a real system, ventilation, filtration, bipolar air ionization, air distribution, and proper system configuration work together.

Experience Matters When Designing an Effective Solution

Marquis Intelligence has used bipolar air ionization as part of indoor air quality improvement systems for more than two decades. Their experience covers different bipolar ionization technologies. In some projects, they combine both main technologies within the same building. This approach can also be used in home ventilation systems.

Marquis Intelligence also has extensive experience with these systems in commercial, public, hospitality, and healthcare buildings.

For this reason, selecting a solution should not begin with the question: Which bipolar ionizer should we install? The first step is to define what we want to achieve in the specific space and identify its limitations.

Only then can we select the appropriate technology, device, installation location, and operating method.

When designed in this way, bipolar air ionization in a central ventilation system is more than an additional device. It becomes part of an engineered indoor air quality solution for the home or another type of building.

SEE ALSO: Residential Ventilation by Marquis Intelligence

This article is part of the Marquis Intelligence professional series “Home Ventilation.”
Document No. and Title: MI-HV-009.26 – 9 Benefits of Bipolar Air Ionization in a Central Home Ventilation System

The post 9 Benefits of Bipolar Air Ionization in a Central Home Ventilation System appeared first on Marquis Intelligence.

The number 100 is often associated with completeness, achievement, and a milestone that is easy to remember. However, the true value of this anniversary lies in the knowledge preserved through these published articles.

Why Is Air the Only Topic of the Marquis Intelligence Blog?

Because air is the company’s core field of expertise.

Marquis Intelligence designs and implements ventilation and air purification systems. We develop solutions for commercial kitchen ventilation and exhaust air purification. We integrate technologies that improve indoor air quality and maintain the systems we install.

That is why air is not an abstract subject on this Blog. It is something we design for, distribute, purify, extract, control, and manage through regular maintenance.

This technical foundation has also led to articles about health, the environment, history, standards, and the broader social importance of clean air. These topics explain why air quality and the proper operation of technical systems matter.

Do the Articles Need to Be Engaging and Easy to Understand?

Of course. Technical accuracy is not enough if only a narrow group of specialists can understand the content.

Our articles combine technical explanations with real-world stories, historical events, readers’ questions, and everyday situations. Case studies present the problem, site conditions, engineering approach, and implemented solution. Articles on scientific topics present research findings in language that remains precise while still being easy to read.

Making technical content understandable does not mean simplifying it to the point of inaccuracy. It means allowing designers, investors, facility managers, and building occupants to understand why a particular technical decision matters.

Everyone breathes air. Everyone should therefore understand how its quality can affect health, comfort, and quality of life.

Clean air is a right for everyone.

How Are Marquis Intelligence Blog Articles Created?

Marquis Intelligence Blog articles serve as records of our knowledge about air. We create them by combining different sources of knowledge and practical experience.

Some content comes from scientific papers, professional publications, international standards, regulations, and educational webinars. Other content comes directly from our work: engineering design, technical implementation, system commissioning, and equipment maintenance.

Depending on the topic, we also use measurement results, project documentation, service reports, and the experiences of building occupants.

Each article offers new knowledge, a different perspective, or practical experience. In this way, it helps readers understand the subject more clearly.

A great deal of engineering knowledge would otherwise remain hidden in technical calculations, quotations, project files, and system performance reports. The Blog allows us to preserve that experience and share it beyond a single project, building, or group of people involved in its implementation.

SEE ALSO: Grande Case Study: Electrostatic Precipitator at Dijamant, Zrenjanin

Lessons from 100 Blog Posts

One hundred articles do not necessarily mean one hundred completely separate conclusions. Air is the golden thread that connects them all. However, several lessons recur across different topics, buildings, and periods:

• Air cannot be considered separately from the space.
  Its quality depends on the purpose of the building, the number of occupants, pollution sources, the type of ventilation, and how the space is used.
• Ventilation and air purification are not the same.
  Ventilation provides controlled air exchange, while air purification targets specific pollutants. Many buildings need both.
• No single technology is best for every problem.
  The value of a technical solution depends on selecting the right technology, designing and positioning it correctly, installing it properly, and verifying the results.
• Responsibility for a system does not end with commissioning.
  Maintenance determines whether the system will continue to deliver its designed performance after years of operation.
• Air quality connects different disciplines.
  Engineering intersects with medicine, energy, architecture, environmental science, safety, and the way people use buildings.
• Knowledge becomes more valuable when we share it.
  Experience from one project can help another investor, designer, or user identify a problem earlier and make a better decision.

These recurring lessons have also helped shape the Marquis Intelligence air knowledge repository. After all, repetition is the mother of learning.

Who Is the Content Intended For?

Different topics naturally appeal to different groups of readers.

Articles about health and history are easy to relate to everyday experience and therefore appeal to a broad audience. Technical analyses and articles about standards and regulations are more directly relevant to designers, engineers, investors, and facility managers.

Case studies often connect these groups.

An example from a hospital may be relevant to ventilation designers as well as healthcare professionals.

An article about indoor air quality in a space where smoking is permitted may interest engineers, hospitality business owners, employees, and guests.

A story about commercial kitchen ventilation raises several issues at once: fire safety, odors, energy losses, working conditions, and the building’s impact on its surroundings.

The audience of the Marquis Intelligence Blog therefore cannot be limited to a single profession or field of interest. It connects professionals who work with air with the people who breathe it every day.

Some Marquis Intelligence articles also leave a strong personal impression on readers. After we published an article about the Great Smog of London, we heard from a man who had personally experienced the event. More recently, our article about Gordana Blagić, Technical Director and co-owner of Marquis Intelligence, inspired one of our LinkedIn followers to write a poem for her.

These reactions show that topics related to air can sometimes go beyond their technical context and become part of a personal memory, experience, or emotion.

SEE ALSO: Twenty Years of Gordana Blagić at Marquis Commerce

When a Blog Becomes a Knowledge Platform

After 100 published articles, the Marquis Intelligence Blog has long since grown beyond the boundaries of a conventional company blog.

Unlike a product catalogue, it does not simply describe what a particular piece of equipment can do. It explains when a technology makes sense, what its limitations are, and how its performance can be verified in a real building.

Unlike a purely theoretical platform, the Blog draws directly on practical experience from engineering design, project implementation, system commissioning, and maintenance.

The articles are written by team members who take part in these processes. Their different perspectives allow us to explore air from engineering, health, historical, regulatory, environmental, and business perspectives.

In this way, the Blog has become an air knowledge platform. It is understandable to people and organized clearly enough for modern search systems to recognize and interpret its content.

SEE ALSO: FAQ – Marquis Intelligence Blog

How Is the Marquis Intelligence Air Knowledge Repository Organized?

According to company records, the published articles are organized into eight specialist series, while 17 articles currently stand alone. Since the archive contains exactly 100 blog posts, the number of articles in each group also represents its percentage of the total content.

• Marquis Intelligence – Business and Development: 24 articles
• Air Pollution and Health: 14 articles
• Learn More About Air Through History and People: 13 articles
• Mini Case Studies: 9 articles
• Home Ventilation: 8 articles
• News from the World of Ventilation and Clean Air Standards: 7 articles
• Air Quality, Environment and Sustainability: 7 articles
• Commercial Kitchen Ventilation and Exhaust Air Purification: 1 article
• Other articles not currently included in a series: 17 articles

This classification shows the primary series for each article, but it does not create rigid boundaries between topics. The articles overlap and connect through internal links, forming a unified system of knowledge.

How Do the Different Series Interconnect?

An article from the business series may also document technology development, project implementation, and system maintenance. A historical article may connect medicine, ventilation, and infection control.

A health-related topic may raise questions about air quality in a home, school, hospital, or workplace.

The Commercial Kitchen Ventilation and Exhaust Air Purification series has only recently been formally introduced. However, the same field of expertise already appears in case studies, project stories, and articles about exhaust systems.

Standalone articles are no less important. Some address specific topics, while others may form the starting point for future content clusters. A new series only makes sense when there are enough related articles to develop a particular subject systematically.

When Knowledge Becomes Recognizable

Some articles on the Marquis Intelligence Blog rank among prominent Google search results, while others also appear in AI Overviews.

This visibility did not come from a single article or a single keyword. We built it through consistency, technical depth, authentic experience, and strong connections between related content.

For the search query “Blog as an air knowledge repository,” Google AI Overview associated the phrase with the Marquis Intelligence Blog. It particularly recognized the Blog’s educational, health, environmental, and historical dimensions.

These are important parts of the content, but engineering remains its foundation.

Google Search Console data for generative AI features provides further evidence of this visibility. During the 28 days preceding the preparation of this article, our blog post “The Great Smog of London 1952” appeared more than 5,000 times in results associated with generative artificial intelligence.

SEE ALSO: The Great Smog of London (1952): Lessons from the Past

The design and maintenance of ventilation systems, air purification, commercial kitchen ventilation, and exhaust air treatment form the technical core from which the other topics have developed.

Visibility is therefore not a goal in itself. It is a result of recording, organizing, and making knowledge available in a clear and accessible way.

The phrase “air knowledge repository” was not chosen simply because it makes an appealing title. It describes content that connects different disciplines while keeping each of them clearly linked to air.

The 100th Blog Post as the Beginning of a New Cycle

The 100th blog post is not the end. It marks the point from which the Marquis Intelligence air knowledge repository will continue to grow.

The next cycle will bring new technical questions, case studies, and thematic areas. Another challenge will be to improve the platform’s architecture and organization. The goal is to make the content easier to search, more clearly interconnected, and simpler to use.

However, the fundamental principle remains the same: Knowledge should be preserved, connected, and made understandable.

Air is invisible.

Knowledge about it should not be.

This 100th blog post was published exactly on the fourth anniversary of the Marquis Intelligence Blog.

This article is part of a series of publications presenting the work and business results of Marquis Intelligence.
Document No.: MI-PROM-26.023 – The Blog as an Air Knowledge Repository

The post The Blog as an Air Knowledge Repository appeared first on Marquis Intelligence.

Large population studies show a link between long-term exposure to polluted air and a higher incidence of dementia. This does not mean that every exposed person will develop dementia. However, the increased risk is clear.

Dementia and Alzheimer’s Disease

Dementia is a general term for a group of symptoms. These include declining memory, thinking, reasoning, and the ability to perform everyday activities.
A person may have changes associated with more than one type of dementia.

Alzheimer’s disease is the most common cause of dementia. It accounts for approximately 60–70% of all dementia cases.

Vascular dementia results from blood vessel damage and impaired blood supply to the brain.

What Do the Latest Studies Show About Air Pollution and Dementia?

A systematic review and meta-analysis published in The Lancet Planetary Health in 2025 included 51 studies and data from more than 29 million people.

The studies examined whether long-term exposure to air pollution increases the risk of dementia. They defined long-term exposure as a period of at least one year.

Which Air Pollutants May Increase the Risk of Dementia?

Researchers found a statistically significant association between dementia and three indicators of air pollution:

• PM2.5: Every additional 5 µg/m³ in average long-term exposure was associated with an approximately 8% higher relative risk of dementia.
• Nitrogen dioxide (NO₂): Every additional 10 µg/m³ was associated with an approximately 3% higher relative risk.
• Soot, or black carbon: Every additional 1 µg/m³ was associated with an approximately 13% higher relative risk.

These percentages refer to changes in relative risk, not absolute risk.

A person’s actual absolute risk depends on age, genetics, cardiovascular health, lifestyle, and other factors.

Exposure to PM2.5

PM2.5 refers to suspended particulate matter with an aerodynamic diameter of up to 2.5 micrometres. This fraction includes particles with different actual sizes, shapes, densities, chemical compositions, and origins.

A US cohort study published in JAMA Internal Medicine in 2023 followed 27,857 people over the age of 50 for an average of 10.2 years. Researchers found the most consistent association with new cases of dementia for PM2.5 from agriculture and wildfires. The study examined long-term exposure. It does not show that a single wildfire increases the risk of dementia.

SEE ALSO: 11 Questions and Answers: How Do PM2.5 Particles Affect Health?

PM2.5 and the Risk of Alzheimer’s Disease

A large US cohort study published in PLOS Medicine in 2026 included 27.8 million Medicare beneficiaries aged 65 and older. An increase of 3.8 µg/m³ in five-year average PM2.5 exposure was associated with an approximately 8.5% higher relative risk of a new Alzheimer’s disease diagnosis. The association was slightly stronger in people who had previously suffered a stroke.

How Can Air Pollution Increase the Risk of Dementia?

Scientists are still studying the mechanisms that could explain why air pollution increases the risk of dementia. Evidence points to several interconnected processes.

Systemic Inflammation

Particles that penetrate deep into the lungs can trigger inflammatory responses.Inflammatory signals can then affect blood vessels and the brain.

Oxidative Stress

Air pollutants can impair the body’s ability to neutralize reactive molecules. This can damage cell membranes, proteins, and DNA.

Blood Vessel Damage

Air pollution is associated with hypertension, atherosclerosis, heart disease, and stroke. These conditions can contribute to vascular brain damage and dementia.

Possible Direct Pathways to the Brain

Ultrafine particles and some components of air pollution can enter the bloodstream.

Air pollution most likely affects the body through several pathways at the same time. It can act through the lungs, blood vessels, and immune system. Under certain conditions, it may also directly affect nervous tissue.

SEE ALSO: PM2.5 Particles Affect the Heart and Cardiovascular System
SEE ALSO: Air Pollution Affects Our Brain

Can Cleaner Air Help Reduce the Risk of Dementia?

In July 2026, the World Health Organization (WHO) published the second edition of its guidelines for reducing the risk of cognitive decline and dementia. For the first time, WHO included specific recommendations for reducing exposure to air pollution.

One recommendation addresses household air pollution. The other addresses ambient air pollution, particularly PM2.5.

A US study of 2,239 women aged 74 to 92 also points to the potential benefits of cleaner air. None of the participants had dementia at the beginning of the study. Over the preceding decade, a reduction in PM2.5 of 1.78 µg/m³ or in nitrogen dioxide of 3.91 ppb was associated with an approximately 20% lower relative risk of dementia. The median follow-up period was 6.1 years.

The study was observational. It therefore does not prove that improved air quality alone caused the lower risk. However, it shows that cleaner air may also be important later in life.

We Can Influence Our Own Exposure

Individuals have limited influence over outdoor air quality. However, we can reduce our exposure to some extent. We can monitor air quality and avoid spending time outdoors during periods of high pollution. But also, we can avoid strenuous outdoor exercise during these periods and choose routes away from busy roads.

We have much more control over the air quality in our own homes. Our decisions largely determine the quality of the air we provide for ourselves and other members of our household.

According to the Harvard University Healthy Buildings Program, we spend an average of 65% of our lives at home. Indoor air quality is therefore an important part of our total exposure. It is also something we can directly influence.

General Recommendations

The first step is to reduce the air pollution generated indoors.

Recommendations include:

• avoid cooking over an open flame whenever possible;
• limit the use of candles, incense, and other combustion sources;
• effectively extract pollutants generated during cooking;
• choose materials and products with lower pollutant emissions;
• do not smoke indoors;
• maintain good household hygiene;
• provide adequate ventilation;
• monitor PM2.5 and carbon dioxide (CO₂) concentrations;
• regularly maintain ventilation systems and replace filters.

A Local Air Purifier Is Not a Substitute for Ventilation

Local air purifiers can effectively reduce PM2.5 concentrations in a room if they have an appropriate filter and sufficient capacity. However, they do not supply fresh air. They therefore cannot reduce the carbon dioxide produced by occupants.

Air purifiers with standard particulate filters also do not remove gaseous pollutants such as nitrogen oxides (NOx) and sulfur oxides (SOx). Reducing these pollutants requires appropriate molecular filtration.

NOx and SOx can enter a building with outdoor air. Indoor combustion can also generate these pollutants.

Central Ventilation Systems Offer More Options

Compared with decentralized solutions, a central ventilation system usually offers more options for treating the air supplied to a building. More available space and higher available fan pressure allow the use of several filtration stages. These may include prefilters, fine particle filters, and molecular filters for specific gaseous pollutants.

The system treats the air before distributing it to individual rooms. At the same time, it can provide a controlled supply of fresh air, extract stale air, recover heat, and distribute air more evenly throughout the home.

Decentralized ventilation systems can be a good solution when there is no space for ductwork. However, limited space inside the unit and a smaller available filter area usually restrict the possibilities for multi-stage air treatment.

SEE ALSO: Mini Case Study: Verifying the Performance of a Central Ventilation System in an Apartment

Is a Central Ventilation System a Guaranteed Solution?

A central ventilation system does not provide these benefits automatically. Its performance depends on correct calculations, proper filter selection, available fan pressure, system airtightness, airflow balancing, and regular maintenance.

For this reason, the selection process should not start with the question: Which unit should I buy? Marquis Intelligence first analyzes the sources of pollution, outdoor air quality, how occupants use the space, and the existing technical conditions. Based on this analysis, we determine the required ventilation, particulate and molecular filtration, additional air treatment technologies, control strategy, and maintenance requirements.

The goal is not simply to purify air that is already inside the room. We need to provide enough fresh air and properly treat the air that we introduce into the home in a controlled way.

Clean Air Is a Good Foundation for a Healthier Life

Many factors contribute to dementia. Evidence shows that air pollution increases the risk of dementia. We cannot change our age or genetics. However, we can reduce our exposure to polluted air.

This does not mean that an air purifier, filter, or ventilation system can prevent dementia. Their role is to reduce our exposure to air pollutants and provide healthier conditions in the place where we spend most of our lives – our home.

References

1. World Health Organization. Dementia. Updated 3 July 2026. WHO.
2. Best Rogowski CB, Bredell C, Shi Y, et al. Long-term air pollution exposure and incident dementia: a systematic review and meta-analysis. The Lancet Planetary Health. 2025. DOI: 10.1016/S2542-5196(25)00118-4
3. Zhang B, Weuve J, Langa KM, et al. Comparison of Particulate Air Pollution From Different Emission Sources and Incident Dementia in the US. JAMA Internal Medicine. 2023;183(10):1080–1089. DOI: 10.1001/jamainternmed.2023.3300
4. Deng Y, Liu Y, Hao H, et al. The role of comorbidities in the associations between air pollution and Alzheimer’s disease: A national cohort study in the American Medicare population. PLOS Medicine. 2026;23(2):e1004912. DOI:10.1371/journal.pmed.1004912
5. World Health Organization. Risk reduction of cognitive decline and dementia: WHO guidelines, second edition. 2026. WHO
6. Wang X, Younan D, Millstein J, et al. Association of improved air quality with lower dementia risk in older women. Proceedings of the National Academy of Sciences. 2022;119(2):e2107833119. DOI: 10.1073/pnas.2107833119

This article is part of the “Air Pollution and Health” series, in which Marquis Intelligence, as a socially responsible company, highlights the adverse effects of air pollution on human health.

Document: MC-AP&H-015.26 – Does Air Pollution Increase the Risk of Dementia?

The post Does Air Pollution Increase the Risk of Dementia? appeared first on Marquis Intelligence.

Its foundations were laid much earlier, at a time when microorganisms were not yet fully understood and air could not be analyzed using modern instruments. Yet, in the story of the development of air hygiene, two days in August symbolically connect three pioneers of this field.

Two Days in August That Changed the History of Medicine

The history of medicine is filled with remarkable discoveries. It is rare, however, for just two days on the calendar to connect three individuals whose work would fundamentally change the way we think about health, hospital hygiene, and the environments in which patients are treated.

In the history of medicine, 12 and 13 August symbolically unite three people who probably never considered themselves part of the same story and whose lives never crossed.

Each of them addressed a different problem. One focused on the hospital environment. Another studied the transmission of disease. The third transformed surgical practice. Today, we know that each of them, in his or her own way, contributed to the understanding of what we now call air hygiene.

Air Hygiene and the Beginning of Antiseptic Surgery

On 12 August 1865, the Scottish surgeon Joseph Lister performed an operation on an eleven-year-old boy using an antiseptic technique. The boy had suffered a severe compound fracture of his leg. At that time, injuries of this kind almost invariably resulted in amputation or death from infection.

Lister’s antiseptic procedure proved successful. The boy recovered, and this event marked the beginning of a new era in surgery. It was a turning point that would soon confirm that the observations of Ignaz Semmelweis had been far ahead of their time.

Lister subsequently extended his antiseptic approach to wounds, surgical instruments, the operating field, and even the air within the operating theatre. The spraying of carbolic acid represented the first documented attempt at chemical air disinfection in the history of medicine.

A Profound Historical Injustice

Only one day later, on 13 August 1865, Ignaz Semmelweis died.

The man who had spent years trying to convince his colleagues that simple hand hygiene could save thousands of lives did not live to see medical practice confirm the fundamental principle for which he had fought. The irony of history was even greater: he died of a systemic infection – the very condition against which he had devoted most of his professional life.

Exactly forty-five years later, on 13 August 1910, Florence Nightingale also passed away.

Thus, just two dates on the calendar symbolically connect three pioneers whose ideas continue to shape the way we think about hygiene, infection prevention, and the quality of the hospital environment.

Three Different Paths Toward the Same Goal

At first glance, Joseph Lister, Ignaz Semmelweis, and Florence Nightingale worked in completely different fields.

Their methods differed, as did the problems they sought to solve. Even their conclusions were reached under entirely different circumstances. Yet all three were trying to answer the same question: What can we change in the patient’s environment to save more lives?

Today, this question seems perfectly natural. In the mid-nineteenth century, it was revolutionary.

1. Joseph Lister – When Theory Became Practice

Unlike Florence Nightingale and Ignaz Semmelweis, Joseph Lister was not primarily known for statistical analyses. His greatest contribution was transforming emerging scientific knowledge into practical medicine.

Inspired by Louis Pasteur’s work on microorganisms, Lister concluded that infection was not an inevitable consequence of surgery. If microorganisms could be prevented from entering a wound, infection could also be prevented.

He began using carbolic acid to antiseptically treat wounds, surgical instruments, and the operating field. Later, he even attempted to disinfect the air by spraying carbolic acid throughout the operating theatre.

From today’s perspective, it is clear that this was not the ultimate solution. Nevertheless, it represented the first serious effort to regard the air in a healthcare environment as a factor capable of influencing clinical outcomes.

Lister did more than embrace a new scientific concept. He demonstrated that it could be successfully applied in everyday medical practice.

SEE ALSO: Lord Lister and the First Chemical Air Disinfection

2. Ignaz Semmelweis – When the Numbers Spoke

While Florence Nightingale was studying the hospital environment, Ignaz Semmelweis was trying to understand why maternal mortality was dramatically higher in one maternity ward than in another.

He did not begin with a theory but with careful observation and analysis of numerical data. He compared outcomes, searched for differences, and rejected assumptions that were inconsistent with the evidence. After introducing mandatory hand disinfection, maternal mortality declined dramatically.

Today, hand washing seems self-evident. However, in the middle of the nineteenth century, it represented one of the greatest revolutions in the history of medicine.

Semmelweis had no access to modern microbiology. He could not measure aerosols. He knew nothing about PM₂.₅, VOCs, or HEPA filtration. Yet he understood something far more fundamental. He reached a conclusion that would permanently change medical practice: The chain of disease transmission can be broken.

That principle remains just as important today.

SEE ALSO: Ignaz Semmelweis: The Savior of Mothers and Newborns

3. Florence Nightingale – When the Hospital Became Part of the Treatment

Florence Nightingale did not view the hospital merely as a place where patients were treated. She regarded it as an integral part of the healing process itself.

During the Crimean War, she encountered overcrowded hospital wards, inadequate ventilation, poor sanitary conditions, insufficient natural light, and inefficient organization of care. Rather than accepting these conditions as inevitable, she began to observe, record, and compare the outcomes.

She did not believe assumptions. She believed data. Her statistical analyses demonstrated that improvements in sanitary conditions – including better ventilation and access to fresh air – were accompanied by a significant reduction in mortality.

At a time when the role of microorganisms was only beginning to be understood, Florence Nightingale demonstrated that the environment surrounding the patient could have a decisive influence on treatment outcomes.

SEE ALSO: Florence Nightingale’s Lamp Brings a Glimmer of Hope

What Truly Connected These Three Pioneers?

Their contributions to hygiene and the hospital environment took different forms:

•   Lister transformed surgical practice.
•   Semmelweis interrupted the transmission of infection through hand hygiene.
•   Nightingale transformed the entire hospital environment.

What united them was their way of thinking. They noticed what others overlooked, measured outcomes, and trusted evidence more than established beliefs. Then, based on those findings, they changed medical practice.

This is precisely how modern air hygiene solutions are developed today.

The process does not begin with the assumption that a particular technology is the best. It begins with the problem itself – with understanding the sources of contamination, the potential routes of transmission, and the desired outcome. Only then is the appropriate solution selected.

Air Hygiene Today

Since the time of these pioneers, medicine has made extraordinary progress. International cleanroom standards have been established. Ventilation systems have become increasingly sophisticated. High-efficiency filtration, indoor air quality monitoring, and numerous technologies for further improving air quality have been developed.

Today, air hygiene is no longer limited to reducing the presence of microorganisms.

It encompasses the control of airborne particles, chemical pollutants, and unpleasant odors; the provision of appropriate ventilation and airflow patterns; and the prevention of unwanted pathways of contamination between different areas.

The COVID-19 pandemic served as a historic reminder that air is more than simply the medium in which we exist. Under certain conditions, it can also become an important route for the transmission of infectious aerosols.

At the same time, numerous scientific studies have further highlighted the importance of air quality for overall health, including respiratory diseases, cardiovascular health, mental well-being, reproductive health, and many other aspects of human health.

Examples from Contemporary Practice

Today, these historical lessons have very practical applications.

For more than three decades, Marquis Intelligence has participated in the design and implementation of air quality improvement solutions across a wide range of facilities, including healthcare institutions.

These projects include the Institute for Cardiovascular Diseases of Vojvodina in Sremska Kamenica, the Clinical Centre of Vojvodina in Novi Sad, the Institute of Public Health of Montenegro in Podgorica, as well as numerous other public and private healthcare facilities.

Interestingly, the implementation of one of the advanced air treatment technologies in healthcare facilities began with education.

From Education to Practical Implementation

During a professional presentation organized by Marquis Intelligence on advanced technologies for improving air hygiene, a consulting engineer involved in the design of the Clinical Centre of Vojvodina attended the event.

Interested in the potential application of dielectric barrier discharge (DBD) technology within ventilation systems, he invited the Marquis Intelligence engineering team to deliver an additional presentation at his design office. Shortly thereafter, another presentation was organized for representatives of the healthcare institution itself.

Following the official opinion issued by the competent professional authority, a decision was made to implement this technology within the central ventilation systems of the new hospital building.

The journey from a new idea to its practical application has changed very little over the past century and a half.

Even today, progress depends on professional dialogue, scientific evidence, openness to new knowledge, and the willingness to improve established practice.

SEE ALSO: Mini Case Study: Impeccably Clean Air in a Hospital in Novi Sad

Today, We Continue to Ask the Same Question

Florence Nightingale, Ignaz Semmelweis, and Joseph Lister did not have access to modern instruments. They could not measure PM₂.₅ concentrations or monitor indoor air quality in real time. High-efficiency filtration systems and international cleanroom standards did not yet exist.

Nevertheless, they possessed what remains the foundation of all serious science and engineering:

•   they observed carefully;
•   they asked questions;
•   they monitored the results;
•   they changed practice when evidence demonstrated that a better solution existed.

Perhaps that is precisely why the symbolism of 12 and 13 August remains so powerful.

Within the span of just two days on the calendar, history forever linked three individuals who demonstrated that health depends not only on the medicine we practice, but also on the environments we create.

At Marquis Intelligence, we continue to work according to the same principle.

It is not enough simply to deliver air into a room. We must understand how it behaves, how it moves, and how it affects the people who breathe it.

Perhaps this is the most enduring message shared by Florence Nightingale, Ignaz Semmelweis, and Joseph Lister.

This article is part of the “Learn More About Air Through History and the People Who Shaped It” series from the Marquis Intelligence Archive.Document ID: MI-LAH-013.26 – Air Hygiene: Three Pioneers, Two Days, and One Goal

The post Air Hygiene: Three Pioneers, Two Days, and One Goal appeared first on Marquis Intelligence.

What Is Sustainable Gastronomy: A Philosophy or a Reality?

The term sustainable gastronomy may sound like a modern buzzword. However, its meaning is highly practical.

Simply put, sustainable gastronomy considers food throughout its entire journey: from the origin of ingredients, methods of production, storage, and transportation, to preparation, serving, consumption, and the waste generated after a meal.

This understanding of sustainable gastronomy is also supported internationally. The Food and Agriculture Organization of the United Nations (FAO) describes gastronomy not only as the art of food, but also as local cuisine, regional cooking traditions, and food culture.

Sustainability in gastronomy means that agriculture, fisheries, food preparation, and related processes are carried out without depleting natural resources, ensuring that these activities can continue in the future without harming the environment or human health.

This is precisely where the connection with air quality begins.

Do Gastronomy and Air Quality Really Have Anything in Common?

Food is produced, protected, processed, transported, stored, prepared, served, and consumed. Every one of these stages leaves an environmental footprint through land use, water consumption, energy use, and its impact on air quality.

For this reason, sustainable gastronomy and air quality are not separate topics. Their relationship begins long before food reaches the kitchen and continues in the spaces where it is prepared and consumed.

Agricultural Production and Air Pollution

Have you ever considered that agricultural production contributes to air pollution – not just heavy industry?

Unfortunately, emissions generated by agriculture are far from negligible.

Ammonia Emissions

According to the European Environment Agency (EEA), agriculture is responsible for approximately 93% of ammonia (NH₃) emissions in Europe. The principal sources include livestock farming, animal housing facilities, manure management, manure storage, and the application of both organic and mineral fertilizers.

Ammonia is not merely an agricultural issue. Once released into the atmosphere, it can react with other compounds and contribute to the formation of secondary particulate matter. These particles affect human health, ecosystems, and overall environmental quality.

This is why sustainable gastronomy begins long before food reaches the kitchen. It starts with the way food is produced and with understanding the impact that production has on the air we breathe.

Agricultural Machinery, Crop Protection Products, and Organic Dust

Agriculture is essential, but it is not environmentally neutral. Soil cultivation, agricultural machinery, livestock production, manure storage, crop protection, and harvesting all have implications for air quality.

Agricultural machinery can contribute to pollutant emissions through the combustion of fossil fuels. Harvesting and other outdoor agricultural activities may also release significant quantities of organic dust. Crop protection products, including pesticides and herbicides, raise additional concerns regarding drift, evaporation, human exposure, and impacts on ecosystems.

These issues should not be oversimplified. Production systems vary considerably.

Nevertheless, it is important to understand that every meal has its own production history.

That history also includes air.

Food Transportation, Processing, and Storage

Once food has been produced, its journey continues. It is transported, stored, often refrigerated, processed, packaged, distributed, and sold. Frequently, it undergoes another stage of transportation – to restaurants, hotels, retail stores, homes, or other places where it is prepared and consumed.

Each of these stages contributes to emissions and to the overall environmental footprint of food. Cold-chain logistics, industrial processing, transportation vehicles, packaging, and distribution all represent important components of that footprint.

Local or Imported Food – Which Is More Sustainable?

Not every imported or processed food product is automatically unsustainable. Likewise, not every locally produced food is automatically the best choice for the planet.

Sustainability depends on numerous factors, including production methods, seasonality, transportation distance and mode, energy efficiency, packaging, and the amount of waste generated during production, processing, distribution, preparation, and consumption.

The essential message is straightforward: food does not arrive on our plates without environmental consequences. Its journey affects natural resources, energy consumption, the climate, and air quality.

Food Waste and Greenhouse Gas Emissions

According to the United Nations Environment Programme (UNEP), food loss and food waste account for approximately 8–10% of global greenhouse gas emissions.

This means that food which is produced but never eaten already carries a substantial environmental footprint.

When organic waste ends up in landfills, methane may be generated. Methane is a greenhouse gas with a powerful impact on the climate. Consequently, food waste is not merely an economic or ethical issue – it is also a climate issue.

Every uneaten meal represents wasted land, water, energy, labor, transportation, and emissions. An additional paradox is that enormous quantities of food are discarded worldwide while hunger remains a serious global challenge.

Reducing food waste is therefore one of the most practical ways to make gastronomy more sustainable.

It is equally important not to overlook waste generated by primary and secondary food packaging, as packaging itself carries its own material, energy, and environmental footprint.

Is It More Sustainable to Eat Bacon or Lettuce?

At first glance, the answer appears obvious. Lettuce seems healthier and more sustainable than bacon.

However, comparing foods from a sustainability perspective is not always so straightforward.

One frequently cited study conducted by Carnegie Mellon University found that lettuce may be associated with higher greenhouse gas emissions than bacon when emissions are evaluated per unit of caloric value. The explanation is simple: lettuce has a very low caloric density, meaning that much larger quantities are required to provide the same number of calories.

Nevertheless, this example should not be interpreted as suggesting that bacon is either healthier or more sustainable than lettuce. Rather, it demonstrates that the outcome depends on the comparison criteria. Comparing foods by calorie, kilogram, serving size, nutritional value, or their overall impact on health and the environment can lead to very different conclusions.

This is precisely why sustainable gastronomy requires a comprehensive perspective.

The Kitchen as a Source of Indoor and Outdoor Air Pollution

The kitchen is most often perceived as a place where irresistible flavors and aromas are created. From the perspective of air quality, however, it is an environment characterized by high concentrations of vapors, aerosols, odors, heat, and humidity.

During food preparation, more than 200 chemical compounds may be released into the air. This is particularly evident during grilling, frying, and other high-temperature cooking processes. This is one of the most obvious examples of how gastronomy and air quality are directly connected.

The type and quantity of these compounds depend on the ingredients being prepared, their fat content, cooking temperature, preparation method, cooking duration, the energy source used in the kitchen, and the effectiveness of the ventilation system.

SEE ALSO: 8 Facts Why Kitchen Ventilation Is Crucial for Health

Scientific literature also associates long-term work in professional kitchens with an increased risk of obstructive lung diseases among kitchen staff.

In commercial kitchens, however, the issue does not end indoors. Kitchen exhaust air can also affect the outdoor environment, particularly when it contains odors, grease, aerosols, and by-products generated during the thermal preparation of food.

For this reason, sustainable gastronomy must also address air quality during food preparation.

Ventilation as Part of Sustainable Gastronomy

Ventilation in areas where food is prepared and consumed is not merely a technical issue. In gastronomy – and particularly in the hospitality industry – it forms part of the overall guest experience. Although often unnoticed, it is essential.

If kitchen exhaust air is not properly extracted and purified, it may affect human health, have environmental consequences, and increase the risk of fire.

SEE ALSO: Commercial Kitchen Exhaust Ventilation: From Fire Risk to Safe Operation

Air Quality in Restaurants, Hotels, Apartments, and Homes

In restaurants, hotels, apartments, and homes, sustainable gastronomy does not end with the selection and preparation of ingredients. It also includes the quality of the indoor environment.

Indoor air quality affects comfort, health, and the overall perception of a space. Guests may not be able to explain why they feel comfortable in a particular environment, but they immediately notice when the air feels heavy, stuffy, smoky, or unpleasant.

SEE ALSO: Mini Case Study: Kitchen Exhaust Air Purification at Mövenpick Hotel & Residences Teuta Kotor Bay

Sustainable gastronomy cannot be considered complete if it overlooks the people who prepare, serve, and consume food.

How Does Marquis Intelligence Contribute to Projects in the Gastronomy Sector?

Marquis Intelligence is a company specializing in indoor air quality, ventilation, and air purification. Given the close relationship between gastronomy and air quality, it is clear where and how the company contributes through its engineering solutions.

These projects most commonly include:

• Kitchen exhaust ventilation and purification systems for commercial kitchens, including the staff cafeterias at Microsoft and Nordeus in Belgrade, Mövenpick Teuta Kotor Bay, Mamula Island Hotel, and Maya Bay and ONE restaurants in Montenegro.
• Ventilation and air purification systems for restaurant dining areas, staff cafeterias, and other spaces where food is consumed, including Hilton Belgrade, Franš and Madera restaurants in Belgrade, and The Beaumont Hotel in London.

These solutions contribute to cleaner air, greater comfort, and a higher-quality gastronomic experience.

SEE ALSO: Mini Case Study: Hilton Belgrade Hotel
SEE ALSO: FAQ –  Extraction and Purification Of Exhaust Air  From Kitchen Hoods

The Invisible Ingredient of Every Meal

The average adult inhales approximately 12,000 liters of air each day. This means that during a single hour spent at the table – whether enjoying lunch, dinner, or a memorable culinary experience – a person inhales approximately 500 liters of air.

During that same period, they may drink only one glass of water, wine, or another beverage – approximately 0.2 to 0.3 liters.

This means that while eating, we consume more than just food and beverages. We are continuously breathing the air in the environment around us.

For this reason, indoor air quality should be recognized as an integral part of the gastronomic experience.

Sustainable Gastronomy and Air Quality: An Inseparable Connection

It can be concluded that sustainable gastronomy and air quality are inseparably connected at multiple levels.

At the beginning of the food chain, this relationship is reflected in the impact of food production on air quality. At the end of the chain, it becomes evident in the spaces most closely associated with gastronomy: restaurants, hotels, professional kitchens, as well as apartments and homes where food is prepared and consumed.

It is here, at the final stage of the journey, that air becomes part of the gastronomic experience. It influences the comfort of the environment and the overall enjoyment of a meal.

Unfortunately, this influence is still too often overlooked.

References

1. Food and Agriculture Organization of the United Nations (FAO). “Calling all foodies: this one’s for you!”
2. European Environment Agency (EEA). “Ammonia emissions from agriculture and other sources.” European Zero Pollution Dashboards, 2024.
3. European Environment Agency (EEA). “Air pollution in Europe: 2024 reporting status under the National Emission Reduction Commitments Directive.”
4. United Nations Environment Programme (UNEP). “Food Waste Index Report 2024: Think Eat Save — Tracking Progress to Halve Global Food Waste.” UNEP, 2024.
5. United Nations Framework Convention on Climate Change (UNFCCC). “Food loss and waste account for 8–10% of annual global greenhouse gas emissions.”
6. Recknagel, Sprenger, Schramek. “Taschenbuch für Heizung und Klimatechnik”, section 3.6.11-1.2.
7. World Health Organization (WHO). “WHO global air quality guidelines: particulate matter, ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide.” WHO, 2021.

This article is part of the “Air Quality, Ecology and Sustainability” series by Marquis Intelligence. The series explores sources of air pollution, engineering and technological solutions, and their impact on air quality.

Document ID: MI-AES-007.26 – Sustainable Gastronomy and Air Quality: From Farm to Table

The post Sustainable Gastronomy and Air Quality: From Farm to Table appeared first on Marquis Intelligence.

Scented Candles as Decoration and Gifts

Scented and decorative candles have long ceased to be merely a source of light. Today, they serve as interior design elements, gifts, collectible items, and part of a carefully curated home atmosphere.

People choose them for their color, shape, packaging, fragrance, and brand. They are popular gifts for many occasions. In recent years, scented candles have also found their place in private collections, decorative arrangements, and promotional gift programs offered by many brands.

Why Have Scented Candles Become a Subject of Research?

People use scented candles every day in millions of homes.

Their popularity has drawn the attention of researchers. Studies now examine whether scented candles pollute indoor air. They also assess how much these products may add to people’s overall exposure to indoor pollutants.

Indoor air quality deserves serious attention. We spend a large part of our lives indoors.

The problem starts when people equate fragrance with freshness. A pleasant atmosphere does not automatically mean good air quality.

Smell does not define air quality. The composition of the air we breathe does.

What Is Released from Scented Candles?

A candle can release fragrance compounds even when it is not burning. If you can smell it, substances are already entering the air.

These substances often include volatile organic compounds (VOCs).

Once the candle starts burning, emissions increase.

The flame heats the wax and speeds up the evaporation of fragrance ingredients. Melted wax releases additional aromatic compounds.

The wick and wax also undergo combustion. This process produces heat, light, water vapor, carbon dioxide, fine particles, soot, and various chemical compounds.

Why Is It Important What Candles Release into the Air?

Scientific literature indicates that exposure to certain airborne pollutants may be associated with respiratory problems, nervous system disorders, impacts on reproductive health, and an increased risk of certain diseases.

For some individuals, exposure to intense fragrances may cause headaches, dizziness, nausea, eye irritation, or a feeling of discomfort. Sensitivity to fragrances varies significantly among people, meaning that reactions can be highly individual.

Air pollution is most commonly associated with the respiratory system, but its effects are not limited to the lungs. Fine particles and certain chemical substances may have systemic effects on the human body.

SEE ALSO: Air Pollution and Health

What Did the REHVA Study Reveal About Whether Scented Candles Pollute Indoor Air?

The REHVA Journal, published by the Federation of European Heating, Ventilation and Air Conditioning Associations (REHVA), featured a study conducted by researchers from the Norwegian University of Science and Technology (NTNU).

The objective of the study was to investigate whether scented candles pollute the air in an apartment and to what extent kitchen exhaust ventilation can mitigate this effect.

The experiment involved 12 candles, while concentrations of PM2.5 particles, CO₂, temperature, and other air quality parameters were monitored.

The results showed a significant increase in PM2.5 particle concentrations and carbon dioxide levels during candle burning. In the scenario without the operation of kitchen exhaust ventilation, PM2.5 concentrations reached nearly 50 µg/m³. At the same time, the average CO₂ concentration was approximately 1,700 ppm, considerably above the commonly recommended value of 1,000 ppm and indicative of insufficient air exchange within the space.

SEE ALSO: CO₂ in Your Home – Is It There and Where Does It Actually Come From?

The Impact of Ventilation

The study did not examine apartments equipped with decentralized or centralized ventilation systems. Instead, it analyzed only the impact of kitchen exhaust ventilation.

However, the issue cannot be reduced solely to the individual compounds released during the burning of scented candles. In indoor environments, their contribution to air pollution adds to other pollution sources, including cooking, cleaning products, air fresheners, smoking, fireplaces, and various other sources of contamination.

Although kitchen ventilation systems are not designed with the purpose of improving air quality throughout an entire apartment, the research results showed that they nevertheless reduced concentrations of certain pollutants generated by candle combustion.

SEE ALSO: Residential Ventilation by Marquis Intelligence

What Does the Research Published in Scientific Reports Show?

More recent research published in 2025 in the journal Scientific Reports further confirms that scented candles pollute indoor air. In this study, air samples were collected in residential spaces at three distances from a scented candle: directly next to it, 3 meters away, and 6 meters away from the source.

The results showed that particles do not behave in the same way. Larger PM10 particles had a shorter range and remained closer to the source, i.e., the candle flame. The smaller the particles, the more easily they spread throughout the space. PM2.5 and PM1 particles remained suspended in the air for longer periods and traveled farther from the source.

SEE ALSO: 11 Questions and Answers: How Do PM2.5 Particles Affect Health?

The study also indicated changes in the composition of the airborne microbiome following the use of scented candles. The authors note that additional research is needed but conclude that both the duration and location of candle use should be taken into consideration in order to reduce potential health risks.

What Do Studies Show About Emissions from Scented Candles?

The findings of the REHVA and Scientific Reports studies are not exceptions. Scientific literature indicates that the use of scented candles can generate volatile organic compounds (VOCs), as well as substances such as formaldehyde, benzene, and toluene.

In a study conducted by Derudi and colleagues, emissions of air pollutants from scented candles were analyzed under controlled conditions.

Maupetit and Squinazi investigated emissions of benzene and formaldehyde during the use of scented candles and fragrance sticks in indoor environments.

The amount of emitted substances depends on the type of wax, fragrance composition, wick quality, burning duration, and the level of ventilation within the space.

Are Scented Candles Similar to Air Fresheners?

Although they function in different ways, scented candles and air fresheners share one common characteristic – they introduce additional chemical substances into indoor spaces with the aim of creating a more pleasant smell.

For both categories of products, the same question arises: does a pleasant fragrance truly mean better air quality?

SEE ALSO: Air Fresheners: A Threat to Our Health

Can Residential, Local, and Room Air Purifiers Help?

If scented candles pollute the air, a logical question is whether household air purifiers can remove the resulting pollutants.

Residential air purifiers may help reduce the concentration of certain particles, but they do not eliminate the source of the problem. They do not prevent pollutants from being generated, they do not address increased CO₂ concentrations, and they cannot reliably remove all gaseous compounds that may be produced during the use of scented candles.

It is important to note that the studies mentioned in this article did not include apartments equipped with centralized ventilation systems and controlled fresh-air supply. Therefore, additional research is needed to better understand the impact of different ventilation systems on pollutant concentrations generated by candle burning.

From an air quality perspective, it is always more effective to prevent pollutants from being generated than to remove them afterward.

How Can the Risk Be Reduced?

Indoor air quality experts often emphasize three simple principles: ventilation, moderation, and education. This means ensuring adequate air exchange, reducing the frequency of use of products that emit pollutants, and understanding that a pleasant smell does not necessarily indicate healthier air.

In practice, this means:

• avoiding the use of candles, especially on a daily basis, in large numbers, and in poorly ventilated rooms;
• when candles are used, burning as few as possible and for the shortest possible period while ensuring adequate air exchange;
• avoiding candles that visibly smoke, produce soot, or emit particularly intense fragrances;
• choosing products with more clearly declared ingredients and without harmful or hazardous substances.

Conclusion

Scented candles can contribute to a pleasant atmosphere in the home and enhance the emotional experience of a space. At the same time, research shows that scented candles pollute indoor air.

When they are not lit, they release fragrance compounds. When they are lit, they generate not only fragrance but also combustion by-products, including fine particles, carbon dioxide, and other compounds.

This is important because we spend a significant portion of our lives indoors, and the air we breathe at home affects our daily comfort, concentration, sleep quality, and health.

Scented candles are a good example of why indoor air quality should not be assessed based solely on smell or a subjective sense of comfort. Air may seem fresh while still containing particles and chemical compounds that are invisible to us.

Indoor air quality should be viewed as a set of measurable characteristics rather than merely a subjective perception of comfort.

References

1. Alam, A., Nacinovi, J., Oppi, K., Loste, T., & Cao, G. Field Investigation of Indoor Air Quality in One Norwegian Apartment Building with Burning Candles. REHVA Journal, Vol. 61, Issue 1, 2024.
2. Yun, H., Seo, J. H., Kim, Y. G., & Yang, J. (2025). Impact of Scented Candle Use on Indoor Air Quality and Airborne Microbiome. Scientific Reports, 15, 10181. https://doi.org/10.1038/s41598-025-95010-0
3. Derudi, M., Gelosa, S., Sliepcevich, A., Cattaneo, A., Rota, R., Cavallo, D., & Nano, G. (2012). Emissions of Air Pollutants from Scented Candles Burning in a Test Chamber. Atmospheric Environment, 55, 257–262.
4. Maupetit, F., & Squinazi, F. (2009). Characterization of Benzene and Formaldehyde Emissions from Burning Incense and Scented Candles Indoors: Development of Exposure Scenarios and Recommendations for Use. Environmental Risk & Health, 8, 109–118.

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It is also commonly assumed that such systems are more cost-effective than central ventilation systems. This, however, is not necessarily true. The total cost depends on the number of required units, installation complexity, electrical works, maintenance, and the specific technical requirements of the space.

In many cases, decentralized ventilation can be a justified solution, particularly where a central ventilation system cannot be installed or is not economically viable. At the same time, it is important to understand that these systems have significant limitations and are not equally suitable for every building or every room.

What Are Decentralized Ventilation Systems in the Home?

Decentralized ventilation systems in the home are based on multiple individual ventilation units, typically with heat recovery.

These units are installed locally, most often within the external walls of the rooms being ventilated. Together, multiple units form a decentralized ventilation system intended to ventilate the building.

In practice, units are often installed in pairs or groups to ensure a meaningful airflow direction through space.

Are All Decentralized Ventilation Systems the Same?

No. Decentralized ventilation systems in the home include several technically different solutions. The key differences relate to airflow principles and the construction of individual units. Regardless of the type, decentralized systems share certain characteristics that directly influence their application potential.

Common Technical Characteristics and Limitations

The capacity of individual units is limited and, in most cases, corresponds to the needs of a single room. This limitation is dictated by the unit’s construction. Higher airflow rates require larger devices, which impact architectural and structural design.

Therefore, the required total airflow in a building is achieved by installing multiple units distributed across rooms.

Their application is limited in spaces with high pollution loads, where continuous and controlled air extraction is required.

These characteristics define the practical applications of decentralized systems and form the basis for understanding their advantages and limitations.

1. Single-Fan Wall Units

These are the most used devices installed on external walls. The unit consists of a tubular casing containing a heat-recovery core, filters, and a fan that periodically reverses direction. During operation, one phase supplies fresh air, and the other phase extracts indoor air.

Heat transfer occurs through the core, which accumulates heat from exhaust air and transfers it to incoming air when airflow reverses. The cycle typically changes every few minutes.

Key characteristics:

• alternating (not continuous) airflow
• fluctuating pressure conditions (positive/negative)
• need for paired operation to maintain balance

Due to cyclical airflow reversal, these devices do not maintain a stable negative-pressure regime, which is essential for reliable air extraction.

2. Dual-Fan Wall Units

These units use separate fans for supply and exhaust air. Air flows simultaneously and continuously through a heat exchanger (typically plate-type), with separated airflow paths.

Key characteristics:

• continuous and more stable airflow
• clearly separated supply and exhaust streams
• no air mixing within the unit

Technically, these devices are closer to central systems, but they remain local solutions intended for individual rooms.

3. Floor and Parapet Units

In addition to wall units, floor-standing and parapet units also exist. Their effect is generally limited to a single room.

Depending on the manufacturer, the unit may include heating or cooling functions for the air supply. Unlike reversible units, they provide continuous airflow direction.

Where Do Decentralized Ventilation Systems Have an Advantage?

Decentralized systems are particularly useful in existing buildings where central systems cannot be installed due to structural limitations, such as thick partition walls or low ceiling heights.This is especially relevant in renovations and older buildings where duct installation would be complex or economically unjustified.

SEE ALSO: Residential ventilation by Marquis Intelligence

Their advantage lies in less invasive installation inside the building. However, façade works are typically more extensive than with central systems. Centralized systems require two openings (façade or roof). Decentralized systems require one opening per unit. Condensate drainage must also be addressed for each unit, even if quantities are small.

Importantly, a simpler installation does not automatically mean a better technical solution.

SEE ALSO: FAQ – Home Ventilation

Often Overlooked Limitations

Decentralized systems depend on each room having access to an external wall. Rooms without façade access cannot be easily ventilated.

Wall thickness must also be sufficient for installation.

Attempts to connect internal rooms via ducts increase pressure drop and reduce airflow, often beyond these devices’ capacity.

Each unit also requires a power supply, which is often overlooked but essential for users to understand.

Impact of External Conditions and Operational Stability

According to the “EwWalt” research project (RWTH Aachen), units with alternating operation can be sensitive to external pressure changes, especially wind.

Due to axial fan characteristics, airflow may decrease under unfavorable conditions, and effective airflow can be about 15% lower than in continuous systems.

System performance depends on installation conditions and external influences.

(Source: REHVA Journal, EwWalt research project – Energetic assessment of decentralized ventilation units with alternating operation)

How do decentralized home ventilation systems affect the building’s façade?

Installation openings are not small – typically 150-200 mm in diameter. When repeated across multiple rooms, the impact becomes technically and aesthetically significant.

In practice, this can be the deciding factor. In one case in Belgrade, the owner of an architectural studio in a luxurious villa considered installing a decentralized ventilation system. After analyzing the required number of devices and the layout of openings on the facade, he gave up on the investment.

These solutions are not suitable for all types of façades. For example, they are not applicable to fully glazed façades or certain lightweight façade systems.

Air Purification in Decentralized Systems

In decentralized ventilation systems, air purification is, in most cases, limited to mechanical filtration. The use of molecular filters with smaller capacities is possible, but in practice it is rare.

Due to the limited available pressure of the fan and the device’s compact design, the use of more advanced air purification technologies is generally not feasible.

This means that air quality remains largely dependent on outdoor air quality and basic filtration. Considering that only 1% of the world’s population breathes outdoor air that meets World Health Organization (WHO) health guidelines, this represents an additional limitation. (Source: World Economic Forum, based on WHO data)

Energy Efficiency of Decentralized Ventilation Systems

Decentralized ventilation systems with heat recovery are a better solution than ventilation without recovery (e.g., only fans for air intake and exhaust or natural ventilation by opening windows and doors). However, they are generally less energy efficient than well-designed central home ventilation systems.

Although individual units consume little energy, the total system often includes many units, which can increase overall consumption.

Maintenance of Decentralized Systems

Centralized systems are maintained at a single location; decentralized systems require maintenance at each unit. That means entering every room, replacing multiple filters, and cleaning multiple heat exchangers. This increases the time and cost of system maintenance.

Due to limited pre-filtration, heat exchangers become dirtier faster, while micro-condensation accelerates particle accumulation. In practice, the maintenance costs of decentralized systems are often underestimated, whereas those of centralized systems are generally lower and easier to control.

SEE ALSO: HVAC and IAQ systems Maintenance– a pillar of reliability

The Marquis Intelligence approach to ventilation system selection

In practice, the choice between a decentralized and a centralized ventilation system is not based on the type of device but on the actual needs of the space and the facility’s technical capabilities.

Marquis Intelligence bases its analysis on space function, pollution and humidity load, architectural constraints, and air quality requirements.

Based on this, it is defined whether it is possible and justified to implement a central ventilation system or whether a decentralized approach is an acceptable solution.

The goal is not to choose a specific type of system, but to achieve stable, controlled air quality in space while respecting all technical and operational factors.

When Does Decentralized Ventilation Make Sense?

Decentralized systems are justified mainly where central systems cannot be installed – especially in renovations and older buildings.

Their key advantage is simpler installation. However, this must always be evaluated alongside: limited capacity, need for multiple units, façade impact, more complex maintenance, and limited air purification. These factors define their real application.

This text is part of the Marquis Intelligence professional series “Home Ventilation”.
Document: MI-HV-008.26 – Decentralized ventilation systems in the home: advantages and limitations of application

The post Decentralized Ventilation Systems in the Home: Advantages and Limitations of Application appeared first on Marquis Intelligence.

With the opening of this resort, Montenegro welcomed its first Mövenpick hotel within the global Accor hospitality group. The resort is located in the Bay of Kotor, an area renowned for its exceptional natural beauty and cultural-historical significance. Mövenpick Teuta Kotor Bay features hotel rooms, luxury residences and penthouses, a diverse selection of restaurants, wellness facilities, a private beach, and outdoor relaxation areas.

In such an environment, air discharged from the hotel kitchen should remain completely unnoticed.

Food Preparation Odors as a Potential Reputation Risk in Hospitality

In the hospitality kitchen odors can become a negative reputational factor. Guests generally perceive unwanted food odors as part of an unpleasant overall experience.

This is especially important in properties that include terraces, residential units, open-air restaurants, wellness facilities, and premium apartments. Guests expect an atmosphere of freshness, tranquility, and comfort throughout the property.

At this point, a technical solution ceases to be merely equipment and becomes part of the invisible technology of luxury. At Mövenpick Teuta Kotor Bay, this requirement was recognized and addressed from the earliest stages of project development.

Air Quality as Part of the Guest Experience

Luxury hotels are typically defined by their architecture, interior design, views, gastronomy, and wellness amenities. These are the elements guests notice immediately.

However, a lasting impression is often shaped by what guests do not see. Unpleasant odors, ventilation noise, stuffiness, or air carrying traces of food preparation can undermine even the most carefully designed hospitality environment.

Guests do not think about kitchen hoods, exhaust ductwork, filtration systems, treatment chambers, or control systems. They simply experience the space. What they consciously notice is usually discomfort: noise, unpleasant odors, excessive heat or cold, or poor air quality.

When the air remains pleasant and outdoor, wellness, and dining areas are free from kitchen odors, the technology has fulfilled its purpose. In a resort such as Mövenpick Teuta Kotor Bay, which builds its identity around the combination of the sea, heritage, sustainability, and wellness, such details are never left to chance.

Good Air Quality Is Becoming a Growing Priority in Hospitality

This approach is not an isolated example within Marquis Intelligence projects. Similar solutions have been implemented in the Bay of Kotor region and its surroundings for Restaurant Dojmi in Kotor, Restaurant ONE in Tivat, and Mamula Island Hotel. In addition, a previous mini case study on Hilton Belgrade demonstrated how IAQ solutions in hospitality can be adapted to different zones within a hotel property.

SEE ALSO: Mini Case Study: Hotel Hilton Belgrade

In all of these examples, the principle remains the same: guests do not need to understand how the system works, but they should be able to feel the difference.

Why Kitchen Exhaust Air Purification Matters in the Hotel

Kitchen exhaust air is not simply air that needs to be removed from a space.

During food preparation, particularly in professional and hotel kitchens, a complex mixture is generated containing warm air, significant amounts of water vapor, grease particles, smoke, aerosols, and odors. If such air is simply extracted from the kitchen and discharged outdoors without adequate treatment, the problem is not solved. It is merely relocated.

SEE ALSO: FAQ – Kitchen Exhaust Air Extraction and Purification

In standard buildings, the consequences are often technical and safety-related: grease accumulation in the ductwork, reduced system efficiency, unpleasant odors in the surrounding area, and increased fire risk.

In a luxury hotel, the consequences can be even broader.

Kitchen odors in terraces, restaurant areas, wellness facilities, or residential apartments are unacceptable. They affect not only guest comfort but also the reputation of the hotel brand.

Environmental Responsibility and Premium Guest Experience

As part of a hospitality brand with a strong commitment to sustainable practices, Mövenpick Teuta Kotor Bay addressed the issue of kitchen odor control from the earliest stages of project planning. In this context, kitchen exhaust extraction and air purification are not optional additions but a natural component of modern sustainable hospitality standards.

PHOENIX Systems at Mövenpick Teuta Kotor Bay

For Mövenpick Teuta Kotor Bay, Marquis Intelligence supplied two PHOENIX kitchen exhaust air purification systems. Their role extends beyond simply removing air from the kitchen. Before being discharged into the outdoor environment, the exhaust air undergoes a controlled purification process.

PHOENIX systems are engineered to effectively remove grease, particulate matter, and unpleasant odors from kitchen exhaust air. In previous project presentations, Marquis Intelligence reported system performance figures of more than 99% removal of grease and particulates and more than 92% neutralization of unpleasant odors.

In practice, these results are important for more than technical reasons.

They enable intensive kitchen operations while minimizing the impact on surrounding spaces. In a luxury hotel environment, this means that operational activities remain in the background while the guest experience stays clean, calm, and unobtrusive.

Installation and Maintenance Are Essential for Safe and Efficient Operation

The treatment chambers were installed on a dedicated platform to ensure easy access for regular maintenance. In luxury hospitality, technical systems must be not only efficient but also reliable over the long term. For that reason, maintaining kitchen exhaust and air purification systems is not an additional responsibility but a prerequisite for safety, stability, and service life.

Good engineering is often recognized precisely in such details – in aspects guests never see but upon which the continuity of quality depends.

SEE ALSO: HVAC and IAQ System Maintenance – The Pillar of Reliability

This is where the distinction between equipment as a product and an engineering solution as part of a property’s long-term value becomes evident.

In luxury hospitality, technology must operate without drawing attention to itself. It must be powerful yet quiet. Efficient yet unobtrusive. Present yet invisible.

That is the essence of the invisible technology of luxury.

From Technical Risk to Premium Experience

In a previous technical article, Marquis Intelligence explained why commercial kitchen exhaust ventilation is about much more than simply removing air from a kitchen.

Without proper treatment, kitchen exhaust air can lead to grease accumulation, odor dispersion, reduced system efficiency, and increased fire risk. These problems are not theoretical. They often become apparent only after a system begins to lose performance or when consequences become visible within the building and its surroundings.

SEE ALSO: Commercial Kitchen Exhaust Ventilation: From Fire Risk to Safe Operation

In a high-end hotel, the same technical challenge acquires an additional dimension.

The objective is not merely to ensure safety and functionality. The goal is to ensure that technical processes take place without compromising the atmosphere of the property, the reputation of the brand, or guest expectations.

In other words, what may be a safety issue in one facility becomes an experience issue in a luxury resort.

Every Property Has a Different Context

Ventilation solutions for commercial and hotel kitchens cannot be approached as universal systems.

In some projects, the key challenge may be limited installation space or a protected façade. The challenges may also be a low discharge point, noise restrictions, or proximity to pedestrian areas. In another, such as a luxury resort, the challenge lies in preserving a premium experience across the hotel, restaurant, wellness, and residential areas.

In a previous mini case study focused on commercial kitchen ventilation in a city center environment, Marquis Intelligence demonstrated how spatial limitations, architectural protection requirements, discharge point locations, and user proximity require a comprehensive engineering approach.

SEE ALSO: Mini Case Study: Commercial Kitchen Ventilation in Constrained Conditions in the City Centre

At Mövenpick Teuta Kotor Bay, the context is different, but the principle remains the same.

The Solution Does Not Begin with Equipment

Kitchen exhaust air purification in hotels cannot be approached by starting with equipment selection alone. The solution begins with understanding the space.

When a single resort integrates hotel rooms, residences, apartments, restaurants, wellness facilities, beaches, terraces, and outdoor relaxation areas, kitchen exhaust extraction and purification must be considered part of the property’s overall operational and experiential design.

Sustainable Hotels and Responsibility Toward Air Quality

Sustainability in hospitality is often associated with energy efficiency, water conservation, waste reduction, and responsible resource management. However, sustainability also includes what a property releases into its surrounding environment.

Kitchen exhaust air does not disappear once it passes through a kitchen hood. If left untreated, it leaves the building carrying odors, grease particles, and airborne contaminants. In sensitive tourist destinations, urban environments, and historically significant areas, such an approach is no longer sufficient.

This is especially true for a resort whose identity relies on natural surroundings, open-air experiences, seaside living, and the reputation of an international hospitality brand. For this reason, kitchen exhaust air purification becomes part of a responsible relationship toward the environment in which the hotel operates.

It contributes to environmental protection, odor reduction, preservation of guest comfort, and the long-term operational stability of building systems.

When Engineering Is Invisible but Noticeable

If a system performs properly, guests will never know where the treatment chambers are located, how air moves through the ductwork, or how it is purified before discharge. Yet they will know that they feel comfortable. The terrace does not smell like a kitchen. The wellness area remains a place of relaxation. Restaurant spaces maintain freshness and comfort.

Mövenpick Hotel & Residences Teuta Kotor Bay presents how modern luxury increasingly depends on systems that remain behind the scenes. Architecture, views, design, wellness, and service create the first impression. Clean air, the absence of unpleasant odors, and a stable indoor environment determine how long that impression lasts.

Through the implementation of PHOENIX kitchen exhaust extraction and air purification systems, Marquis Intelligence contributed to creating the technical foundation for a premium hospitality experience in one of the Adriatic region’s most prestigious new resorts. The true technology of luxury often remains invisible.

Sources and Additional Context

• Forbes article on the Mövenpick Hotel & Residences Teuta Kotor Bay resort
• Blic: “Swiss Luxury on the Adriatic Coast: Montenegro’s First Mövenpick Hotel Opens”
• Official Mövenpick Teuta Kotor Bay / The Queen of the Bay project website
• Previous Marquis Intelligence LinkedIn posts related to the Mövenpick Teuta Kotor Bay project

This article is part of the Marquis Intelligence “Mini Case Studies” series.

Document ID: MI-MCS-08.2Q-26

Document title: Kitchen Exhaust Air Purification at Mövenpick Hotel Teuta Kotor Bay

The post Mini Case Study: Kitchen Exhaust Air Purification at Mövenpick Hotel Teuta Kotor Bay appeared first on Marquis Intelligence.