What effects does poor indoor air quality have on health?
In one of its publications, the Superior Health Council lists the most frequently reported health problems associated with poor air quality.
- respiratory symptoms,
- irritation of the mucous membranes,
- irritation of the eyes,
- skin irritation,
International research also links exposure to poor air quality with a number of diseases such as:
- asthma (and asthma symptoms);
- lung cancer;
- cardiovascular disease (CVD);
- upper and lower respiratory tract infections/symptoms;
- acute poisoning.
What is ventilation? And why is it important?
Ventilating a room allows its air to be constantly replaced.
Natural ventilation involves leaving the doors or windows open to allow air to circulate inside the building, and some of the indoor air to be replaced by air from outdoors.
Mechanical ventilation requires the installation of a ventilation system that pumps outdoor air inside the premises or building and/or removes indoor air at the same time. This kind of system can be installed either in a specific place (toilet, for example), or throughout the building (automatically controlled system).
Whether natural or mechanical, ventilation helps to dilute the contaminants that may be present in the air inside buildings; these could be microorganisms, bacteria or chemical pollutants such as fine particles or volatile organic compounds, for example.
What is the difference between ventilation and aeration?
Ventilation is the process through which "clean" air (normally outdoor air) is intentionally and continuously fed into an indoor space, while stale is removed. This can be done through natural or mechanical means.
Aeration is the natural process through which indoor air is replaced by outdoor air when doors or windows are open, for a short period of time.
How can ventilation stop the spread of viruses?
When we breathe, speak, cough or sneeze, we emit a larger or smaller amount of water droplets in the air we exhale. If we are infected by viruses or microbes, these droplets are loaded with them.
The largest drops fall very quickly onto surfaces and the ground, but can contaminate people in close proximity, which is why it is important to maintain a certain physical distance between people, wear a mask and respect barrier gestures.
The finer drops or micro-droplets, on the other hand, remain suspended in the air for several hours; these are called "aerosols".
In a room, these aerosols gradually spread throughout the space. Their diffusion is comparable to that of perfumes or cigarette smoke.
The higher the concentration of aerosols in a room, the higher the risk of contamination.
Thanks to ventilation, the outdoor air combines with the aerosol-laden indoor air, which reduces the concentration of aerosols in the room, and thus the risk of contamination by the bio-pollutants (such as viruses) that the aerosols are likely to contain. This makes it possible to limit the risk of serious respiratory diseases.
Are there any threshold values above which the air is decontaminated?
There is no threshold value for ventilation rate, air change rate or CO2 concentration above which the risk of contamination by viruses or other types of pollutants can be excluded.
The more intense and regular the ventilation, the lower the risk.
This is why we must strive to achieve a CO2 concentration rate indoors that is comparable to that of the outdoor air (i.e. approximately 400 ppm).
A room is considered well ventilated if the CO2 concentration is less than 900 ppm (or 500 ppm above the outdoor concentration).
In practice, if the ventilation or purification flow rate is 40 m³/hour per person, an adult engaged in gentle activity will almost never exceed 900 ppm (or 500 ppm above the outdoor concentration).
This air ventilation or purification rate corresponds to the World Health Organization (WHO) recommendations and is also contained in the Code of Well-being at Work.
This minimum ventilation rate must be higher for intense activities, since the production of CO2 and the production of aerosols (and therefore the breathing of these aerosols) are then higher. It must also be higher if the number of people present increases, or if the nature of the activities is itself a source of pollution (for example, by producing fine particles).
Is ventilation a good idea in these times of high energy prices?
Energy consumption remains an important point of attention. Maintaining a CO2 concentration in indoor air below a threshold of 1,200 ppm and a minimum ventilation rate of 25 m³/h, for example, does not result in a large increase in consumption PROVIDED that the ventilation rate is adapted to the number of people in the room and/or the CO2 concentration measured.
From an energy point of view, it is beneficial to have, if possible, a system with heat recovery and a demand control system. The demand control system automatically increases and decreases the ventilation rates depending on whether there are more or fewer people in the room and therefore depending on the CO2 concentration measured by the CO2 meter. Heat recovery involves the use of a heat exchanger built into the ventilation system that can achieve an efficiency level of 80% or more.
These concepts were explained in more detail during the kick-off meeting of the Indoor Air Quality Platform on 12 October 2022.
Are there any quality criteria for ventilation systems?
There are no specific technical or quality requirements for ventilation systems. It is recommended that the system be tested on delivery to check that the intended rate is achieved.
In the context of the Covid-19 pandemic, marketing criteria have been determined for air purification systems but not for mechanical ventilation equipment.
However, attention should be paid to the equipment's acoustics, as it is important to avoid "cutting off" the mechanical ventilation (or air purification) in the rooms because the noise is considered excessive. However, if the facility has to be shut down, it is important to monitor the CO2 concentration to ensure that it remains as low as possible, preferably below the recommended limits (below 900 ppm if possible and not exceeding 1,200 ppm). If the CO2 concentration exceeds these thresholds, it is strongly recommended that the ventilation system be reactivated to limit the risk of contamination.
What is a CO2 meter? Is it the same thing as a CO2 sensor or an indoor air quality meter?
A CO2 meter is a device that measures the concentration of CO2 in a given space.
All these names designate the same type of device, with the distinction that an indoor air quality meter does not just focus on measuring CO2, but can also measure other air quality criteria, such as the concentration of fine particles in the air.
Why is it useful to measure CO2 in indoor spaces?
Measuring the concentration of viral particles in the air is complicated. CO2, which we also emit when we breathe, is much easier to detect and measure. The concentration of CO2 in indoor air depends mainly on the number of people in the room, the physical activity taking place there and the effective ventilation rate.
Measuring the concentration of CO2 in the air is a good indicator of the ambient air quality in an enclosed space; a high concentration of CO2 shows that the ventilation is insufficient in this space. As the air exhaled by the people present is loaded with aerosols (microdroplets produced by respiration) that can be contaminated with microorganisms, bacteria or viruses, a high concentration of CO2 in a room is therefore an indicator that the air quality is probably not good.
To maintain healthy air quality and reduce the risk of being contaminated by aerosols, it is necessary to aerate and ventilate to replace the air in enclosed spaces.
A high concentration of CO2 in an enclosed space does not necessarily mean that the air is loaded with viruses. Measuring the CO2 level makes it possible to detect reference thresholds above which the air in the room should be replaced or an air purification device should be used.
Ideally, the CO2 rate in the air should not exceed 900 ppm (or a maximum of 1,200 ppm). Some scientific studies have shown that above a concentration of 1,000 ppm, CO2 has effects on human performance (particularly intellectual performance) and that it is preferable to remain below this threshold.
The natural CO2 concentration of the outdoor air is an average of 400 ppm. Ideally, it should be close to this threshold in enclosed spaces.
CO2 meters measure the CO2 content of a room. They do not act as a ventilation or aeration device.
What are the legal requirements for a CO2 meter?
In the context of the Covid-19 pandemic, the Ministerial Decree of 9 March 2022 set the conditions for the placing on the market of CO2 meters. This decree is no longer in effect as of 30 September 2022. However, it is still recommended that people follow the criteria it imposed, which are also contained in the recommendations of the "Ventilation" Taskforce of the Coronavirus Commission.
How to choose a CO2 meter? What should I look out for?
It is important to buy CO2 meters that correspond to the recommendations of the "Ventilation" Taskforce of the Corona Commission. Buying another type of device does not guarantee correct measurements and risks making the planned ventilation and air purification measurements completely ineffective.
In addition, publications with practical recommendations facilitate:
- the choice and use of CO2 meters for measuring indoor air quality: "Selection and use of CO2 sensors during COVID-19";
- the introduction of measures for monitoring indoor air quality "Recommendations for the Practical Implementation of Ventilation and Air Quality Monitoring during COVID-19".
These documents were drafted by the "Ventilation" Taskforce of the Coronavirus Commission during the Covid-19 pandemic. It is still recommended that people follow these recommendations.
Where is it preferable to install (a) CO2 meter(s)?
Ideally, the unit should be installed:
- in a prominent and central location;
- at least 1.5 m from people because the air they breathe out can influence the measurements.
Therefore, it should not be placed:
- next to a door, window or other opening that is open frequently or for long periods of time;
- near the ventilation system air intake.
It is also advisable to start by monitoring the areas in which the air quality is potentially less good, i.e. in the corners of a room, near the air extraction point (if there is one), in areas where there is the highest density of people, etc.
What is an air purification device?
An air purification device is a system that captures and/or inactivates the contaminants (microorganisms, fine particles, etc.) present in the air. It then provides air that is decontaminated and, therefore, potentially purified of pollutants (such as fine particles).
There are two main categories of devices based on:
- capture: capture of particles that potentially contain viruses or bacteria (HEPA filter, electrostatic precipitation);
- inactivation: damage to all or some of the microorganisms in an air stream, so that they can no longer multiply or propagate (e.g. UV-C).
Efficiency and safety requirements were set out in a ministerial decree in May 2021. This decree has since been extended until 29 May 2022. It is no longer in force, but a Royal decree is being prepared to replace this Ministerial decree.
Why is the use of an air purifier recommended?
The use of air purification systems, in addition to ventilation, further reduces the risk of contamination.
In some places, it might be easier to install an air purification system as installing a ventilation system would require significant renovation work. The use of an air purification system is then recommended, as it will significantly improve indoor air quality while waiting for the possible subsequent installation of a ventilation system.
If I use an air purifier, do I also need to install a ventilation system?
Affordable air purification systems do not currently eliminate the many indoor air pollutants with the same efficacy, which means that a minimum level of ventilation remains necessary. This minimum is set at 25 m³/hr per person by both the CODEX (if the sources of indoor air pollution are controlled) and by the Law of 6 November 2022.
Technically, it would be possible to work only with an air purification system, but that requires strict monitoring of the pollution sources and good installation. Such installations currently only exist in certain fields, such as space travel.
Why install a purification system if it does not lower CO2 concentrations?
The use of this type of device makes it possible to purify indoor air and improve its quality. Clean air guarantees a lesser presence of biological contaminants (moulds, bacteria and viruses) and possibly also chemical contaminants (particles, formaldehyde that can be released from furniture or floor coverings, etc.). See on this subject: Indoor air pollution: we are all exposed to it!
Aerating, ventilating, purifying and treating the air help limit the spread of these contaminants as explained in the short video by the SPF Employment: Ventilate - YouTube.
The measurement of the CO2 concentration is an indicator of air quality, but CO2 is not a contaminant in itself.
Which air purification systems are authorised?
As of 29 May 2022, the Ministerial decree imposing rules for the placing on the market of air purification devices is no longer in force. As a result, the FPS no longer publishes a list of authorised devices.
However, a new royal decree will be issued in 2023 to regulate the placing of these devices on the market. A new list of authorised devices will also be published on the FPS website.
Can air purifiers used against tobacco smoke also be used for the prevention of respiratory diseases?
If the ventilation equipment is provided for under the law on the prohibition of smoking in certain public places, the ventilation rate of these devices can be taken into account.
For air purifiers, the necessary technical information must be available or the data sheets must be requested from the manufacturer. These devices must be proven to be effective against airborne respiratory diseases and not cause any adverse effects because they contain ozone or because too many free radicals have been formed.
If the purification device is suitable for cigarette smoke, it will also have a positive effect on aerosols. It should be noted that the particles that make up smoke (PM 2.5 or less) are as fine as those in aerosols containing respiratory pathogens. Therefore, a purifier placed on the market before 12 May 2021 (Ministerial Decree of 12 May 2021) but capable of measuring a CADR of type PM 2.5 or a second-hand smoke (SHS) flow, can also be used to prevent respiratory diseases. It is therefore advisable to read the documentation accompanying the device carefully to verify its performance levels. The use of these purifiers is recommended provided that the CADR (Clean Air Delivery Rate) value or the purified air flow rate mentioned in the documentation is used. It should also be noted that the CADR is only guaranteed if the device has been well maintained.
Which sectors are targeted by the Law of 6 November 2022?
The sectors targeted by the law will be defined in a Royal decree to be published in early 2023.
The aim is to implement a phased approach, by initially targeting enclosed spaces accessible to the public which have already put in place measures to improve indoor air quality in the context of the Covid-19 pandemic.
These are rooms and spaces that host the public in:
- establishments in the sports sector, including fitness centres;
- establishments in the events sector, including discos and dance halls;
- food and beverage establishments in the HORECA sector;
- infrastructures where recreational activities (sport-youth-culture) take place.
The enclosed spaces accessible to the public for which the Law of 6 November 2022 and the implementing decrees must apply will be defined based on the type of activity held there, and not the sector to which they belong.
Where is it best to display the CO2 meter results to the public?
It is recommended that the CO2 meter be installed in a location that is clearly visible to visitors, unless an alternative, publicly accessible, real-time display system is provided.
Is one CO2 meter per venue sufficient?
At least one device per venue is recommended.
If two units installed in the same space in an area frequented or likely to be frequented by the public show very different concentrations, this may be the result of a build-up of stale air in certain areas or a faulty measurement device.