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Indoor air quality study

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Air quality monitoring

Good air quality is a key factor in human health and safety, whether in industry, the office or the home. Air can be polluted by pollutants, which are particles that are harmful to living organisms and move with the air. Air pollution is measured in parts per million (ppm). This unit corresponds to the number of molecules to be measured per million air molecules. The higher the pollution level, the more polluted the air, and the poorer its quality.

Pollutants, as well as other chemicals, can cause health problems, resulting in reduced productivity, as well as discomfort and stress for staff. In fact, polluted indoor air can cause coughing, dizziness, headaches, mucous membrane irritation and fatigue in the short term, and respiratory and heart disease in the long term.

Indoor air quality

According to theWorld Health Organization (WHO ) , indoor air pollution, including workplace exposure, is responsible for around 3% of the global burden of disease. We spend up to 90% of our time indoors, whether at home, at school, on the move or at work.

It is therefore important to check indoor air quality:

  • To ensure that pollution regulations do not exceed defined limit values.
  • To check that control measures are working properly.
  • How to choose the right level of personal protective equipment (PPE).
  • To be able to assure workers that their health and well-being are not at risk

What are VOCs?

Volatile organic compounds (VOCs) are chemical substances containing carbon. They can come from a variety of sources, such as those described below, cosmetics, air fresheners, fossil fuels, chemicals emitted by motor vehicles or in the industrial sector.

VOCs play an important role in both indoor and outdoor air pollution. Not all VOCs are harmful, but some are considered air pollutants, such as benzene, formaldehyde and toluene. Others, like methane (emitted by swamps and ruminants) are naturally present in the environment and are important for the Earth’s biogeochemical cycle.

Examples of VOCs

Exposure to VOCs can be reduced by a number of measures. For example, it is recommended to properlyventilate interior spaces, use low-VOC cleaning products and building materials, limit the excessive use of chemicals and promote the use of clean energy sources.

In addition, environmental regulations aim to control and reduce VOC emissions from various industrial sources. EOLIOS is able toassess VOC emissions and monitor their concentration in the air, as well as their impact on indoor and outdoor air quality.

What are fine particles?

Fine particles are airborne particles with a diameter of 2.5 microns or less. They are therefore known as PM2.5. These fine particles can be emitted by a variety of sources, including motor vehicles, power stations, industrial plants, biomass fires and combustion processes. They contribute to air pollution and therefore have a negative impact on health and the environment.

More on the subject:

Where do pollutants come from?

Pollutants in rooms come from various sources of indoor pollution:

  • Tobacco smoke: contains toxic substances such as carbon monoxide, formaldehyde and VOCs.
  • Household and DIY products: some products emit VOCs such as ammonia and aerosols.
  • Building/decorating materials: paints, varnishes, glues, carpets and plastics release VOCs during and after installation.
  • Furniture and upholstery: upholstered furniture, carpets and curtains contain chemicals such as brominated flame retardants, which break down and disperse into the outside air.
  • Heating/cooking appliances: wood-burning stoves, fireplaces and gas stoves release carbon monoxide, fine particles and other pollutants when poorly maintained or inefficient.
  • Molds and allergens: molds release spores and harmful substances, and allergens such as animal hair, dust mites and pollens pollute indoor air.
  • Combustion equipment: industrial furnaces such as those used in glass factories, or the combustion exhaust from generators, release pollutants.

Main factors affecting indoor air quality

Indoor air quality can be worsened by a number of factors:

  • Poor ventilation
  • Temperature control problems
  • Humidity too high or too low
  • Refurbishing with paint
  • Renovation dust
  • Cleaning equipment
  • Chemicals and pesticides

Consequently, good ventilation, the use of environmentally-friendly cleaning and construction products, and humidity management are essential measures for reducing indoor pollution.

Notion of indoor comfort and air quality

A satisfactory level of indoor comfort is essential for the physical and mental health of staff, and therefore for their productivity. What’s more, a well-managed, comfortable environment can lead to energy savings. Consequently, it is very important to create or optimize layouts that promote a good level of interior comfort.

Indoor comfort is defined by the many criteria listed below.

No draughts

Proper air velocity can help reduce the build-up of pollutants, wick away moisture and maintain an even temperature in the interior space. This speed can be altered by ventilation systems, heating or air-conditioning units and openings.

Air velocities in occupied areas are generally limited to less than 0.2 m/s.

Temperature uniformity

The absence of strong temperature stratification in the occupied zone ensures satisfactory comfort. In fact, the temperature must be uniform in both summer and winter, as high temperatures tire occupants and excessively cold temperatures reduce their concentration.

Good indoor air quality

  • Air humidity

If humidity is too low, the result is dry air that prevents proper breathing, drying out the eyes, nasal passages and throat. Too much humidity encourages the growth of bacteria, mold and dust mites.

  • Ventilation

Outside air is safer, so it’s important to replace indoor air often with fresh outside air. To achieve this, ventilation systems are installed in spaces where opening windows is not enough.

  • Clean air

Polluted air impairs occupants’ health. That’s whyindoor air needs to be changed frequently, andoutdoor air needs to be filtered to avoid bringing too much pollution back into the room.

CFD simulation of indoor air pollution

CFD modeling is a versatile tool for solving engineering problems linked to theanalysis of the propagation of various impurities and particles in the air. CFD modeling is used to reproduce air movement, taking into account heat and mass transfer, gaseous impurities and their dispersion, and the transfer of mechanical particles in suspension. This makes it possible to study the diffusion of pollutants in rooms, which follow air flow lines, thanks to aeraulics.

The concentration of pollutants in a room varies according to the ventilation mode chosen, creating an uneven distribution throughout the volume. Pollutants naturally tend to rise. By analyzing the distribution of pollutants in the room space, it is possible tooptimize design solutions adapted to air quality.

Example of air quality in a factory

Example of virus propagation

Some viruses are spread orally. The droplets in the air are likely to contain the virus, and so air currents favor the spread of the virus. To effectively combat airborne infection, it is crucial to accurately predict how these droplets and aerosols spread, and to estimate theimpact of airflow on the risk of infection.

We carry out simulations using computational fluid dynamics (CFD ) to study the behavior of droplets and aerosols and find appropriate solutions to minimize the risk of oral infection.

Solutions proposed by EOLIOS

Our team can help you check andoptimize your various processes. To this end, we are able to carry out on-site measurement campaigns to obtain air quality measurements. This measurement phase is preliminary to our simulation studies.

Particle measuring instruments

We can model room ventilation systems in several stages:

  • Audit to determine the origin of dust for complex processes.
  • Evaluation of the design solution for air distribution to check compliance of the pollution parameters generated in the plant premises with the values required with the calculated temperature, velocity and humidity values. Airflow modeling is performed using three-dimensional mathematical modeling methods (CFD approach).
  • Development of adjustments to the design solution, enabling the required pollution level parameters to be achieved throughout the room.
  • Detailed analysis of pollution parameters in the vicinity of the technological process, optimization in terms of air distribution, humidification, capture…
  • Specific contamination study for laboratory premises

In this way, we can determine the air quality throughout the room and deduce an indoor comfort level.

EOLIOS can also design ventilation systems specifically to improve air quality, for example in complex areas such as cleanrooms. This kind of place demands impeccable cleanliness. It is therefore possible for us to determine air flows to ensure that pollutants do not reach risk areas and that air quality is very high.

Air & wind : on the same subject