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Indoor Air Quality

According to the Fédération ATMO, France's national network of authorised air quality monitoring associations, we breathe nearly 15,000 litres of air every day. It therefore comes as no surprise that the quality of this air is vital to our health. But how can we accurately define air quality and assess it? It isn't always easy to understand all the different terms such as pollutants, pollens and particles, or to distinguish between what's simply an inconvenience and what's a real threat to our health.

What does air quality mean?

  • Composition of the air
Ambient air is made up of 78% nitrogen, 21% oxygen and 1% other gases. However, it also contains many other suspended substances, whether gaseous or solid. Some are caused by natural phenomena (emissions from plants, soil erosion, the spreading of pollen, volcanic eruptions, etc.), while others come from human activities such as industry, transport, heating and agriculture. These chemical compounds are present in the ambient air in varying proportions and while some are harmless, others are a genuine public health and environmental problem. This is what is known as atmospheric pollution.
  • Primary and secondary pollutants
There are two types of pollutants in the air: primary pollutants are directly emitted into the atmosphere, while secondary pollutants are the result of chemical reactions between precursor pollutants or with their environment. This is the case with ozone for example, which is caused by a chemical reaction between nitrogen oxides, certain volatile organic compounds and the sun's rays.
  • What are the main pollutants?
The pollutants that are responsible for atmospheric pollution and are specially monitored include:
-Volatile organic compounds (VOCs): methane, which poses no risk to human health, is distinguished from non-methane volatile volcanic compounds (NMVOCs). Emitted during combustion processes (energy production, transport) and the evaporation of solvents (notably paint), VOCs are responsible for the greenhouse effect and are involved in the chemical reactions that form ozone and certain fine particles.

-Microparticles: these particles suspended in the atmosphere mainly come from heating, industry and transport, as well as activities such as building and public works, and quarrying. Their composition therefore varies depending on their source. The harmfulness of these particles depends on both their composition and size.

-Carbon dioxide (CO2): carbon dioxide is a gas that's naturally present in the air. It is produced by activities such as human respiration (as well as animal and plant respiration) and isn't harmful per se. Nevertheless, the emissions produced by heating, transport and industry considerably add to the greenhouse effect. This is why carbon dioxide emissions are also monitored.

-Carbon monoxide (CO): this highly poisonous gas is produced by the incomplete burning of fuel (coal, wood, oil or gas) and mainly comes from domestic heating and industry. It is carefully monitored indoors, where its presence can cause poisoning and even death.

-Nitrogen oxides and sulphur dioxide: nitrogen oxide and nitric oxide emissions are mainly caused by road transport, industry and agriculture. Meanwhile, sulphur dioxide is a residue from sulphur-based combustion. These are the ozone precursor pollutants, a gas that's harmful to the environment and health.

-Another pollution factor that's closely monitored is the ammonia produced by farming activities (organic discharges from livestock and nitrogen fertilisers), which is a fine particle precursor.

-Heavy metals: mostly produced by industrial activities, these substances are strictly regulated. They include lead, mercury, arsenic, cadmium and nickel.

-Pesticides: used in crop treatment, pesticides spread in the air after being sprayed, as well as through volatilisation from plants or the soil. Once in the air, pesticides increase pollution peaks in towns and cities and contaminate the rain. Pesticides are also precursors of secondary pollutants such as ozone.

What are the health risks from poor air quality?

Atmospheric pollution has a variety of effects on our environment: an increase in the greenhouse effect, climate change, the modification of ecosystems, the acidification of habitats, etc. Some particles and pollutants are also harmful to our health in varying degrees depending on the substances, their concentration and the fragility of the people exposed to them. Some are only toxic above a certain level, while others such as formaldehyde and carbon monoxide are dangerous even at low doses.
The pollution in the air enters our bodies through the lungs, where gaseous exchanges between our body and the environment take place. Depending on the size of the particles and their ability to accumulate in the body, pollution has varying effects on our health. The most vulnerable individuals (children, the elderly or those with an illness) are of course more sensitive to air pollution.
The WHO (World Health Organisation) has conducted extensive research into the potential health effects of pollution and estimates that 7 million deaths worldwide are caused by pollution in the ambient air.
PREV’AIR, the French national air quality forecasting platform managed by INERIS (the national institute for environmental technology and hazards), classifies the risks linked to atmospheric pollution based on their effects on four areas of the body: the neurological system, the respiratory system, the cardiovascular system and the hormonal system.
  • Atmospheric pollution effects on the nervous system: some pollutants can reach the brain and contribute to the neurodegenerative disease Alzheimer's.
  • Atmospheric pollution effects on the cardiovascular system: the finest particles and nanoparticles can reach very deep areas of the lungs and pass into the blood. By accumulating in the blood vessels, these pollutants can contribute to heart rate and coagulation problems and in the long-term create a higher risk of heart attack, thrombosis and stroke.
  • Atmospheric pollution effects on the respiratory system: many pollutants such as ozone and fine particles penetrate deep into the lungs and can affect the breathing, causing asthma and respiratory illnesses.
  • Atmospheric pollution effects on the hormonal system: we now know that some pollutants are endocrine disruptors that contribute to hormonal system disorders.
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How air quality is measured

Specific measuring devices are available for measuring pollutant emissions and assessing atmospheric pollution. These usually measure the data on each pollutant separately so that the sources of each component can be determined more easily. Pollutant sensors use sophisticated technologies such as lasers, flame ionisation, infrared, etc.
The various measuring devices are installed in stations in areas with heavy traffic or nearby monitored sites. Another type of station called a "fund station" also exists to obtain more global measurements further away from emission areas. The data is available online and categorised from 0 to 100 based on the ATMO index to make it easier to understand.

What about indoor air quality?

Although we often associate pollution with the outdoor air in towns and cities, indoor air quality is just as much of a concern, what's more nationwide. Indeed, pollution doesn't just come from the outside. It's also found indoors in the form of particles and VOCs given off by construction materials, paint, cleaning products and various heating systems. There's also the carbon dioxide produced when the people in a home breathe, which builds up when a space is insufficiently ventilated.
That's why indoor air quality is a major public health issue and why it's important to make sure the spaces we live in are properly ventilated, either mechanically or manually. Combined with regular maintenance of heating devices and making sure that we choose low-pollutant materials and furniture, this ventilation helps to reduce the potentially dangerous emissions in a home.

Indeed, indoor pollution also kills. The WHO estimates that 3.8 million deaths worldwide are caused by indoor air pollution in homes, mainly due to the use of fuels and pollutant technologies.

The agencies involved in monitoring air quality

Globally, the WHO has issued recommendations on the maximum thresholds for each pollutant. Europe-wide, the air quality framework directive has introduced legislation that draws on this WHO data, and the European Environment Agency centralises the data collected by each country.
In France, an advanced air quality monitoring structure has been put in place by the ministry for the ecology, sustainable development and energy.
  • At a local level, structures called AASQAs (authorised air quality monitoring associations) are responsible for gathering data and informing the public, particularly in the event of a local alert. They are grouped together within the ATMO network.
  • Nationwide, the LCSQA (central air quality monitoring laboratory) oversees the coordination and technical development of the mechanism, notably by drawing on the INERIS (national institute for environmental technology and hazards) and the LNE (national metrology and testing laboratory).

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