Air pollutants and their impacts on health

There are many pollutants in the air we breathe and can have more or less long-term impacts on our health. Find out about the different air pollutants and their effects on health ! 

Reading time : 6 minutes 

Sommaire :
Nitrogen dioxide (NO2) 
Sulfure dioxyde (SO2) 
Ozone (O3) 
Carbon monoxide (CO) 
Volatile organic compounds (COV) 
Fines particles 

1/ Nitrogen dioxide(NO2) 

What is it ? NO2 or nitrogen dioxide is a gaseous pollutant. It has a characteristic, acrid and pungent odor. 

What is the source ? Nitrogen dioxide comes from combustion processes. 

Impact on health ? The nitrogen dioxide can cause eye, nose, and throat irritation and may also cause lung irritation if inhaled and reduce lung function. High concentrations of NO2 , expose to an increased risk of asthma attack, and to an increasing number of hospitalizations due to problems of the respiratory system. Pollutants having an impact on health. 

2/ Sulfure dioxide (SO2) (health pollutants) 

What is it ? The SO2 is a colorless, pungent odor gas similar to a burnt match. It can be the source of acid rain if it combines with water. 

What is the source ? Sulfur dioxide is produced by the combustion of fossil fuels (coal and oil) and the smelting of iron ores containing sulfur.

Impact on health ? SO2 affects the respiratory system and lung function and causes eye irritation. Inflammation of the respiratory system leads to coughing, mucus production, exacerbation of asthma, chronic bronchitis, and sensitization to respiratory infections. In people with asthma, it can interfere with lung function even at low concentrations. On days of high SO2 concentrations, hospital admissions and mortality increase. Pollutants therefore having an impact on health.


3/ Ozone (O3) 

What is it ? Ozone is a secondary pollutant, it is not produced directly by a polluting source, but is formed under the action of solar radiation which reacts with several “precursor” pollutants. More specifically, these are nitrogen oxides (NOx) and volatile organic compounds (VOCs). Car traffic is primarily responsible for the emission of these chemical compounds. This gas has a typical odor (odor after a storm with strong electrical activity). Ozone episodes, i.e. high concentrations of this pollutant occur during the months of May, June, July and August, as well as exceptionally at the end of April and the beginning of month of september.

NB: ozone as a pollutant is found at ground level while ozone which protects us from the sun’s UV rays is found in the upper atmosphere.

What is the source ? Several conditions must be met for significant concentrations to appear in the lower layers of the atmosphere:
– Strong sunshine.
– A high temperature (at least 25 ° C);
– Weak wind;
– The presence of pollutants responsible for the formation of ozone: nitrogen oxides (NOx) and volatile organic compounds (VOC)

Impact on health ? Due to its strong oxidizing power, ozone can cause a number of more or less serious health problems depending on the concentration and predisposition of each; strenuous outdoor physical activities are not recommended in the event of peak ozone pollution. Pollutants having an impact on health.


4/ Carbon monoxide (CO) (Health pollutants) 

What is it ? : It’s a odorless, colorless, flammable gas, the carbon monoxide (CO), is formed during the incomplete combustion of organic materials (gas, coal, fuel oils, fuels, wood).

What is the source ? One of the sources is automobile traffic. Significant levels of CO can be encountered when an engine is idling in an enclosed space. If a domestic heating appliance malfunctions, high levels of CO can also be detected in homes.

Impact on health ? CO attaches itself instead of oxygen to hemoglobin in the blood, leading to a lack of oxygen for the body (heart, brain, etc.). The first symptoms are headache and dizziness. These symptoms worsen with the increase in the CO concentration (nausea, vomiting, etc.) and can, in the event of prolonged exposure, lead to coma and death. The long-term effects of low exposures have yet to be investigated. Pollutants having an impact on health.


5/ Volatile organic compounds (VOCs) (pollutants and health)

What is it ? Volatile organic compounds include more than a hundred compounds, which can be of biogenic (natural) or anthropogenic (human) origin. VOCs are all molecules made up of hydrogen and carbon atoms (hydrocarbons), and those whose hydrogen atoms are replaced by other atoms such as nitrogen, chlorine, sulfur, or oxygen. . These are gases and vapors that can evaporate more or less quickly at room temperature. These compounds have an odor.

What is the source ? Emissions from vegetation or other natural phenomena such as forest fires, volcanic eruptions, etc. are natural sources of VOCs. In urban and / or industrialized environments, most of them come from human activities: they are emitted by combustion phenomena (exhaust gases in particular, factory chimneys, ovens, etc.) or by evaporation. They are used in the manufacture of many products: varnishes, solvents, scented candles, paints, glues, gardening products, household products, deodorants,….

Impact on health ? : VOCs have a double effect on health:

  • An indirect effect, they are precursors of ozone in the air
  • A direct effect as a toxic substance. The most harmful VOCs, such as benzene or formaldehyde, are classified as CMR (carcinogenic, mutagenic and reprotoxic). They are subject to increased regulation, particularly in the workplace.

The regulatory thresholds for VOCs depend on the substances involved and their harmfulness.

6 / Fine particles (pollutants and health)

o   PM10

What is it ? : PM10 are particles in suspension representing a complex mixture of organic or inorganic chemicals. The characteristic shared by PM10 is a diameter less than 10 µm (generally between 10 µm and 2.5 µm). Due to their size these particles tend to sediment (fall to the ground under their weight or during precipitation)

What is the source ? The main anthropogenic sources are the combustion of diesel and gasoline in motor vehicles, solid domestic fuels (coal, biomass, etc.), industrial activities, automobile traffic, agricultural or mining activities, excavation work .

Impact on health ? PM10 is reluctant to pass into the bloodstream and becomes less deeply rooted in the lungs (it does not reach the alveoli of the lungs) than smaller particles. They are mainly the cause of respiratory problems. However, they can also be linked to allergic problems and the development of more diverse diseases if other pollutants (pollen, viruses, bacteria, carcinogenic pollutants, etc.) are found attached to their surface.


o   PM2.5

What is it ? : PM2.5 are particles in suspension representing a complex mixture of organic or inorganic chemical compounds. The characteristic shared by PM2.5 is a diameter less than 2.5 µm (generally between 1 µm and 2.5 µm). PM2.5 particles stay suspended in the atmosphere longer than PM10, they can stay suspended for days or even weeks. Consequently, these particles can be transported over long distances and undergo physicochemical transformations.

What is the source ? : Particles of biogenic origin are, for example, mineral particles resulting from soil erosion, sand of desert origin, fire, etc. Particles of anthropogenic origin are, for example, soot from domestic heating, particles emitted directly by the combustion of automobile fuels or resulting from the wear of tires and brakes, or particles from the resuspension of deposits on the roadway by traffic.

Impact on health ? When fine particles, especially particles smaller than 2.5µm, enter the pulmonary alveoli, they can pass into the bloodstream and cause serious problems, including heart attacks, coronary artery disease, heart rhythm disturbances and stroke. They are also linked to various respiratory problems as well as to the development or deterioration of the condition in certain psychiatric diseases such as schizophrenia, bipolarities ...


o   Pollen

What is it ? The pollen grain is the male reproductive element of plants. There are two main types of pollen: Pollens carried by animals which are large and generally not very allergenic. They mainly concern flowers which are generally showy and fragrant; Pollens carried by the wind which are very allergenic and smaller in size. Note: A pollen grain has a microscopic size.

What is the source ? The source of pollen are plants and trees. The taxa found vary according to the seasons and regions. Pollen grains can attach themselves to fine particles of various kinds, and a pollen grain can itself be considered a fine particle. The diameter of the pollen varies according to the taxa.

Impact on health ? More than 20% of the French population suffers from respiratory allergy. The number of children with allergies continues to increase. A pollen allergy is called pollinosis. The symptoms can be mild or severe, even disabling (severe rhinitis with irritation and itching of the nose, sneezing attacks, conjunctivitis and tearing, etc.).

The amounts of pollen that can cause an allergy depend on the allergenic power of the pollen in question (ragweed, birch, grasses or cypress are very allergenic, for example).



o   Pollen

C’est quoi ? : Le grain de pollen est l’élément reproducteur mâle des plantes. On distingue deux types principaux de pollens :

  • Les pollens transportés par les animaux qui sont de grandes tailles et généralement peu allergisants. Ils concernent surtout les fleurs généralement voyantes et parfumées ;
  • Les pollens transportés par le vent qui sont très allergisants et de plus petite taille.

Nb : Un grain de pollen a une taille microscopique.

Quelle est la source ?  : La source du pollen sont les plantes et les arbres.  Les taxons retrouvés varient selon les saisons et les régions. Les grains de pollens peuvent se fixer sur des particules fines de diverses natures et un grain de pollen peut lui-même être considéré comme une particule fine. Le diamètre du pollen varie suivant les taxons. 

Impact sur la santé ? : Plus de 20 % de la population française souffre d’allergie respiratoire. Le nombre d’enfants allergiques ne cesse d’augmenter. Une allergie au pollen s’appelle une pollinose. Les symptômes peuvent être bénins comme sévères, voire invalidants (fortes rhinites avec irritations et picotements du nez, crises d’éternuements, conjonctivites et larmoiements…). 

Les quantités de pollen pouvant provoquer une allergie dépendent du pouvoir allergisant du pollen en question (l’ambroisie, le bouleau, les graminées ou le cyprès sont très allergisants par exemple).

Retrouvez notre calendrier pollinique dans notre article ici. 

7 / Radon (pollutants and health)

What is it ? Radon is a radioactive gas, colorless and odorless, which is found naturally in granite and volcanic rocks of ancient massifs (Brittany, Vosges, central France, Corsica, Pyrenees, Rhône-Alpes)

What is the source ? The source of radon is natural. It comes from the decay of radium and, initially, that of uranium. It is naturally present in rocks and more in granitic and volcanic subsoils: Brittany, central France, Alps, Vosges, Corsica. Thirty departments at risk are identified in France.

Impact on health ? Radon is not a health risk in the open air because its concentration is minimal. It becomes so when it accumulates in confined spaces. It is classified as certain carcinogen (group 1) by the IARC for lung cancer. Radon is the second leading cause of lung cancer, behind tobacco and ahead of asbestos: 9.8% of lung cancer cases are thought to be due to radon. The interaction between radon and tobacco increases the risk of lung cancer threefold.

For indoor air in homes, the WHO has divided the recommended threshold for radon by 10 (from 1000 to 100 Bq / m3). Pollutants having an impact on health.



8 / Pesticides (pollutants and health)

What is it ? : The term “pesticide” includes phytosanitary products, certain biocidal substances as well as certain antiparasitics for human and veterinary use. Pesticides can be found in various forms: gaseous and particulate (with larger or smaller diameters). Pesticides can be very numerous in the air studies (AASQA) found more than 114 active substances in the air this was equivalent to 67% of the substances that were sought.

What is the source ? During spreading, depending on weather conditions and application methods, 25% to 75% of phytosanitary products do not settle on the treated areas. This rate can even reach up to 90% on wet soils. It contaminates the air, mists and rains.

Impact on health ? Their effects vary according to the pesticides involved (they can have endocrine disrupting effects, be carcinogenic or toxic, etc.). Pollutants having an impact on health.



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