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Atmosphere, atmosphere
There are many chemical compounds in the atmosphere, often invisible to the naked eye because of their very small size. Even if they are present in much smaller quantities than nitrogen and oxygen, it is important to measure these compounds because they have an impact on the quality of the air we breathe.
Above the oceans, far from the continents, there are few air pollutants (only those that can travel over great distances). By contrast, in our cities, many activities (industries, road traffic…) emit pollutants. Some will be airborne (and may therefore also be found in rural areas), while others will transform into other pollutants. All will have a more or less significant impact on the quality of the air we breathe. For example, ozone is a compound that can cause respiratory problems when it enters the lungs, especially in fragile individuals (children, asthmatics…). It is therefore important to understand how ozone is formed in the atmosphere in order to try and reduce its concentration and hence its impact on people’s health.
Researchers in atmospheric chemistry are trying to better understand the emissions, transformations and impacts of these pollutants. Their experiments rely on techniques in chemistry and physics as well as computer-based simulation studies.
The measurements performed in a laboratory can reproduce the chemical reactions that take place in the atmosphere while allowing the parameters (temperature, radiation…) of the experiment to be modified. Measurements under real atmospheric conditions are complex to implement (because all the measuring instruments have to be transported) and often limited in time, but they help measure the chemical compounds present in the air as comprehensively as possible.
Laboratoire des sciences du climat et de l’environnement, CNRS-CEA-Université Versailles St-Quentin
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