Gaseous air pollution - Gas measurement

While not completely exhaustive, this article covers the majority of pollutants of interest that are present in the gas phase in the lower troposphere, from near sources to remote regions where persistent substances and by-products of (photo)chemical reactions remain in small traces.

The compounds described in this article are of interest for a wide variety of reasons: either as source tracers, or because of their impact on health and/or the ecosystem. Their monitoring can also be part of other approaches, such as understanding reaction mechanisms and supporting the modeling of phenomena.

As a result, the range of concentrations covered is very broad: while the concern is most often to meet detection limits in the parts-per-trillion (ppbv) range, for some substances the requirements can be more stringent, requiring techniques capable of quantifying at the parts-per-trillion (pptv) level, or even lower.

Some pollutants are described as "semi-volatile", meaning that they are present both in the gaseous phase and in airborne particles. Polycyclic aromatic hydrocarbons and dioxins have been chosen for inclusion in this article, as they have this characteristic.

For each compound, the sources and properties are briefly described, followed by the various techniques that can be used, referring the reader if necessary to the general principles discussed in the article , the more technical recommendations for implementation are presented in article .

Interested readers may also refer to the section on Air in the Techniques de l'Ingénieur Environment publication .