Pollution plumes in Paris air are richer in gaseous aromatic compounds than in Los Angeles
What is the origin of the volatile hydrocarbons, other than methane, present in city air?
Mainly gasoline-powered vehicles, according to a study carried out by a French-US team including French researchers from the Laboratoire Interuniversitaire des Systèmes Atmosphériques and the Laboratoire des Sciences du Climat et de l’Environnement. The study also shows that the proportion of gaseous aromatic compounds in hydrocarbon emissions is two to three times greater in pollution plumes in Paris than in Los Angeles, even though the total quantity of hydrocarbons emitted in Los Angeles remains considerably greater than in Paris. The research is published in the journal Journal of Geophysical Research.
The proportion of gaseous aromatic compounds in hydrocarbon emissions is two to three times greater in pollution plumes in Paris than in Los Angeles.
Volatile organic compounds (VOC), which include hydrocarbons (compounds made up solely of carbon and hydrogen), are major air pollutants as well as precursors of harmful compounds such as tropospheric ozone and secondary organic aerosols. In urban areas, there are many VOC emission sources from human activity, including the distribution, storage and burning of fossil fuels, as well as activities that make use of solvents. However, although these sources are well known, there is still no consensus as to their relative significance, even though such information is needed to measure their impact.
In 2009-2010, as part of the MEGAPOLI and CALNEX programs, an international team including scientists from France carried out two campaigns to study the main air pollutants, including VOCs, in the
megacities of Paris and Los Angeles. Using ground-based gas chromatographs and a proton-transfer reaction mass spectrometer on board the French ATR-42 research aircraft, the team measured
concentrations of these pollutants in pollution plumes in both cities.
By comparing the data obtained with other data already available for several European and US cities, the researchers confirmed that in urban areas volatile hydrocarbons other than methane (i.e. compounds containing 2-12 carbon atoms) are mainly produced by automobiles, a conclusion in line with previous. Volatile hydrocarbons are only one component of automobile pollution and do not concern particle emissions from automobiles.
To know more, please read the press release from CNRS.