Exhaust fumes of the cars in the collimator
An article from car technician’s in EmpaAnother reason for Globalwarming Awareness 2007
The goings beyond of the values limit for fine dust and ozone as well as increasing emissions of gases for purpose of greenhouse - very quickly in the research of the culprits one looks in direction of the cars and the trucks. But for how much the traffic does car contribute makes some with the air pollution ? And how to estimate or to calculate this contribution ? It is of that that one discussed at the time of a conference to which Schweizerische Automobiltechnische Gesellschaft (SATG) had invited to take part in Empa. More than 80 engineers and specialists in the automobile branch learned there that it is before all the installations of air-conditioning and the cold starts which contribute to emissions of pollutants of the motor vehicles. The quality of the air improves constantly in Switzerland - put aside in the great agglomerations urban. There, according to Christian Bach who directs the Laboratory Combustion engines of Empa, values recorded for ozone and fine dust these last years on a high level stagnate. This is due above all to the fact that today on the Swiss roads the cars are more numerous than ever and than currently in the Swiss cities, a number increasingly higher of “clean” cars causes a pollution as high as at one time less low number of “dirty” cars. The diesel engines mainly emit tiny particles of which mass - because of their weak cut - does not seem important but which by their considerable number is regarded as worrying in the mediums of health. The 18 percent of dust fine PM10- are the particles of a diameter lower than 10 micrometers - leave directly the mufflers. These particles are able to penetrate deeply in the lungs - and not only in the respiratory tracts higher like the larger particles caused by the mechanical wear of the tires or the brakes - and to cause respiratory diseases, and even lung cancers. “It is also why we support the efforts of the Confederation in favour of the introduction of the filters to particles for the principal persons in charge for these emissions which are the diesel engines”, Bach declares. In the cities, beside fine dust, ozone is also a problem, that above all in summer. It is not enough by far, according to Bach, to reduce only the precursors of ozone in exhaust fumes. It is indeed the relationship between these substances, such as the hydrocarbons and oxides of nitrogen, which make that there is or not ozone formation. And this report/ratio is quite simply “ideal” for the ozone formation under the estival weather conditions. It is what the measurements carried out by the Laboratory show Atmospheric pollutants of Empa. Certain new systems of gas cleaning of exhaust lead even to an increase in the ozone formation - that because of an increased proportion of nitrogen dioxide in the fraction of nitrogen oxides ; the nitrogen dioxide being notably more reactive than other nitrogen oxides, the formation of ozone is increased. What is worrying, it is the increase in the emissions of gases for purpose of greenhouse, that in spite of new laws, the Protocol of Kyoto and the international pressure. Average the techniques, such as catalysts, do not make it possible to prevent these emissions. Only vehicles rejecting month of carbon dioxide, by using example of the cars of the biodiesel produces starting from colza or other plants, could slow down this increase. However what seems extremely beautiful on paper does not function as well in practice because the production of the biocarburants emits it also gases for purpose of greenhouse. For Christian Bach, the challenge to take up is clear : “Parallel to a reduction of their particulate emissions and nitrogen oxides, the vehicles of the future will have especially to consume less fuel”