Pollutant emissions of combustion engines

Man and pollution are intimately linked, but our perception of it has changed considerably over the centuries. From episodic phenomena linked to particular meteorological situations, we now know that pollution is more insidious, and that even background pollution can have consequences in terms of public health.

From the 1980s onwards, photochemical pollution, or the increase in ozone concentration in large urban areas, became a major issue. At the same time, measurement networks developed and evolved. Since the 1950s, these networks have focused on pollutants produced by the combustion of fixed installations, i.e. black smoke, SO ₂ . They are now moving towards measurements of nitrogen oxides NO _x (NO and NO ₂ ) initially, then ozone O ₃ and particulates with PM ₁₀ (particles with diameters less than 10 μm).

Air quality standards are becoming increasingly stringent. For example, for NO ₂ , the annual average not to be exceeded in France is 48 μg/m ³ for 2006, and should be 40 μg/m ³ by 2010.

Ozone (O ₃ ), a secondary pollutant derived exclusively from the photolysis of NO ₂ , is also particularly closely monitored.

In the major conurbations of industrialized countries, this pollution is mainly due to the increase in road traffic, and although vehicle emission standards have evolved considerably, ozone pollution is still a problem. Often, the sharp reduction in emissions is offset by the increase in traffic.

What's more, all the world's weather stations are recording an increase in average temperature (+0.5°C to +0.7°C since 1860). At the same time, many glaciers are retreating, and some are even disappearing. In 1995, an IPCC report [IPCC 1995] confirmed the influence of human activities on climate change and put forward the hypothesis of an average warming of 1 to 3.5°C by 2100, which would lead to a sea-level rise of 15 to 95 cm. The 3rd United Nations Climate Change Conference in Kyoto sees the adoption of a protocol to the Climate Convention, known as the "Kyoto Protocol". It commits 38 industrialized countries, including the USA (which will denounce it in 2001), Canada, Japan, the EU countries and the countries of the former Communist bloc, to reducing their greenhouse gas emissions (CO ₂ ,...