General conclusion and outlook
Air Quality and Automobile. Technological Solutions to Limit the Impact on Air Qality

Although air quality continues to improve (reduction in NO₂ and fine particle (PM) concentrations in major cities in particular), threshold exceedances are still observed for NOx, PM and O₃ in France as well as in other European countries [BM 2 502].

The road transport sector is the biggest contributor to urban NOx emissions and the second biggest contributor to PM emissions, after the residential/tertiary sector. Over the past 30 years, road transport emissions have been steadily declining, thanks to regulations and the fitting of increasingly efficient...