Samenvatting
The limit values for nitrogen dioxide emissions have been exceeded in the urban area of Geneva. In November 1987, a "Turn off your engine" campaign was organised to encourage drivers to switch off their engines at red lights. Air pollution was measured during a three- month period with the aim of determining the effects of the campaign. The concentration depends in (1) traffic flow, (2) diffusion factors, and (3) the extent to which the campaign is observed.