Urban air quality

Growth of urban sprawl along the French Riviera, 1975-90

Maps show growth of urban sprawl along a 10-km strip of the French Mediterranean coast between 1975 and 1990. Two maps on the left identify agricultural and forested areas that were urbanized during 1975-90. Near map shows the end result - some 35 per cent of the strip is now built on Source: Blue Plan 2001

Across Europe, transport and mobility are becoming major issues for most cities. In the urban areas of Western Europe, half of all car trips are for less than 6 km while 10 per cent are for less than 1 km. The major factor affecting the increase in traffic is increasing travel distances to work, shopping, schools and leisure activities. These distances are increasing because origins and destinations (residential areas, industrial areas, shopping areas and so on) are being located further apart and often primarily linked with roads. Also, as a result of globalization, increasing competition forces people to find work in different locations and different jobs at different times of the day. Alternatives to the car such as public transport, walking and cycling facilities are often poorly developed or ill-adapted to newly emerging urban patterns (EEA 2001). Major exceptions are Denmark and the Netherlands where infrastructure for alternatives to the car is well developed.

The increase in vehicle traffic has significant implications for urban air quality, although this has been partially offset by a reduction in major air pollutant emissions from transport in Western European countries. Nevertheless, considerable numbers of people in urban areas are still exposed to high pollution levels, leading to some health-related issues. Projections for 2010 show that 70 per cent of the urban population are still likely to be exposed to particulate matter levels in excess of threshold values, 20 per cent to excess NO₂ and 15 per cent to excess benzene (EEA 2001).

The number of exceedance days for NO₂ in CEE cities is much lower than in EU cities, and far below the number allowed by EU directives. However, with affluence levels and the number of vehicles increasing, photochemical smog - associated with increasing NO_x, hydrocarbons and carbon monoxide - has recently become a problem. The move towards leadfree petrol and mandatory catalysers on private vehicles is now helping improve urban air quality in these countries.