| Change since | |
 |
1970 |
 |
1990 |
 |
1998 |
Coverage: United Kingdom
Source: Defra, NETCEN
- Urban air quality has generally improved significantly since 1993, while rural air pollution, caused largely by ozone, has shown no overall trend.
- Shorter term trends can be masked by variation caused by the weather. The hot summer and other pollution episodes in 2003 led to an unusually high number of pollution days. The assessment reflects the high 2003 figures rather than being a conclusion about the underlying trend, which remains unclear.