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Does the amount of air pollution around me change at different times?

Yes it can. Air pollution levels change with location, different weather conditions, and with the activities that are taking place.

Air pollution gathers around the areas where it is formed. So places that have lots of traffic, domestic wood fires, industry or farming can have higher levels of pollution.

Closing roads to traffic can reduce air pollution on those roads almost straightaway. This year Global Action Plan calculated that air pollution on a major road in London was 89% lower when the roads were closed for the London Marathon than on a normal Sunday. This is because generally the more traffic there is, the more pollution there usually is, so rush hour can be particularly bad.

Pollution can change at different times of year too. Ozone pollution forms in direct sunlight, so more is generated on particularly sunny days and levels are likely to be higher in spring and summer. In winter, when there is particularly cold air at ground level and warmer air above it, air pollution can become trapped until the weather changes again.


Some seasonal events, like bonfires and fireworks, can also result in higher levels of air pollution during the displays and for a time after.

A line illustration of different types of weather

Air pollution on a major road in London was 89% lower when the roads were closed