What is air pollution

Air pollution comes from a range of sources, including some nearby, like vehicles and other sources within the city, and some further afield. The proportion of pollution that reaches us from each source depends on the weather, the location, the time of day, and a number of other factors. Wherever you are, you’ll breathe in some of this pollution.

There are several different pollutants, but the main ones which affect our health are nitrogen dioxide (NO2) and particulates (PM10 and PM2.5). Road transport is the biggest source of both of these.

Air pollution concentrations depend on the emissions level and how the emissions are dispersed in the air. A combination of still air (low dispersal) and the morning rush hour (high emissions) mean the highest pollution levels are often in the morning. There’s often a second smaller, more spread out peak in the late afternoon and evening too when people are travelling home.

Air pollution is different on different days, it’s usually lower at the weekend than on weekdays.