What is air pollution?
Air pollution is the release of particles and noxious gases into the atmosphere; these emissions can be natural or manmade
and are considered to have an effect on human health.
Natural emissions of particles come from the sea, the soil and from
plants. Manmade emissions are largely the result of the combustion of fossil fuels such as coal, oil, petrol or diesel.
The main pollutants of concern are carbon monoxide, nitrogen dioxide, ground level ozone, particulates, sulphur
dioxide, hydrocarbons and lead. Each has different sources, health effects and chemical behaviours, making the task of
understanding and controlling air pollution as a whole very complex.
While it is we who produce the pollution, it is primarily the weather that dictates what will happen once it is released
into the air. During wet or windy conditions pollution concentrations remain low, either blown away, or removed from the air by rain.
During still hot weather pollution is able to build up to harmful amounts, leading to what are
known as pollution episodes. Concentrations also increase in winter
when low winds lead to a build up of traffic pollution in London.