Air pollution

You breathe in and out around 20,000 times every day without thinking about it. Most of the time the air is clean. But sometimes substances mix in that do not belong there: exhaust fumes, soot and tiny particles. You often cannot see them, but they can make people ill and harm nature. This is called air pollution.

Where the dirt comes from

Most pollutants come from burning. Cars and lorries emit exhaust fumes, and so do factories and heating systems. Power plants that burn coal or gas also blow substances into the air. On top of that come dust from building sites and tyre wear from the roads. In many cities traffic is the biggest source, in other areas it is industry or heating with wood and coal.

Smog and fine dust

When a lot of pollutants gather over a city, smog forms: a haze that blurs the view and stings the eyes. Fine dust is especially tricky, meaning tiny particles so small that they reach deep into the lungs. From there some of it can even pass into the blood. Because you cannot see or smell fine dust, its danger is easily underestimated.

Effects on people and the environment

Dirty air irritates the eyes and airways and can damage the heart and lungs over time. Children and older people are especially sensitive. Nature suffers too: sulphur and nitrogen oxides from exhaust gases combine with water in clouds and fall as acid rain, which harms forests and waters. Some pollutants even attack buildings and monuments, whose stone is slowly eaten away.

How the air gets cleaner

The good news: air can be cleaned. Filters on chimneys and on exhaust pipes hold back soot and dust, and the catalytic converter in a car turns poisonous exhaust gases into more harmless ones. Electric cars and electric buses give off no exhaust at all, even though dust still comes off their tyres and brakes. Anyone who cycles or walks produces almost none of either. In many cities the air is much cleaner today than thirty years ago, because laws set strict limits. A limit says how much of a pollutant may be in the air at most, for fine dust for example 50 micrograms per cubic metre. Cleaner air is therefore possible if many people help.