Monday 2 July 2012


Britain was the first nation to coin the term ‘acid rain’: it was used to describe worrying conditions in Manchester over 100 years ago.

Acid rain is not a new phenomenon.  All rainfall has a natural acidity, but pollution in the atmosphere increases this acidity more than a thousand times.  Acid rain not only affects habitats when it falls as rain; acidity can also be present and be just as damaging in snow, hail, cloud, fog, mist or even airborne dust.

Burning coal and oil releases the gases sulphur dioxide and nitrogen oxide in the atmosphere.  Fumes from motor vehicles add more nitrogen oxides as well as hydrocarbons to this chemical cocktail.  Sunlight acts on the nitrogen oxide and hydrocarbons to create other pollutants such as ozone.

In turn these pollutants react with sulphur and nitrogen oxides to form sulphuric and nitric acid in the tiny droplets of water that go up to make the clouds.  In this form the acids are carried on the wind to fall as acid rain, often great distances away.

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