Acid Rain Facts



  • All rain is slightly acidic, but air pollution can turn rain into harmful acid rain.
  • Acid rain forms when sunlight makes sulphur dioxide and nitrogen oxide combine with oxygen and moisture in the air.
  • Sulphur dioxide and nitrogen oxides come from burning fossil fuels such as coal, oil and natural gas.
  • Acidity is measured in terms of pH. The lower the pH, the more acid the rain is. Normal rain has a pH of 6.5. Acid rain has a pH of 5.7 or less.
  • A pH of 2-3 has been recorded in many places in the eastern USA and central Europe.
  • Acid fog is ten times more acid than acid rain.
  • Acid rain washes aluminium from soil into lakes and streams, and so poisons fish. Limestone helps to neutralize the acid, but granite areas are vulnerable.
  • Spring meltwaters are especially acid and damaging.
  • Acid rain damages plants by removing nutrients from leaves and blocking the plants’ uptake of nitrogen.
  • Acid rain has damaged 20 percent of European trees; in Germany 60 percent of trees have been damaged.