Air Pollution

Air pollution is caused by releasing gases into the atmosphere. These gases may be made when fuels are burned or may be used in manufacturing. Many of the effects of air pollution have global implications.There are three major air pollution issues at the moment.

  1. Global warming (The green house effect)
  2. Depletion of the Ozone layer
  3. Acid rain

These problems will be dealt seperately.

The Greenhouse Effect - Global Warming

The heat energy from the sun warms up the Earth. Some of this energy radiates back into space. The water and carbon dioxide in the atmosphere absorb some of this radiated energy and pass it back to the Earth. As a result the Earth gets warmer. In recent years it has been discovered that the average temperature of the Earth has been rising. Scientists have also noticed that the amount of carbon dioxide in the atmosphere has increased. Scientists now think these two facts are linked.

Scientists fear that further increases in the Earth's temperature could have dramatic effects. For some places the weather will be pleasantly warmer. It is envisioned that the weather in Britain will be like the south of France. Many areas though could turn to desert. Central USA, where corn and wheat are grown for the world market, may be unable to sustain the crops due to drought. Other food producing areas could be equally effected. The biggest fear is that even a slight increase in the average temperature of the Earth (possibly only 1°C) could melt some of the ice at the polar ice caps. This would cause the sea level to rise and low-level land could flood. The main cause of the increase in CO2 levels in the atmosphere is the increase in burning of fossil fuels. Another problem is the cutting down of the rain forrests which absorb CO2 for photosynthesis. Get rid of the trees and you reduce the amount of CO2 which is absorbed.

Depletion of the Ozone Layer

The Ozone layer is a layer of gas about 5 km thick at a distance of 25-30km above the Earth's surface. Ozone (O3) absorbs harmful ultraviolet (U.V.) radiation from sunlight. U.V. light can cause skin cancer and cataracts over the eyes. It also kill phytoplankton in the sea. Phytoplankton is the main food source of the sea. In recent years it has been discovered that there are hole developing in the ozone layer. This has resulted in an increase in the number of skin cancer cases. Scientists believe the main cause of this Ozone depletion is the reaction between ozone and the CFC gases which have been released from aerosol sprays and old fridges. The amount of CFCs used in aerosols has been greatly reduced, but there are still CFC gases used in fridges. Even if the CFCs are totally eradicated, it will be some time before the Ozone holes heal. By then many people may have died from skin cancer.

Acid Rain

Normal rain has a slightly acidic pH due to dissolved carbon dioxide, but some rain is more acidic than this. It is caused by sulphur dioxide and oxides of nitrogen. The main source of these gases is from burning fossil fuels, especially coal. The acid rain has a number of effects.

  1. It kills plants and has wiped out many trees in some forests in places like Germany. The acid causes toxic ions to be released into the water in the soil. These are absorbed by the plants. The animals which depend on the plants will also die.
  2. It makes lakes acidic and kills plant and animal life.
  3. It dissolves brick work in buildings and can cause structural damage.

It does not need to actually rain to cause a problem. A dry deposition can coat plantlife with an acidic dust. This can often be felt by humans as the air causes peoples eyes to sting.

Countries which suffer the problem generally do not create the pollution. They try to deal with it by neutralizing the acid with lime, but this is only a temporary cure.To deal with the problem properly the gases which cause acid rain ought to be removed from the smoke before it is let into the atmosphere. This is effective but expensive and without government funding, companies are reluctant to spend the money, especially as the pollution does not effect their own country.