What are the main types of pollution, and what can be done to prevent pollution or to reduce its effects?

Media coverage of pollution of our air and water and land often shocks us. Environmental research has given us valuable information about the different aspects of pollution, and it behoves us to be aware of our often inadvertent interference with the environment so that we will be able to take intelligent and appropriate steps to avert a possible catastrophe -- our own destruction through environmental pollution. Pollution can affect what we eat, our air and the water we drink.
Pollution can be incidental, usually the result of an accident as in Bhopal in India or at Chernobyil in the former USSR. Then there is persistent pollution - pollution that goes on all the time but does not receive as much attention as incidental pollution. We are all familiar with the pollution caused by thick smoke from factories and the damage caused to the ozone layer of the atmosphere by the use of aerosol sprays.

Air is polluted by substances that may occur as solid particles, liquid droplets, gases or as mixtures of these forms. Carbon monoxide (CO) is the most abundant and widely distributed in the air we breathe. Anthropogenic source contributes most to this type of pollution. The presence of CO in motor-car exhaust is well known. Other pollutants in emissions of internal combustion engines are hydrocarbons and nitrogen oxides. Air is also polluted by sulphur oxides. Apart from these gases there are small, solid particles and liquid droplets collectively called particulates which are feared to affect the respiratory system. Modification of the internal combustion engines and development of exhaust system reactors are two measures to control pollution by motor-car emissions. The four types of equipment used to control particulate emissions are gravity settling chamber, cyclone collector, wet scrubbers and electrostatic precipitators.

The signs of water pollution are obvious: disgusting odours from lakes and beaches, shortage of drinking water, the toll on fish population and oil floating on the surface of water. Pollutants from such sources as sewage, industrial wastes and effluent from slaughterhouses reduce dissolved oxygen in water which is a fundamental requirement for animal and plant life in water. Lakes suffer from acidification. Acidity damages aquatic life. Burning of fossil fuels, such as coal and oil, in power stations, factories, engines and other combustion processes produce sulphur and nitrogen gases which combine with oxygen and water vapour and finally causes acid rain. Generally water has buffering ions to neutralise acidity. When it lacks them, alkaline substances can be added. Environmental damage caused by acid rain can also be lessened by reducing the amount of sulphur and nitrogen gases released into the atmosphere.

Our dependence on oil-based technology leads to oil pollution of water, especially the sea. Oil spills such as the blowout in 1969 at Santa Barbara when 10,000 tons of oil entered the ocean are