Pollution is the most serious of all environmental problems and poses a major threat to the health and well-being of millions of people and global ecosystems. Other major environmental problems are either wholly or partly caused by pollution; these include global warming, climatic change and the loss of biodiversity through the extinction of many species. In the future, environmental pressures can only increase as a result of population growth and the expectation of higher living standards. For at least thirty years people have become increasingly aware of these issues. As a result governments and regulatory bodies have responded by taking action against grossly polluting activities and by enforcing tighter limits on the emission of pollutants into the environment. As the level of control improves so the financial costs increase exponentially, hence an effective limit must be imposed which does not impose unacceptable burdens on industrial producers. As a consequence of the increasing economic and legal pressures which result from pollution control, there is a growing need for greater under- standing of the scientific principles underlying environmental pollution.