Pollution

Pollution is the release of harmful environmental contaminants, or the substances so

Pollution

released. Generally the process needs to result from human activity to be regarded as pollution. Even relatively benign products of human activity are liable to be regarded as pollution, if they precipitate negative effects later on. The nitrogen oxides produced by industry are often referred to as pollution, for example, although the substances themselves are not harmful. In fact, it is solar energy (sunlight) that converts these compounds to smog.

Pollution can take two major forms: local pollution and global pollution. In the past, only local pollution was thought to be a problem. For example, coal burning produces smoke, which in sufficient concentrations can be a health hazard. One slogan, taught in schools, was "The solution to pollution is dilution." The theory was that sufficiently diluted pollution could cause no damage. In recent decades, awareness has been rising that some forms of pollution pose a global problem. For example, human activity (primarily nuclear testing) has significantly raised the levels of background radiation, which may lead to human health problems, all over the world. Awareness of both kinds of pollution, among other things, has led to the environmentalism movement, which seeks to limit the human impact on the environment.

Carbon dioxide emissions are sometimes referred to as pollution, on the basis that these emissions have led, or are leading, to raised levels of the gas in the atmosphere and, furthermore, to harmful changes in the Earth's climate. Such claims are strongly disputed, particularly by political conservatives in Western countries and most strongly in the United States. Due to this controversy, in many contexts carbon dioxide from such sources is labeled neutrally as "emissions.

Traditional forms of pollution include land pollution, air pollution, water pollution, and radioactive contamination while a broader interpretation of the word has led to the ideas of ship pollution, light pollution, and noise pollution.