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The Lachine Canal, in Montreal, is badly pollutedPollution is the release of harmful environmental contaminants, or the substances so 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 all over the world, which may lead to human health problems. 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.
Whether something is pollution can depend on context. Blooms of algae and the resultant eutrophication of lakes and coastal ocean is considered pollution when it is fueled by nutrients from industrial, agricultural, or residential runoff.
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 are labelled neutrally as "emissions." See global warming for a very extensive discussion of this topic.
Traditional forms of pollution include air pollutionNew Mexico releases sulfur dioxide and particulate matter into the air. Air pollution is a broad term applied to all chemical and biological agents that modify the natural characteristics of the atmosphere. Some definitions also consider physical perturba, water pollutionWater pollution has many sources and characteristics. Humans and other organisms produce bodily wastes which enter rivers, lakes, oceans, and other surface waters; in high concentrations these wastes result in bacterial contamination and excessive nutrien, and radioactive contaminationRadioactive contamination is the uncontrolled distribution of radioactive material in a given environment. Many radioactive isotopes are produced artificially, either for their specific properties (such as medical radioisotopes) or as a byproduct (such as while a broader interpretation of the word has led to the ideas of ship pollutionShips can pollute the waterways and oceans in many ways. There are spills from oil tankers, sulfur dioxide and nitrogen dioxide gases from exhaust fumes. Ships create noise pollution that disturbs natural wildlife, and water from ballast tanks can spread, light pollutionLight pollution (also known as photopollution luminous pollution or just excessive or obtrusive lighting) is excess light, created by human activities. Among other effects, this can obscure the night sky enough to hide most stars and other celestial objec and noise pollutionAny man-made sound that penetrates the environment is noise pollution . Noise pollution can be caused by many sources including highways, vehicles, factories, concerts, air-conditioners, engines, machine, planes, helicopters, alarms, public address system.
Serious pollution sources include chemical plants, oilOil is a generic term for fluids that are not miscible with water. The name comes from Latin oleum for olive oil. Oil is frequently used to refer to petroleum an "oil shortage" generally means an inadequate supply of petroleum rather than cooking oil. refineries, nuclear waste dumps, regular garbage dumps (many toxic substances are illegally dumped there), incinerators, PVC factories, car factories, plastics factories, corporate animal farms creating huge amounts of animal waste. Some sources of pollution, such as nuclear power plants or oil tankers, can release very severe pollution when accidents occur. Some of the more common contaminants are: chlorinated hydrocarbons (CFH), heavy metals like lead (in lead paint and until recently in gasoline), cadmium (in rechargeable batteries), chromium, zinc, arsenic and benzene.
Pollutants are thought to play a part in a variety of maladies, including:
cancer, lupus, immune diseases, allergies, and asthma. Some illnesses are named in relation with certain pollutants: for example, Minamata disease caused by mercury compounds.
