Pollution


Pollution is the introduction of contaminants into the natural environment that cause harm. Pollution can take the form of any substance or energy. Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants.
Although environmental pollution can be caused by natural events, the word pollution generally implies that the contaminants have a human source, such as manufacturing, extractive industries, poor waste management, transportation or agriculture. Pollution is often classed as point source, or nonpoint source pollution.
Many sources of pollution were unregulated parts of industrialization during the 19th and 20th centuries until the emergence of environmental regulation and pollution policy in the later half of the 20th century. Sites where historically polluting industries released persistent pollutants may have legacy pollution long after the source of the pollution is stopped. Major forms of pollution include air pollution, water pollution, litter, noise pollution, plastic pollution, soil contamination, radioactive contamination, thermal pollution, light pollution, and visual pollution.
Pollution has widespread consequences on human and environmental health, having systematic impact on social and economic systems. In 2019, pollution killed approximately nine million people worldwide ; about three-quarters of these deaths were caused by air pollution. A 2022 literature review found that levels of anthropogenic chemical pollution have exceeded planetary boundaries and now threaten entire ecosystems around the world. Pollutants frequently have outsized impacts on vulnerable populations, such as children and the elderly, and marginalized communities, because polluting industries and toxic waste sites tend to be collocated with populations with less economic and political power. This outsized impact is a core reason for the formation of the environmental justice movement, and continues to be a core element of environmental conflicts, particularly in the Global South.
Because of the impacts of these chemicals, local, country-level, and international policy have increasingly sought to regulate pollutants, resulting in increasing air and water quality standards, alongside regulation of specific waste streams. Regional and national policy is typically supervised by environmental agencies or ministries, while international efforts are coordinated by the UN Environmental Program and other treaty bodies. Pollution mitigation is an important part of all of the Sustainable Development Goals.

Definitions and types

The term "pollution" in the modern environmental sense was rare before the 1860s. The old sense referred to the desecration of something sacred. According to Adam Rome:
To describe what we now call air pollution–i.e., the gaseous, chemical, and metallic by-products of combustion and industrial processes–people usually talked of "the smoke nuisance." There were several variations of that term–"the smoke problem," "the smoke evil," even "the smoke plague."

Various definitions of pollution exist, which may or may not recognize certain types, such as noise pollution or greenhouse gases. The United States Environmental Protection Agency defines pollution as "Any substances in water, soil, or air that degrade the natural quality of the environment, offend the senses of sight, taste, or smell, or cause a health hazard. The usefulness of the natural resource is usually impaired by the presence of pollutants and contaminants." In contrast, the United Nations considers pollution to be the "presence of substances and heat in environmental media whose nature, location, or quantity produces undesirable environmental effects."File:Smog in the centre of Moscow, 06.08.2010.JPG|thumb|Smog in the center of Moscow, Russia in August 2010
The major forms of pollution are listed below along with the particular contaminants relevant to each of them:
One of the most significant natural sources of pollution are volcanoes, which during eruptions release large quantities of harmful gases into the atmosphere. Volcanic gases include carbon dioxide, which can be fatal in large concentrations and contributes to climate change, hydrogen halides which can cause acid rain, sulfur dioxide, which is harmful to animals and damages the ozone layer, and hydrogen sulfide, which is capable of killing humans at concentrations of less than 1 part per thousand. Volcanic emissions also include fine and ultrafine particles which may contain toxic chemicals and substances such as arsenic, lead, and mercury.
Wildfires, which can be caused naturally by lightning strikes, are also a significant source of air pollution. Wildfire smoke contains significant quantities of both carbon dioxide and carbon monoxide, which can cause suffocation. Large quantities of fine particulates are found within wildfire smoke as well, which pose a health risk to animals.

Human generation

are one of the leading causes of air pollution. China, United States, Russia, India, Mexico, and Japan are the world leaders in air pollution emissions. Principal stationary pollution sources include chemical plants, coal-fired power plants, oil refineries, petrochemical plants, nuclear waste disposal activity, incinerators, large livestock farms, PVC factories, metals production factories, plastics factories, and other heavy industry. Agricultural air pollution comes from contemporary practices which include clear felling and burning of natural vegetation as well as spraying of pesticides and herbicides.
About 400 million metric tons of hazardous wastes are generated each year. The United States alone produces about 250 million metric tons. Americans constitute less than 5% of the world's population, but produce roughly 25% of the world's carbon dioxide|, and generate approximately 30% of world's waste. In 2007, China overtook the United States as the world's biggest producer of, while still far behind based on per capita pollution.
File:Yangzhou - industrial area west of Wenfeng Temple - P1130239.JPG|thumb|An industrial area, with a power plant, south of Yangzhou's downtown, China
Chlorinated hydrocarbons, heavy metals, MTBE, zinc, arsenic, and benzene are some of the most frequent soil contaminants. A series of press reports published in 2001, culminating in the publication of the book Fateful Harvest, revealed a widespread practise of recycling industrial leftovers into fertilizer, resulting in metal poisoning of the soil. Ordinary municipal landfills are the source of many chemical substances entering the soil environment, emanating from the wide variety of refuse accepted, especially substances illegally discarded there, or from pre-1970 landfills that may have been subject to little control in the U.S. or EU. There have also been some unusual releases of polychlorinated dibenzodioxins, commonly called dioxins for simplicity, such as TCDD.
Pollution can also occur as a result of natural disasters. Hurricanes, for example, frequently result in sewage contamination and petrochemical spills from burst boats or automobiles. When coastal oil rigs or refineries are involved, larger-scale and environmental damage is not unusual. When accidents occur, some pollution sources, such as nuclear power stations or oil ships, can create extensive and potentially catastrophic emissions.
Plastic pollution is choking our oceans by making plastic gyres, entangling marine animals, poisoning our food and water supply, and ultimately inflicting havoc on the health and well-being of humans and wildlife globally. With the exception of a small amount that has been incinerating, virtually every piece of plastic that was ever made in the past still exists in one form or another. And since most of the plastics do not biodegrade in any meaningful sense, all that plastic waste could exist for hundreds or even thousands of years. If plastic production is not circumscribed, plastic pollution will be disastrous and will eventually outweigh fish in oceans.
Raised levels of greenhouse gases such as carbon dioxide in the atmosphere are affecting the Earth's climate. Disruption of the environment can also highlight the connection between areas of pollution that would normally be classified separately, such as those of water and air. Recent studies have investigated the potential for long-term rising levels of atmospheric carbon dioxide to cause slight but critical increases in the acidity of ocean waters, and the possible effects of this on marine ecosystems.
In February 2007, a report by the UN's Intergovernmental Panel on Climate Change, representing the work of 2,500 scientists, economists, and policymakers from more than 120 countries, confirmed that humans have been the primary cause of global warming since 1950. Humans have ways to cut greenhouse gas emissions and avoid the consequences of global warming, a major climate report concluded. But to change the climate, the transition from fossil fuels like coal and oil needs to occur within decades, according to the IPCC's final 2007 report.