Pollution is the introduction of contaminants into the natural environment that cause adverse change.[1] Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants.
Pollution has widespread consequences on human and environmental health, having systematic impact on social and economic systems. In 2019, pollution killed nine million people worldwide (one in six deaths), a number unchanged since 2015.[2][3][4]Air pollution accounted for 3⁄4 of these earlier deaths.[5][6] A 2022 literature review found that levels of anthropogenic chemical pollution have exceeded planetary boundaries and now threaten entire ecosystems around the world.[7][8] 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.[9] This outsized impact is a core reason for the formation of the environmental justice movement,[10][11] and continues to be a core element of environmental conflicts, particularly in the Global South.
Because of the impacts of these chemicals, local, country 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.[12]
: the overabundance of electromagnetic radiation in their non-ionizing form, such as radio and television transmissions, Wi-fi etc. Although there is no demonstrable effect on humans there can be interference with radio-astronomy and effects on safety systems of aircraft and cars.
Water pollution, caused by the discharge of industrial wastewater from commercial and industrial waste (intentionally or through spills) into surface waters; discharges of untreated sewage and chemical contaminants, such as chlorine, from treated sewage; and releases of waste and contaminants into flowing to surface waters (including urban runoff and agricultural runoff, which may contain chemical fertilizers and pesticides, as well as human feces from open defecation).[16][17][18]
surface runoff
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 Administration 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."[13] In contrast, the United Nations considers pollution to be the "presence of substances and heat in environmental media (air, water, land) whose nature, location, or quantity produces undesirable environmental effects."[14]
The major forms of pollution are listed below along with the particular contaminants relevant to each of them:
describes situations where toxins (such as heavy metals) may pass through trophic levels, becoming exponentially more concentrated in the process.
emissions cause ocean acidification, the ongoing decrease in the pH of the Earth's oceans as CO2 becomes dissolved.
Carbon dioxide
The emission of leads to global warming which affects ecosystems in many ways.
greenhouse gases
can outcompete native species and reduce biodiversity. Invasive plants can contribute debris and biomolecules (allelopathy) that can alter soil and chemical compositions of an environment, often reducing native species competitiveness.
Invasive species
are removed from the air by rain and fertilise land which can change the species composition of ecosystems.
Nitrogen oxides
and haze can reduce the amount of sunlight received by plants to carry out photosynthesis and leads to the production of tropospheric ozone which damages plants.
Smog
Soil can become infertile and unsuitable for plants. This will affect other in the food web.
Organic pollution of watercourses can deplete levels and reduce species diversity.
oxygen
Recycling
Reusing
Waste minimisation
Mitigating
Pollution prevention
Compost
Cost
Pollution has a cost.[68][69][70] Manufacturing activities that cause air pollution impose health and clean-up costs on the whole of society. A manufacturing activity that causes air pollution is an example of a negative externality in production. A negative externality in production occurs "when a firm's production reduces the well-being of others who are not compensated by the firm."[71] For example, if a laundry firm exists near a polluting steel manufacturing firm, there will be increased costs for the laundry firm because of the dirt and smoke produced by the steel manufacturing firm.[72] If external costs exist, such as those created by pollution, the manufacturer will choose to produce more of the product than would be produced if the manufacturer were required to pay all associated environmental costs. Because responsibility or consequence for self-directed action lies partly outside the self, an element of externalization is involved. If there are external benefits, such as in public safety, less of the good may be produced than would be the case if the producer were to receive payment for the external benefits to others. Goods and services that involve negative externalities in production, such as those that produce pollution, tend to be overproduced and underpriced since the externality is not being priced into the market.[71]
Pollution can also create costs for the firms producing the pollution. Sometimes firms choose, or are forced by regulation, to reduce the amount of pollution that they are producing. The associated costs of doing this are called abatement costs, or marginal abatement costs if measured by each additional unit.[73] In 2005 pollution abatement capital expenditures and operating costs in the US amounted to nearly $27 billion.[74]
