Polluent

Polluent is a term used to describe a substance or agent that causes pollution. In scientific usage, the standard term is pollutant; polluent may be encountered as a misspelling or as an informal variant in non-technical writing. When used, it generally carries the same meaning as pollutant: a material that enters air, water, or soil and degrades environmental quality or harms living organisms.

Polluents can be categorized by medium: air polluents (e.g., sulfur dioxide, nitrogen oxides, ozone, particulate matter), aquatic polluents (nitrates, phosphates, pesticides, heavy metals, pharmaceuticals), and soil polluents (hydrocarbons, persistent organic pollutants, metals). They can also be described by source (point-source like a factory discharge; nonpoint-source like agricultural runoff) and by effect (toxicants, irritants, nutrients causing eutrophication).

Concentration and exposure determine risk. Polluents are typically quantified in units such as micrograms per cubic meter for air or milligrams per liter for water, and risk assessments consider dose, duration, and population sensitivity. Health effects range from respiratory irritation and cardiovascular problems to neurological impacts and ecosystem disruption; some polluents bioaccumulate.

Mitigation includes emission controls, filtration, water treatment, and remediation of contaminated sites. Regulatory frameworks establish permissible limits, monitoring requirements, and reporting obligations. Because polluent is not standard in many jurisdictions, most policies reference pollutant or contaminant terms.