pollution

Pollution is the introduction or presence of substances, energy, or organisms in the environment at levels that cause harm or discomfort to living organisms, ecosystems, or materials. It results from human activities and, to a lesser extent, natural processes such as volcanic eruptions, but the term is most commonly associated with anthropogenic contaminants. Pollution can be accidental or deliberate, and effects may be acute or chronic.

Common forms of pollution include air pollution (pollutants such as sulfur dioxide, nitrogen oxides, particulate matter, and volatile organic compounds); water pollution (pathogens, heavy metals, nutrients, chemical contaminants); soil and land pollution (industrial chemicals, pesticides, improper waste disposal); and noise, light, and thermal pollution. Plastic pollution, including microplastics, intersects several categories by spreading through air, water, and soil.

Pollution sources are varied. Major anthropogenic sources include energy production and industry, transportation, agriculture, and waste management. Natural sources, such as wildfires and volcanic activity, can contribute pollutants as well, though they typically have lower and shorter-lived impacts; human activity generally sustains longer-term, widespread pollution.

Impacts of pollution span human health, ecological integrity, and economic activity. Air and water pollutants can cause respiratory and cardiovascular diseases, gastrointestinal illness, and birth defects; pollution can reduce biodiversity, disrupt ecosystems, and degrade soil and water resources. Some pollutants also contribute to climate change.

Policy and technology address pollution through regulation, monitoring, and clean-up. Approaches include emission standards, environmental impact assessments, and pollution-control technologies; prevention strategies emphasize cleaner production, waste reduction, recycling, and proper waste disposal. Remediation and cleanup efforts target existing pollution in air, water, and soil.