Air pollution
Air pollution is contamination of the atmosphere by substances or energy that harm human health, other organisms, or ecosystems.
Particulate matter: A mixture of tiny solid particles and liquid droplets suspended in air. These airborne particles are a major pollutant class, especially when small enough to enter deep into lungs.
Air quality index: A scale that communicates how current or forecast air pollution may affect health. It translates measured pollutant concentrations into public-facing health guidance.
Air pollution and health: The effects of airborne contaminants on human health, including respiratory and cardiovascular disease. It summarizes the bodily harms that motivate air-quality standards and pollution controls.
Fossil fuel combustion: The burning of coal, oil, or natural gas to release usable energy. Combustion emits pollutants directly and supplies precursors for secondary pollution.
Indoor air pollution: Contamination of air inside buildings by particles, gases, or biological agents at harmful levels. It shares health hazards with outdoor pollution but involves distinct sources and exposure settings.
Ground-level ozone: A reactive gas formed near the ground when sunlight drives reactions among nitrogen oxides and volatile organic compounds. It forms in polluted air rather than being emitted directly, illustrating how atmospheric chemistry creates pollutants.
Air quality monitoring: The systematic measurement of pollutants in outdoor or indoor air. Monitoring establishes pollution levels, reveals patterns, and checks whether standards are met.
Asthma: A chronic respiratory condition involving inflamed, narrowed airways and recurring breathing symptoms. Air pollutants can trigger symptoms and contribute to asthma attacks.
Motor vehicle emissions: Gases and particles released by road vehicles through exhaust, fuel evaporation, and tire or brake wear. Traffic is a concentrated urban source of nitrogen oxides, particles, and other pollutants.
Greenhouse gas: A gas that absorbs and emits infrared radiation, contributing to the greenhouse effect. Some pollutants also warm the climate, but many greenhouse gases are not directly toxic at ambient levels.