airquality

Air quality refers to how clean or polluted the surrounding air is, relative to health, comfort, and environmental standards. It varies by location, time, weather, and human activity, and it can change over short intervals.

Major outdoor pollutants include fine particulate matter (PM2.5 and PM10), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), and volatile organic compounds (VOCs). Concentrations are reported in µg/m3 for particulates and in ppb or ppm for gases.

An Air Quality Index (AQI) translates pollutant levels into a single value to inform the public. Standards vary by country; international references include the WHO guidelines. Data are gathered from fixed monitoring stations, models, and increasingly satellite observations.

Poor outdoor air quality is linked to respiratory and cardiovascular diseases, asthma, infections, and premature death. Children, the elderly, and people with chronic conditions are especially vulnerable. It also affects ecosystems, visibility, and climate processes.

Sources include road traffic, industry, power generation, and agriculture, along with natural events such as wildfires and dust storms. Weather, topography, and seasonal patterns strongly influence pollutant concentrations and dispersion.

Monitoring uses ground-based networks, satellites, and low-cost sensors. Models forecast air quality and support policy. Indoor air quality—driven by building design and ventilation—is a related but distinct concern.

Mitigation focuses on reducing emissions, switching to cleaner energy, improving transport and urban planning, and enhancing ventilation standards. Public alerts during high-pollution episodes help protect health.