PM2.5, PM10, AQI levels, and air pollution worldwide
This air quality monitor displays live PM2.5, PM10, ozone, nitrogen dioxide, and AQI readings worldwide. Users searching for air quality near me, AQI today, or smoke air quality can see current pollution levels, dominant pollutants, and health category assessments from monitoring stations globally.
The Air Quality Index converts pollutant concentrations into a 0–500 scale with categories from Good (0–50) through Moderate (51–100), Unhealthy for Sensitive Groups (101–150), Unhealthy (151–200), Very Unhealthy (201–300), and Hazardous (301+). The dominant pollutant — usually PM2.5 in wildfire-affected and urban areas, or ozone during hot stagnant days — sets the overall AQI. Different countries use slightly different index scales, but health categories align.
PM2.5 refers to fine particulate matter under 2.5 micrometres. These particles bypass airway defenses and penetrate deep into lung tissue and bloodstream, driving cardiovascular and respiratory mortality. The WHO 2021 guideline sets the annual mean limit at 5 µg/m³, down from 10 µg/m³ in earlier versions. Many major cities routinely exceed 35 µg/m³ during pollution episodes, with peaks during wildfires, winter heating seasons, and atmospheric inversion events.
Major pollution sources include vehicle emissions (NOx, particulates), coal and biomass combustion (PM, SO2), industrial processes, agricultural ammonia (precursor to secondary PM), wildfire smoke, dust storms, and volcanic gases. Secondary pollutants like ground-level ozone form through photochemical reactions during sunny stagnant weather. Indoor pollution from cookstoves, smoking, and building materials adds substantially to total exposure for many populations.
When AQI exceeds 150, sensitive groups should limit prolonged outdoor exertion. When AQI exceeds 200, all populations should reduce outdoor activity. N95 or KN95 respirators provide effective protection from PM2.5 when properly fitted; surgical and cloth masks offer minimal protection from fine particles. Indoor air filtration with HEPA units, sealing air leaks during pollution events, and limiting cooking emissions are key residential protections.
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