Understanding where pollution comes from helps explain air quality patterns and their health impacts. Different pollutants have different sources and effects.
Particulate Matter (PM)
PM2.5 consists of fine particles smaller than 2.5 micrometers from vehicle exhaust, wildfires, and industry. They penetrate deep into lungs and bloodstream, causing heart and lung disease. PM10 includes coarser particles (2.5-10 micrometers) from construction, road dust, and agricultural activities.
Ground-Level Ozone
Ozone is not emitted directly but forms when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react with sunlight. Levels peak on sunny summer afternoons in urban areas. It causes chest pain, worsens asthma, and reduces lung function.
Other Key Pollutants
Nitrogen Dioxide comes primarily from traffic and worsens asthma. Sulfur Dioxide from power plants creates acid rain. Carbon Monoxide from vehicle exhaust and heating reduces oxygen delivery to organs. Each pollutant has different peak times and locations.
Indoor Air Quality
Indoor pollution sources include cooking (especially gas stoves), heating, building materials releasing VOCs, cleaning products, and mold. Indoor AQI can be 2-5x higher than outdoor during certain activities like frying or using harsh cleaners.