Particulate matter is a mix of tiny solid particles and liquid droplets in the air. It comes from vehicle exhaust, power plants, fires, construction dust, and chemical reactions in the atmosphere. The particles vary in size. PM10 is coarser, like dust and pollen. PM2.5 is fine enough to penetrate deep into the lungs and enter the bloodstream.

Health effects are severe. PM2.5 exposure causes heart attacks, strokes, lung cancer, and asthma attacks. It is linked to premature birth and cognitive decline. The World Health Organization calls it one of the greatest environmental risks to health. Millions die each year from exposure. The smallest particles are the most dangerous because the body cannot expel them.

Reducing particulate matter requires action at the source. Cleaner fuels, filters on smokestacks, and electric vehicles cut emissions. Indoor cooking with clean stoves saves lives in developing countries. Air quality monitoring helps identify hotspots. Cities like Beijing have reduced PM2.5 significantly through these measures. The problem is solvable with technology and political will.

Common sources

• Vehicle exhaust
• Coal and biomass burning
• Wildfires and agricultural burning
• Construction dust
• Industrial processes