What Are the Sources of Air Pollution?

Air pollution is predominantly caused by production-related pollution, which specifically includes:

① Fuel combustion: The burning of coal and petroleum releases large quantities of harmful substances. For example, coal combustion produces smoke and dust as well as sulfur dioxide (SO₂), while oil combustion generates sulfur dioxide, carbon monoxide (CO), and other pollutants.

② Industrial exhaust gases: Production processes emit smoke, dust, and waste gases. Thermal power plants, iron and steel mills, petrochemical plants, and cement factories are among the most prominent polluters.

③ Agricultural pollution: This includes ammonia volatilization caused by fertilizer application (which reacts with acidic substances to form ammonium salts, an important component of PM2.5); crop straw burning (which releases large amounts of PM2.5, CO, and polycyclic aromatic hydrocarbons, PAHs); and dust particles and droplets produced during pesticide spraying.

Next is domestic pollution. Coal burning in household cooking stoves and heating boilers emits smoke, dust, sulfur dioxide, and other harmful gases.

In addition, there is traffic pollution. Motor vehicles, trains, ships, and aircraft all discharge exhaust gases. Among these, motor vehicle exhaust is closest to the human breathing zone and can be directly inhaled. Its primary pollutants include nitrogen oxides (NOₓ), hydrocarbons, carbon monoxide, and particulate matter (PM2.5/PM10), among others.