The causes of air pollution come from both natural and human activities and include a variety of pollutants released into the air:
- Burning of fossil fuels such as coal, oil, petroleum, and gasoline for electricity, transportation, and industrial activities. This releases pollutants like sulfur dioxide, nitrogen oxides, carbon monoxide, particulate matter, and volatile organic compounds (VOCs).
- Traffic emissions from petrol and diesel vehicles emit carbon monoxide, nitrogen oxides, VOCs, and particulate matter, which are major contributors to urban air pollution and smog formation.
- Industrial sources including power plants, factories, oil refining, construction, mining, and use of hazardous materials emit a range of pollutants including heavy metals, particulate matter, and chemical pollutants.
- Household activities such as burning wood, coal, charcoal, and other fuels for cooking and heating, indoor tobacco smoking, use of gas stoves, and household chemicals contribute to indoor and outdoor air pollution.
- Agricultural activities produce methane and ammonia from livestock digestion and fertilizer use, which contribute to ozone formation and particulate pollution. Open burning of agricultural waste also releases harmful emissions.
- Natural sources like wildfires, dust storms, volcanic ash, pollen, and sea salt particles contribute to air pollution although their impact is often episodic or seasonal.
- Waste burning and open dumps release soot, methane and toxic gases that pollute the air especially in low-income regions where waste is improperly disposed.
- Chemical products and solvents including volatile organic compounds emitted from paints, cleaning agents, personal care products, and degreasing operations also exacerbate air pollution.
These pollutants can come from direct emissions or form as secondary pollutants such as ozone, generated by sunlight-driven reactions in the atmosphere. The combined effect of these sources causes smog, haze, acid rain, and various health hazards, posing serious threats to human health and the environment worldwide.
