Air pollution, a major environmental risk to health, refers to the presence of pollutants in the air that can cause damage to living organisms or the atmosphere. Air pollutants can be solid particles, liquid droplets or gases that can be natural in origin or man-made. Some of the main air pollutants are particulate matter, ground level ozone, sulphur dioxide, nitrogen dioxide and carbon monoxide. Major sources of outdoor pollution include burning fossil fuels (coal and oil) for daily heating, power generation and operating motor vehicles such as cars, buses, etc. Other sources are dust from fields and rock quarries, as well as smoke from wood and crop fires. Another equally dangerous source of air pollution is smoking. The common practice of burning wood, charcoal and animal dung as fuel in chulhas exposes many people to an unprecedented amount of indoor pollutants. Sources of indoor pollution also include pollen, mould, household products, pesticides, etc. Annually, around 1.3 and two million untimely deaths can be attributed to outdoor and indoor air pollution respectively.
Air pollution is mainly responsible for respiratory related health problems that include dry cough, hay fever, allergies, bronchitis, wheezing, asthma, chest discomfort reduced lung function. It can also lead to heart disease, lung cancer, COPD, etc. and researches have linked it to developmental and mental disorders as well.