The problem of air pollution Air pollution is the biggest problem in the world. The definition of air pollution is “The presence in the atmosphere of one or more contaminants that are harmful, or tend to be harmful, to the health or well-being of humans, animals, or plants.” Acid rain and smog are the two main effects of air pollution. The main source of air pollution comes from industry, which causes many problems for plants, animals and humans. Thermoelectric power plants, refineries, petrochemical industries and mines release dangerous pollutants into the air; for example, sulfur dioxide, carbon monoxide, nitrogen oxides and lead. The burning of coal, the production of paper or the smelting of metals also cause terrible pollution. Private homes and office buildings are also responsible for air pollution. When chemical and synthetic materials are used for construction, air pollution can become a problem. Smoking, cooking, burning coal or wood at home causes indoor air pollution. If ventilation is poor, it's even worse. Additionally, active volcanoes, desert storms, and forest fires cause air pollution. Acid rain, smog and the greenhouse effect cause air pollution. Acid rain is a mixture of sulfuric and nitric acids, found in snow, rain and fog. It seriously affects soil, water, plants, buildings and the health of animals and people. Smog is a fog that contains smoke and ozone. It is found in areas where there are high temperatures, heavy traffic and occurs especially during the winter period when there is less wind. The reaction of ozone, nitrogen oxide and carbon monoxide with heat and sunlight produces smog. During the industrial revolution, 500 people died in London due to smog. A few years later, 1,000 people died when the smog lasted three days. In 1952, 4,000 people died there due to smog that lasted nearly a week. The greenhouse effect also causes air pollution. It increases the temperature of the world, as there is too much carbon dioxide and not enough oxygen due to pollutants in the air. Smog causes many health problems. Especially respiratory problems