Air Pollution When the air is dirty it has become polluted. Air pollution is made up of gases, dust, odors, particles, smoke, fumes, and other substances which can be harmful to humans, animals, plants, and all living organisms. The air is contaminated and unclean. Air pollution affects the Earth's atmosphere. The atmosphere of the Earth is like a blanket of air which protects all life. Without the atmosphere, life would not exist. The atmosphere protects living organisms from the heat of the Sun during the day, and at night it prevents the warm air from escaping. Basically, the atmosphere helps keep the living things on Earth from burning up or freezing. The pollution in the air, though, may affect this 'blanket' and becomes harmful to life on Earth. The substances in the air causing the dirty air are called pollutants . Some examples of pollutants may include gases called carbon monoxide, nitrogen oxide, hydrocarbons, and others. There may also be sand, dust particles, and other substances that evaporate and become pollutants. A primary pollutant is one that is directly released into the air causing pollution. An example is carbon monoxide, which comes from cars and trucks on the road. A second primary pollutant is sulfur dioxide, which comes from the burning of coal. A secondary pollutant is a substance or substances mix together in the air due to a chemical reaction. When these substances mix together, the air pollution is much more dangerous and harmful to organisms. An example is photochemical smog . It is difficult to avoid the pollution in the air since it is the place where people get the oxygen to breathe and live. Pollution can travel with the wind from one place to another and spread over a large number of miles. Pollution can be caused by humans or it can also occur naturally. For example, natural pollution may come from volcanoes, forest fires, wind storms, pollen in the air, and other sources in nature. The three main causes of pollution by humans includes the release of smoke and fumes from manufacturing plants and various industries. Power plants release carbon monoxide and furnaces that burn waste are two examples of manmade pollution. Gasoline refineries also release dangerous chemicals in the air called hydrocarbons. The second cause is the burning of fossil fuels such as from cars, trucks, trains, airplanes. This type of pollution occurs often because people rely on transportation every day. Another main cause of pollution is from household and farming chemicals. On farms crop dusting may pollute the air, homes may be sprayed with chemical to kill bugs or to help the grass grow. There are several effects of air pollution including acid rain , which is when rain is mixed with the pollution in the air. This acid rain can cause harm to trees, animals, fish, and other living organisms. It can cause problems with breathing and irritation to the eyes, nose, or throat. Sometimes people can also get headaches or have allergic reactions. Long-term effects can include lung cancer, heart disease and other health problems. In summary, air pollution is basically dirty air caused by chemical pollutants. There are primary and secondary pollutants and both can cause short-term or long-term problems for living things.