Pollutant – It is a substance in the atmosphere, which has negative affects for plants, human beings, and animals. A pollutant may cause long or shirt term damage by spreading pollution by human beings activities in the atmosphere. There are many pollutants are biodegradable and so it will not preserve in the atmosphere for the long period. Several pollutants such as sulphur oxides,  carbon monoxide, nitrogen oxides, carbon dioxide, hydrocarbons, and many more.

Origin of Pollutants – There are several origins of pollutants, which are discussed below-

1. Sulphur dioxide – It is produced by the burning of fossil fuels such as oil and coal in home and industry. Coal always contains some sulphur as impurity, thus,  when coal is burned, the sulphur of coal burns to form sulphur dioxide, which goes into the air. Oils contains some sulphur compounds, which produce sulphur dioxide on burning. Sulphur dioxide is also emitted by the chemical industries engaged in the extraction of metals from their sulphide ores. When sulphur ores of metals such as copper, zinc, and iron are roasted in air, sulphur dioxide is produced and this sulphur dioxide goes into the air and pollutes it.
2. Carbon monoxide – Incomplete combustion of all carbon containing fuels, which produces carbon monoxide (Incomplete  combustion take place in insufficient supply of oxygen). Carbon monoxide is produced by the burning of wood, coal, and oil in factories and homes. The exhaust gases of the internal combustion engines such as cars, airplanes, trucks, buses, and many more contain a lot of carbon monoxide may spread in the atmosphere. Cigarette smoke is a yet another source of carbon monoxide.
3. Nitrogen oxides – Whenever a material burns in air, small amounts of nitrogen oxide is formed or produced because the heat produced by the burning material may causes some of the nitrogen and oxygen of the air to combine to form nitrogen oxides. Nitrogen oxides are also discharged into the air by car exhaust and some  chemical industries. Several biological processes such as the anaerobic breakdown of nitrogenous compounds by bacteria also produce nitrogen oxides.  Forest fires and lighting may constitute the natural sources of nitrogen oxides.
4. Hydrocarbons – Incomplete combustion of motor vehicle exhausts, fuels, and biological decomposition of organic matter from natural gas and fields, petro-chemical plants, and petroleum refineries are major sources for the release of hydrocarbons into the atmosphere.
5. Particulates – Particulate pollutants include stone dust, asbestos dust,  ordinary dust, common salt, lead, and agricultural chemicals such as herbicides, pesticides, insecticides, and fungicides. The main source of lead is the car exhaust fumes, which come from tetraethyl lead used as antiknock in petrol, Slate making units, lime kilns, cement factories, stone crushers quarries, asbestos, and sheet factories, all are sources of various particulate pollutants.