There are quite a lot of factors (leading) in air pollution, particularly in our modern time. The first source of pollutants comes from urban settings including sulfur dioxide, nitrogen dioxide, and carbon monoxide. These (are emitted) directly into the air from fossil fuels such as fuel oil, gasoline, and natural gas that (bring) in power plants, automobiles, residential heating systems and other industrial processes. Other pollutants in the atmosphere (include) dust, smokes, fumes, and mists. They are significant air pollutants because of their very harmful (effects) on human health. Very small solid materials or liquid droplets in the atmosphere are also very harmful (because) when we breathe in, these materials will (result) to our respiratory system. Carbon monoxide is an odourless, invisible gas which is formed (as a result of) incomplete combustion. It is the most abundant of air pollutants. Gasoline-powered (vehicles) are the main source, although residential heating systems and certain industrial processes also emit significant amounts of this gas. Exposure to carbon monoxide can be harmful since it displaces oxygen in the bloodstream, (resulting in) difficulty in breathing at high concentrations.