Pollutants are compounds which are dangerous to the environment.

They can also be harmful to humans in the long-term range. They come from mineral and fossil sources or are produced by humans themselves.

Many pollutants have a poisonous effect on the body. Carbon monoxide is an example of a substance which is damaging to humans. This compound is taken up in the body instead of oxygen. That makes the body suffocate and in severe cases may lead to death.