Air pollution is a problem because it can cause damage to animals, trees, plants, crops and water sources in the environment. Pollution in the air causes problems for aviation because it reduces visibility, while also being responsible for damaging buildings and other structures. Pollutants in the air can end up in natural water supplies that humans use for drinking, which can result in water that is toxic and unhealthy for humans to consume. When polluted air in breathed in, it can cause symptoms such as burning eyes and nose, and can even trigger respiratory issues in those that have asthma. Chemicals found in polluted environments, such as vinyl chloride and benzene, are very toxic and can result in lung injuries, birth defects and cancer.