Air pollution

Air pollution is the presence of substances in the atmosphere that are harmful to humans and other living beings, or cause damage to the environment. Air pollution can be chemical, physical or biological. There are many different types of air pollutants, such as gases, particulates, lead and biological molecules. Air pollution can cause diseases, allergies, and even death; it can also cause harm to animals and crops and damage the natural environment or built environment. Air pollution can occur naturally or be caused by human activities.