A 50-minute lesson, such as the one outlined in the section on Classroom Applications , provides only a brief overview of some of the issues that are involved. If time allows, teachers are advised to combine or follow up this lesson with some of the materials outlined in the section on Internet Resources to create a more extensive teaching unit. Air pollution is any visible or invisible substance found in the air that is not part of the normal composition of air. Some air pollution is natural and has always been a part of the earth's history. However, over the past one hundred years or so, pollution created by humans has become a major environmental problem.
Air pollution affects everyone.
It is a threat to the health of human beings and many other living things on the planet. Pollutants in the air produce smog and acid rain. They also cause cancer and many other serious health problems. They cause ozone depletion in the upper atmosphere , and they increase the possibility of global climate change. Most people are familiar with visible air pollution, like smog, but some of the most dangerous air pollutants are invisible to the human eye.