Pollution occurs when waste is not disposed of properly or when there is too much waste. There are three main types of pollution: air, water, and land pollution. Air pollution happens when pollutants such as dust, smoke, and toxic gases from factories are released into the environment and can combine to form smog. Breathing air pollution can cause health problems and acid rain damages the environment. Both natural causes like volcanoes and human activities from industries, vehicles, and construction can contribute to air pollution.