Pollutants found in indoor air are often several times higher than outdoors. Indoor air pollutants cause effects ranging from odor, annoyance, and irritation to illness, cancer, and even death. Since people spend the majority of their time indoors, it is important to recognize and control indoor air pollution. Some indoor air pollutants also adversely affect materials in the building and the building structure itself. The majority of indoor pollution comes from the building itself, its contents, or its occupants and their activities. Building materials and consumer products are important sources of indoor air pollutants. Some outdoor air pollutants enter with ventilation air. Interactions between substances in indoor air can also produce pollutants and some of these are more odorous, irritating, or hazardous than the chemicals that form them. Reducing or eliminating pollution sources best achieves control of indoor air quality. Appropriate ventilation strategies can reduce concentrations of pollutants that can't be eliminated by source control.
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