While most of us are aware of the dangers posed by outdoor air pollution, awareness of airborne chemical and biological pollutants present indoors and its implications for human health is more limited. Some indoor air gases and pollutants such as radon, asbestos, carbon monoxide, biological contaminants, and volatile organic compounds (VOCs) pose a serious threat to our health and well-being. Over the past several decades, our exposure to indoor air pollutants is believed to have increased due to a variety of factors, including the construction of more tightly sealed buildings; reduced ventilation rates to save energy; use of synthetic building materials and furnishings; and use of chemically formulated personal care products, pesticides, and household cleaners. Since an average person spends increasing amount of time indoors, it is important to understand the health risks posed by prolonged exposure to indoor pollutants and the energy and...