According to the EPA, there are 13 common indoor air pollutants divided into four categories: biological pollutants, combustion byproducts, legacy pollutants, and volatile organic compounds (VOCs).The last category includes a variety of chemicals released into the air from many indoor sources (indoor combustion sources such as tobacco smoke, heating or cooking, and burning of candles), and also from common household products including paints, furniture and construction materials, cleansers and disinfectants, air fresheners, indoor pesticides, etc. Polybrominated diphenyl ethers (PBDEs) are organic compounds used as flame retardants to achieve the required level of fire protection safety in a variety of commercial and domestic products,