Exposure to indoor contaminants represents one of the most wide-spread exposures affecting public employees. Contaminants generated indoors can be concentrated in indoor air by inadequate or improperly operating ventilation systems that do not provide enough dilution ventilation. Contaminants can also be introduced by construction/ renovation projects within the building or from exterior sources entering a building. Health effects caused poor indoor air quality can range from general malaise, such as fatigue and headache to more serious symptoms such as asthma and infections. Indoor air quality issues represent approximately 60% of the complaints investigated by PEOSH.