The Occupational Safety and Health Administration has established safe carbon monoxide levels at a maximum of 50 parts per million in enclosed spaces, according to the U.S. Department of Labor. These standards apply to work environments in construction, maritime or general industry.
Carbon monoxide is a colorless, odorless gas that has adverse physiological effects when highly concentrated, states the Centers for Disease Control and Prevention. Overexposure leads to headache, rapid breathing, nausea or weakness. Victims may also experience dizziness, confusion or hallucinations along with blue coloring, chest pain or fainting. Exposure occurs through inhalation, skin or eye contact and affects the cardiovascular system, lungs, blood and central nervous system.