The U.S. Environmental Protection Agency (EPA) on Monday announced it is proposing to keep the current national air quality standards for carbon monoxide (pdf), while it gathers more information from monitoring carbon monoxide levels in selected metropolitan areas.
According to the agency, the current standard is protective of public health, and would not put those susceptible to health problems associated with breathing carbon monoxide at risk. Carbon monoxide can cause harmful health effects by reducing oxygen delivery to the body’s organs and tissues. It is also recognized by the National Toxicology Program as a carcinogen. At extremely high levels, carbon monoxide can cause death.
Carbon monoxide is a colorless, odorless gas emitted from incomplete combustion processes. Nationally and particularly in urban areas, the majority of carbon monoxide emissions come from motor vehicles.
The EPA’s current health standard for carbon monoxide is 9 parts per million (ppm) measured over 8 hours, and 35 ppm measured over one hour. These are the same levels originally established by the agency in 1971. Since then, the EPA has reviewed the standard four times, finding after each review that the standard was protective of public health.
To develop more complete information about real world exposures to carbon monoxide, EPA is proposing to revise its air monitoring requirements. The proposed changes would require a more focused monitoring network with carbon monoxide monitors placed near highly travelled roads, in urban areas with populations of 1 million or more. The data from the monitors would be valuable in scientific studies used in future reviews.
The agency estimates that 77 carbon monoxide monitors in 53 urban areas will be needed to fully implement the proposed monitoring program.