What is the ambient residential carbon monoxide action level according to EPA?

The ambient residential carbon monoxide action level set by the Environmental Protection Agency (EPA) is 9 parts per million (ppm). This level is significant because it is established to protect public health from the harmful effects of carbon monoxide exposure, which can occur in residential settings through sources such as gas appliances, fireplaces, and vehicles running in enclosed spaces. Continuous exposure to levels above this action level can lead to adverse health effects, particularly for vulnerable populations such as children, elderly individuals, and people with pre-existing health conditions. Maintaining carbon monoxide levels at or below 9 ppm helps ensure a safer living environment and reflects the importance of monitoring air quality in homes.