Updated: Sep 14, 2022
CO is one of six common air pollutants regulated by the U.S. Environmental Protection Agency (EPA). Known as a criteria pollutant, the Clean Air Act requires the EPA to set National Ambient Air Quality Standards (NAAQS) for CO, as well as ground-level ozone, particulate matter, lead, sulfur dioxide, and nitrogen dioxide – all of which are known to harm your health, your property, or the environment generally.
What is Carbon Monoxide?
Again: CO is a colorless, odorless gas that can be harmful when inhaled in large amounts. Carbon monoxide is released when something is burned.
The greatest sources of CO are:
Cars, trucks and other vehicles or machinery that burn fossil fuels
Items in your home such as unvented kerosene and gas space heaters, leaking chimneys and furnaces, and gas stoves
How Can Carbon Monoxide Impact Your Health?
Here’s why carbon monoxide is so deadly: When you breathe air with a high concentration of CO, it reduces the amount of oxygen that can be transported in the bloodstream to critical organs such as the heart and brain.
As previously discussed, CO can cause dizziness, confusion, unconsciousness and death when inhaled at very high levels – something that is far more likely to happen indoors than outside.
The fact is, extremely elevated levels of CO aren’t very likely outdoors. In the rare instance that outdoor CO levels are elevated, it can be a concern for folks with some types of cardiovascular issues.
That’s because people with heart disease already have a reduced ability to get oxygenated blood to their hearts when more oxygen than usual is needed. And it means they are particularly vulnerable to the potential health impacts from CO when they exercise or otherwise under increased stress.
For these people, even short-term exposure to elevated carbon monoxide levels could lead to waning oxygen to the heart, leading to chest pain (which is also known as angina).
How is Carbon Monoxide Regulated? How Much is Too Much?
According to the EPA’s National Ambient Air Quality Standards, carbon monoxide levels are not permitted to exceed an average of 9 ppm (parts per million) over an eight-hour period, or an average of 35 ppm during any one-hour period in a calendar year.
Some Good News About Carbon Monoxide Levels
The EPA requires that states meet NAAQS standards for each of the criteria pollutants, including carbon monoxide.
Areas within each state are “designated” as either attaining carbon monoxide standards or not meeting them – in some cases, an entire state may attain a standard. Those areas that do not meet the standards are known as “nonattainment areas.”
The good news when it comes to carbon monoxide levels in the U.S.? According to the EPA, there have been no nonattainment areas for CO as of 2010 (the most recent federal data available).