Carbon Monoxide Trends
Air quality monitors measure concentrations of CO throughout the country. EPA, state, tribal and local agencies use that data to ensure that CO remains at levels that protect public health and the environment. Nationally, average CO concentrations have decreased substantially over the years. The charts below show national and regional trends in CO concentrations. For information on CO standards, sources, health effects, and programs to reduce CO, please see our Carbon Monoxide Pollution page.