Using a nationwide network of monitoring sites, EPA has developed ambient air quality trends for carbon monoxide (CO). Trends starting in 1980, 1990, and 2000 are shown here. Under the Clean Air Act, EPA sets and reviews national air quality standards for CO. 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. For information on CO standards, sources, health effects, and programs to reduce CO, please see www.epa.gov/airquality/carbonmonoxide.
Air quality trends can vary regionally. The following climatically consistent regions within the contiguous United States provide a relevant way to look at regional trends in air quality.
Air quality trends can vary from one area to another. Local trends can be viewed at individual monitoring locations in the map below or in this KML file (KML, 352 KB) using Google Earth or another KML browser.Carbon monoxide monitors that meet mimimum trends completeness criteria
Carbon monoxide monitors that have some data during the trend period but do not meet the mimimum trends completeness criteria for 1990-2012