Tracking Air Quality

Outdoor Air Quality Monitoring in the United States: Monitoring Networks

Federal, state, local, and tribal air agencies operate and maintain a wide variety of outdoor air monitoring systems across the United States. Many of these systems serve several environmental objectives. At a basic level, they let us know how clean or polluted the air is, help us track progress in reducing air pollution, and inform the public about air quality in their communities through the Air Quality Index (AQI). The AQI is a tool to help you quickly learn when air pollution is likely to reach unhealthy levels.

Air Quality System Database

The Air Quality System (AQS) database contains ambient air pollution data. The data are collected by EPA and state, local, and tribal air pollution control agencies. The United States has approximately 4,000 monitoring stations, mainly in urban areas. AQS also contains meteorological data, information about each monitoring station such as its location and its operator, and data quality assurance and quality control information.

AQS is important because it helps EPA and others to

• assess air quality,
• assist in determining which areas of the country are meeting air quality standards,
• evaluate state plans for controlling air pollution,
• perform modeling for permit review analysis, and
• perform other air quality analyses such as trend analysis and health effect studies.

AQS information is also used to prepare reports for Congress, as required by the Clean Air Act.

CDC's tracking program is working with EPA to produce air quality indicators in areas without air monitors. These indicators are produced by combining air monitoring data with emissions and meteorological data to create daily estimates of ozone and airborne fine particulates. This process will help construct a more complete picture of air pollution across the country.

EPA provides air quality data to CDC for this Tracking Network. In the future, CDC's tracking program wants to integrate health and air quality data to produce more easy-to-understand indicators of the health impacts of air pollution. These indicators will do more than communicate the concentrations of air pollutants and the number of people living in areas that exceed standards. These new indicators could estimate outcomes such as the number of hospital admissions or deaths associated with those concentrations.

Read specific air quality indicators information:

Ozone - Days Above Regulatory Standard (Monitor + Modeled)  (Monitor only) The number of days in which the daily maximum 8-hour average ozone concentration exceeds a standard provides an indication of short-term spikes in ozone concentrations. This may give you an idea of how many days per year you may be exposed to unhealthy levels of ozone. PM2.5 - Days Above Regulatory Standard (Monitor + Modeled)  (Monitor only) These data help summarize short-term trends in particle pollution concentrations. This may give you an idea of how many days per year you may be exposed to unhealthy levels of particulate matter. Annual PM2.5 Level (Monitor + Modeled)  (Monitor only) These data help summarize long-term trends in particle pollution concentrations. This will give you an idea of what the yearly level of PM2.5 is in an area.

Search Air Quality Data: Date Display Annual PM 2.5 Level (Monitor + Modeled) Annual PM 2.5 Level (Monitor only) Mortality benefits associated with reducing PM2.5 concentration levels Ozone - Days Above Regulatory Standard (Monitor + Modeled) Ozone - Days Above Regulatory Standard (Monitor only) PM2.5 - Days Above Regulatory Standard (Monitor + Modeled) PM2.5 - Days Above Regulatory Standard (Monitor only)