AirCompare Basic Info

Moving to a different city, or planning a vacation?

Use AirCompare to find out where and when air quality is better for you.

AirCompare maps provide information for counties that monitored outdoor air quality in the last five years and tailor that information for groups more likely to be affected by different levels of pollution.

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Additional Information

The data summarized in this website come from the EPA's Air Quality System (AQS) Data Mart. The AQS Data Mart contains outdoor air pollution data collected by EPA, state, local, and tribal air pollution control agencies from thousands of monitors.
AirCompare provides information based on the five outdoor air pollutants that are part of the Air Quality Index - carbon monoxide, nitrogen dioxide, ozone, particulate matter, and sulfur dioxide. AirCompare does not account for pollen, mold, air toxics or indoor air quality conditions. Contact state or local air quality agencies for additional information.

Not all pollutants are monitored in every county. And the number of days each pollutant is measured may vary from one county to another. Ozone is typically monitored daily during the "ozone season" - when ozone is expected to be relatively higher. This season varies by state, but generally includes the summertime when meteorological conditions are more conducive to ground-level ozone formation. Particle pollution monitoring varies from area to area, but most areas sample everyday or every three days. Carbon monoxide is monitored year-round at most monitoring sites.

Sensitive Groups and the Air Quality Index

Index Value Level of Health Concern What it Means
301 - 500 Hazardous Health warnings of emergency conditions. The entire population is more likely to be affected.
201 - 300 Very Unhealthy Health alert: everyone may experience more serious health effects.
151 - 200 Unhealthy Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects.
101 - 150 Unhealthy for Sensitive Groups Members of sensitive groups may experience health effects. The general public is not likely to be affected.
51 - 100 Moderate Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
0 - 50 Good Air quality is considered satisfactory, and air pollution poses little or no risk.

AirCompare provides comparisons of air quality based on factors that have been shown to increase risk from air pollution. These factors can include life stages (children and older adults), specific health conditions (heart or lung disease), and increased likelihood of exposure from being active outdoors. The Air Quality Index (AQI) is the official index for air quality across the United States. The AQI ranges from 0 to 500. The higher the AQI value, the greater the level of air pollution and the greater the health concern.

When AQI values are between 101 and 150, or code orange, members of sensitive groups may experience health effects. This is because they are more likely to be affected at lower air quality levels than everyone else. For example, children and older adults, people with lung disease, and people who are active outdoors (outdoor workers) are at greater risk from exposure to ozone. Older adults and children, and people with heart or lung disease are at greater risk from exposure to particle pollution. Everyone is more likely to be affected when the AQI values are above 150, or code red and higher.

Learn more about the AQI and how air quality affects health

Which pollutants and levels affect each group?

Any pollutant: code red or higher
also
Ozone: code orange or higher
Particle pollution: code orange or higher
Sulfur dioxide: code orange or higher
Any pollutant: code red or higher
also
Particle pollution: code orange or higher
Carbon monoxide: code orange or higher
Any pollutant: code red or higher
also
Ozone: code orange or higher
Particle pollution: code orange or higher
Any pollutant: code red or higher
also
Ozone: code orange or higher
Sulfur dioxide: code orange or higher
Any pollutant: code red or higher