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Getting Started with AQI Monitoring in the United States

June 17, 2026 · The Clime Team
Getting Started with AQI Monitoring in the United States

Monitoring the Air Quality Index (AQI) is essential for safeguarding your health and making informed decisions about outdoor activities. In the United States, several resources and tools are available to help you stay informed about air quality in your area.

What is the Air Quality Index (AQI)?

The AQI is a standardized system used to communicate the quality of air in a specific location. It measures the concentration of pollutants such as particulate matter (PM2.5 and PM10), ozone (O₃), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and carbon monoxide (CO). The AQI scale ranges from 0 to 500, with higher values indicating worse air quality and greater potential health risks.

Why Monitor AQI?

Regularly monitoring AQI levels helps you understand the air quality in your area, enabling you to take necessary precautions during periods of poor air quality. This is particularly important for sensitive groups such as children, the elderly, and individuals with respiratory or heart conditions.

How to Monitor AQI in the United States

There are several reliable resources available for monitoring AQI levels across the U.S.:

  1. AirNow: Operated by the U.S. Environmental Protection Agency (EPA), AirNow provides real-time AQI data, forecasts, and health recommendations for over 400 cities. You can access their website at AirNow.gov. Additionally, AirNow offers a mobile app for convenient access to AQI information on the go. (airnow.gov)

  2. AirData: Also managed by the EPA, AirData offers access to air quality data collected from outdoor monitors across the U.S. It provides tools to download data, generate reports, and visualize trends. Visit AirData EPA for more information. (epa.gov)

  3. LocalAirData: This platform offers real-time AQI data for any U.S. location, allowing you to check air quality by city, state, or ZIP code. Explore their services at LocalAirData. (localairdata.com)

  4. AirQuality.directory: Provides instant, accurate air quality data for any U.S. address, including information on pollutants and health impacts. Access their services at AirQuality.directory. (airquality.directory)

Understanding AQI Levels

The AQI scale is divided into six categories, each representing a different level of health concern:

  • 0-50 (Good): Air quality is satisfactory, and air pollution poses little or no risk.

  • 51-100 (Moderate): Air quality is acceptable; however, there may be a risk for some people, particularly those unusually sensitive to air pollution.

  • 101-150 (Unhealthy for Sensitive Groups): Members of sensitive groups may experience health effects; the general public is less likely to be affected.

  • 151-200 (Unhealthy): Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects.

  • 201-300 (Very Unhealthy): Health alert: the risk of health effects is increased for everyone.

  • 301-500 (Hazardous): Health warning of emergency conditions: everyone is more likely to be affected.

Protecting Your Health Based on AQI Levels

Depending on the AQI level, you can take specific actions to protect your health:

  • Good (0-50): Enjoy outdoor activities as usual.

  • Moderate (51-100): Sensitive individuals may consider limiting prolonged outdoor exertion.

  • Unhealthy for Sensitive Groups (101-150): Sensitive individuals should limit prolonged outdoor exertion; others may consider limiting prolonged outdoor exertion.

  • Unhealthy (151-200): Sensitive individuals should avoid prolonged outdoor exertion; others should limit prolonged outdoor exertion.

  • Very Unhealthy (201-300): Everyone should avoid prolonged outdoor exertion.

  • Hazardous (301-500): Everyone should avoid all outdoor exertion.

Conclusion

Regularly monitoring AQI levels is crucial for making informed decisions about outdoor activities and protecting your health. Utilize the resources mentioned above to stay informed about air quality in your area.

Highlights:

  • AirNow: Air Quality Index (AQI) Monitoring and Forecasts | U.S. Climate Resilience Toolkit
  • AirNow Mobile App | AirNow.gov
  • Air Data: Air Quality Data Collected at Outdoor Monitors Across the US | US EPA, Published on Wednesday, January 28

Frequently Asked Questions