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Understanding AQI Alerts: A Guide for Non-Technical Users

June 17, 2026 · The Clime Team
Understanding AQI Alerts: A Guide for Non-Technical Users

Air Quality Index (AQI) alerts are essential tools for informing the public about the quality of the air we breathe. These alerts help individuals make informed decisions to safeguard their health, especially during days when air pollution levels are elevated.

What Is the Air Quality Index (AQI)?

The AQI is a standardized system used to communicate the level of air pollution and its potential health effects. It measures concentrations of pollutants like ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. The AQI scale ranges from 0 to 500, with higher values indicating worse air quality and greater health risks. (airnow.gov)

How Are AQI Levels Categorized?

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

  • 0 to 50 (Green): Good – Air quality is satisfactory, posing little or no risk.
  • 51 to 100 (Yellow): Moderate – Air quality is acceptable; however, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
  • 101 to 150 (Orange): Unhealthy for Sensitive Groups – Members of sensitive groups may experience health effects; the general public is less likely to be affected.
  • 151 to 200 (Red): Unhealthy – Everyone may begin to experience health effects; members of sensitive groups may experience more serious effects.
  • 201 to 300 (Purple): Very Unhealthy – Health alert: The risk of health effects is increased for everyone.
  • 301 and higher (Maroon): Hazardous – Health warning of emergency conditions: everyone is more likely to be affected. (airnow.gov)

What Do AQI Alerts Mean for Your Health?

AQI alerts provide guidance on how to protect yourself during days with poor air quality:

  • Good (0-50): No health impacts expected.
  • Moderate (51-100): Sensitive individuals may experience mild health effects; others are unlikely to be affected.
  • Unhealthy for Sensitive Groups (101-150): Sensitive individuals should limit prolonged outdoor exertion; the general public is less likely to be affected.
  • Unhealthy (151-200): Everyone may begin to experience health effects; sensitive individuals may experience more serious effects.
  • Very Unhealthy (201-300): Health alert: The risk of health effects is increased for everyone.
  • Hazardous (301 and higher): Health warning of emergency conditions: everyone is more likely to be affected. (airnow.gov)

How Are AQI Alerts Issued?

Air quality agencies monitor pollution levels and issue alerts when AQI values reach certain thresholds. These alerts are communicated through various channels, including local news, weather forecasts, and official websites. For example, a local air quality agency might issue a "Code Orange" alert when AQI values are forecasted to be between 101 and 150, indicating that sensitive groups should limit prolonged outdoor exertion. (apcb.org)

How Can You Stay Informed?

To stay updated on air quality conditions in your area:

  • Check Local News: Many local news outlets provide daily air quality updates.
  • Visit Official Websites: Websites like AirNow.gov offer real-time AQI information.
  • Use Mobile Apps: Several apps provide AQI updates and health recommendations.

How Can You Protect Yourself During Poor Air Quality Days?

On days when AQI levels are elevated:

  • Limit Outdoor Activities: Reduce prolonged or heavy exertion outdoors, especially if you belong to sensitive groups.
  • Stay Indoors: Keep windows and doors closed to minimize exposure.
  • Use Air Purifiers: Consider using air purifiers to reduce indoor pollution levels.

By understanding AQI alerts and taking appropriate precautions, you can protect your health and well-being during days with poor air quality.

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Frequently Asked Questions