Air Quality & Health
Air pollution affects everyone, but certain groups face greater risks. Here's what each AQI level means for your health and what actions to take.
The Air Quality Index (AQI) is divided into six categories, each associated with a different level of health concern. Understanding these categories helps you make informed decisions about outdoor activity.
Who are “sensitive groups”?
- • People with asthma, COPD, or other lung diseases
- • People with heart disease or cardiovascular conditions
- • Children and teenagers (lungs still developing)
- • Adults over 65 (immune and respiratory systems more vulnerable)
- • Pregnant women
- • People who exercise heavily outdoors (breathe more air per minute)
Health Effects by AQI Level
Air quality is satisfactory, and air pollution poses little or no risk.
Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
Members of sensitive groups may experience health effects. The general public is less likely to be affected.
Some members of the general public may experience health effects.
Health alert: The risk of health effects is increased for everyone.
Health warning of emergency conditions: everyone is more likely to be affected.
Detailed Health Recommendations
Good (0-50)
- • All outdoor activities are safe
- • No restrictions for sensitive groups
- • Ideal for outdoor exercise
Moderate (51-100)
- • Generally safe for outdoor activities
- • Sensitive groups should monitor symptoms
- • Consider reducing prolonged outdoor exertion
Unhealthy for Sensitive (101-150)
- • Sensitive groups should limit outdoor activities
- • Consider indoor exercise alternatives
- • Watch for symptoms like coughing
Unhealthy (151-200)
- • Everyone should reduce outdoor exertion
- • Sensitive groups should avoid outdoor activities
- • Consider wearing masks outdoors
Very Unhealthy (201-300)
- • Everyone should avoid outdoor exertion
- • Sensitive groups should stay indoors
- • Use air purifiers indoors
Hazardous (301+)
- • Everyone should stay indoors
- • Keep windows closed
- • Use air purifiers continuously
Activity Guidelines by Group
| AQI | General Public | Sensitive Groups |
|---|---|---|
| 0–50 (Good) | No restrictions | No restrictions |
| 51–100 (Moderate) | No restrictions for most | Consider reducing prolonged exertion |
| 101–150 (USG) | Reduce prolonged outdoor exertion | Avoid prolonged outdoor exertion |
| 151–200 (Unhealthy) | Avoid prolonged exertion outdoors | Avoid all outdoor exertion |
| 201–300 (Very Unhealthy) | Avoid outdoor exertion | Stay indoors if possible |
| 301+ (Hazardous) | Stay indoors, keep windows closed | Stay indoors, run air purifier |
Long-Term Exposure
Even moderate AQI levels (51–100), when experienced day after day, can have measurable health impacts. The World Health Organization (WHO) air quality guidelines are stricter than US EPA standards, reflecting evidence that harm begins at lower concentrations.
People living in cities with persistently high AQI face elevated lifetime risks of heart disease, stroke, lung cancer, and chronic respiratory disease. Children growing up in polluted environments may have permanently reduced lung capacity.