Air Quality

The Air Quality Index (AQI) runs from 0 to 500 — the higher it climbs, the more people are affected and the more serious the effects. Each hour it’s set by whichever pollutant is worst at the time.

• Good0–50

  Air quality is satisfactory and poses little or no risk.

• Moderate51–100

  Acceptable, though unusually sensitive people may notice minor effects.

• Unhealthy for Sensitive Groups101–150

  Children, older adults, and people with heart or lung conditions may feel effects; most others won’t.

• Unhealthy151–200

  Everyone may begin to feel effects, and sensitive groups more seriously.

• Very Unhealthy201–300

  A health alert — the risk of effects is heightened for everyone.

• Hazardous301–500

  Emergency conditions; the entire population is likely to be affected.