Wildfire Smoke and the AQI: What Each Level Means and How to Protect Your Home

Updated 2026-11-07 · CA Fire Map editors

Wildfire smoke can travel hundreds of miles, so your air can be unhealthy even when the fire is far away. The fine particles in smoke (PM2.5) are the main health concern.

Reading the AQI

The US Air Quality Index runs from 0 to 500:

• 0-50 Good (green).
• 51-100 Moderate (yellow). Unusually sensitive people should consider reducing heavy exertion outdoors.
• 101-150 Unhealthy for Sensitive Groups (orange). Children, older adults, pregnant people and people with heart or lung disease should limit time outdoors.
• 151-200 Unhealthy (red). Everyone should reduce outdoor exertion.
• 201-300 Very Unhealthy (purple).
• 301 and higher Hazardous (maroon).

Where to check

• The AirNow Fire and Smoke Map combines official monitors and low-cost sensors.
• AirNow.gov for forecasts by ZIP code.
• PurpleAir for neighborhood-level sensor readings.
• Your local air district for smoke advisories and burn-day decisions.

Keeping smoke out of your home

• Close windows and doors when smoke is heavy, if it is safe to do so in the heat.
• Run a portable HEPA air purifier sized for the room, especially in bedrooms.
• If you have central air, use the highest-rated filter your system supports (MERV 13 is commonly recommended) and set the fan to recirculate.
• Avoid adding indoor pollution: no candles, frying or vacuuming without a HEPA filter.
• A well-fitted N95 respirator gives protection outdoors. Cloth and surgical masks don't filter fine smoke particles well.

For state guidance, see Smoke Ready California from the California Air Resources Board.