Indoor air planning for wildfire smoke

Start with one room you can keep comfortable

For a smoke event, begin with a room where your household can spend time together, with doors and windows that close. Check that you can keep it cool enough with windows shut. A filter alone does not make a hot home safe, and a room plan never overrides an evacuation instruction.

Measure the room's floor area before comparing purifiers. Big advertised coverage numbers may assume only one air change per hour. For smoke, the clean air delivery rate at the fan speed you will actually use is a more useful starting point.

Match the purifier to the room

• Air purifiers for wildfire smoke
  Use our room-size table, compare two larger-room options, and check filter replacement costs.

The EPA recommends a smoke CADR of at least two-thirds of the room area in square feet. A 300-square-foot room therefore starts at 200 cfm smoke CADR. Taller ceilings, open doorways, and lower fan settings complicate that estimate. Confirm the smoke rating rather than substituting a dust, pollen, or unspecified CADR figure.

Plan for ongoing use: where the unit sits, whether its highest setting is tolerable, replacement-filter availability, and electricity during an outage. EPA guidance also describes do-it-yourself filtration for situations where a commercial cleaner is unavailable or unaffordable.

Put your room dimensions to work

A 15 by 20 foot room is 300 square feet. Applying EPA's two-thirds rule gives a starting smoke CADR of 200 cfm. Use actual floor area and check the smoke-specific label on the purifier.

Know when to leave

Keep a household communication and evacuation plan alongside your clean-room plan. If you need filtration when electricity fails, include the purifier's real operating load in your backup power plan.

Sources: EPA indoor air filtration guidance and EPA clean-room planning.