Air Scrubbing 101

Smoke combines fine particles with gases. Particle filters address the particles; some gases need substantial, purpose-designed sorbent media. No household purifier removes every smoke pollutant. A fading odor is not a reliable clearance test.

Check gaps around doors, windows, and window AC units. Use appropriate seals without obstructing exits, combustion air, or required ventilation. Reducing indoor pollution sources is useful too. Follow local instructions, and do not stay in an overheated home just to keep windows shut.

MERV describes filter capture across tested particle-size bands. MERV 13 is a useful smoke upgrade when compatible with the HVAC system. HEPA is a separate high-efficiency standard; it does not mean a unit moves enough air for every room. Fit, filter condition, and airflow all matter.

Look for tobacco-smoke CADR in cubic feet per minute (cfm), rather than marketing coverage alone. Our tool follows AHAM’s wildfire rule of smoke CADR at least equal to floor area at an 8-foot ceiling, increasing it for taller rooms. Separate rooms need separate consideration. Published ratings often reflect the highest, loudest speed.

Bath fans and vented range hoods can draw replacement air through leaks or make-up-air openings. A recirculating hood behaves differently. ERVs, HRVs, and supply intakes bring in outdoor air, but their filters vary. Check the actual supply-filter rating and manufacturer’s smoke-event instructions. Do not assume a grease screen or coarse filter captures fine smoke. Limit unnecessary exhaust while managing moisture and cooking emissions; never disable required combustion ventilation.

Pick a room that can stay comfortably cool, with space for an unobstructed cleaner. Run it at a useful speed and follow its placement directions. A closed door can help isolate the space, but this does not make the room smoke-proof or establish that it is safe to remain during an emergency.

A fan-and-filter cleaner can reduce particles when a rated commercial unit is out of reach. Follow EPA’s illustrated instructions, use a newer safety-certified fan (2012 or later, with a UL or ETL mark), and follow the fan manufacturer’s directions. Performance varies with design, filter, and sealing; our tool does not assign an unmeasured DIY unit a CADR.

Inspect filters during smoky periods and follow replacement directions. Restore appropriate ventilation when outdoor air improves. Ash, burned materials, or persistent contamination after a nearby fire may need professional assessment and cleanup. An air cleaner is not a substitute for that work.