I need quiet bedroom air
Calculate the necessary smoke CADR, then prioritize noise and replacement-filter cost.
Size the room →The Clean Air Toolkit
Know what is outside. Make the air inside better.
Live local conditions, honest sizing math, a DIY option, and a small set of assessed products—without fear-based marketing or an email gate.
Choose your situation
Three useful paths—not thirty nearly identical products
I need the most clean air per dollar
A Corsi–Rosenthal box trades polish and quiet for exceptional airflow on a modest budget.
See the 20-minute build →Smoke is already here
Close the right openings, create one clean room, run filtration continuously, and monitor conditions.
Use the smoke-day checklist →Ownership-cost calculator
The price tag is not the price
Filters and electricity can outweigh a small difference in purchase price. Compare the approximate cost before committing to a machine.
Practical guidance
Read only what you need next
Immediate planWildfire smoke indoors: what actually helps
Windows, HVAC, clean-room setup, filtration, and when to air the house out.
Buying guideChoose a purifier using CADR—not marketingRoom-size math, useful features, annual filters, and what to skip.
DIY guideBuild a ~$70 Corsi–Rosenthal boxShopping list, assembly, safety, maintenance, and honest trade-offs.
Assessed—not endlessly ranked
A deliberately small product set
These assessments separate evidence for filtration itself from evidence for the exact product. Some product pages contain affiliate links.
Evidence: Established — HEPA filtration reducing indoor PM2.5 is well-established measurement science; intervention studies show portable HEPA units meaningfully cut indoor particle levels during smoke events.
Levoit Core 300S Air Purifier
A small-room HEPA purifier for bedrooms and offices up to ~200 sq ft — quiet enough to sleep next to, with a real particle sensor for auto mode.
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Evidence: Established — HEPA filtration reducing indoor PM2.5 is well-established measurement science; portable HEPA units are a standard public-health recommendation during wildfire smoke events.
Winix 5500-2 Air Purifier
A proven mid-size HEPA workhorse for living rooms up to ~360 sq ft, with a washable pre-filter that stretches HEPA life through smoke season.
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Evidence: Supported — EPA chamber testing found box-fan-plus-MERV-13 DIY air cleaners removed smoke-sized particles at rates comparable to commercial units; evidence is from controlled chambers, not home health-outcome trials.
20-inch Box Fan (CR Box base)
The motor of a Corsi-Rosenthal box — a plain 20-inch box fan that turns four furnace filters into a serious smoke-scrubbing air cleaner.
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Evidence: Established — MERV ratings are a standardized ASHRAE test; MERV-13 media capturing a large share of smoke-sized fine particles is measured filtration physics, not a marketing claim.
MERV-13 Furnace Filters, 20x20x2 (4-pack)
The working surface of a CR box — and the single best upgrade for a home HVAC system during smoke season.
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