Market guide
Size from CADR, room volume and speed
Choose a tested clean-air flow the household can sustainA large advertised room can mean only one air change per hour. Start with the room volume, smoke or dust CADR, target air changes and the fan setting that can actually run.
01
Room
Calculate the air volume
Measure length, width and ceiling height, then note doors, open plans, stairwells and airflow paths that make one room behave like a larger zone.
- Zone
- One portable unit cleans air that reaches it; walls, closed doors and weak mixing can require more than one unit.
- Source
- Identify smoke, dust, pollen, pets, cooking, renovation, gas or moisture sources because controls differ.
02
CADR
Use pollutant-specific tested flow
Compare AHAM smoke, dust and pollen CADR or another clearly documented method rather than raw fan airflow or a marketing square-foot number.
- ACH
- Convert CADR to the room volume and target air changes, retaining the ceiling-height and mixing assumptions.
- Claim
- Do not compare a 4.8-air-change room rating with a one-air-change figure as if they were equivalent.
03
Speed
Size at a tolerable setting
Sound, airflow character, display light and energy use determine whether the unit will run at the speed needed.
- Noise
- A minimum and maximum decibel range does not reveal the sound or CADR at the household's chosen everyday setting.
- Boundary
- CADR and air changes do not guarantee exposure reduction, smoke safety, symptom change, disease prevention or a universal indoor-air result.
Evidence used
First-party sources behind this guide
- 01Verifide air-cleaner directory and CADR guidanceAHAM · checked August 17, 2026Open source
- 02Air cleaners and air filters in the homeU.S. EPA · checked August 17, 2026Open source
- 03Certified air-cleaning devicesCalifornia Air Resources Board · checked August 17, 2026Open source
- 04Room air cleaner product criteriaENERGY STAR · checked August 17, 2026Open source