What an air purifier can - and can't - do for your air
Filtration is genuinely useful. It also can't touch radon. Knowing the difference saves money and protects health.
Air purifiers are having a moment, and for good reason. A HEPA filter captures fine particulates - dust, pollen, smoke, PM2.5 - and activated carbon adsorbs many volatile organic compounds and odours. For a busy office or a kitchen, a well-sized unit measurably improves the air people breathe, and the bar is meaningful: WHO’s guideline for fine particulates is an annual mean of just 5 µg/m³. [8]
Where filtration stops
Radon is a different sort of pollutant. It’s a radioactive noble gas, not a particle, so it passes straight through a HEPA filter and a standard purifier does not meaningfully reduce it. [4] (A purifier can pull some of radon’s particle-bound decay products out of the air, but that doesn’t address the gas itself or the obligation.) Radon is controlled by stopping it entering and by moving air - ventilation and structural mitigation such as sub-slab depressurisation - then confirmed by measurement. [4] The risk is real enough to take seriously: lung-cancer risk rises about 16% per 100 Bq/m³. [1]
How we think about it
We rent purifiers where they genuinely help - particulates, allergens, smoke, VOCs - and we measure and mitigate radon where that’s the actual problem. Selling a purifier as a radon fix would be both wrong and, given the stakes, irresponsible. So we don’t.