Radon gas is a radioactive substance that can enter homes through soil and other sources. While HEPA filters are widely recognized as the most effective air filtration method for particles, how well do they filter out radon gas? In this article, we’ll explore what radon is and whether HEPA filters can remove dangerous radon from your home.
What Is Radon?
Radon is a radioactive gas. It has no color or smell.
As if magic, radon decays into particles, and those particles attach onto other particles in the air. So radon is also a solid.
Is Radon Dangerous?
Where Does Radon Come From?
The ground in some areas has more radon than in other areas. For example, in the US, the Appalachian Mountain region has high radon levels, but the lowland south has low levels.
Outdoors, radon is usually not a problem. That’s because there’s so much air that the amount of radon is very small. So if you’re hiking in the Appalachian Mountains, don’t worry.
But indoors, it can accumulate. In some buildings, it’s particularly problematic in the ground floor or basement floor, because radon can come up from the ground.
Can HEPA Filters Capture Radon?
Radon emerges from the ground as a gas, and HEPA filters do not capture gases. So that’s bad news.
But after radon decays into particles, HEPA filters can be useful. The size of radon particles ranges from .5-300 nanometers.
Fortunately, HEPA filters can remove over 99% of particles in the nanometer range. So a HEPA filter would capture nearly all the radon particles from the air.
For example, here is a test of what percentage of nanoparticles could pass through a HEPA filter and a weaker furnace filter.
To test it with radon, researchers put a HEPA purifier in a basement room that had naturally occurring radon in it. They ran it for 10 days. As expected, the HEPA filter did not capture any of the radon gas:
But the purifier did capture radon after it decayed into particles.
And the HEPA filter captured other particles that radon attached onto and “infected.”
N95 and N99 masks can also capture nanoparticles, so masks should capture radon particles too.