Basics · 8 min read
Radon Myths
The most common radon myths and what is actually true: basements, new homes, neighbors' results, air purifiers, opening windows, and regional risk.
Radon misinformation is unusually persistent, partly because the gas is invisible and partly because plausible-sounding intuitions about it are frequently wrong.
Each of the beliefs below is common, and each leads households to skip testing or to spend money on things that do not help.
Myth: radon is only a basement problem
Basements often measure highest because they have the most soil contact, but slab-on-grade homes measure high routinely. In San Diego, where basements are rare, essentially all mitigation work involves slabs and crawl spaces.
The relevant factor is soil contact and building pressure, not the presence of a basement.
Myth: my neighbor tested low, so I am fine
Radon varies dramatically between adjacent homes. Soil composition changes over short distances, foundations differ, sub-slab fill differs, and each house has its own pressure behavior driven by its own exhaust equipment and envelope.
Side-by-side homes with results differing by a factor of five are well documented. A neighbor's number is interesting, not informative.
Myth: new construction is safe
Modern air sealing reduces the accidental ventilation that used to dilute indoor radon. A tight new home over the same soil can measure higher than the drafty older house it replaced.
Radon-resistant construction features genuinely help when present, but they are not universal and they do not eliminate the need to test.
Myth: an air purifier will handle it
Portable air cleaners capture particles and, with carbon, some gases. They do not meaningfully reduce radon concentration in the volume of air in a home.
Radon is addressed by preventing entry, not by cleaning air after it arrives. Money spent on a purifier for radon purposes is money not spent on mitigation.
Myth: just open the windows
Ventilation does dilute radon while windows are open, and that is real. It is also inconsistent, weather dependent, incompatible with air conditioning or heating, and absent overnight when people are asleep at home.
As a strategy it fails precisely during the hours that contribute most to cumulative exposure.
Myth: California does not have radon
California has lower average levels than several other states, and San Diego County is on the moderate end within California. Elevated homes exist here nonetheless, particularly on granitic soils inland.
An average is a statement about a population. It is not a prediction about an address.
Myth: mitigation is expensive and disruptive
A typical residential system is installed in a single day, requires no relocation, and costs less than many routine home repairs. Operating cost is a few dollars a month.
Compared with most projects that meaningfully improve a home, radon mitigation is fast, bounded, and verifiable.
Key takeaways
- Slab and crawl space homes get radon too, not just basements.
- Neighboring results do not predict your home.
- Purifiers and open windows are not mitigation strategies.
- Regional averages never substitute for a measurement.