Should You Test Your Home for Radon?

Yes, if you can. Radon is a radioactive gas that seeps from the ground into buildings. You can’t see, smell, or taste it, and the only way to know your level is to measure it. Long-term exposure raises the risk of lung cancer, and the US Environmental Protection Agency (EPA) estimates it’s the second leading cause of lung cancer, after smoking. The fix, if you need one, is usually straightforward.

This article is general information, not medical advice.

The Levels

• EPA. Fix your home if the level is 4 pCi/L (about 150 Bq/m³) or more, and consider fixing it between 2 and 4 pCi/L (75 to 150 Bq/m³). The EPA notes the average indoor level is about 1.3 pCi/L (50 Bq/m³), and that getting below 2 pCi/L is difficult.
• World Health Organization (WHO). Its radon fact sheet recommends a national reference level of 100 Bq/m³ (about 2.7 pCi/L), or no higher than 300 Bq/m³ where that can’t be reached.

Units: 1 pCi/L (picocurie per litre) is 37 Bq/m³ (becquerels per cubic metre).

How Risk Rises

The WHO fact sheet states that lung cancer risk rises by about 16% for every 100 Bq/m³ increase in long-term average radon, a relationship it assumes is linear, and that radon is much more likely to cause lung cancer in people who smoke. The EPA’s risk chart estimates that at 4 pCi/L, about 62 of every 1,000 people who smoke would get lung cancer from a lifetime of exposure, and it estimates that radon causes about 2,900 lung cancer deaths a year among Americans who have never smoked.

How to Test

• Short-term tests (2 to 90 days) give a quick first reading. Radon varies from day to day and season to season, so one short test can mislead.
• Long-term tests (more than 90 days) give a better picture of your yearly average, which is what the risk estimates are based on.
• Continuous digital monitors show the level hour by hour and its long-term average; give them several weeks before trusting the average.

Test the lowest lived-in level of the home, away from drafts, windows, and outside walls. If a test is high, a certified radon professional can install mitigation, typically a vent pipe and fan that draw the gas from under the floor.

Following It in Kaizora

Radon Activity Concentration is an air quality metric on Air Quality, in Bq/m³. Each reading records where it was taken, so readings from your basement and your bedroom stay apart on the map. Import an Aranet radon monitor’s file, or log a test kit’s result by hand. A reference range at 100 Bq/m³ or 150 Bq/m³ flags readings above the WHO’s or EPA’s levels; for radon, look at the long-term average, such as a 90-day window, rather than single readings. See Importing From an Aranet4 Monitor.

The Short Version

• Radon is the second leading cause of lung cancer after smoking; testing is the only way to know your level.
• The EPA says fix at 4 pCi/L (about 150 Bq/m³); the WHO recommends a reference level of 100 Bq/m³.
• Risk rises about 16% per 100 Bq/m³ of long-term average; test over months.

Sources

• World Health Organization, Radon (fact sheet).
• World Health Organization, WHO handbook on indoor radon: a public health perspective (2009).
• US Environmental Protection Agency, Health Risk of Radon.