Radon test

What It Means

A radon test measures how much radon, a radioactive gas, is in the air inside a home. Results are given in picocuries per liter (pCi/L). The U.S. Environmental Protection Agency (EPA) sets 4 pCi/L as its action level: at that reading or above, EPA recommends fixing the home. Tests come in two kinds, short-term (2 to 90 days) and long-term (more than 90 days).

How It Sounds at Home

• "We need a radon test before we close on the house."
• "The kit's been in the basement for three days."
• "Our result came back at 4.2, so we're testing again."

The Breakdown

What EPA says to do (A Citizen's Guide to Radon)

Who it applies to. The action level is EPA's recommendation for anyone living in a home, and EPA publishes a separate guide for renters, "A Radon Guide for Tenants". Buhata's own suggestion: keep the lab report with the date, the kind of test and the room it sat in, since it's the record you'll want if you sell, rent out or fix the home.

How to run one

1. Buy a short-term or long-term test kit. A short-term test stays in place 2 to 90 days and gives a faster answer; a long-term test stays more than 90 days and shows the year-round average better.
2. Put it in the lowest level of the home that people actually live in, such as a finished basement or the ground floor.
3. Leave it at least 48 hours, the minimum EPA gives for any radon test, and follow the kit's instructions.
4. Send it to the lab as the kit directs, then read your result against the table above.

What the number means. EPA's action level is 4 pCi/L, which it also gives as 150 Bq/m3. EPA's "Consumer's Guide to Radon Reduction" covers how homes are fixed.

Good to Know

EPA estimates that radon causes about 21,000 lung cancer deaths a year in the U.S., and it puts the average indoor level nationwide at about 1.3 pCi/L. The agency cites the Surgeon General's warning that radon is the second leading cause of lung cancer in the U.S., after smoking, and says smokers face a higher risk from radon. If you have health concerns about a result, talk with your doctor, and use EPA's guides at epa.gov/radon for next steps.

Related Terms and Categories

• Home inspection

  A professional look at a home's condition, usually before buying, that reports which systems and parts need repair or may need replacing soon.

• Carbon monoxide detector

  An alarm that sounds when carbon monoxide, a poisonous gas, builds up to a dangerous level in the air of a home.

• Indoor humidity level

  How much moisture the air inside a home holds, given as relative humidity. EPA advises keeping it below 60%, ideally between 30% and 50%.

• Asbestos

  A group of natural mineral fibers once common in building materials. Left undamaged it's no risk, but disturbed fibers can cause lung disease and cancer.

Home maintenance and repairs