Cooler temperatures best time to test for radon, expert says

Wednesday, November 22, 2017

Cooler temperatures make fall and winter a good time to test your home for harmful radon gas, according to Bob Schultheis, natural resource engineering specialist with University of Missouri Extension.

Radon is a colorless, odorless and radioactive gas caused by the natural breakdown of rocks and soils that contain uranium and radium. Radon is the second leading cause of lung cancer, immediately after smoking.

"Testing in Missouri has shown that all counties have radon and 18 percent of all homes have radon levels above the level considered dangerous," said Schultheis. Not every house has radon, but the EPA recommends that every house is tested because the levels can vary between neighboring houses." See, or a Missouri county-by-county radon risk map.

Energy-efficient or poorly-ventilated homes are more likely to have higher radon levels, said Schultheis. This is because radon enters the home through cracks and openings in floors and walls and through floor drains and sumps.

"The best time to test your home for radon is during cooler weather when it is 60 degrees or less. The house should be closed up at least 12 hours before and during the test," Schultheis said.

The most common radon detectors are charcoal canisters and alpha-track detectors. The charcoal canister units are used for short-term testing. A positive result from a short-term test is no immediate cause for panic. A long-term test (three to 12 months) using an alpha-track detector to verify continuous exposure levels should follow it.

A short-term detector is available free from the Missouri Department of Health and Senior Services at, or can be found for $10-$30 at major hardware stores and home improvement centers

If you do find a radon problem, Schultheis said, spend less time in high-concentration areas, such as basements. Don't smoke, and when practical, ventilate the living area. It is also a good idea to keep crawl-space vents open year-round and seal all floor and wall cracks.

For more information, call the Missouri Radon Information Helpline at 1-866-628-9891, or go online to, or Homeowners can also the Barry County Extension Office for MU Guide G1968, Radon: An Indoor Health Hazard?, or go online to