Now’s a good time to check radon level in your home

DULUTH, Minn. – Carol Thibault understood the dangers of radon when she tested her house a few years ago for the cancer-causing gas. After all, she was director of the St. Louis County (Minn.) Public Health Department.

Thibault wasn’t worried because she had been told her house in Duluth’s Kenwood neighborhood had been built on fill dirt instead of having its foundation dug into undisturbed ground.

When a short-term test found the radon level in her basement to be 2 1/2 times what is considered harmful, Thibault didn’t believe the results. So she got a more accurate three-month test. It measured a level four times what is considered harmful.

Still skeptical, Thibault tested the levels two more times.

“All were really way up there,” she recalled.

Because elevated radon levels are common in homes throughout the country, the U.S. Environmental Protection Agency along with the Surgeon General recommend every home be tested for the invisible, odorless carcinogen. Many health departments make it easier by offering free test kits.

January is National Radon Action Month. It comes as radon levels are at their seasonal highest. In midwinter, houses are sealed up to keep out cold air and the ground’s snowcover impedes radon’s safe release into the air.

When a yearlong radon test found a daily average of 9.8 picoCuries of radon per liter of air in their home, Thibault and her husband, Dave, took action. When tests show an average of 4 or more picoCuries per liter of air in a home, the EPA recommends homeowners take measures to reduce that level. Four picoCuries is the carcinogenic equivalent of more than 200 chest X-rays in a year, according to the EPA. The Minnesota Department of Health is more cautious, setting the acceptable limit at 2 picoCuries per liter, which is 10 times the average outdoor level of radon.

At a cost of $1,360, the couple had a simple pipe and fan system installed that draws radon from beneath their basement and moves it outside. The system, called subslab pressurization, is the recommended solution for homes with high radon levels. For lower levels, sealing cracks and openings while increasing ventilation may suffice.

Radon is a naturally occurring gas in the ground that results from the breakdown of uranium and radium in soil, rocks and water. Outside, it mixes with air and is generally harmless. But when it seeps into homes and gets trapped inside, it can build up to dangerous levels. Exposure over many years can cause lung cancer.

Radon enters homes through cracks in basement floors and walls, pipe openings, floor drains, exposed soil, joints between walls and floors and uncapped, hollow foundation blocks. It gets distributed through the house by natural air movements and by ventilation systems such as forced-air furnaces.

Radon is invisible, odorless, tasteless and causes no health symptoms prior to the onslaught of lung cancer. The only way to determine its presence is with a test, experts say.

Inexpensive charcoal radon testers, similar to those offered free by local health departments, can be purchased at hardware and other retail stores for $8 to $10. They measure radon presence over two to seven days.

“They’re generally put in the lowest lived-in portion of the home, away from windows and doors and away from drafts and high humidity,” said Bob Hart, environmental health specialist for St. Louis County Public Health and Human Services.

If elevated radon levels are found, a test measuring levels over 90 days should be done, Hart said. Such tests are available at some hardware stores and at county health departments, which can help with the testing for around $50.

If that test also records elevated radon levels, action should be taken to reduce the level.

The good news is radon levels can be lowered in any house, Hart said. The first step is sealing cracks and doing a lot of caulking, he said.

When levels are high, as in the Thibaults’ home, the “subslab depressurization” method is used. It’s one of the most effective means, he said, and costs from $500 to $2,500. In the method, a hole is drilled through the basement slab and a 3-inch PVC pipe is run from the hole and out of the house. A fan continually pulls radon from beneath the house and diverts it outside through the pipe.

“That way radon doesn’t even get in the house,” Hart said.

The Minnesota Department of Health recommends new homes be built with features that minimize radon entry such as laying a polyethelene sheeting on the soil before laying a foundation or by incorporating the pipe and fan system to move the radon outside.

With the radon levels now minuscule at Thibault’s home, she has peace of mind. Follow-up tests show radon levels of about 0.3 picoCuries per liter of air. Neither Thibault nor her husband smoke, so they’ve had no adverse health effects.

“Both of us have had chest X-rays since the work was done,” she said. “Everything was fine.”