As the arrival of winter means closed up houses, experts warn that long term exposure to elevated levels of radon gas can pose significant health risks.

Radon exposure is the second leading cause of lung cancer after smoking, according to the U.S. Environmental Protection Agency. Radon is estimated to cause about 21,000 lung cancer deaths in the United States each year. For nonsmokers, radon is the leading cause of lung cancer.

“It is estimated that 513 people in Colorado will be diagnosed with radon-induced lung cancer this year alone,”  Terry Kerwin, director of business development at Protect Environmental, a national radon measurement and mitigation company told The Denver Gazette.

Radon is a colorless, odorless, and tasteless radioactive gas that is naturally present in the environment. It is formed from the decay of uranium and radium, both of which are found in varying amounts in soil, rock, and groundwater.

Unlike some other environmental pollutants, radon does not cause any immediate symptoms, such as coughing or shortness of breath. The health effects become apparent after long-term exposure. Children, particularly those exposed to radon over a long time, might be at a higher risk of developing lung cancer in adulthood.

“I’ve been to too many homes where no one knew to test for radon until someone in the home got the devastating diagnosis of lung cancer,” Kerwin said.

A spokesperson for the Colorado Department of Public Health and Environment said the good news is that the issue can be corrected. 

“The good news is, you can test your home with a simple, free home test kit and find a certified mitigation contractor to fix the problem if your home has elevated radon levels,” said Lauren Whitney, who speaks for the health department. “CDPHE also has a low-income radon mitigation program for those who qualify and need assistance.”

Radon can enter homes and buildings through the ground and can accumulate to dangerous levels indoors.

Created by the radioactive decay of uranium, radon undergoes its own radioactive decay in about four days and transforms into solid radioactive particles. These particles are not gases; they are solid elements that attach to airborne particles, such as dust or smoke in the air. When these particles are inhaled, they can become trapped in the lungs.

It’s not the radon itself that causes cellular damage. Instead, a highly energetic radioactive isotope, Polonium-210, and its ionizing radiation can damage or destroy genetic material in cells inside the body.

When the DNA in a cell is damaged, it can lead to mutations or cell death, which can contribute to the development of cancer or other health problems.

The U.S. Environmental Protection Agency and the Surgeon General’s Office have recommended that all homes be tested for radon every two years. If high radon levels are detected, it is important to take action to reduce exposure, Kerwin said.

Radon mitigation systems, which involve venting radon gas from below the house and dispersing it into the outdoor air, can be installed to lower radon levels to acceptable limits.

The cost of installing a radon mitigation system in a residence can vary based on several factors, including the size and design of the home, the radon levels, the type of foundation, and the chosen mitigation method.

On average, the cost of a radon mitigation system in the United States typically ranges from $800 to $1,500 for a typical residential property.

One might expect radon to be most harmful in older housing, particularly homes with dirt crawlspaces. But modern houses are much more airtight than in the past and may actually be at higher risk of radon contamination, experts said. 

“Since radon is a gas, in some cases, newer more energy-efficient homes can actually have high radon levels because changes to energy efficiency influence the thermal and ventilation characteristics and may trap the toxic gas inside the building where it can accumulate to dangerous levels,” said Kyle Hoylman, chief executive officer at Protect Environmental.

A bill passed last session in Colorado, SB23-206, requires landlords to provide written warnings about radon, a history of radon levels, and testing and mitigation at the property. It also allows tenants to break a lease if high levels are found and the landlord refuses to mitigate.

The health department is offering free test kits and resources, including radon mitigation assistance for homeowners who qualify at coloradoradon.info. The state’s tracking program also has a radon data webpage, which includes information about radon test results by county.