Colorado has high levels of radon, which can cause lung cancer – here’s how to lower your risk

In Colorado, as of 2025, about 500 people a year die from lung cancer as the . Nationally, the number of lung cancer deaths attributed to radon per year.

Radon is present nearly everywhere outdoors, yet typically at levels that are not harmful. It becomes dangerous when it gets trapped and accumulates inside homes, schools and other buildings.

Radon is a that is produced by the breakdown of uranium, a heavy metal present in the soil. People cannot smell it or see it, which makes radon particularly dangerous. When radon gas forms in the soil, it rises and finds its way into homes old and new through cracked foundations, gaps around sump pumps and drains, and crawl spaces.

Many people are unaware of the radon levels in their home. In Colorado, it is estimated that . Thus, many Coloradans may be exposed to elevated radon levels and not know it.

Though tobacco use is the most significant risk factor for lung cancer, accounting for , among people who have never used tobacco. Radon also has a compounding effect with tobacco that further increases lung cancer risk among tobacco users. About 7 in 1,000 nontobacco users with prolonged exposure to elevated radon levels .

Exposure to radon is preventable. As , I aim to help all Colorado residents be aware of their home’s radon level and take appropriate actions to mitigate exposure and reduce their and their family’s risk of lung cancer.

Radon in your home

Because of Colorado’s unique geology, including mountainous regions that consist heavily of granite rock that contains uranium, radon levels are higher in Colorado than in other states.

levels across the country. About 50% of Colorado homes tested for radon have levels higher than the recommended threshold set by the Environmental Protection Agency, . The average level of radon in Colorado homes is 6.4 pCi/L, which is . Radon levels differ across the 64 counties in Colorado based on their geography and makeup of the soil.

If a home is not adequately vented, radon can build up indoors. When radon decays, it releases radioactive particles that, once inhaled, . More specifically, these particles can break chemical bonds in the cell’s DNA that, if not repaired, can lead to cancer. Prolonged exposure to high levels of radon, over several years, can cause lung cancer. Similar to tobacco use, it is the .

Fortunately, there are ways to prevent radon from entering and accumulating inside our homes. Radon mitigation systems use fans and pipes to pull radon gas from below the foundation of the home and vent it outside. These systems can reduce radon .

Know your risk: Testing and mitigating

Testing your home for radon is simple and relatively inexpensive. Test kits are placed in the lowest living area of your house, apartment, condominium or townhome and left for a period of time. The EPA recommends testing for all residential units below the third floor.

There are short-term tests, which take from two to 90 days, and long-term tests, which take 90 days or more. Long-term tests are more accurate for estimating annual average radon levels. Once complete, tests can be mailed directly to a lab for processing.

Test kits typically cost less than US$50 or , including the University of Colorado Anschutz Cancer Center. As of February 2026, the cancer center has distributed more than 1,600 test kits to people in 55 Colorado counties. Nearly 40% of the tests distributed thus far show radon levels above the EPA threshold.

The EPA recommends testing over multiple months, including colder months when windows and doors to the outside are typically closed and radon can become trapped indoors. Testing over several months provides a better understanding of the average annual radon level in the home.

Reduce your risk: Radon mitigation

People with radon levels in their home that are are recommended to seek mitigation measures. This may involve sealing cracks in basement walls and foundations and installing a fan and vent pipe to pull radon gas from underneath the home and vent it outside. Mitigation can cost depending on home structure and location.

There are resources available for people who need radon mitigation and can’t afford it. Colorado’s state health department has that can pay for radon mitigation for people who are eligible based on income requirements.

Radon may be invisible, but its impact on human health is unmistakably real – and largely preventable. By taking action today – testing your home, sharing this knowledge and seeking help when needed – you are investing in a healthier future for yourself and your community.