Its silent, health-menacing presence is with us year-round, but more so in winter.
It's radon, a radioactive, colorless, odorless gas produced by decaying uranium in rocks and soil. It's found in above-average amounts in Southwest Colorado, working its way into houses through fissures in foundation slabs or in crawl spaces.
Radon is the No. 1 cause of lung cancer among nonsmokers and the No. 2 cause of lung cancer overall.
Concentrations are higher in winter when houses are closed against the cold. So if you're not certain about your abode's levels, now is the best time to do the test.
Disseminating information about the effects of radon and promoting mitigation measures in radon-sick homes are keeping Wendy Rice with the Colorado State University Cooperative Extension busy during National Radon Action Month, as designated by the Environmental Protection Agency.
Rice is well into a series of radon-education talks in Durango, Bayfield and Pagosa Springs. The matter is important enough for Gov. John Hickenlooper to proclaim January Radon Action Month to coincide with the annual national campaign.
Since 2006 when radon education began in La Plata County, 2 of every 3 houses tested exceeded the 4 picocuries p=er liter of air that the EPA deems a maximum.
A picocurie – named for physicists Pierre and Marie Curie, who discovered radium – is the unit for measuring the gas released by decaying uranium in the soil. The danger lies in breathing what are called radon daughters, microscopic particles from uranium decay that bind with dust or smoke or collect on walls.
No amount of radon is good, but 4 picocuries was chosen as the recommended limit allowable because remediation can reduce concentrations in dwellings to that level, Rice said.
Chris Herman, principal of Farmington-based HouseMaster, a home-inspection service, does radon mitigation year-round.
“Any structure creates a vacuum, which sucks radon from the soil,” Herman said. “It enters through cracks in a foundation slab or collects in a crawl space.”
Herman and his crew were in an old Animas City neighborhood this week installing a radon-venting system in a fourplex. The structure sits partially on a slab, with a crawl space under the remainder of the building.
They used perforated PVC pipe to form a collection grid and then fix a suction fan to an outside wall to draw out radon and divert it above the eaves to dissipate.
“We use similar methods on all our jobs but adapt them to the situation,” Herman said. “Every house is different. Our work is specific to each.”
Herman guessed he does 30 to 40 radon mitigations a year.
Chrystine Kelley, radon program manager in the Hazardous Materials and Waste Management Division at the Colorado State Department of Public Health and Environment, urged people to obtain a radon test kit.
“Testing your home for radon is simple,” Kelley said. “It's easy and affordable. We provide coupons for reduced-cost test kits at www.coloradoradon.info.”
Radon is found across the United States but at varying levels of concentration, Rice said. The average radon level in houses tested nationally is 1.3 picocuries. In La Plata County, it's 6.0 picocuries.
The milling of uranium in Durango for 15 years after World War II has left the city with more than memories of the industry. Tailings from the mill, where the city Dog Park is now, were used widely in construction and highway road base.
Rice said picocurie readings of 10 to 25 aren't uncommon in La Plata County buildings. The highest reading ever registered was 315 picocuries, she said.
“We have a problem because we're built on shale,” Rice said. “Be aware of the problems and of what can be done to mitigate them. But don't panic.”