Radon – the “Invisible Intruder”
What is it?
Radon is a colorless, odorless radioactive gas that is continuously released from decaying radioactive material naturally found in some rock formation and soils. It varies from location to location, based on the type of bedrock and soil as well as home construction methods and materials. Although this is more likely to be a problem for homes with basements, radon can also be found in homes in China from radioactive material in construction materials such as concrete, granite, marble, and gypsum-based drywall. Since most municipal water is aerated before entering a home, radon in water in major Chinese cities poses little threat.
Radon enters a home through foundation cracks, openings for pipes, through direct release from construction materials, and from the agitation of radon-contaminated water. Outdoors, concentrations are so low to be insignificant, but in enclosed spaces without sufficient ventilation, concentrations can build up to dangerous levels. Ironically, as homes become more energy efficient and sealed, the danger of radon gas build-up may increase.
What is the health impact?
Radon can attach to dust particles and when inhaled, lodge in the lungs. Once there, the radon elements emit radiation that damages lung tissue and eventually cause lung cancer.
The US Surgeon General has declared radon to be the leading cause of lung cancer among non-smokers, exceeding even secondhand smoke. Statistically, radon causes more deaths than home fires, drowning, and airplane crashes combined. At the action level recommended by the EPA, the incidence of lung cancer has already been found to be 50% higher in women. It is known as the “invisible intruder” because it cannot be smelled, seen, and like many forms of cancer, impact may take many years to manifest after exposure.
Children are more susceptible to the effects of radon because their lungs are smaller and their breathing rate is faster.
How do I test for it?
The only way to detect radon is through measurement. There are several tests for radon, both of which require air sampling and laboratory analysis
- Charcoal canister (“immediate”) – this test uses a charcoal canister to sample the air which is then lab analyzed. However, radon levels can fluctuate widely depending on environmental factors such as temperature, air pressure and humidity, so this “snapshot” test may not be representative.
- Alpha-track (“longer-term”) – this test measures radiation emitted in the air over a period of several months to a year. We recommend this method since it is more likely to provide a more accurate picture of radon levels over time.
We recommend both of these tests in conjunction – while the alpha-track detector test is reliable, the charcoal canister test can provide an early warning of high radon levels.
The US EPA has set a level of concern or “action level” above which remedial action should be taken. This is currently 4 picocuries per liter of air (pCi/L). Exposure at this level is equivalent to more than 200 chest X-rays per year and presents a lung cancer risk that is 9 to 12 times higher than that of people not exposed to radon. Smokers are at an even higher risk due to the synergistic effect of radon. For example, tests have shown that approximately 2 out of every 1000 non-smokers will develop lung cancer at the action level of radon exposure, and approximately 10 of every 1000 smokers will develop lung cancer from smoking alone. However, when combined with radon exposure, the risk of lung cancer among smokers nearly triples to 30 out of 1000.
The EPA also recommends that remedial action be considered if radon levels are between 2-4 pCi/L.
If a problem is found, how can I remediate?
Strategies to permanently reduce radon levels depend on home type, location, and construction methods. In general, recommended action plans rely on one or more of the following:
- Sealing the source of radon emitting rock or soil with special sealants to prevent gas entrance
- Increased ventilation through opening windows, exhaust fans, or installing vent systems
- Creating positive air pressure within the home to prevent gas entrance
As with any remediation, it is important to follow-up with independent testing following corrective work to ensure that the problem has been resolved. We can work with you to recommend a strategy to fit your circumstances and help select a qualified remediator to correct the problem.
 A Citizen’s Guide to Radon. EPA Doc #402-K02-006, May 2002
 Based on 21,000 radon-attributed deaths. US EPA & The National Academy of Sciences, 2003.
 University of Iowa, 2000
 Radon – A Physician’s Guide: The Health Threat with a Simple Solution. EPA Doc #402-K-93-008. Sep 1993