Understanding the Radon Action Level in US: Is Your Home at Risk?

“There is no safe level of radon, reducing radon inside your home or building will always help reduce your risk of lung cancer,”

– Centers for Disease Control and Prevention.

Being the biggest source of natural-occurring background radiation, we are exposed to radon gas daily. It is colorless, odorless, and tasteless, making it difficult to detect without proper testing. Radon can seep into buildings, especially homes, and accumulate to potentially harmful levels.

The likelihood of lung cancer due to radon exposure depends on several factors:

• Radon concentration - The higher the radon concentration in a person's living environment, the greater the risk of lung cancer.
• Exposure duration - Prolonged exposure to elevated radon levels increases the risk. The longer someone is exposed to high radon concentrations, the higher the likelihood of developing lung cancer.
• Smoking status - Smokers are at a higher risk of developing lung cancer from radon exposure compared to non-smokers. Smoking and radon exposure have a synergistic effect, meaning their combined impact is greater than the sum of their individual effects.
• Overall health - Other factors such as pre-existing lung conditions and genetics can influence an individual's susceptibility to lung cancer.

See: Radon-Induced Lung Cancer: The Silent Threat to Non-Smokers

Outdoor radon levels typically vary between 0.135 to 0.405 pCi/L (or 5 to 15 Bq/m³). The World Health Organization recommends all nations set a reference level of 2.7 pCi/L (100 Bq/m3) for radon gas. With every increment of 2.7 pCi/L, the risk of developing lung cancer increases by 16%.

Living in a basement with a radon level of 20 for a duration of five years poses an equivalent risk to living in a house with a radon level of 10 for a period twice as long. If you, or someone you know, is currently living in the basement, take proactive steps to check for harmful radon exposure.

Additionally, children may face an elevated risk due to their lung structure and faster respiratory rate, potentially resulting in higher levels of exposure.

In 2023, Alaska topped the chart by being the state with the highest average radon level (10.7 pCi/L) in the U.S. Other states that took the top 10 spots are (from highest):

Early this year, it was found that over 70% of homes in Iowa have average radon levels above the Environment Protection Agency (EPA) threshold of 4pCi/L. On average, the radon level in Iowa homes is 8.5 pCi/L. The phenomenon can be attributed to the state’s glacial history. The passage of glaciers over Iowa led to the deposition of finely ground rocks that contain radium. The deposit constitutes a large surface area that emits radon gas.

If you reside in high radon areas, EPA recommends to:

1. Test – Radon testing kits are inexpensive and can be purchased online or from hardware stores. EPA recommends testing all homes below the third floor. Long-term radon measurements (remain in your house for more than 90 days) are typically more reliable for determining a home's year-round average radon level compared to short-term tests. This is because short-term tests, usually lasting anywhere from 2 to 7 days, may not accurately represent fluctuations in radon levels over time. Radon levels can vary due to factors like weather conditions, ventilation changes, and seasonal influences.
2. Mitigate - If your radon levels are elevated, consider hiring a professional radon mitigation contractor to reduce radon concentrations in your home. They can install ventilation systems and other measures to lower radon exposure. Based on the house dimensions, a radon mitigation system typically costs between $800 and $1,200. This investment not only makes your home safer but also alleviates concerns about potential lung health issues.
3. Maintain – The mitigation system requires occasional maintenance, such as repairing or replacing parts and regularly checking the warning device. The EPA recommends retesting of home radon levels every two years.

If your home radon level is below 4pCi/L, you can prevent radon accumulation by ensuring good air circulation in the house. This can be done by opening the windows and increasing air flow using fans or vents. However, these strategies only provide a temporary effect in maintaining low indoor radon levels.