This Common Household Substance Is Now Tied to Stroke Risk

You might never have heard of radon, but this colorless, odorless gas is likely lurking in your home. Unfortunately, it’s the second-leading cause of lung cancer — and now it’s connected to increased stroke risk.

A recent study published by the American Academy of Neurology found a clear association between radon exposure and the risk of stroke.

Radon is a naturally occurring radioactive gas emitted by rocks, soil and water. It typically makes its way into homes through cracks in basement walls, construction joints and any gaps around a home’s pipes.

The study followed more than 158,000 female participants, with an average age of 63, for 13 years.

Participants had no strokes prior to the study, but there were 6,979 strokes among participants during the 13-year study period.

Researchers divided the study participants into three groups, based on the average radon concentrations in the areas they lived in:

• More than 4 pCi/L (picocuries per liter of air)
• Between 2 and 4 pCi/L
• Less than 2 pCi/L

The Environmental Protection Agency (EPA) recommends indoor radon concentrations of no more than 4 pCi/L.

After accounting for factors like smoking, diabetes and high blood pressure, the researchers found that the participants in the group with the highest average radon exposure had a 14% increased risk of stroke compared with participants in the group with the lowest average exposure.

Those in the middle-exposure group had a 6% increased risk.

Study co-author Dr. Eric A. Whitsel of the University of North Carolina in Chapel Hill, said it was important to note that researchers found an increased stroke risk even in participants exposed to radon concentrations that were half the EPA’s limit.

The study included only female participants who were middle-aged or older and who were primarily white, so researchers point out that the results may not apply to other populations.

What you can do about radon exposure

The EPA has a map that shows the average indoor radon levels across the United States.

Counties in Southern states tend to have lower levels, typically less than 2 pCi/L. But counties in the Midwest and Northeast tend to have higher levels, greater than 4 pCi/L.

The EPA provides state-level maps as well, so you can easily tell the average indoor radon level in your county.

Note, however, that homes with high radon levels have been found even in counties with low average indoor levels. So don’t assume you have a low risk of radon exposure simply because you live in an area with low average levels.

The Centers for Disease Control and Prevention (CDC) recommends everyone test their home for radon, particularly anyone who’s never done it before.

There are two types of testing kits available for purchase. Short-term kits measure radon for two to 90 days and provide quick results. Long-term kits measure radon levels in the home for more than 90 days. The results of long-term kits are more likely to accurately reflect your home’s year-round average level.

Testing is important since you can’t detect radon on your own because it is invisible and odorless.

Increasing airflow in the home, such as by opening windows, can help reduce radon levels in your home, albeit temporarily. The CDC also recommends sealing cracks in floors and walls and quitting smoking, as smoking increases the risk of lung cancer from radon.

To learn more about radon and what you can do to mitigate your exposure to it, visit the EPA website’s radon resources webpage.