Higher Indoor Radon Is Linked to More Heart Failure in Women

Your heart may be affected by something you can’t see or smell in your house, and the good news is that you can check for it. In a study of 43,188 postmenopausal women across the US, women who lived where indoor radon was highest had more heart failure over about 16 years than women who lived where it was lowest.

Radon is a gas measured in picocuries per liter (pCi/L) of air. Researchers have long linked it to other health topics. This study asked a newer question: does it show up in heart failure too? Heart failure means the heart has trouble pumping as well as the body needs. It does not mean the heart has stopped.

How the study worked

Researchers followed women from the Women’s Health Initiative, a large US research project. The women were ages 50 to 79 when they joined between September 1993 and December 1998, and none had heart failure at the start. Doctors reviewed medical records to confirm heart failure hospitalizations through February 17, 2024. The study was published November 2, 2026, in JAMA Network Open. It was an observational cohort study, and radon was estimated from county-level levels rather than measured in each woman’s home, so it shows a link and not proof of cause.

What they found

The women were sorted into three groups by the radon level in their county, using categories from the US Environmental Protection Agency (EPA). About 36% lived with less than 2 pCi/L, 41% with 2 to 4 pCi/L, and 23% with more than 4 pCi/L. The average age was 63.

Over an average of 16.2 years, 3,446 women developed heart failure. Women in the highest radon group had about 1.2 times the rate of heart failure of women in the lowest group (1.19 exactly). That held up when the researchers tested their results in different ways.

The researchers also looked at two more specific outcomes at the highest level:

• Heart failure with reduced ejection fraction. This is the type where the heart muscle pumps out less blood with each beat. The rate was about 1.2 times higher (1.24).
• Deaths from heart failure. The rate was about 1.4 times higher (1.37).

The middle group, at 2 to 4 pCi/L, did not look different from the lowest group on these two outcomes.

To give a sense of size, the researchers compared the highest radon level to a 16 mm Hg rise in the top number of a blood pressure reading. They also compared it to a 4.8-point rise in body mass index. That puts radon in the same neighborhood as some well-known heart factors.

What does “radon level” mean for my home?

The study used county-level estimates, which describe an area. Levels can differ from one house to the next, even on the same street. The only way to know the level in your home is to test it. Your county’s category does not tell you what is in your living room.

The authors describe radon as a possible “modifiable” factor in heart failure. That means it is a risk factor you can look into and act on, unlike your age or your family history.

What you can do today

Order a home radon test kit. The EPA has information on radon and how to test. Many hardware stores and state radon programs also offer kits. Set the kit up as the instructions say, mail it to the lab if it asks you to, and write the result on your calendar. Then you will know your own number instead of a county estimate.

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