It’s so stressful, in fact, that its impact on biological age was almost double that of unemployment, and 50% greater than living as a former smoker, according to a study from U.K. and Australian researchers published Tuesday in The British Medical Journal’s Journal of Epidemiology & Community Health.

Repeatedly being unable to make rent and exposure to pollution or other environmental hazards at a rental property also lead to faster biological aging, according to the study.

While not often examined or emphasized, the findings “demonstrate the importance of housing to health, and the importance of having a secure and affordable place to live,” Amy Clair, a researcher at the Australian Centre for Housing Research and lead researcher on the study, told Fortune.

Because faster biological aging is associated with poorer health, increased risk of chronic illness, and death, renting’s association with faster biological aging “should be a significant concern for policymakers,” she added.

“Housing circumstances can ‘get under the skin’ with real and significant consequences for health,” the authors wrote.

How housing can affect health

We’re all familiar with chronological age, or the number of candles on our cake. One could say that biological age refers to how old our cells are, though the explanation is a bit simplistic. The measure refers to how fast you’re aging, and can differ greatly from your age.

Researchers used data from the U.K. Household Longitudinal Study, along with additional health information and blood samples from nearly 1,500 participants. Blood samples provided information on biomarkers associated with aging.

While researchers found that renting accelerated biological aging, there was one exception: Those whose rent was subsidized by the government did not experience faster biological aging than homeowners whose homes had been paid off.

The biological ages of study participants were determined at just one point in time. Further research is planned that will follow participants over time, tracking changes in their housing situation and testing again for biological age.

Biological aging data via blood test was only collected from white European individuals, one weakness of the study, the authors flagged. Further caveats: Housing conditions may impact other aspects of health aside from the epigenome. And prior housing conditions may have a continued impact on the epigenome, even after one moves.

“Greater support with housing costs and restrictions on increasing housing costs may protect people from housing arrears and its health consequences,” they wrote.

But there’s good news, the authors added. Because biological aging is reversible, “housing policy changes can improve health.”

Why is renting so stressful?

Potential stressors associated with renting mentioned in the study include possible lack of heating, location, overcrowding, stigma, and the hassle of moving.

And there’s price. Rent levels in the U.S. reached a high last year, Zillow senior economist Jeff Tucker said in the company’s 2022 report on renting.

The typical market rate rent in the U.S. last year was nearly 60% of annual median household income, the report found.