Science May 18, 2022 10:38 AM EDT
Deep in the frozen ground of the north, a radioactive hazard has lain trapped for millennia. But U.K. scientist Paul Glover realized some years back that it wouldn’t always be that way: One day it might get out.
Glover had attended a conference where a speaker described the low permeability of permafrost — ground that remains frozen for at least two years or, in some cases, thousands. It is an icy shield, a thick blanket that locks contaminants, microbes and molecules below foot — and that includes the cancer-causing radioactive gas radon.
READ MORE: How thawing permafrost is transforming the Arctic
“It immediately occurred to me that, well, if there is radon underground, it will be trapped there by a layer of permafrost,” recalls Glover, a petrophysicist at the University of Leeds in England. “What happens if that layer suddenly isn’t there anymore?” Ever since then, Glover has worked on methods to estimate how much radon — which is released as the element radium decays — might be liberated as climate change causes the permafrost to thaw.
Significant areas of Arctic and sub-Arctic ground contain permafrost — but today it is melting, and the rate of that thaw is accelerating. In a report published in January, Glover and coauthor Martin Blouin, now technical director at the mapping software firm Geostack, used modeling techniques to show that homes with basements built on areas of permafrost could be exposed to high levels of radon gas in the future. “As the permafrost melts, this reservoir of active radon can flood to the surface and get into buildings — and by being in buildings, cause a health hazard,” Glover says.
No one knows exactly how quickly radon diffuses through icy ground, but by using the rate of diffusion of carbon dioxide and adjusting for the properties of radon, Glover came up with a figure that he could use in the model. Based on 40 percent permafrost thaw, the calculations reveal that radon emissions could raise radioactivity levels to more than 200 becquerels per meter cubed (Bq/m3) for a period of more than four years in homes with basements at or below ground level. This happens when the 40 percent thaw occurs in 15 years or less.
According to the World Health Organization, the risk of lung cancer increases by about 16 percent with every 100 Bq/m3 of long-term exposure. Some countries, including the UK, set the safe level of average exposure at 200 Bq/m3. But without testing for radon in areas where the geology suggests it’s present, people will not know whether they are at risk — because the gas is odorless, colorless and tasteless.
Glover stresses that the model in the paper is an early attempt to understand how permafrost thaw could affect people’s exposure to the gas. It doesn’t, for example, account for seasonal variation in the rate of permafrost thaw or the effects of soil compaction when ice within it melts, something which could pump yet more radon to the surface.
Some 3.3 million people live on permafrost that will have completely melted away by 2050, according to estimates in a 2021 study. Not all of these people live in areas prone to radon but many do: For example, in parts of Canada, Alaska, Greenland and Russia. And the link between radon exposure and lung cancer is well-established, as is the fact that smoking further increases one’s risk, says Stacy Stanifer, oncology clinical nurse specialist at the University of Kentucky’s College of Nursing. She points to studies suggesting that radon could be behind up to 1 in 10 lung cancer deaths, of which there are 1 million in total worldwide every year.
“Breathing radon is dangerous for everyone, but it’s even more harmful when you also breathe tobacco smoke,” says Stanifer. Smoking is prevalent in Arctic and sub-Arctic communities; for example, a 2012 study reported that nearly two-thirds of Canadian Inuit age 15 and over who live within the Inuit homeland said they smoke cigarettes daily, compared with 16 percent of Canadians overall.
https://www.pbs.org/newshour/science/how-climate-change-is-putting-millions-at-risk-of-radon-exposure
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