Melting permafrost could expose millions to invisible cancer-causing gas

Deep in the frozen ground In the north, a radioactive hazard has been trapped for millennia. But British scientist Paul Glover has realized that things are not always like that: One day it could disappear.

Glover attended a conference where one speaker described the low permeability of permafrost – the ground remains frozen for at least two years or in some cases thousands. It’s an icy shield, a thick blanket to lock in contaminants, bacteria and molecules underfoot – and that includes the cancer-causing radioactive gas radon.

Glover, a petrologist at the University of Leeds, UK, recalls: “I immediately thought, if there was radon underground, it would be trapped there by a layer of permafrost. “What if that class is suddenly no longer there?” Since then, Glover has been working on methods to estimate how much radon – released when the element radium decomposes – could be released when climate change causes the permafrost to thaw.

Cracks in an ice sheet in Greenland.Monica Bertolazzi / Moment / Getty

Significant areas of Arctic and sub-Arctic land cover contain permafrost – but today it is melting and the rate of that thaw is accelerating. In a report published in January, Glover and co-author Martin Blouin, now technical director of mapping software company Geostack, used modeling techniques to show that houses have basements built over permafrost areas that could be exposed to high levels of radon in the future. “As the permafrost melts, this source of active radon can spill to the surface and enter buildings – and when inside buildings, pose a health hazard,” says Glover.

No one knows exactly how quickly radon diffuses through icy ground, but by using the diffusion rate of carbon dioxide and adjusting for radon’s properties, Glover came up with a number he might be able to figure out. used in the model. Based on 40% of the permafrost thawed, calculations show that radon emissions can increase radiation levels by more than 200 becquerels per cubic meter (Bq/m3) over a period of more than 4 years in homes. have a basement level or underground. This happens when a 40 percent thaw occurs in 15 years or less.

According to the World Health Organization, the risk of lung cancer increases by about 16% for every 100 Bq/m3 of long-term exposure. Some countries, including the UK, set a safe average exposure of 200 Bq/m3. But without testing for radon in areas where geology shows it is present, people won’t know if they are at risk – because the gas is odorless, colorless and tasteless.

Glover emphasizes that the model in the paper is an early attempt to understand how permafrost might affect human exposure to the gas. For example, it doesn’t account for seasonal variations in the rate at which permafrost thaws or the effects of compacting the soil as the ice within it melts, something that could pump more radon to the surface.

People living in Canada, Alaska, Greenland and Russia may be exposed to radon gas due to melting permafrost.Image donwogdo / E + / Getty

Some 3.3 million people living on permafrost will melt completely by 2050, it is estimated in a 2021 study. Not all of these people live in areas susceptible to radon, but many do. people living in areas prone to radon: For example, in parts of Canada, Alaska, Greenland, and Russia. And the link between radon exposure and lung cancer is clear, as is the fact that smoking increases a person’s risk even further, says Stacy Stanifer, clinical nurse oncology specialist at the College of Nursing Kentucky said. She points out that studies show radon can cause up to 1 in 10 lung cancer deaths, including 1 million worldwide each year.

“Inhaling radon gas is dangerous for everyone, but it is even more harmful when you breathe in cigarette smoke,” says Stanifer. Smoking is common in arctic and subarctic communities; For example, a 2012 study reported that nearly two-thirds of Inuit Canadians 15 years of age and older who live in an Inuit homeland said they smoke cigarettes daily, compared with 16% of Canadians overall.

Scientists don’t know how much radon is actually emanating from areas where permafrost melts today, said Nicholas Hasson, a geologist and PhD. student at the University of Alaska Fairbanks: “I’ll call this a vacancy.” He notes that, in real life, permafrost layers are complex and irregular, and agrees with Glover that field measurements are essential to confirm the model. Instead of a uniform layer of ice underground, imagine permafrost like a lumpy, chunky piece of Swiss ice cheese, with some areas being much thicker than others and places with water. underground runoff, exacerbating the thaw.

Spring thaws and icebergs in northern Canada.UCG / Universal Images Group / Getty Images

Hasson and colleagues studied sites where permafrost thaws unusually quickly and releases methane, a greenhouse gas many times more potent than carbon dioxide. He suggested that similar “chimneys” could spew high amounts of radon in some places.

For human health, what really matters is the amount of radon entering people’s homes. Scientists and even homeowners themselves can use radiation detectors to assess this. A study published online in February 2022, which has yet to be reviewed, measured radon levels over the course of a year at more than 250 homes in three towns in Greenland. For example, out of 59 homes in Narsaq, 17 were found to have radiation levels above 200 Bq/m3.

Lead author Violeta Hansen, a radiologist at Aarhus University in Denmark, emphasizes that these are preliminary results based on a small number of houses. She says that more research will be needed before the health risks associated with radon in properties like this can be assessed across Greenland. She is currently leading an international project that will conduct field experiments and collect radon measurements from homes in various countries, including Canada and Greenland. “We need to get back to the masses with proven, low-cost mitigations,” says Hansen.

Lake Baikal in Siberia.Photo Anton Petrus / Moment / Getty

Aaron Goodarzi, a radiobiologist at the University of Calgary in Canada, says it’s important to avoid panicking people when there’s no data and definite solutions. The good news is that there are tried and tested methods for reducing radon levels in a home once a homeowner knows it’s there. For example, Goodarzi points to a technique called under-plate depressurization, in which a sealed pipe is inserted underneath the house and connected to a fan. This sucks up any radon from underneath the building before blowing it up into the atmosphere. “Think of it simply as a detour,” he said.

The type of building matters. Glover’s model found that houses built on stilts or stilts, and therefore located off the ground, did not experience increased radon levels. Fortunately, many homes in the Arctic and sub-Arctic are built this way. But for those that are not the case, the costs of radon mitigation can be very high for low-income communities in these regions. “It is a matter of fairness that needs to be considered,” said Goodarzi, who noted that the responsibility may lie with social housing administrators in some areas to ensure that the housing they provide is healthy.

A Health Canada spokesperson said that the government agency now recommends homeowners check their properties for radon levels and use certified suppliers to install mitigation technologies if needed. set.

Many people may not think much about radon, due to the fact that it is not visible. Glover says getting the message now, before the permafrost melts, could save lives.

“We know that people die from it,” he said. “But at the same time, there’s a lot that we can do to protect ourselves.”

This article originally appeared in Magazine worth knowing, an independent press effort from the Annual Review. Sign up to receive new mail. Melting permafrost could expose millions to invisible cancer-causing gas

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