Radon is a colourless and odourless radioactive gas that can be found in almost any soil, with higher or lower concentrations. It is the second leading cause of lung cancer in the world, but few efforts have been made in Chile to determine its presence. A research team from the Andrés Bello University, the Saphir Millennium Institute and the University of Tarapacá are implementing a project to measure radon gas concentrations across Chile: measurements began in schools and universities in northern Chile during the first half of 2022 and should have results by mid-2023.

By Jorge Román

Cover image: the UNAB, Saphir and UTA team mapping radon in northern Chile. Credits: Jilberto Zamora Saa

It's not just coronavirus that likes stuffy rooms.

Radon is an odourless, colourless, tasteless radioactive gas that is produced naturally by the decay of uranium. Radon releases are very high in uranium mines (of course), but traces of uranium have been found to be present in most of the world's soils: therefore, almost anyone can be exposed to higher or lower doses of radon gas (Bissett and McLaughlin, 2010; CDC, 2022; WHO, 2021).

Let's not run in circles. Smoking is still (by far) the biggest culprit in lung cancer cases. However, people who smoke and are exposed to radon gas are even more likely to develop lung cancer. Burning wood, coal or other materials that add particulate matter to household air also increases the likelihood of developing radon-derived lung cancer (CDC, 2022; WHO, 2021).

Let's not run in circles. Smoking is still (by far) the biggest culprit in lung cancer cases. However, people who smoke and are exposed to radon gas are even more likely to develop lung cancer. Burning wood, coal or other materials that add particulate matter to household air also increases the likelihood of developing radon-derived lung cancer (CDC, 2022; WHO, 2021).

This does not mean that everyone will develop lung cancer. In fact, it is estimated that radon causes between 3 and 14% of lung cancer cases in each country (WHO, 2021). The exact figure depends on the level of radon present in that country and the prevalence of smoking. For example, in a country with many smokers, smoking could account for more than 90% of lung cancer cases. But that smaller percentage could still be thousands of people who are threatened by a preventable cancer. In the United States, it is estimated that more than 20,000 annual cancer deaths can be attributed to exposure to radon gas (CDC, 2022).

Radon is found in soils, rocks and groundwater, from which it migrates to the surface. It can seep into porous soils and cracks in underground rocks, soils and walls, until it comes to the surface and mixes with the air we breathe. Because it is a gas, it tends to accumulate in enclosed or poorly ventilated areas, so mines, caves and subways are at risk (Bissett and McLaughlin, 2010; CDC, 2022; WHO, 2021).

Outdoors, radon is rapidly diluted in the air and is not usually a problem. But it has been found that in buildings such as homes, schools and offices, the concentration of radon gas can be two to 2,000 times higher than outdoors, and it has been shown that even relatively low concentrations of radon in these buildings can markedly increase the prevalence of lung cancer (WHO, 2021). It is therefore very important to measure radon concentration in inhabited or highly occupied buildings.

Measuring invisible gases

In Chile, there are no regulations governing the measurement of radon gas and setting an allowable limit (AGQ Labs, 2022). However, the issue is mentioned in the second edition of the document Sustainable construction standards for housing in Chile. Volume I: health and well-beingby the Ministry of Housing and Urbanism (Minvu, 2018). In the document, it is suggested to include in the bidding conditions for new construction the verification of permitted radon concentration levels for indoor enclosures, in addition to considering measures for prevention, reduction, extraction and monitoring of indoor radon gas concentration (Minvu, 2018).

Although sporadic measurements have been made, there is no systematic survey of radon gas concentrations in Chile. That is why Zamora, together with University of Tarapacá academics Lorena Cornejo, Stavros Kukulis and Luciano Villarroel, have begun this year to systematically map radon emissions in the northern part of the country.

According to Zamora, the measurements are mainly done in schools and universities, as they are very busy buildings, where large groups of people meet for many hours a day. His team's goal is to complete the measurements in northern Chile by mid-2023. Three to four months of monitoring are needed to have a reliable measurement.

Zamora explains that the next stage of the project will be to measure radon concentrations in the south, and that he suspects the measurements will be very different. This is because buildings in the North tend to be much more ventilated than in the South, where the cold forces rooms and offices to be closed to keep the heat in. And, as we have seen previously, lack of ventilation is a factor that increases radon concentration in buildings.

The project to measure radon gas in the North is supported by the Saphir Millennium Institute (funded by the Millennium Science Initiative of ANID), the Centre for Theoretical and Experimental Physics (CTEPP) of the Andrés Bello University and the University of Tarapacá.

References

AGQ Labs (2022, February 25). Radon, what it is and how we can detect it [Institutional]. AGQ Labs. Available here.

Bissett, R. J., & McLaughlin, J. R. (2010). Radon. Chronic Diseases in Canada, 29 Suppl 1, 38-50.

Centers for Disease Control and Prevention (CDC). (2022, January 3). Radon and Your Health [Institutional]. Centers for Disease Control and Prevention. Available here ..

Ministry of Housing and Urban Development (Minvu). (2018). Sustainable building standards for housing in Chile, Volume I: health and well-being: Vol. I. Health and well-being. (second edition). Minvu. Available here.

World Health Organization (WHO) (2021, February 2). Radon and health [Institutional]. World Health Organization. Available here.