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Radon in Your Home

by Wendy Priesnitz

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Q: We are in the market for a new home. A work colleague recently mentioned that, given the area where we’re looking, we should be careful about radon in the soil around any house we’re considering. What is radon, how does it get into buildings, and is it harmful enough that we should be worried? 

A: Radon is – as its name might suggest – a radioactive gas resulting from the natural breakdown of uranium. As radon decays, it produces something called “radon daughters.” Two of these – polonium-218 and polonium-214 – decay rapidly themselves, and emit alpha particles. When alpha particles interact with an object, the energy in them is absorbed by the surface of the object.

Human skin is thick enough to not be affected, but if you breathe in alpha particles, they can be absorbed by and damage bronchial and lung tissue. When lung cells are damaged, they have the potential to result in cancer when they reproduce. Until recently, research into the dangers of radon exposure were focused on uranium miners. But two independent scientific studies in Europe and North America have shown that lung cancer risks extend to levels that are found in some homes.

In confined spaces like a house basement (or a uranium mine), radon can accumulate and be dangerous. A non-smoker exposed to elevated levels of radon over a lifetime has a one in twenty chance of developing lung cancer. That estimate increases to a one in three chance if a smoker is also exposed to elevated levels of radon over a lifetime.

A 2010 report, Reducing Environmental Cancer Risk: What We Can Do Now by U.S. President Obama’s Cancer Panel has some of the most strongly-worded recommendations ever in regard to radon exposure. The report notes that the cancer risk attributable to residential radon exposure has been underestimated but is clearly demonstrated, and urges government to better address the risk. According to the report, radon is the second leading cause of lung cancer in the United States and the leading cause of lung cancer among people who have never smoked.

R. William Field, a University of Iowa professor of occupational and environmental health and epidemiology, says, “Radon is likely our leading environmental cause of cancer mortality in the United States. During the past fifty years, over a million people have died nationwide from radon-related lung cancer.”

In 2008, Field testified before the President’s Cancer Panel regarding environmental factors in cancer. At that meeting, he discussed ever-increasing exposure to radon due to new homes being built without radon-resistant features faster than existing houses are mitigated to reduce radon.

The Canadian government is also concerned about residential levels of radon. It says that in 2006, an estimated 1,900 lung cancer deaths in Canada were due to radon exposure. As part of its National Radon Program, Health Canada is currently conducting a multi-year residential radon survey in an effort to gain a better understanding of radon concentrations in houses across Canada. Thousands of houses will be tested and many more residents will complete phone surveys.

The cancer risk attributable to residential radon exposure has been underestimated. It is the second leading cause of lung cancer and the leading cause among people who have never smoked.

Testing for Radon

Predicting the level of radon in a building is difficult. Radon testing is the only way to be sure if the gas is present in your home. Experts recommend that homeowners periodically check their homes for radon levels and that homebuyers conduct a radon test in any home they are considering buying.

You can either hire a company to do the testing or do it yourself. The typical cost for a test is between $50 and $100, according to the Canadian Lung Association. Radon detectors are available at hardware stores, building supply centers, and online, and through some health departments. The detector is exposed to the air in a house for an indicated period of time. (Some kits suggest a few days but several months is the preferable term.) After testing is completed, the home test kit is returned to the manufacturer for laboratory analysis.

Testing should be conducted with the doors and windows closed, during the cooler months. The test kit should be placed in the lowest lived-in level of the house, and away from drafts, high heat, high humidity, and exterior walls.

The concentration of radon in the air can be measured in two different ways. The international community uses the becquerel per cubic meter of air measurement, while the USA uses picocuries per liter. One pCi/L is equivalent to 37 Bq/m³.

In 2009, the World Health Organization set its recommended radon reference level to 100 Bq/m³, for residential structures, with an upper limit that should not exceed 300 Bq/m³. Canada’s guideline for maximum exposure to radon in indoor air is 200 Bq/m³ (updated in 2007 from 800). The reference level in the USA is 4 pCi/L or approximately 150 Bq/m³. Reference levels for individual countries in the EU range from 200 to 400 Bq/m³.

Radon is colorless and odorless, and can seep into your home from the surrounding soil.

How Radon Gets Into A Home

Radon is colorless and odorless, and can seep into your home from the surrounding soil. If your home is in an area where the soil and rocks contain uranium, granite, shale, or phosphate, you’ll likely find radon. It may also be found in soils contaminated with certain types of industrial waste such as the by-products of uranium or phosphate mining.

In fact, at one time, some houses were built using the sand-like uranium tailings (pulverized rock) as construction material. As a result, some houses contain levels of radon gas and radon daughters even higher than those in mines.

However, radon can be a problem in buildings of all types. It seeps through small spaces in the soil and rock on which a house is built. It enters through dirt floors, gaps in suspended floors and around pipes, cracks in concrete walls, sump pumps, joints, basement drains, under the furnace base, and jack posts if the base is submerged in the floor.

Reducing Radon Levels

If testing indicates that high levels of radon are present in your home, you should act quickly to reduce the levels. According to the U.S. Environmental Protection Agency (EPA), high levels of radon can be solved at a price comparable to having a hot water heater installed or the house painted. A trained contractor with experience in radon mitigation can examine your house, locate the source of radon, and make repairs.

There currently is no certification program in Canada for radon mitigation contractors, although Health Canada is developing one. In the U.S., certification programs are offered through the National Environmental Health Association and the National Radon Safety Board. Canadian contractors who have undergone that training are recognized by Health Canada.

Renovations to basement floors, particularly dirt ones, sealing cracks and openings, and sub-floor ventilation can prevent radon from entering. Two coats of paint followed by a sealant are recommended for cement basement floors and foundation walls. Levels of radon three feet below the ground level can be a few hundred percent higher than the levels inside a basement, so it’s important to ensure that all cracks are filled.

Soil depressurization ventilates the soil surrounding the house so that radon is drawn away before it can enter. This system can be installed in an existing house and is increasingly being put in place during construction of new houses.

Increasing the ventilation within your home will also help lower the levels of radon.

Wendy Priesnitz is Natural Life's editor and a journalist, author, and former broadcaster with over 40 years of experience.


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