Radon gas danger

A deadly radioactive gas may be lurking in Canadian homes without people knowing it.

Radon (Rn) is a colourless, odourless, radioactive gas, which occurs naturally in the environment as a result of the breakdown of uranium.

Rn escapes easily from the ground into the air, where it disintegrates through short-lived decay products called radon progeny. As radon progeny decay, they emit radioactive alpha particles and attach to aerosols, dust and other particles in the air.

As people breathe, Rn progeny are deposited on the cells lining the airways where the alpha particles can damage DNA and potentially cause lung cancer.

Radon is the second leading cause of lung cancer, behind only smoking. Radon exposure accounts for 10 per cent of all lung cancers. People who smoke and who are also exposed to radon have an even greater risk of developing lung cancer.

The risk of lung cancer increases by 16 per cent per 100 Bq/m³ increase in Rn concentration, according to the World Health Organization (WHO).

One Becquerel corresponds to the transformation (disintegration) of one atomic nucleus per second. Radon concentration in air is measured by the number of transformations per second in a cubic metre of air (Bq/m³).

Health Canada recommends that the average annual level of Rn in the air in a normal living area should be 200 Bq/m³ or less.

Background information 

Radon is radioactive because it decays, losing an alpha particle and forming the element Polonium, which is also radioactive.

How fast an element decays is measured in terms of ‘half-life’ or half the amount of an element will decay during a certain amount of time. Rn has a half-life of 3.8 days while Uranium’s is 4.4-billion years.

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“Canada remains a leading world uranium producer, accounting for 18 per cent of world primary production. All of the uranium production in Canada comes from Saskatchewan mines,” said the Canadian Nuclear Association.

“The energy potential of Saskatchewan’s uranium reserves is approximately equivalent to 4-billion tonnes of coal or 19-billion barrels of oil,” said the Saskatchewan Energy and Resources.

In the outdoor air, radon is diluted and is not a health risk, however the gas can seep from the ground into buildings. Indoors, radon levels are higher, with highest levels found in places such as mines, caves and water treatment facilities.

WHO says the average outdoor radon level varies between 5 and 15 Bq/m³.

Drinking water obtained from groundwater sources may also contain radon. To date, epidemiological studies have not found an association between radon in drinking water and cancer of the digestive and other systems.

Testing  

The Homeowner Protection Centre (HPC) suggests that only about 8 per cent of Canadians can name radon as the leading cause of lung cancer among non-smokers in Canada.

Testing devices are inexpensive and can be purchased from The Lung Association of Saskatchewan for $50, which also includes the analysis from the Saskatchewan Research Council. Radon test kits are commonly available at Canadian hardware stores and most cost less than $50.

It is recommended that testing be done for a three month period, preferably between October and April when indoor Rn levels are generally higher.

Testing should be carried out in the lowest level that is normally occupied for more than four hours a day. It is recommended that apartment buildings be tested below the third level, although Rn has been known to travel through elevator shafts and air ducts to higher floors.

Few Canadians have tested their homes for the carcinogen and fewer still have taken the relatively inexpensive steps to radon-proof their homes.

“Homeowners have the ability to protect their families from radon with affordable solutions, but they can’t take action if they’re not aware,” said Executive Director of the HPC Michael Lio.

In 2007, Health Canada lowered the recommended guideline for indoor Rn levels by 75 per cent or from 800 Bq/m³ to 200 Bq/m³. 

The concentration of radon in a home depends on:

• the amount of uranium in the underlying rocks and soils
• the routes available for the passage of radon into the home
• the rate of exchange between indoor and outdoor air, which depends on the construction of the house, the ventilation habits of the inhabitants, and the sealing of windows.

Reduction 

Radon levels in homes can be reduced by:

• improving the ventilation of the house
• sub-slab depressurization or soil suction by increasing under-floor ventilation
• avoiding the passage of radon from the basement into living rooms
• installing traps in floor drains
• installing a radon sump system in the basement
• sealing floors and walls (radon barrier)
• installing a positive pressurization or ventilation system.

Sub-slab depressurization involves a vent pipe and fan which pulls Rn from beneath the house and distributed in outside. Health Canada states that active soil depressurisation performed by a contractor is the most common method of reducing radon levels.

The cost of repair can run from $50 to over $3000, depending on the level of radon found in the building.

Radon safety should be considered when new houses are built, particularly in high Rn areas. Passive systems of mitigation have been shown to be capable of reducing indoor radon levels by up to 50 per cent.

More information about radon and radon testing can be found by calling the Lung Association of Saskatchewan at 1-888-566-LUNG, or by visiting the web site.