Methods For Measuring Radon

Methods For Measuring Radon
Several methods can be used to measure radon in a home:

• Charcoal Detectors – These devices consist of a container filled with charcoal and covered with a screen and filter. They are exposed to the air in your home for a specified time period (usually 2 to 7 days), sealed and then sent to a laboratory for analysis.
• Passive Alpha-Track Detectors – These detectors use a small sheet of special film enclosed in a container with a filter-covered opening. Passive alpha-track detectors  areexposed to the air in a home for a period that can range from several months to one year. Passive alpha-track detectorsmust be returned to a laboratory for analysis.
• Active Alpha-Track Detectors – This type of detector is similar to a passive alpha-track detector. However, it offers more accurate measurement by using a small electric air pump. Active alpha-track detectors are usually used to measure radon for periods of one week to about two months. Active alpha-track detectors must be returned to a laboratory for analysis
• Electret Ion Chamber – This method uses a special plastic canister that contains a disk called an “electret” with an electrostatic charge. It is exposed and the change in the electret’s charge read to determine the radon level. There are two versions, one for short-term tests of a few days or weeks, and one for long-term tests of several weeks or months. Electret ion chambers may be read in the home using a special analysis device or mailed to a lab for analysis.
• Continuous Monitors – These devices typically measure radon over a series of minutes and report the results in hourly increments. Results are normally available in the home. The cost of continuous monitor measurements is generally more expensive than other devices.

Specialized measurement methods not listed above are also available. They require an experienced technician with analytical equipment to visit the house. Because these measurements are expensive, they are not commonly used for initial radon testing in a home. However, they find greater application in follow-up measurements, research work, and to evaluate the success of radon reduction work.

Units of Measure
Your home’s measurements will be reported to you in one of three ways. Results from devices that measure concentrations of radon gas are reported as either “Becquerels per cubic metre” (Bq/m3) or “picoCuries per Liter” (pCi/L). Canada and other countries which have adopted the metric system use Bq/m3. One pCi/L equals 37 Bq/m3.

For devices that measure the radiation emitted from radon progeny, the results are reported as “Working Levels” (WL) or milliWorking Levels (mWL). The ratio between radon gas and its radon progeny varies with a number of factors, including the air exchange rate. In most houses, 0.025 WL is approximately equivalent to 200 Bq/m3 (5.4 pCi/L) of radon.

Purchasing Radon Detectors and Measurement Services
Radon detectors and radon measurement services can be difficult to find in many parts of Canada, even in large urban centres.

Charcoal and passive alpha-track devices are available in some retail stores that sell building, hardware or health care products. These detectors are sometimes offered by mail through ads placed in magazines about home improvement or health issues. Active alpha-track detectors, electret ion chambers and continuous monitor radon measurements may be available from companies in Canada. Contact your provincial or territorial agency for suppliers of radon detectors.

Professional home inspectors can be contacted to identify whether local sources exist for radon detection devices and services in your community. When choosing radon detectors, the lowest price may not be your best choice. The level of service, accuracy of detectors, expertise and advice can vary considerably between different suppliers of radon detectors and measurement services.

For more advice about the availability of radon measurement devices and services in your region, contact your provincial or territorial government.

At present, Canada does not have a national program for certification of radon testing and mitigation companies, however, development of such a program is currently underway by Health Canada. In the interim, Health Canada recognizes the certification programs offered in the United States through either the National Environmental Health Association or the National Radon Safety Board. Both organizations operate a certification program for individuals who offer radon measurement and mitigation services to the public. The program is designed to provide a list of individuals who have qualified through an educational and examination process to provide high quality radon testing and mitigation services.

Periodic performance checks and continuing education requirements must be met in order to maintain the qualification following initial certification. Health Canada encourages Canadians to use an individual or company that participates in one of these certification programs. Information on these certification programs may be found at: http://www.radongas.org or http://www.nrsb.org.

Determining Your Home’s Radon Level
Because radon levels in a home can vary significantly over time, use an extended measurement period, preferably a full year.

While the variation differs from home to home, it is not uncommon to see radon levels in a house change by a factor of two to three or more over a one-day period. Seasonal variations can be even more dramatic with the highest levels usually experienced during winter.

A year-long measurement period will give a much better indication of your exposure than a measurement of shorter duration. Passive alpha track and long-term electret ion chamber detectors are the most practical methods for this type of extended measurement.

When conducting the radon test yourself observe the manufacturer’s instructions and the guidelines below when placing a radon detector in your home:

• Make the measurement in the lowest lived-in area of your home, such as the basement, if it is finished.
• Avoid taking measurements in the kitchen. The exhaust fan as well as humidity and airborne particles from cooking may affect the accuracy of some types of radon detectors. Also, avoid bathrooms since relatively little time is spent in this room.
• Place the detector where it will not be disturbed during the measurement period but avoid small enclosed areas, such as a cupboard or closet.
• Do not place the detector close to an outside wall or near a sump or floor drain.  Avoid locating the detector in drafts from heating or air conditioning vents, near windows or doors, or sources of heat, such as stoves, fireplaces or strong sunlight.
• Place the detector at least 200 mm (8 in.) below the ceiling and 500 mm (20 in.) above the floor.

Health Canada is now developing standard protocols for radon testing in homes, schools and other large buildings.When completed, these protocols will provide detailed instructions and guidance to radon testing companies and homeowners on how to perform a radon test.

Some people may not want or be able to wait a year for the results. For example, news of high radon levels in your community, renovating a basement as living space, or making an offer-to-purchase on a home may hasten your desire to know whether there is a radon problem. If haste is a priority over accuracy, you can use a charcoal detector. Otherwise, a one-month measurement is the minimum recommended test duration with a one-year test being the optimum. The cost of radon testing is approximately $50 to $100.

Contact your REALTOR at Coldwell Banker Vantage Realty for more tips and advice on what you can do if you are concerned about Radon in your home.

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