Question:
I like your column because I learn much new stuff from it.
I've heard about radon a lot lately and know it is a cancer-causing natural radioactive gas that you can't see, smell or taste. We are concerned about our house which is a bungalow built in 1981, and the basement was fully finished. If you have any suggestions as to how to test it and protect from its harmful impact, it would be greatly appreciated.
Sincerely,
Lulu.
ANSWER:
There has been more information about radon in the news the last few years due to changes in government policy regarding safe levels in homes. I recently attended a seminar about radon testing and remediation which reminded me that I have not addressed this issue in my column for some time.
You are correct that radon gas is naturally occurring and can be present in our homes and buildings in small amounts, or dangerous levels, without our knowledge. Radon gas is caused by the breakdown of uranium in soil and is normally so highly diluted by air that it does not create a health concern in the natural environment. Unfortunately, that is not true in enclosed spaces, like our homes, which can accumulate high levels. While information on radon is widely distributed and available from Health Canada, remediation is at the discretion of individual homeowners and recommended only, not enforced.
The highest concentration of radon in most homes will occur on the lowest level of the home, typically the basement. Research has shown that most radon enters the living space through sub-slab soil, beneath the basement floor. This can be through cracks in the concrete slab, openings, sumps, or catch basins for weeping tiles. Homes with exposed soil in crawl spaces may be particularly susceptible to radon intrusion, especially with our local clay soils. There are many recommendations for solutions to minimize radon-gas intrusion, but testing to see if there is a problem should be done before any major remediation is undertaken.
Along with recommendations for maximum indoor levels of radon, Health Canada also provides guidelines for testing procedures. Due to the variability of radon concentrations over time, even within a 24-hour period, long-term testing is recommended. Tests should collect data for a minimum of 30 to 90 days and preferably three to six months. The testing should be done on the lowest level of the home and may be done with several different types of passive or active collection devices. There are active collection devices for radon that can be almost instantaneous, or for a short period of time, but the reliability is questionable. It is too easy to have false negative results with this type of testing, especially if done during the summer months when windows may be open and the living space not enclosed. Active collection equipment used for three months will be very costly, so passive collectors are the most practical.
The two most widely used and reliable types of long-term passive testers are Alpha-Track Detectors and Electret Ion Chambers. Once the testing period has ended, these small devices are sealed and sent to a laboratory for analysis. The lab will analyze the detectors and provide a report to the homeowner with average radon levels and any accompanying recommendations based on the levels found. These detectors may be placed in the home by a radon evaluation specialist or by the homeowners, but should be undisturbed for the duration of the testing period. The testing should be done during the heating season, when exterior doors and windows to the home are normally sealed, and follow Health Canada guidelines for location.
As far as things to do to minimize radon intrusion before you test your home, commonsense items may be the simplest. Any area where there is potential for soil or soil gases to be exposed to the living space in your house should be sealed. Sealing the floor-drain catch basin, in an older home, or the sump pit lid, if present, should be the next step. If you have exposed soil in a crawlspace, it should be well sealed with 6Mil Polyethylene sheathing, caulked at the seams and edges to prevent communication between the soil and the air in the home.
Once you have done the testing to see if you have a problematic radon level in your home, remediation can vary from the minor items above to installation of mechanical ventilators or specialized sub-soil depressurizations systems. These items should only be installed by well trained, qualified radon remediation specialists. More information can be found in an excellent free publication from Health Canada and CMHC entitled Radon, a guide for Canadian Homeowners or at the Canada Mortgage & Housing Corp. website at www.cmhc.ca.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the President of the Canadian Association of Home & Property Inspectors - Manitoba (www.cahpi.mb.ca). Questions can be e-mailed to the address below. Ari can be reached at (204) 291-5358 or check out his website at www.trainedeye.ca.
trainedeye@iname.com
