Radon
is a radioactive gas that is formed when uranium breaks down naturally. It
has no colour, odour, or taste. Radon is slowly released from the ground,
water, and some building materials that contain very small amounts of
uranium, such as concrete, bricks, tiles and gyproc. When radon is released
to outdoor air, it is diluted by the atmosphere and is not a concern.
However, in enclosed spaces like dwellings, it can sometimes accumulate to
high levels.
What is the current Canadian guideline for radon in indoor air?
The current Canadian guideline for radon in indoor air for dwellings is 800
Becquerels per cubic metre (800 Bq/m³). The new guideline being proposed by
Health Canada is 200 Bq/m³.
What is the difference between Bq/m³ and pCi/L?
Both these units are measurements of radioactivity. The international
community uses the Becquerel per cubic metre of air, while the USA uses the
Picocurie per litre to measure radon. One Bq/m³ is equivalent to
approximately pCi/Lx37.
Are there certain parts of Nova Scotia that have higher levels of radon
than others?
Within the province, areas that have certain types of rock (shale and
granite) and soil can have higher levels of uranium in the ground and likely
more radon. This is also true of most other Canadian provinces. A radon test
for an individual building is the only way to tell for certain whether radon
is present.
What are the health effects of radon?
The
only known health risk associated with exposure to high levels of radon in
indoor air is an increased lifetime risk of developing lung cancer. This is
because radiation from inhaled radon gas can damage cells in the lungs. The
effects depend on the levels of radon and how long a person is exposed to
these levels. The proposed new Canadian guideline is based on an exposure
period of about 70 years spent in a dwelling that contains elevated levels
of radon 75% of that time. Exposure to radon and tobacco use together can
significantly increase your risk of lung cancer, however, not using tobacco
products remains the most effective way to reduce the risk of lung cancer.
How does radon enter the dwelling?
Because radon is a soil gas it can enter a dwelling through any opening that
contacts the soil around or underneath the building. For example, it can
seep in through cracks or holes in basement floors or walls, including
openings for utility connections, and through hollow support posts. If there
is radon in the dwelling's water supply, radon can also enter the space via
running tap water. Both old and newer structures can have elevated levels of
radon.
How can a building be tested for radon?
There
are several methods that can be used to test a dwelling for radon. Here are
some of the more common devices.
- Electret Ion Chamber (E-perm): These units come
in two variations; one for short term tests (typically a few weeks) or
long term (several weeks or months). These units are returned to our
laboratory for analysis.
- Continuous Monitors: As the name implies these
devices will measure radon over a period and report the results per
hour.
How can I decide whether my house should be tested?
House construction methods and materials can affect the radon level,
however, radon will be present in varying amounts in all types of houses.
Because radon enters a building from the ground, the upper floors of a
multi-story building usually have lower radon levels than the ground floor.
Radon levels vary from house to house, so your neighbour's test results
should not be used to make decisions about your house. The only way of
knowing the radon level in your house is to have it tested, whether your
house is new or old. It is possible to perform an instant radon test, but
the result will not give a reliable indication of the average radon level.
Due to the variation in radon levels from day to day, the longer the test
period, the more reliable the results of the test.
Are the radon detectors themselves dangerous or do they contain toxic
substances?
No. Radon detectors do not pose a health risk.
After completing work to reduce radon levels in a dwelling should the air
be retested?
Yes. To ensure that the radon levels in the dwelling have been lowered and
meet the guideline a retest must carried out.
Where in the building should I perform the test?
The highest radon concentration is most likely to occur in basements and
lower floors, especially if those areas have poor ventilation. A radon test
should be carried out in lower level rooms of dwellings where the occupants
spend the most time, such as bedrooms or living rooms. The instructions
included with your testing unit will help you place it properly.
How long should a radon test be conducted?
Because there are so many variables that affect radon, including weather,
local soil and rock type, building type and construction materials, the
longer the radon test is carried out the more accurate the result. The Nova
Scotia Department of Environment and Labour recommends testing be carried
out over a period of at least three months and, if possible, in the coolest
months of the year. During the heating season ventilation is lowest and
radon levels are usually at their highest. For accurate results, carefully
follow the instructions included with your test unit.
What methods can be used to reduce the radon levels in a dwelling?
The methods used to reduce radon levels in a dwelling can vary considerably
depending on the characteristics of the dwelling, the radon level and the
radon entry points. Increasing the ventilation and closing entry points,
especially on the ground floor, may reduce the indoor radon levels. However,
the reduction may only be small and additional methods of radon reduction
may be required, particularly if the initial radon level was very high. More
comprehensive measures may be required that need the services of a qualified
contractor.
Is anything being done to prevent radon problems in new houses?
Yes. In 1995, the National Building Code introduced measures to prevent soil
gas from entering homes. This building code was updated in 2005. Radon is
considered a soil gas. Increasing the ventilation and closing entry points,
especially on the ground floor, may reduce the indoor radon levels. However,
the reduction may only be small and alternative methods of radon reduction
may be required, particularly if the initial radon level was very high.
Will high levels of radon affect the value of my house?
Where a high radon level is detected, it can most often be successfully
reduced at a cost which is usually small when compared to the value of the
house.
I am building a new house, can I have the site
tested for radon?
Although techniques are available for measuring radon levels in soil, it is
difficult to determine what the radon level in a new house will be from the
results of soil measurements. For this reason, site radon measurements are
not a reliable means of predicting, before construction, whether a building
will have a high radon level.
Individual dwelling owners may wish to reduce radon levels as much as they
reasonably can, using methods they find affordable and practical. However,
the level in a dwelling should not be above the proposed new Canadian
guideline of 200 Bq/m³.
I am interested in buying a house. How can I find out if the radon level
has been measured?
You can ask if the house has been tested for radon. If you cannot be sure
then you can request that it be tested.
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