Radon and your health: what the evidence says

What is radon, and how does it reach the lungs?

Radon is a gas that comes out of the ground and is breathed in with ordinary indoor air. It is radioactive, it forms through the natural breakdown of uranium in soil and rock, and it has no colour, odour or tastesource.

The Canadian Nuclear Safety Commission explains that radon decays into short-lived radioactive particles, that these can be inhaled and lodge in lung tissue, and that alpha radiation there can damage cellssource. That is as far as this page takes the biology. The detail beyond it belongs to the scientific and medical literature and not to a company that measures buildings.

One practical point follows from the description. The subject is the air indoors, where the gas can collect, and the amount in that air is something an instrument can measure. Everything a homeowner can do about radon starts from that measurement.

What is the known health effect of radon?

An increased risk of lung cancer, and nothing else appears on Health Canada's list. Health Canada names a higher risk of lung cancer as the only known health effect of radon, and describes that risk as long-term and not immediatesource. It also identifies radon as the leading cause of lung cancer in people who have never smoked, and as the second leading cause overall, after smokingsource.

Two words in that summary deserve a second look. "Risk" is a statement about likelihood across many people, and it is not a forecast for any one of them. "Long-term" places the subject in exposure over time and not in what happens on a given day in a given room.

Read together, the two statements explain why radon is treated as a public health matter in Canada and also why it is handled calmly. The concern is real and well documented. The response to it is a measurement and, where needed, a repair to the building.

Are there symptoms of radon exposure?

Health Canada lists none, and the risk it describes is a long-term one. Our wording on this point is deliberate: Health Canada lists lung cancer as the only known health effect of radon; it does not list headaches, coughs or fatiguesource.

The senses give no information about the gas either, since it has no colour, odour or taste. Health Canada's position is that levels vary from one house to another, even between similar houses side by side, and that testing is the only way to be sure of a home's levelsource.

So the two questions are separate. Whether a building holds a high level of radon is answered by a detector. How a person in that building is feeling is a matter to raise with a physician on its own terms. Neither question can be used to answer the other.

How much lung cancer in Canada is linked to radon?

Health Canada publishes two national figures, and they are best read one at a time. It estimates that 16% of lung cancers in Canada are from radon exposuresource. It attributes more than 3,000 lung cancer deaths in Canada each year to radonsource.

The first figure is a share of cases and the second is a count of deaths. We do not derive one from the other, because the source does not. Both describe the country as a whole. Neither one says anything about a particular household or a particular person.

For Alberta there is a figure from a researcher, and it is his and not ours. As reported by the Western Wheel, Dr. Aaron Goodarzi of the University of Calgary has said that roughly one new radon-induced lung cancer case occurs every day in Albertasource. We repeat it as his statement, with its source, and we have not calculated or checked it ourselves.

What does the risk depend on?

On three things, according to Health Canada: the level of radon, the duration of exposure and smokingsource. Only the first of them is a property of the house.

The table also marks the limit of what a page like this can say. It can name the factors. It cannot weigh them for a particular person, and it does not try. Nothing here should be read as telling any reader where they personally stand.

What the factors do show is where effort is best spent. The level in the home is the one item on the list that can be measured with a small device and changed with a repair. That is the reason the rest of this site is about testing and mitigation and not about medicine.

How does smoking change the risk?

It raises it considerably. Health Canada states that smokers exposed to radon face a much higher combined risk than non-smokerssource.

We give no number for that combined risk, because the statement we rely on does not include one. What it does make plain is that radon and smoking are not two unrelated subjects. For a household where someone smokes, that is one more reason to find out the radon level in the home.

The reverse reading would be a mistake. The first of the statements quoted earlier is about people who have never smoked, so a smoke-free household has the same reason to test as any other.

Does the 200 Bq/m³ guideline separate risk from no risk?

No. It marks the point at which Health Canada recommends action. The Canadian guideline is 200 Bq/m³, and corrective action is recommended when the annual average in a home is above itsource. Above that level the recommendation is to mitigate within one year, sooner the higher the level, and to reduce radon as low as reasonably achievablesource.

The closing words of that recommendation matter. A guideline that asked only for a result just under the line would not add "as low as reasonably achievable". Health Canada's recommendation to act applies above 200 Bq/m³, and under that figure the decision rests with the owner. No level is risk-free and lower is better.

The guideline is also about an average over a year, not a reading on one afternoon. Our guide to reading a radon test report explains which results can be compared with it and which cannot.

Why is this relevant to homes in Calgary?

Because results at or above the guideline are common in local measurements. The Cross-Canada Survey of Radon Exposure found about 1 in 6 houses in the Calgary area (15.5%) at or above 200 Bq/m³, a further 36.9% between 100 and 199 Bq/m³, and an average of 102.5 Bq/m³source.

A survey describes a region and not an address. Health Canada's recommendation is that every home be tested for radon, wherever it is located and whatever the type of buildingsource. A survey result is a reason to test, and it is never a substitute for testing.

The season matters here as well. Health Canada asks for at least 91 days of a test to fall in the heating season, when windows are closed and indoor radon tends to be highestsource, and Calgary's heating season is a long one. Our guide to timing a radon test in a Calgary winter covers that side of the subject.

What can a homeowner do about radon?

Measure the level, and reduce it if the result calls for that. Both steps are well established, and both are in a homeowner's hands.

Measuring comes first, because nothing else can be decided without a number. Our overview of radon testing for Calgary homes explains the kinds of test, and the long-term test we place and report is the one the guideline is built around. When the report arrives, the tool that checks a radon result against the guideline shows where the figure sits.

Reducing comes second, and only where the measurement points to it. Health Canada reports that a radon reduction system can usually be installed in less than a day, lowers radon by more than 80% in most homes, and costs about as much as other common home repairssource. A system lowers the level in the building; it does not bring it to zero, and the figure it reaches in a given house is found by testing afterwards. Our page on how radon is reduced in Calgary houses describes the work.

That follow-up has two parts. The installer takes a short verification reading once the fan is on. The long-term confirmation is done with an independent laboratory kit, which the homeowner places and mails.

When is radon a question for a doctor?

Whenever the question is about a person and not about a building. Questions about personal health belong with a physician, and this page is not medical advice.

We keep to that boundary on purpose. Our work is measuring radon in homes and lowering it, and the health statements on this page are Health Canada's and the Canadian Nuclear Safety Commission's, each with its source listed below. Where those sources stop, this page stops too. It gives no personal risk estimate and makes no statement, in either direction, about any other health condition.

The step within a homeowner's control is the same in every case: measure the level in the home and, if needed, reduce it. If you already have a result and are unsure how to read it, send it with the form on this page, with the unit, the dates and the room, and we will tell you what it means for the building.