Symptoms of Radon Exposure: What Canadians Should Know (and What Health Canada Recommends)

Flat-vector illustration of stylized human lungs in muted slate-blue on a cream parchment background, with a small coral-red radioactive trefoil symbol in the upper-right corner — visual marker for the article on symptoms of radon exposure in Canada

A note before you read. This article is general health information for Canadians, drawn from publicly available Health Canada, World Health Organization, International Agency for Research on Cancer, and Canadian Cancer Society sources. It is not medical advice. If you have any health concerns, please speak with your physician. See full disclaimers at the bottom.

If you're searching for symptoms of radon exposure, you probably expected a list — a cough, headaches, fatigue, something to compare to what you're feeling. Here is the honest answer from Health Canada, and it's actually good news: radon doesn't produce symptoms you can feel. It's colourless, odourless, and tasteless, and the body has no way to detect it.

That fact is also exactly why Canadian public-health bodies want every home tested. The only health risk associated with long-term exposure to elevated radon is a long-term one — increased lifetime lung cancer risk — and the only way to know whether your home has elevated radon is a real radon test. There is no symptom checklist that will tell you. There is no doctor's visit that will tell you. There is no "wait and see" approach that will tell you.

This guide explains what Health Canada actually says about radon and your health, walks through the questions Canadians commonly type into Google ("can radon cause headaches?", "is radon poisoning real?", "how does radon affect kids?"), and finishes with the one practical step that resolves the whole question: a long-term radon test in your home.

The 60-second answer

  • Radon is colourless, odourless, and tasteless. You can't feel it, smell it, taste it, or see it. (Health Canada)
  • There are no acute or short-term symptoms. Health Canada describes the radon health risk as long-term, not immediate.
  • Long-term exposure to elevated radon is associated with increased lifetime lung cancer risk. Health Canada estimates radon contributes to about 16% of Canadian lung cancer deaths. (source)
  • It's the leading cause of lung cancer among Canadians who have never smoked (Health Canada, Canadian Cancer Society).
  • About 1 in 5 Canadian homes has elevated radon levels. A long-term radon test is the only way to know yours. (Health Canada) Order a $89 long-term radon test kit →

Table of contents

  1. Why there are no symptoms — what Health Canada actually says
  2. How radon affects health (in plain language)
  3. The Canadian context: what the data shows
  4. Who should especially consider testing
  5. What you can actually do
  6. FAQ — including the "can radon cause headaches / fatigue / etc." questions
  7. Disclaimers
  8. Sources

Why there are no symptoms — what Health Canada actually says

Health Canada describes the radon health risk in unambiguous terms: "The health risk from radon is long-term not immediate. The longer you are exposed to high levels of radon, the greater your risk." (source)

Translation: radon doesn't make you feel sick today. It doesn't cause headaches, dizziness, fatigue, or any acute symptom that you'd associate with exposure to a household hazard. The risk it carries is statistical and long-term — a small contribution to lifetime lung cancer risk that compounds over years of exposure to elevated levels.

That's why a routine doctor's visit can't detect radon exposure. There's no blood test, no urine test, no imaging study a Canadian doctor can run that will tell you whether your home has elevated radon. The question isn't really a medical question — it's a building question. The information lives in the air in your home, not in your body. The only way to answer it is to measure the air in the home with a radon test.

The International Agency for Research on Cancer (IARC, the WHO's cancer research arm) classifies radon as a Group 1 carcinogen — its highest classification, the same one that applies to tobacco smoke and asbestos. The Canadian Cancer Society's plain-language summary: "Breathing in radon gas can damage cells that line the lungs. Exposure to radon gas increases your risk of lung cancer." (source) The good news is that radon is a measurable and fixable risk: a long-term test reveals your level, and if it's elevated, mitigation works well.

How radon affects health (in plain language)

Here is a straightforward explanation of what radon is and how it interacts with the body — useful background, without the alarmism that often surrounds discussions of household carcinogens.

What it is. Radon is a naturally occurring radioactive gas produced by the breakdown of uranium in soil and rock. It seeps into homes through cracks in foundations, gaps around service penetrations, sump pits, and crawl spaces, and accumulates indoors — especially in basements during the heating season when homes are sealed against the cold.

What it does in the lungs. When radon is inhaled, the gas itself doesn't do much. What matters are the tiny radioactive particles produced as radon decays. Those particles can attach to lung tissue and continue to decay there, releasing alpha radiation that can damage the DNA of nearby lung cells. Over many years of exposure to elevated levels, that DNA damage accumulates and can — in a small percentage of long-term-exposed people — eventually lead to lung cancer.

Why this matters in Canadian homes specifically. Outdoor radon is harmless because the gas dilutes immediately. Indoor radon is the issue: in enclosed indoor spaces with limited fresh air, radon can accumulate to concentrations meaningfully higher than the outdoor background. Health Canada's action guideline is 200 becquerels per cubic metre (Bq/m³). Above that level, Health Canada recommends taking corrective action; below it, no action is required, though the Canadian Cancer Society notes there is no level that is considered entirely free of risk.

The reassuring part. Radon is one of the few significant household health risks that is straightforward to measure and straightforward to address. A long-term radon test costs around $89 and tells you definitively whether you have a problem. If you do, mitigation systems typically reduce radon by up to 95% at a typical Canadian cost of $2,500–$4,500. Most Canadian homes test below the guideline; for the ones that don't, the path forward is clear.

The Canadian context: what the data shows

For Canadian context, Health Canada publishes a clear set of figures:

  • About 1 in 5 Canadian homes has radon levels above the 200 Bq/m³ guideline, with significant regional variation.
  • About 16% of Canadian lung cancer deaths are estimated to be associated with radon exposure.
  • Radon is the leading cause of lung cancer among Canadians who have never smoked.
  • For Canadians who do smoke, exposure to elevated radon raises lung cancer risk further than smoking alone — Health Canada describes this as an "even higher risk" combination.

(Source for all four: Health Canada — Radon: What You Need to Know (2025))

The takeaway isn't that every Canadian has a problem. The takeaway is that radon levels vary substantially from home to home, even between neighbouring houses on the same street, and the only way to know about your home is to test it. About four out of five homes test below the guideline; for the one that doesn't, a $89 test followed by professional mitigation typically reduces radon to levels well below the Health Canada guideline of 200 Bq/m³ (Health Canada cites mitigation reductions of more than 80%; CARST cites up to 95%).

Order a $89 long-term radon test kit →

Who should especially consider testing

Health Canada's recommendation is that every Canadian home should be tested, regardless of the occupants. That said, certain groups have particular reasons to make testing a priority:

Smokers and former smokers. Health Canada states explicitly: "People who smoke and are exposed to radon have an even higher risk of lung cancer." (source) For Canadians who smoke or used to smoke, knowing your home's radon level is one of the more meaningful health-related decisions you can make.

Families with children. Children breathe more rapidly than adults relative to body size and have many decades of remaining life expectancy. Long-term radon exposure beginning in childhood compounds over a longer time horizon than the same exposure beginning later in life. Health Canada's recommendation to test every Canadian home applies regardless of whether children live there, but the case is even stronger when they do.

People who spend a lot of time on lower levels. Basements and lower-level rooms typically have the highest indoor radon concentrations — they're closest to the soil source, and indoor air pressure dynamics (the "stack effect," where warm air rising through the home creates negative pressure at the lowest level) actively pull soil gas into the basement. If your basement is a finished living space — a home office, a bedroom, a kids' play area — hours spent there are concentrated radon-exposure hours.

Owners of older homes. Most Canadian homes built before 2010 were constructed without any radon-aware features. The 2010 National Building Code introduced a basic "rough-in" provision that some provinces adopted slowly, and the 2024 Ontario Building Code now requires a vent pipe rough-in plus soil-gas barrier — but most existing housing stock predates all of this. Older homes are statistically more likely to have higher radon levels, though the only way to know any specific home's level is still to test it.

Long-term occupants of any home that's never been tested. Health Canada recommends retesting every 5 years even after a low result. A home you've lived in for 15 years and never tested is, statistically speaking, the most worthwhile test you can run.

Being in any of these groups doesn't necessarily mean your home has elevated radon — it just means the value of knowing is higher for you than for the average homeowner.

What you can actually do

The action item is straightforward. Test your home for radon, with a long-term test, that produces a real lab result. That's the practical step Health Canada and the Canadian Cancer Society both recommend, and it resolves the question for any Canadian home in one step.

The Health Canada–recommended test is a long-term alpha-track lab test, deployed for at least 91 days (3 months), ideally during the heating season (October–April) when indoor radon concentrations are typically highest, in the lowest lived-in level of your home. After the test period, the detector is mailed to a laboratory certified by the Canadian National Radon Proficiency Program (C-NRPP), which returns your home's time-weighted average radon concentration in becquerels per cubic metre (Bq/m³) — compared to the Health Canada guideline of 200 Bq/m³.

Two outcomes, both of them clarifying:

  1. Below 200 Bq/m³. No action is required. You can stop wondering. Health Canada recommends retesting every 5 years, and some homeowners choose to act at lower levels because radon risk is on a continuum, but no further intervention is needed for most homes that test below the guideline.

  2. Above 200 Bq/m³. Mitigation is recommended. A C-NRPP-certified mitigation contractor installs a sub-slab depressurization system — the standard, well-established Canadian approach — at a typical cost of $2,500–$4,500. These systems typically reduce radon by up to 95%. Once installed, you re-test (ideally with an independent provider, not the mitigator's own check) to confirm the system is working.

A long-term radon test kit costs around $89 all-in with RadonTest.ca. You order online, place the detector in your home for 91+ days, mail it back in the prepaid Canadian return envelope, and receive your lab report within a few weeks. That's the whole process. After it, you'll know — for the first time, with confidence — whether radon is something you need to think about for your home.

Order your $89 long-term radon test kit →

If you want to compare different test types and ongoing monitors, see our comparison guide. If you're testing in the context of buying or selling a home, see our real estate guide. If you're a new-build owner in Ontario, your test may also support a Tarion radon warranty claim.

FAQ

What are the symptoms of radon exposure in humans? There are no immediate or acute symptoms of radon exposure. Radon is colourless, odourless, and tasteless. The Health Canada–described health risk is long-term, not immediate, and is associated with elevated lifetime lung cancer risk after many years of exposure to elevated levels. (Health Canada, Canadian Cancer Society)

How quickly can radon make you sick? Radon does not produce acute illness. Health Canada describes the radon health risk as long-term, not immediate. The lung cancer risk associated with radon is the result of cumulative exposure over many years, not exposure over hours or days.

Can a doctor test me for radon exposure? No. There is no medical test (blood, urine, imaging) that detects radon exposure in your body. To know whether your home has elevated radon, you test the air in the home — it's a building test, not a body test. Order a long-term test kit →

Is radon poisoning real? "Radon poisoning" is sometimes used loosely to refer to long-term exposure leading to lung cancer, but it isn't a poisoning in the everyday sense — radon doesn't produce acute symptoms like headaches, vomiting, or dizziness. The technically accurate framing is radon-induced lung cancer, which develops over many years of cumulative exposure.

What happens if you breathe high radon for a short time? Brief exposure to elevated radon (a few weeks at a friend's basement, a hotel stay, etc.) carries very low individual risk. The lung-cancer risk associated with radon is driven by cumulative long-term exposure — years of breathing elevated levels in your home. The home you actually live in is the one worth testing.

Are children at greater risk from radon? Children breathe more rapidly relative to body size and have more decades of remaining life expectancy during which any DNA damage can accumulate. Long-term radon exposure beginning in childhood compounds over a longer horizon than exposure beginning later in life. Health Canada's recommendation to test every Canadian home applies regardless of who lives there; the case for testing is even stronger when children are part of the household.

I've smoked for years. Does radon matter for me? Yes, particularly. Health Canada states: "People who smoke and are exposed to radon have an even higher risk of lung cancer." (source) Smoking and elevated radon together produce a particularly elevated lifetime risk relative to either alone. For smokers and former smokers, knowing your home's radon level is one of the more meaningful health-related decisions you can make.

My basement is finished and I spend a lot of time there. Should I be worried? "Worried" isn't quite the right word — about four out of five Canadian homes test below the Health Canada guideline. But basements typically have the highest indoor radon concentrations (they're closest to the soil source, and the stack effect tends to pull soil gas into lower levels of the home). If your basement is a regularly-used space, the case for testing is stronger. Order a $89 kit →

Does radon cause headaches, fatigue, dizziness, nausea, or skin problems? No — none of these are known effects of radon exposure. The Health Canada–described radon health risk is long-term, not acute, and doesn't affect day-to-day how-you-feel. If you have persistent symptoms in your home that improve when you leave, the more likely culprits are mould, carbon monoxide (especially if there's a fuel-burning appliance), VOCs from new furnishings, or other indoor air quality issues — worth investigating with a qualified professional. Important note on carbon monoxide: if you suspect carbon monoxide poisoning, leave the home and contact emergency services. Carbon monoxide and radon are different gases requiring different responses.

Is there a level of radon that carries no risk? The Canadian Cancer Society notes that no level of radon exposure is considered free of risk, and recommends reducing levels in your home to as low as reasonably achievable. (source) Health Canada's 200 Bq/m³ figure is a pragmatic action guideline — above it, mitigation is recommended; below it, no action is required, though any reduction lowers lifetime risk.

What's November "Radon Action Month"? November is recognized in Canada as Radon Action Month — it falls at the start of the heating season when indoor radon levels are typically highest, making it the ideal time to start a 91+ day long-term test. If you've been thinking about testing, the October–April heating season is the optimal start window.

Test your home — the simple step that resolves the question

Health Canada has been clear on this for a long time. There is no symptom checklist that will tell you. There is no doctor's visit that will tell you. There is one practical way to know whether radon is worth thinking about in your home: a long-term radon test that produces a real lab result.

RadonTest.ca — $89 all-in (plus applicable tax). Long-term 91-day alpha-track test kit. C-NRPP-listed device. Analysed at Lex Scientific in Guelph, Ontario — Canadian lab, C-NRPP listed, ISO/IEC 17025 accredited by CALA. Tracked Canadian shipping both ways. Written lab report PDF delivered to your inbox. About 4 out of 5 Canadian homes test below the Health Canada guideline; for the ones that don't, you'll have the result you need to act.

Order — $89 →

Important disclaimers

Not medical advice. This article provides general health information about radon and lung cancer risk drawn from publicly available materials of Health Canada, the World Health Organization, the International Agency for Research on Cancer, and the Canadian Cancer Society. It is not medical advice and is not a substitute for advice from a qualified medical professional. If you are experiencing symptoms of any kind, or if you have any concern about your health or your radon exposure, please consult a physician.

Statistics and citations. Statistics in this article — including the Health Canada figures cited for the proportion of Canadian lung cancer deaths associated with radon, the proportion of Canadian homes above the 200 Bq/m³ guideline, and the description of radon as the leading cause of lung cancer among Canadians who have never smoked — are taken from Health Canada's published "Radon: What You Need to Know" fact sheet (2025). Verify directly at canada.ca. Health Canada updates its published figures periodically; figures cited reflect the source as of May 2026.

Radon vs. carbon monoxide. Several sections of this article note that some symptoms commonly attributed to "radon" by lay searchers are in fact more consistent with carbon monoxide exposure — a separate, acute threat. If you suspect carbon monoxide poisoning (especially if you have a fuel-burning appliance, attached garage, or fireplace and you experience symptoms that improve when you leave the home), leave the home and call emergency services or your local poison control. Carbon monoxide and radon are different gases requiring different responses.

Mitigation cost. The $2,500–$4,500 mitigation cost range is a typical Canadian residential figure. Actual costs vary by home, foundation, complexity, and contractor. Health Canada cites mitigation reductions of more than 80%; CARST and the CREA homeowner's guide cite reductions of up to 95%. The exact reduction in any specific home depends on the mitigation system design and installation quality.

Testing recommendations. Recommendations to "test for at least 91 days" reflect Health Canada's guidance for the minimum long-term test duration; Health Canada considers 12 months optimal for the most accurate annual average. Some shorter testing protocols exist for specific contexts (real estate transactions, post-mitigation verification) — these are described in our related articles.

No diagnosis or treatment claims. RadonTest.ca sells radon test kits. We do not diagnose, treat, or prevent disease, and we make no claims about doing so. A radon test kit measures the radon concentration in your home; the relationship between radon exposure and lung cancer risk over time is described by Health Canada, the WHO, IARC, and the Canadian Cancer Society in the materials cited throughout this article.

No warranty as to completeness. RadonTest.ca makes no warranty as to the completeness or accuracy of the information herein and accepts no liability for decisions made in reliance on this article. Readers should independently verify any information that bears on a health decision before acting and should consult a qualified medical professional for personal medical questions.

Sources & further reading

Health Canada (federal)

Cancer & research bodies

Canadian radon associations

Related RadonTest.ca articles