No. There are no symptoms of radon exposure, and that is precisely the problem. If you are searching this because you feel unwell in your home, the cause is almost certainly something else.
Radon exposure causes no short-term symptoms at all. No headaches, no nausea, no fatigue, no cough, no rash. You cannot feel it, and there is no point at which your body tells you the level in your house has gone up.
This is not a gap in the science. It is the nature of the risk. Radon damages lung tissue slowly, over years, and the only outcome it is known to cause in people is lung cancer, typically decades after exposure begins.
Something is worth investigating, but it is very unlikely to be radon. Things that do cause symptoms indoors include carbon monoxide, mould, poor ventilation, volatile compounds from renovation materials, and dust.
Carbon monoxide in particular is worth ruling out immediately. It causes headaches, dizziness, nausea and confusion, it can kill quickly, and a detector costs very little. If people or pets feel better when they leave the house and worse when they return, treat that as urgent and get out and get help. That symptom pattern is a classic sign of carbon monoxide, not radon.
You measure. That is the entire answer, and it is why radon gets talked about differently from other household hazards. A long-term test over three months in the lowest level you use will tell you what you are living with. Nothing else will.
Radon is the second leading cause of lung cancer in Canada after smoking, and the leading cause among people who have never smoked. Risk rises with concentration and with years of exposure, and it rises very steeply for smokers, because the two effects multiply rather than add.
It is also a risk you can remove. Mitigation is a day's work and removes most of the radon, and the risk stops accumulating from the moment the level comes down.
Fix the house, and talk to your doctor if you are worried, particularly if you also smoke or used to. Past exposure cannot be undone, but the risk is cumulative, which cuts both ways: lowering the level now genuinely reduces what you accumulate from here.
No. Radon produces no acute symptoms of any kind. If you feel unwell at home, look at carbon monoxide, mould, ventilation or air quality instead, and rule out carbon monoxide first because it is both dangerous and easy to detect.
Lung cancer from radon typically develops over decades. This is a long-exposure risk, which is why a high reading is a reason to arrange mitigation rather than a reason to leave the house tonight.
Children breathe more air relative to their body size and have more years ahead of them for a cumulative risk to accumulate, which is a good argument for fixing a high reading in a family home rather than deferring it. There is no evidence of any short-term effect on anyone, of any age.
Considerably. Radon and smoking multiply each other's effect on lung cancer risk rather than simply adding, so a smoker in a high-radon house carries a much higher risk than either factor alone would suggest. It is the strongest single reason to test and fix.
Sources. Health Canada radon guidance and published measurement data; the 2024 Cross-Canada Survey of Radon; World Health Organization Handbook on Indoor Radon; United States Environmental Protection Agency; Canadian National Radon Proficiency Program. Costs described are general ranges, not quotes.