You can't see it, you can't smell it and you can't taste it — yet it's the second-biggest cause of lung cancer in Ireland after smoking, and almost no buyer checks for it before they hand over half a million euro. It's called radon: a colourless, odourless radioactive gas that seeps up out of the ground into Irish homes and causes about 350 cases of lung cancer a year, according to the Environmental Protection Agency. Roughly a third of the country sits in a high-radon area. And here's the part that gets me: awareness is actually going backwards, and most buyers walk through a viewing without ever asking the one question a €50 test would answer.
What radon is — and why it's your problem now
Radon forms naturally as uranium in the ground breaks down. Out in the open air it just disperses and does no harm. But indoors it's a different story — it seeps up through floors, cracks and service entries, and it builds. Over years of breathing it in, it does real damage to your lungs. It's the single biggest source of radiation exposure most Irish people will ever get, and it comes free with the house.
Here's the catch, and it's a nasty one: you cannot see it, smell it or feel it. It won't show up on a structural survey, it won't show up on the BER, and you'll never spot it on a second viewing no matter how good your eye is. Whatever level the house has, you inherit it the day you get the keys. And the people who cop the most exposure are the ones who spend the most time at home — which, after you've just bought the place, is usually you.
Awareness is falling, and that's the worrying bit
Now for the trend that should bother you. The EPA's National Radon Survey 2025 found that awareness of radon has dropped from 82% in 2020 to 71% in 2025. More than half of people don't even know radon is linked to lung cancer — and of the ones who do, most have still never tested their home. The EPA has been going county by county, more or less pleading with households to test, precisely because the message is fading just as the risk stays exactly where it always was. The gas didn't go anywhere. We just stopped talking about it.
The numbers worth carrying around
If you take nothing else from this, take these. They're the whole story on a beer mat:
| What | Figure |
|---|---|
| Lung-cancer cases a year in Ireland linked to radon | ~350 (EPA) |
| Share of the country classified high-radon | ~1 in 3 |
| National reference level for action | 200 Bq/m³ |
| Awareness, 2020 → 2025 | 82% → 71% |
| Cost of a long-term test | ~€50 |
| Typical cost to fix a high reading | €800–1,500 |
Where it's actually a problem
Radon isn't spread evenly across the country. It tracks the geology under your feet, and it can change sharply from one area to the next — sometimes within the same town, on the same street. The EPA's radon map grades the country right down to small areas, showing the percentage of homes predicted to be above the reference level. Parts of the west, the midlands and the south-east carry notably higher predicted exposure than the national average. But because it's so local, the only number that genuinely matters to you is the one for the specific address you're bidding on. Not the county. Not the town. That house.
The good news: cheap to find, usually cheap to fix
Here's where I can put your mind at ease a bit. Unlike most of the nasty surprises that turn up late in a purchase, radon is one of the easiest to deal with — if you actually check. A long-term test is just a small detector you leave in place for about three months, and it'll set you back around €50. Some local- authority libraries now lend out digital radon monitors for free, so it can cost you nothing but the walk in. And if a reading does come back above 200 Bq/m³, fixing it is usually straightforward — a radon sump or better sub-floor ventilation — and typically runs about €800–1,500. That's a line item on a half-million-euro purchase. It's not a deal-breaker.
So here's what to do before you bid
Check the area's radon band as part of your homework, the same way you'd look at price, BER and flood risk. If the address sits in a high-radon area, treat a test as standard — not optional. Either budget for one, or make a clear radon test a condition of sale the moment you go sale-agreed. The cost is trivial next to what you're spending on the house, and on a high-radon address it's the one invisible risk you should never wave away with “ah, it's probably grand.” Test it, and then you'll actually know.