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Comment by abpavel | Hacker News Reader

Incorrect. There is no such thing as safe dose with Radon. You're thinking of gamma rays and 50mSv/year safe limit. You won't find safe limit for Radon. There are guidelines when you should be very concerned, but there is no safe limit.

It decays into radioactive lead, and once we breath it in, it's hard to get rid of, and stays in our bodies.

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I have a hard time making sense of this. Would it mean 1 atom of Rn is always fatal for any individual? The fact that it accumulates in the body doesn't mean it is fatal at any dose.

No, of course not, but Radon is highly radioactive and extremely small amounts are enough to measurably elevate your risk of cancer. We’re talking numbers like a few million molecules in a room.

We need to be more specific: Radon is a gas that goes through alpha decay. It is this specific combination that makes it dangerous. The gaseous form enables easy ingestion by breathing and alpha particles are extremely damaging at short ranges - sub-mm in solid matter. The dead outer skin layer is normally able to perfectly absorb alpha particles which make most emitters effectively harmless. Ingested alpha emitters are different as the emitted alpha particle enters living cells immediately. At that point it is a game of chance whether something gets destroyed or altered that is important for cell reproduction. Also, ingested radioactive emitters are impossible to remove from the human body.

> Also, ingested radioactive emitters are impossible to remove from the human body.

I think that’s only true for things we don’t metabolize?

Right. I should have rather said that there are no medical treatments that can remove ingested radioactive emitters in any meaningful way.

Chelation has been used to remove ingested Am, Pu, and Cm. It takes a while, though.

The regulations use a linear no threshold limit to be safe. But it has not been proven that there is a linear no threshold dose response. So I am not incorrect.

.. but it's also pretty much unavoidable in some places, as it leaks out of the granite in the ground.

It's mapped, in UK, and a standard part of House buying checklists.

Eg https://www.ukradon.org/information/ukmaps .

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