Radon converter
Convert radon between the US picocuries per liter and the European becquerels per cubic meter.
That's about the same as the US action level. Living with that level adds roughly 7.4 mSv of dose a year.
What it means
How much radon is that?
Radon varies hugely with weather, season and ventilation. A single short test can be out by a factor of two, which is why long-term tests are recommended.
Every unit
Your radon level in every unit
Learn
Three things worth knowing
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1 pCi/L = 37 Bq/m³
So the US action level of 4 pCi/L is 148 Bq/m³, a little under half the European figure of 300.
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Curies and becquerels
A becquerel is one decay a second; a curie is 37 billion, roughly the activity of a gram of radium. The US kept the older unit, which is why the conversion is so awkward.
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Ground floor readings are highest
Radon comes up from the soil, so a basement can read several times what a first-floor bedroom does. Where you test matters as much as when.
Shortcuts
Popular radon level conversions
Background
About radon levels
Radon is a radioactive gas that seeps out of the ground and collects indoors. It is the second biggest cause of lung cancer after smoking.
The US acts at 4 pCi/L, which is 148 Bq/m³; the EU reference level is 300 Bq/m³. The same house can therefore be "above the limit" in one country and below it in another.