If you live in a country where there are a lot of concerns about loose radiation, for instance, after an enormous earthquake has compromised and destabilized nuclear reactors, this completely makes sense. It’s being put out by the mobile phone provider Softbank in Japan.

From Reuters:

The smartphone in the company’s “Pantone” series will come in eight bright colours and include customised IC chips made by Sharp Corp (6753.T) that measure radiation levels in microsieverts per hour.
The phone, which goes on sale this summer, can also keep track of each location a user tests for radiation levels.

If your brain is up to some more science the morning after Memorial Day weekend, here’s some more data on what the phone does, courtesy of The Register:

A special button on the front of the Pantone 5 launches the radiation detector, as demonstrated an hour into the operator’s press launch, which geo-tags the level in microSieverts per hour and uploads it to the Softbank cloud. There’s much mention of the isotope Caesium-137 during the press briefing, but the use of microSieverts/hr suggests that the detector is a dosimeter measuring radiation dose from all sources as opposed to an actual Caesium-137 detector which would be expected to read in Becquerels. That said, any detectable radiation from the Fukushima incident would probably result mostly from the presence of long-lived Cs-137 from the breached cores at this point, so it’s not unreasonable to mention the isotope in this context.