That's a typo. 7 microCurie would be 260 kBq, not 360 kBq. This whole thing's a farce; there's nothing remotely interesting, or alarming, about a sealed alpha

That's a typo. 7 microCurie would be 260 kBq, not 360 kBq. This whole thing's a farce; there's nothing remotely interesting, or alarming, about a sealed alpha source this small. There's countless millions of residential smoke detectors of exactly this size, isotope, and basic design. (The multiple other commenters are also speaking correctly, that modern smoke detectors are about 1/10th this size. The older 20th-century models are a bit larger).