The problem is that the source is generalizing, which is fine for saying beta has usually shorter range and is less dangerous than gamma, but is too general to

The problem is that the source is generalizing, which is fine for saying beta has usually shorter range and is less dangerous than gamma, but is too general to be applicable here. Beta radiation just describes a certain kind of radiation, namely emitting an electron (or positron). However it doesn't directly tell you how much energy that electron has. Wikipedia on Beta particles says that "Beta particles with an energy of 0.5 MeV have a range of about one metre in air; the distance is dependent on the particle energy." [1] Tritium beta decay just has an energy of 0.018590 MeV [2] and I wouldn't be surprised if reach isn't proportional but for example cubic (I don't know the formula) thus the huge difference in reach. [1] https://en.m.wikipedia.org/wiki/Beta_particle#:~:text=Beta%20particles%20with%20an%20energy,less%20ionising%20than%20alpha%20particles https://en.m.wikipedia.org/wiki/Beta_particle#:~:text=Beta%2.... [2] https://en.m.wikipedia.org/wiki/Tritium https://en.m.wikipedia.org/wiki/Tritium