Bear spray expiry dates: good news, and staggering peer-reviewed pseudoscience

Last year my 4-year-old can of bear spray reached its expiry date, completely unused, and I wondered how sound the basis of that date was. Reddit showed plenty of others wondering or asserting on the matter, several outdoorsy sources reported on testing, and there was a journal article from researchers at Brigham Young University.The good news starts with: the active ingredient, capsaicin, does not degrade.It continues with: the other big concern is propellant leakage - and you can check that by...