Bear spray in the wild is proven to be more effective deterrent than firearms and while there is plenty of marketing spiel about the potency of sprays, not all manufacturer’s make such explicit claims about it longevity and shelf life so make sure that you are vigilant and check on the expiration date. Generally speaking, the best by date will be stamped on the bottom of the canister and expect it to have a 3-4 year shelf life. It’s not that the contents of the spray degrade and become ineffective but more so that the product starts to lose its ability to spray effectively. Bear spray will usually comprise of an active ingredient (such as a capsaicinoid) along with a carrier (propylene glycol) and a physical propellant (a popular one being nitrogen). With the passage of time and especially if the product remains unused, the pressure inside the canister is reduced, and it is this that compromises the spray’s effectiveness, and in particular, it’s useful range.\r