As you browse the Internet, you will find that various brands of defense sprays have different lengths of time for their shelf life (expiration dates). It can get confusing. Water-based units may have the potential for a longer life than solvent-based formulas because of the gaskets and solvents that are used, but in general, all of the products experience the same effects of time, and that is in the depletion of the propellant—the stuff that pushes the formula out of the canister.
Fact is, as soon as all aerosol products are filled, they start losing propellant. The propellant is still very effective; you just can’t get it to spray out of the canister. Make sure your pepper spray has not expired. If it has expired, you know where to find the best prices and customer service.
What do you do if your pepper spray is expired? After getting a replacement, you need to dispose of your expired pepper spray. The first thing to check is if your city has any special ordinances for disposing of it. You’ll need to empty all the contents before you can dispose of it, too; just make sure you’re not standing upwind. If the spray isn’t emptied, the canister will be classified as hazardous waste, which may or may not require a fee for disposal.
There’s always a risk of getting the contents on you when you empty it, but should that happen, avoid touching your face, remove the contaminated clothing, and wash your hands and other affected areas with soap immediately. If you start to feel the burn, apply milk or baking soda past to the area.
Safety Girl Blog 