Helmet Safety Checks
When it comes to shelf life, helmets are just like the chicken in your fridge; they come with an expiry date. The inner padding and the outer shell might look just fine but after a few years of banging and crashing, their protective capabilities may have worn out.
If you take a look at the back of the helmet, you should find a CSA (Canadian Standards Association) sticker along with a valid expiry date. That'll tell you how much life is left in your helmet. If it's within a couple of months of that expiry date, you should seriously consider investing in a new helmet immediately.
A quick visual inspection of the entire helmet should also be done to make sure it hasn't suffered any damage. There shouldn't be any cracks on the outer shell and the padding inside should be intact and securely fastened to its original spot.