I have heard of people using their masks. We have had more than a few heart attacks and CPR cases, adn we have also had at least one fatality. (Yes, they did try to revive him.) It can happen at any time, so keep it around. Besides, if someone used the mask with the oxygen cylinder and forgot to replace it, you can use yours.
I just ran the O2 station at our refresher, made this point and had everyone take out there masks. The % of those with an O2 port was way below 50%, mine was included in those not haveing a port!
why?? old masks that had never been out of the case since purchase---and many, like myself, carry those compact barriers on a key chain or in a pocket and see no need to replace an older or outdated mask.
I'll probably replace the mask, just because mine is so hard from age that it probably won;t seal that well if I ever did need it---but want to wager 50 cents on how many others will be replaced??