OK, provided I have several protective masks that all are new/unissused, i.e. hold an airtight seal, would a filter designed for most NBC situations be okay just for CN/CS if it expired less than a year ago?   Im only asking because a buddy of mine, who just got out of the marines said that they frequently trained with expired filters during NBC training, which of coure uses CN/CS gas.....

Any ideas?
I can get these filters for a 1/3 the prices as new unexpired filters....

Thanks for any responses....

I am not an authoritative source on this but I had similar experiences in the Army. In Basic they use/re-use those masks with the same filters over and over for the privates and run them through the gas chamber every 10 weeks or so - and we all know that the levels of CS in the chamber is off the charts compared to a canister or two popping in an open, windy environment.

I cant cite a specific source but I have heard and read that filtering CS/CN wasn't a huge issue like a true NBC environment and 'used' NBC filters will last a long time for CS/CN. Other than my basic training example I cant provide much direct help.

I would feel pretty comfortable with a reasonably old/used/opened NBC filter (military grade C2A1) for "just" CS/CN but like I said - I am far from being an authority.

Thanks for your response.  I too was in Army basic training, unfortunately never looked that close at the expiration of the filter.  I was more concerned what we were going to have to eat that day at the mess hall LOL.  But like my buddy explained it, because the particles for CN/CS are so big, these filters are still capable of protection from these agents.  All I need is the CN/CS protection, because I dont have the equipment to detect NBC enviroments.  Thank you again.