Good point, but the Israeli gas masks sold over here are not second hand/expired. I have seen new ones for sale for about $50 - these are made in pretty huge quantities as far as I can tell and probably the cheapest decent gas mask out there.

Surplus Israeli masks are generally suplied with a teargas caninster, not the NBC one.

I can remember reading somewhere that a typical gas mask filter is going to deteriorate after so many years of storage, so it kind of makes me wonder if a gas mask is going to protect you if you've had one in storage for x number of years. LW.

Gasmasks are made from rubber, which will degrade after time. This will cause masks to leak. The problem generally can't be detected by the wearer, but only by testing equipment. The shelf life of gasmask are usually about 10 years and the canisters range from 5 to 20 years.

I read the instruction and I found some more weak points:
- the filter does not have a defined pressure difference, too much makes it hard to inhale, too little lets unfiltered gas through
- the nose is left open, depending on the resistance of the filter a certain percentage of gas is inhaled through the nose
- there is no inhale valve, that will cause CO2 and moisture to flow back to the inhalation tube due to the fluctuation of pressure during breathing
- the exhale valve is designed to work under water, the closing time may cause leaks on inhaling when used on dry land, I would not trust it to seal properly anyway
- when the mouthpiece is not sealed carefully with the lips it will allow unfiltered gas to leak in
- the mouthpiece will not allow to speak

Considering those weaknesses in addition to the lack of eye protection the mask may give a false sense of safety. The gas mask must be used properly all the time or else there will be a complete bypass for the unfiltered gas. A stress situation is bound to lead to erratic use as the mistakes are fairly easy to make. If there is a need to own a gas mask a proper specimen should be bought and proper maintenance should be done too.

The really weak points are the valves. They degrade much faster than the rest of the mask. The problem is that they get stiffer and no longer work properly. The difference between a good valve and a one that is past it´s prime is barely noticeable especially if you are not an expert. So at least the valves should be replaced on a mask bought from surplus.