Quoted:
I have posted detailed responses on this topic many times over the years but I will give you the executive summary.
Gas masks as a prep item are mostly a placebo. In just about every chemical scenario you can imagine all you need to do is move 150m upwind and you're fine. Without 24/7 monitoring and detection your mask is worthless. Unless you wear it on your hip 24/7 you might as well not have it. Unless you have a suit and are well practiced in decon and gear survey you will still be exposed ot the agent. In a chem/bio event you have 9 SECONDS to don and clear your mask. can you do it?
Now, all that being said... I can identify one reason and one reason only to have a gasmask as a prep item. To shield yourself from the use of CS/CN as an area denial weapon.
The biggest thing I'm worried about is getting out along the freeways. I can get the mask on in 3-5 seconds as timed at the Chemical Weapons Depot in Utah. Most of the freeways by my home are in bermed areas that are about 150 feet deep.
Thanks for the advice. I'll go looking through the archives for your other posts.