Gas Masks: PURPOSE: Protect against inhalation of biological agents and some chemicals,including sarin, mustard gas and lewisite. DO THEY WORK?

A good model like the Advantage 1000 CBA-RCA does, but you have to be wearing it when the gas hits. To do that, you have to know when to put it on, and unfortunately some biological and chemical weapons have no odor (see air sniffer). Surplus Israeli army models can't be trusted to be in good condition. Fiber masks designed for medical workers keep out some germs but not chemical or biological weapons.