Street Medic Wikia (beta), the online resource for street medics that anyone can edit The best protection against chemical weapons is a gas mask. There are several important factors to consider when looking for a gas mask. Shatter-proof lenses are important. For convenience, look for a mask that uses standard NATO filters. Try it on to check for limited visibility, comfort, ease of use, etc. and be sure to practice with it before you're in the streets fumbling with unfamiliar straps.