Is there one mask that can handle all the different types of chem/bio weapons?
It is my understanding and I could be totally wrong, that you need specific filters for different gases/germs, not knowing what was released, is it possible to be equipped to handle all gases/germs?
Particles are rated in an "N" (not resistant to oil) number, petroleum protection has an "R" (resistant to oil) number and "P" (proofed to oil). The industry rating numbers are nominal 95 (%), 99 (%), and 100 (%) as in actually 99.97%.
A near universal chemical filtration medium is activated charcoal. It is manufactured by a baking process creating a spongy physical structure which produces acres/gram of surface area to capture harmful particles/molecules.
Activated charcoal is a terrific emergency water filter when sandwiched between several coffee filters in a gravity feed seet up. If left "wet" for a while, it can also become a nasty home to bad microbes so be practical.
Commercial respirators are rated and color coded for families of chemical effectiveness. Magenta colored filters aree for acid gasses/halogens=chlorines/organic vapors. Mayor Rudy was wearing these after the first dust death cloud envelopes Manhatten. Pesticide rated filters are black.
When in doubt, go for both. 3M company is a leading manufacture of respirators.
Also there's Tyvek suits available.