I used to have a gas mask I used at some anti-nuclear power actions a long time ago, and I was very happy with its performance but you wouldn't want that kind now.
I had a British civilian "respirator" model 1942.It worked well in those days because we didn't
have to deal with "Less lethal projectiles". It had glass eye pieces that would shatter now
if hit by a projectile.It also restricted your vision somewhat.I've been told at least one person
was injured in Montreal because of broken glass from a "civilian" gas mask.
These days you want a military gas mask with lexan eye pieces.The pamphlet "Health
and Safety at Militant Actions" by on the ground collective recommends the US M17 or something like it.
Remember to get anti-fogging/anti-dimming wipes (sold in drug stores) and use them before the action starts so that your lenses don't fog up when you put your gas mask on.
If you smell gas faintly, that's normal, don't panic and remove your gas mask-you'll find that it is much worse without it.(I've seen people make this mistake).
There is an argument against using a gas mask, and my action medic instructor presented it last year. Police may be more likely to target someone with a gas mask.Some states
have anti-mask laws (don't know about PA) and the point of a black bloc is for everyone to
look the same so that no one can be singled out. He recommended what ON The Ground recommends as a cheap alternative.Shatter proof swim goggles with a tight seal, a bandanna soaked in apple cider vinegar carried in a plastic bag, and a paper respirator underneath for a tight seal.This is what I've always carried just in case,and I used it the 4th night at the RNC, but it wasn't a fair test because we mostly encountered smoke and
flash grenades.
Details

on't wear ski goggles, the felt or foam lining traps chemicals.
Never wear contacts if there is any chance of chemical attack.
If you are pregnant or asthmatic, don't go to a potentially hassled action-find another way to take part.(Again,I've seen people get hurt this way.)
Consult with other members of your affinity group, on what they are using and how they plan to respond.
Don't panic, thats what the cops want.
Good luck,I plan to be there somewhere.
