I'm stuck outside of the theatre. Just as the cutscene starts, I pull off my mask (I've run out of filters).
I can't seem to find another filter, and end up choking to death. lol.
there are a lot of filters around scattered in the ECHOES map (remember you have to change the filter manually using the T key on PC) for example, in the final section (spoilers..) when Pavel gives you a "lift" to get inside the theater entrance.. do not go down in the scalators, run right (kill the mutant dogwolf first thing) there are a row of small of rooms, in the end, there is a long brown-orange case with ammo, a filter and a medikit.
I kinda wish there were a visual or audible radiation detector ther than Geiger clicks when near heavy radiation. Either that or the protagonist automatically pulling his mask off when he's in breathable air.
There's a lot of times when I forget to or don't know if it's safe to pull off the mask, and it just eats up filter time. I've yet to have a problem running out of filters, but I've not played on Hardcore or Ranger Mode yet.