Better to be live and look scary than be handsome in coffin. Some life-hack for you. Instead of using costly 3M filters attached to 3M respirator you can place small pieces of medical cotton  into compartments with membranes  for inhaled breath and cover them with the shreds of papers used for ULPA filters. In turn that coverings cab be fixed tightly  by rubber bands of appropriate diameter. I'm using bands cut off from the end of children balloons.