In general, he recommends limiting the use of an N95 mask to about two or three days. N95 Suppliers china N95 masks supplier which lowers the amount of toxic fumes in the air. Green Walgreen N95 mask you may be able to prolong that time limit by an extra year or two if you store your respirator in its original packaging. The FDA classifies face masks into three categories based on their efficiency in filtering air particles: group 1, group 2 and group 3. But what do you do when you're done? It may come as a surprise to some people that N95 masks are not meant to be washed and reused over and over again.