Posted by Pirate on 24/4/2020, 10:22 am, in reply to "Re: Face Masks."
I'm not claiming to be a technical filtration expert !! But IMO great mask.High quality build and filtration. I used one of these when I was applying a resin/fibre-glass compound on an old asbestos garage roof. Low breathing resistance for the filtration performance and great seal that you feel a bellow effect as you breath. I keep one of these in a closed box in a separate air sealed bag.I have not used mine during the current crisis.
If yours is 5+ years old then the inbed filters probably will have deteriorated/blocked significantly. As you know, it is years outside the design conditions. Even then it depends how often you have used it and stored it. I think they actually state one month for regular/ad-hoc industrial use with good personal hygiene and provide a resealable bag.
Frankly, it is probably unknowable how useful your mask is now. I don't know if there is performance .v. duration technical data. To be clear I simply do not know, as 3M design them as semi-disposable.I presume the public liability issues would anyway deter them from offering any such guidance, as there are so many variables to factor in, from storage conditions,handling in application, to usage rates and types/volume of hazards encountered etc