At one shop that I worked at they, had a guy come around with a test hood that you put over your head with your respirator. then they sprayed some stuff that was supposed to smell like citrus.
If you smelled anything ,your mask or mask fit was not acceptible.
I use a Binks charcoal respirator with new charcoal filters and those waffled prefilters. I have used this particular style for years. I do have a serious 'stash, so fit is an issue with mine
I get a new one every couple of months and change the pre filters every couple of days and the charcoal ones every other week or so depending on how much painting I am doing.
Mask is kept in an air tight ziplock when not in use.
I wish I had this advise when I was younger.
My lungs are fine but my hearing is shot. can't hear small high pitched sounds and hearing someone talking to me in a room full of people with normal conversation sounds is impossible!
I do wear earmuffs now, (Too soon old,too late smart!!!)
I want to be able to hear my grandchildren
Just my .02
CCDually