Shelf life of the unopened product is 3 years from date of manufacture when stored within temperature range of -20ºC to +25ºC & less than 80% relative humidity. Manufactured date printed onto filters, maximum life span is 6 months once filter is removed from original packaging, however life span is determined by the wearers ability to taste, smell or notice increase in breathing resistance. Ensure mask is correctly fitted prior to each use & co