Performance of organic vapour filters: effects of diccontinuous and multiple vapour exposures.

Organic vapour filters are extensively used in respiratory protective equipment (RPE) for providing protection against vapours present in workplace air. The filters, while effective when new, will eventually become overloaded and allow the vapour to breakthrough and expose the wearer to a toxic hazard. There is anecdotal evidence to suggest that RPE wearers may be using filters which have passed their useful service life (ie the breakthrough time has been reached). Presently, there is no reliable method of assessing when breakthrough actually occurs in practical usage. Filters may be subject to different patterns of use (eg intermittently during the day, or for short periods on different days or different weeks) and may be used to protect against different vapours, simultaneously, or at different times. None of these scenarios are routinely tested as part of the certification process for organic vapour filters which are based on short duration, high concentration challenges.