For about 25 years, powered air-purifying respirators have been used whenever workers were exposed to a high level of contamination or required a higher assigned protection factor.
Today, however, PAPR use has increased for a number of reasons. Users want a higher level of protection and know more about environmental hazards. PAPRs offer more breathing comfort and safety features. They're lighter and easier to use. No fit testing is required with a hooded PAPR.
Unlike negative-pressure air-purifying respirators, a PAPR provides a positive pressure within the hood or facepiece being worn with it, so OSHA has assigned PAPRs a much higher protection factor. For example: a standalone full-face negative-pressure air-purifying respirator has an OSHA APF of 50, while the same full-face respirator carries an APF of 1,000 when used as part of a PAPR. In late 2006, OSHA released its APF chart, which is now part of the OSHA Respiratory Protection standard (29 CFR 1910.134).
Some applications for which an air-line respirator previously was used can now support the use of a PAPR. A PAPR is more comfortable to breathe through than a negative-pressure facepiece. Employees who work for longer shifts like the comfort of breathing through a PAPR, which translates into a higher degree of productivity. Some workers are switching to PAPRs for no other reason than the higher level of protection offered by PAPRs, which of course is a good thing.
One of the biggest reasons why users are switching to PAPRs is because of the latest advancements in PAPR design. Many older PAPRs lack the built-in comfort and safety features of today's technology, and have bulky blower-modules, no audible or visible warnings for low flow or battery depletion, etc. The batteries of older technology run for short periods of time and require a long time to recharge.
Reduced OSHA exposure limits for certain contaminants (e.g., hexavalent chromium) have increased the number of workers who can use PAPRs for appropriate protection from these hazards. Also, NIOSH is currently developing a proposed PAPR standard. You can download a concept paper (.pdf file) for this proposed standard from the NIOSH Website.
In summary, PAPRs may be the best respiratory protection for some workers, in terms of higher protection, increased comfort, longer-term protection and better job productivity. Respiratory manufacturers and distributors can help you explore your options and compare respirators to find those best suited for your use.