What is the ACTUAL assigned protection factor for Powered Air Purifying Respirators (PAPR) WITHOUT a tight-fitting face piece?

Sounds like a simple question and often the answer is easy when dealing with reputable respirator manufacturers; however, the idea that providing a PAPR to a worker assures a higher protection factor is just wrong.  When we look at OSHA’s Assigned Protection Factors (APF) in 1910.134(d)(3)(i)(A) we see Table 1. – Assigned Protection Factors where PAPRs have two (2) APFs “⁴25/1,000” for “Helmet/hood” and a dedicated APF for “loose fitting face piece” of 25.  It is footnote #4 in Table 1 that so many look over. Basically OSHA has assigned a protection factor of 25 for PAPR with a “Helmet/hood”, unless…