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Table 2 Filtering facepiece, air-purifying respirator(APR) and powered air-purifying respirator (PAPR) classification according to NIOSH/EN (National Institute for Occupational Safety and Health (NIOSH) and European Norms (EN) with stated assigned protection factor (APF)

From: Use of powered air-purifying respirator (PAPR) by healthcare workers for preventing highly infectious viral diseases—a systematic review of evidence

Respirator type NIOSH nomenclature EN nomenclature Minimum filtration capacity for particles > 0.3 microns OSHA APF EN Standard APF
Face filtering respirator   FFP1 80%   4 fold
  FFP2 94%   10 fold
N95   95% 10 fold  
N99 FFP3 99% 10 fold 20 fold
P100   99.97% 10 fold 20 fold
Air-purifying respirator (APR) APR half facepiece APR half facepiece As per selected filter 10 10
Air-purifying respirator (APR) APR full facepiece APR full facepiece As per selected filter; 10–50 10–50
Powered air-purifying respirator (PAPR) PAPR half facepiece PAPR half facepiece 99.97% 50 50
PAPR full facepiece PAPR full facepiece 99.97% 1000 1000
PAPR helmet/hood PAPR helmet/hood 99.97% 25–1000 25–1000
Loose-fitting facepiece Loose-fitting facepiece 99.97% 25 25
  1. Explanation: Please note: “Minimum filtration capacity tends to be a unified measure for any and all particles whether biological or particulate”