Table 2.

Summary of standard tests for evaluating mask effectiveness.

Tests	Details	Organization/Regulation
Particle filtration efficiency (PFE)	•Uses charge-neutralized NaCl aerosols at a high, fixed flowrate [75] •Masks/respirators preconditioned 24 h before testing [75] •Evaluates filtration efficiency •Highly conservative and stringent test	•NIOSH [75]
Bacterial/Viral filtration efficiency (BFE/VFE)	•Uses various bacteria/viruses suspended in aerosols [68] •Evaluates filtration efficiency	•FDA
Fluid resistance	•Uses synthetic blood squirted at the mask at various pressures [75] •Mask is qualatively evaluated to determine if blood has penetrated	•ASTM (test method F1862) •FDA (surgical masks)
Pressure differential (ΔP)	•Determines the “breathbility” of a mask •Measures difference in pressure up- and downstream of mask •High ΔP means the mask is difficult to breathe in