. Author manuscript; available in PMC: 2019 Oct 18.

Published in final edited form as: J Occup Environ Hyg. 2008 May;5(5):286–295. doi: 10.1080/15459620801960153

TABLE I.

Non-Powered Particulate Air-Purifying Respirator Classification (summary)

Respirator	Minimum Filtration Efficiency %	Challenge Aerosol	Max Filter Loading	Usage Limitation	Certification Preconditioning^C	Certification Flowrate
N95	95	NaCl	200 mg	Non-oil aerosols only	Y	85 lpm
R95	95	DOP	200 mg	8-hrs/one workshift^A	N
P95	95	DOP	Lowest efficiency	Per user instructions^B	N
N99	99	NaCl	200 mg	Non-oil aerosols only	Y
R99	99	DOP	200 mg	8-hrs/one workshift^A	N
P99	99	DOP	Lowest efficiency	Per user instructions^B	N
N100	99.97	NaCl	200 mg	Non-oil aerosols only	Y
R100	99.97	DOP	200 mg	8-hrs/one workshiff^A	N
P100	99.97	DOP	Lowest efficiency	Per user instructions^B	N

^A.

In oil aerosol environment.

^B.

P-series respirator filter service life recommendations are manufacturer specific.

^C.

N-series filters require preconditioning at 85% relative humidity and 38°C for 25 hours.