(a) Non-powered air-purifying particulate respirators (series N, R, and P).

(1) Non-powered air-purifying particulate respirators utilize the wearer's negative inhalation pressure to draw the ambient air through the air-purifying filter elements (filters) to remove particulates from the ambient air. They are designed for use as respiratory protection against atmospheres with particulate contaminants at concentrations that are not immediately dangerous to life or health and that contain adequate oxygen to support life.

(2) Non-powered air-purifying particulate respirators are classified into three series, N-, R-, and P-series. The N-series filters are restricted to use in those workplaces free of oil aerosols. The R- and P-series filters are intended for removal of any particulate that includes oil-based liquid particulates.

(3) Non-powered air-purifying particulate respirators are classified according to the efficiency level of the filter(s) as tested according to the requirements of this part.

(i) N100, R100, and P100 filters must demonstrate a minimum efficiency level of 99.97 percent.

(ii) N99, R99, and P99 filters must demonstrate a minimum efficiency level of 99 percent.

(iii) N95, R95, and P95 filters must demonstrate a minimum efficiency level of 95 percent.

(b) Powered air-purifying particulate respirators (PAPR classes HE and PAPR100).

(1) Powered air-purifying particulate respirators utilize a blower to move the ambient air through the air-purifying filter elements (filters) to remove particulate contaminants and deliver clean air to the respiratory inlet covering. They are designed for use as respiratory protection against atmospheres considered not immediately dangerous to life or health and that contain adequate oxygen to support life.

(2) Powered air-purifying particulate respirators are classified into two classes, HE and PAPR100, and three series, HE, PAPR100-N, and PAPR100-P. The N-series filters are restricted to use in those workplaces free of oil aerosols. The P-series filters are intended for removal of any particulate that includes oil-based liquid particulates.

(3) All three filter series, HE, PAPR100-N, and PAPR100-P, for powered air-purifying particulate respirators must demonstrate a minimum efficiency level of 99.97 percent.