Used in particulate environments free of oil aerosols. N-series filters cannot be used if oil particles are present. | Used for oil and non-oil particles with time use limitations specified by NIOSH. If oil particles (e.g., lubricants, cutting fluids, glycerine) are present, use an R- or P-series filter. | Used for oil and non-oil particples with time use limitations specified by manufacturer. If oil particles are present and the filter is to be used for more than one work shift, use only a P-series filter. |