OEMS Occupational Exposure Management Systems LLC
Exposure assessment tools for Health & Safety Professionals

Required APF Calculator

Calculates the hazard ratio (exposure ÷ OEL), which is the minimum APF needed, and checks the selected respirator against its OSHA 1910.134 Table 1 APF.

Name of the chemical or agent.

Measured or estimated exposure, same averaging time as the OEL.

OSHA PEL, ACGIH TLV or other limit the program uses.

Units for the exposure, OEL and IDLH.

Class and facepiece from the APF table below.

NIOSH IDLH in the same units. Leave blank if none.

Hazard ratio

Minimum APF needed = exposure ÷ OEL

minimum APF needed

Lowest Table 1 APF that meets it
Selected respirator APF
Result

OSHA assigned protection factors

29 CFR 1910.134, Table 1. The selected respirator is highlighted.

Respirator class and facepieceAPF

Source: OSHA 29 CFR 1910.134(d)(3)(i)(A), Table 1, Assigned Protection Factors; 1910.134(d)(3)(i)(B), Maximum Use Concentration; 1910.134(d)(2), respirators for IDLH atmospheres. APR = air-purifying respirator; PAPR = powered air-purifying respirator; SAR = supplied-air (airline) respirator; SCBA = self-contained breathing apparatus. Filtering facepieces take the half mask APF of 10 (Table 1, note 2). Helmet/hood APF of 1,000 requires manufacturer WPF or SWPF test evidence at 1,000 or more; otherwise 25 (Table 1, note 4).