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Respirator Selection Requirements of Substance-Specific Standards

Quick Tips #330

The Occupational Safety and Health Administration (OSHA) issued its final rule for assigned protection factors (APFs) and maximum use concentrations (MUCs) in the Federal Register on August 24, 2006. This document focuses on the mandatory selection provisions of APFs, MUCs and the APF Table, and their roles in the Substance Specific standards.

Assigned Protection Factor (APF) is the workplace level of respiratory protection that a respirator or class of respirators is expected to provide to employees when the employer implements a continuing, effective respiratory protection program.

Maximum use concentration (MUC) is the maximum atmospheric concentration of a hazardous substance from which an employee can be expected to be protected when wearing a respirator, and is determined by the assigned protection factor of the respirator or class of respirators and the exposure limit of the hazardous substance.

The MUC for respirators is calculated by multiplying the APF for the respirator by the permissible exposure limit (PEL). The MUC is the upper limit at which the class of respirator is expected to provide protection. Whenever the exposures approach the MUC, the employer should select the next higher class of respirators for the employees. Employers must not apply MUCs to conditions that are immediately dangerous to life or health (IDLH).

Employers must use the APFs and MUCs to select the appropriate type of respirator based on the exposure limit of an airborne contaminant. Selection is based on the exposure level found in the workplace and the maximum concentration of the contaminant in which a particular type of respirator can be used.

Table 1 Assigned Protection Factors (5)
Type of respirator (1,2) Quarter mask Half mask Full facepiece Helmet/ hood Loose-fitting facepiece
Air-purifying respirator
5
10 (3)
50
-
-
Powered air-purifying respirator (PAPR)
-
50
1,000
25 (4) / 1000
25

Supplied-air respirator (SAR) or airline respirator

  • Demand mode
-
10
50
-
-

Supplied-air respirator (SAR) or airline respirator

  • Continuous flow mode
-
50
1,000
25 (4) / 1000
25

Supplied-air respirator (SAR) or airline respirator

  • Pressure-demand or positive-pressure mode
-
50
1,000
-
-

Self-contained breathing apparatus (SCBA)

  • Demand Mode
-
10
50
50
-

Self-contained breathing apparatus (SCBA)

  • Pressure-demand or other positive-pressure mode
-
-
10,000
10,000
-
 

Notes:
1 Employers may select respirators assigned for use in higher workplace concentrations of a hazardous substance for use at lower concentrations of that substance, or when required respirator use is independent of concentration.
2 The assigned protection factors in Table 1 are only effective when the employer implements a continuing, effective respirator program as required by this section ( 29 CFR 1910.134 ), including training, fit testing, maintenance and use requirements.
3 This APF category includes filtering facepieces, and half masks with elastomeric facepieces.
4 The employer must have evidence provided by the respirator manufacturer that testing of these respirators demonstrates performance at a level of protection of 1,000 or greater to receive an APF of 1,000. This level of performance can best be demonstrated by performing a workplace protection factor (WPF) or simulated workplace protection factor (SWPF) study or equivalent testing. Absent such testing, all other PAPRs and SARs with helmets/hoods are to be treated as loose-fitting facepiece respirators and receive an APF of 25.
5 These APFs do not apply to respirators used solely for escape. For escape respirators used in association with specific substances covered by 29 CFR 1910 subpart Z, employers must refer to the appropriate substance-specific standards in that subpart. Escape respirators for other IDLH atmospheres are specified by 29 CFR 1910.134 (d)(2)(ii).

 

Common Subpart Z Toxic and Hazardous Substances:

Chemical Respirator Selection Requirements
   
Asbestos
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1001(g)(3)(i)
  2. Cannot use disposable respirators 1910.1001(g)(3)(i)
   
Coal tar pitch None noted
   
4-nitrobiphenyl and
13 carcinogens
None noted for each from 1910.1003 -1910.1016
Vinyl chloride
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1017(g)(3)(i)(A)
  2. Provide an organic vapor cartridge that has a service life of a least one hour when using a chemical cartridge respirator at a concentration of vinyl chloride up to 10 parts per million (ppm) 1910.1017(g)(3)(i)(B)
  3. Select a canister that has a service life of at least four hours when using a powered air-purifying respirator having a hood, helmet, or full or half facepiece, or a gas mask with a front or back mounted canister, at a concentration up to 25 ppm 1910.1017(g)(3)(i)(C)
Inorganic arsenic
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1018(h)(3)(i)(A)
  2. Cannot use half-mask respirators for protection against arsenic trichloride because it is rapidly absorbed through the skin 1910.1018(h)(3)(i)(B)
  3. Provide high-efficiency particulate air (HEPA) filters for powered and non-powered air-purifying respirators 1910.1018(h)(3)(i)(C)
  4. (1) Select for employee use air-purifying respirators that have a combination HEPA filter with an appropriate gas-sorbent cartridge or canister when the employee’s exposure exceeds the permissible exposure level for inorganic arsenic and the relevant limit for other gases.
    (2) Front- or back-mounted gas masks equipped with HEPA filters and acid gas canisters or any full facepiece supplied-air respirators when the inorganic arsenic concentration is at or below 500 milligrams per cubic meter of air (mg/m3), and half mask air-purifying respirators equipped with HEPA filters and acid gas cartridges when the inorganic arsenic concentration is at or below 100 micrograms per cubic meter of air (ug/m3) 1910.1018(h)(3)(i)(D)(1)(2)
Lead
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1025(f)(3)(i)(A)
  2. Must use full-face respirators only for protection against lead aerosols that cause eye or skin irritation at the use concentrations 1910.1025(f)(3)(i)(B)
  3. Provide HEPA filters for powered and non-powered air purifying respirators 1910.1025(f)(3)(i)(C)
Cadmium
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1027(g)(3)(i)(A)
  2. Must use full-face respirators when employee experiences eye irritation 1910.1027(g)(3)(i)(B)
  3. Provide HEPA filters for powered and non-powered air purifying respirators 1910.1027(g)(3)(i)(C)
Benzene
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1028(g)(3)(i)
  2. Use organic vapor cartridge or canister with powered and non-powered air-purifying respirators, and a chin-style canister with full-facepiece gas masks 1910.1028(g)(3)(i)(C)
  3. Ensure that canisters have minimum service life of four hours when tested at 150 ppm benzene at a flow rate of 64 liters per minute, a temperature of 25°C and relative humidity of 85%. For cartridges used on PAPRs, the flow rates for testing must be 115 LPM for tight fitting and 170 LPM for loose fitting 1910.1028(g)(3)(i)(D)
Coke ovens
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1029(g)(3)
  2. Employers may use a filtering facepiece respirator only when it functions as a filter respirator for coke oven emissions particulates 1910.1029(g)(3)
Cotton dust
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1043(f)(3)(i)(A)
  2. Employers must not select or use filtering facepiece respirators at concentrations greater than five times the PEL 1910.1043(f)(3)(i)(A)
  3. Employers must use HEPA filters for powered and non-powered air-purifying respirators for concentrations greater than 10 X PEL 1910.1043(f)(3)(i)(B)
1,2-dibromo-3-chloropropane
  1. Select atmosphere-supplying respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1044(h)(3)(i)
  2. Must use a combination respirator that includes a supplied-air respirator with a full facepiece operated in a pressure-demand or other positive-pressure or continuous-flow mode, as well as an auxiliary self-contained breathing apparatus (SCBA) operated in a pressure-demand or positive-pressure mode 1910.100(h)(3)(ii)(A)

    An SCBA with a full facepiece operated in a pressure-demand or other positive-pressure mode 1910.100(h)(3)(ii)(B)
Acrylonitrile
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1045(h)(3)(i)
Ethylene oxide (ETO)
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1047(g)(3)(i)
  2. Employers cannot use half masks of any type due to eye irritation or injury 1910.1047(g)(3)(i)
Formaldehyde
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1048(g)(3)(i)(A)
  2. If air-purifying respirators are used the cartridge must be replaced as specified by paragraphs 1910.134(d)(3)(iii)(B)(1), which state it must have a National Institute for Occupational Safety and Health (NIOSH) approved end of service life indicator (ESLI) or 1910.134(d)(3)(iii)(B)(2), which states the use of change out schedule based on objective data 1910.1048(g)(2)(ii)
  3. Half-facepiece respirators can only be used if worn with gas-proof goggles 1910.1048(g)(3)(ii)
Methylenedianiline (MDA)
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1050(h)(3)(i)(A)
  2. HEPA filters are used unless MDA is in liquid form or used as part of a process requiring heat, in these two cases a combination organic vapor/HEPA combination canister or cartridge must be used 1910.1050(h)(3)(i)(D)
1,3-butadiene Exempted
Methylene chloride
  1. Select respirators specified in 1910.134(d)(3)(i)(a) - Table 1 – Assigned Protection Factors 1910.1052(g(3)(i)
  2. Cannot use or select half facepiece of any type because methylene chloride may cause eye irritation or damage 1910.1052(g)(3)(i)

Commonly Asked Questions

Q: What is immediately dangerous to life or health (IDLH)? A: Immediately dangerous to life or health is an atmosphere that poses an immediate threat to life, would cause irreversible adverse health effects, or would impair an individual’s ability to escape from a dangerous atmosphere.

Q: How are cartridge change out schedules calculated? A: In the absence of an end of service life indicator (ESLI), a cartridge/canister change out schedule is required for gas- and vapor-removing respirators and should be based on objective information or data that will ensure that canisters and cartridges are changed before the end of their service life. Usually, manufacturers have software to estimate a change out schedule for their cartridges or canisters. Change out schedules are not the same from one manufacturer’s cartridges or canisters to that of another manufacturer. This is because the volume and type of adsorbent varies between manufacturers. Additionally, OSHA has mandatory change out schedules for cartridges for certain substances.
Sources

29 CFR 1910.134(d)(3)(i)(A) and (B)

29 CFR 1910.1001-1018

29 CFR 1910.1025

29 CFR 1910.1027-1029

29 CFR 1910.1043-1045

29 CFR 1910.1047-1048

29 CFR 1910.1050-1052

(Rev. 9/2015)


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Please Note:
The information contained in this publication is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This publication is not a substitute for review of the current applicable government regulations and standards specific to your location and business activity, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.


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