50122 Federal Register / Vol. 71, No. 164 / Thursday, August 24, 2006 / Rules and Regulations 

DEPARTMENT OF LABOR 

Occupational Safety and Health 

Administration 

29 CFR Parts 1910, 1915, and 1926 

[Docket No. H049C] 

RIN 1218–AA05 

Assigned Protection Factors 

AGENCY: Occupational Safety and Health 

Administration (OSHA), Department of 

Labor. 

ACTION: Final rule. 

SUMMARY: In this final rule, OSHA is 

revising its existing Respiratory 

Protection Standard to add definitions 

and requirements for Assigned 

Protection Factors (APFs) and 

Maximum Use Concentrations (MUCs). 

The revisions also supersede the 

respirator selection provisions of 

existing substance-specific standards 

with these new APFs (except for the 

respirator selection provisions of the 

1,3-Butadiene Standard). 

The Agency developed the final APFs 

after thoroughly reviewing the available 

literature, including chambersimulation studies and workplace 

protection factor studies, comments 

submitted to the record, and hearing 

testimony. The final APFs provide 

employers with critical information to 

use when selecting respirators for 

employees exposed to atmospheric 

contaminants found in general industry, 

construction, shipyards, longshoring, 

and marine terminal workplaces. Proper 

respirator selection using APFs is an 

important component of an effective 

respiratory protection program. 

Accordingly, OSHA concludes that the 

final APFs are necessary to protect 

employees who must use respirators to 

protect them from airborne 

contaminants. 

DATES: The final rule becomes effective 

November 22, 2006. 

ADDRESSES: In compliance with 28 

U.S.C. 2212(a), the Agency designates 

Joseph M. Woodward, the Associate 

Solicitor for Occupational Safety and 

Health, Office of the Solicitor, Room S– 

4004, U.S. Department of Labor, 200 

Constitution Avenue, NW., Washington, 

DC 20210, as the recipient of petitions 

for review of this rulemaking. 

FOR FURTHER INFORMATION CONTACT: For 

technical inquiries regarding this final 

rule, contact Mr. John E. Steelnack, 

Directorate of Standards and Guidance, 

Room N–3718, OSHA, U.S. Department 

of Labor, 200 Constitution Ave., NW., 

Washington, DC 20210; telephone (202) 

693–2289 or fax (202) 693–1678. For 

general inquiries regarding this final 

standard contact Kevin Ropp, OSHA 

Office of Public Affairs, Room N–3647, 

U.S. Department of Labor, 200 

Constitution Ave., NW., Washington, 

DC 20210 (telephone (202) 693–1999). 

Copies of this Federal Register notice 

are available from the OSHA Office of 

Publications, Room N–3101, U.S. 

Department of Labor, 200 Constitution 

Ave., NW., Washington, DC 20210 

(telephone (202) 693–1888). For an 

electronic copy of this notice, as well as 

news releases and other relevant 

documents, go to OSHA’s Web site 

(http://www.osha.gov), and select 

‘‘Federal Register,’’ ‘‘Date of 

Publication,’’ and then ‘‘2006’’. 

SUPPLEMENTARY INFORMATION: 

I. General 

A. Table of Contents 

The following Table of Contents 

identifies the major preamble sections of 

this final rule and the order in which 

they are presented: 

I. General 

A. Table of Contents 

B. Glossary 

II. Events Leading to the Final Standard 

A. Regulatory History of APFs 

B. Non-Regulatory History of APFs 

C. Need for APFs 

III. Methodology for Developing APFs for 

Respirators 

A. Introduction 

B. Background 

C. Methodology, Data, and Studies on 

Filtering Facepieces and Elastomerics 

D. Alternative Approaches 

E. Updated Analyses 

F. Summary of Studies Submitted During 

the Rulemaking 

IV. Health Effects 

V. Summary of the Final Economic Analysis 

and Initial Regulatory Flexibility 

Analysis 

A. Introduction 

B. The Rule and Affected Respirator Users 

C. Compliance Costs 

D. Benefits 

E. Economic Feasibility 

F. Economic Impacts to Small Entities 

VI. Summary and Explanation of the Final 

Standard 

A. Definition of Assigned Protection Factor 

B. APF Provisions 

C. Assigned Protection Factors for Specific 

Respirator Types 

1. APF for Quarter Mask Air-Purifying 

Respirators 

2. APF for Half Mask Air-Purifying 

Respirators 

3. APF for Full Facepiece Air-Purifying 

Respirators 

4. APF for Powered Air-Purifying 

Respirators (PAPRs) 

5. APF for Supplied-Air Respirators (SARs) 

6. APF for Self-Contained Breathing 

Apparatuses (SCBAs) 

D. Definition of Maximum Use 

Concentration 

E. MUCs for Mixtures and Hazard Ratios 

F. MUC Provisions 

G. Superseding the Respirator Selection 

Provisions of Substance-Specific 

Standards in Parts 1910, 1925, and 1926 

VII. Procedural Determinations 

A. Legal Considerations 

B. Paperwork Reduction Act 

C. Federalism 

D. State Plans 

E. Unfunded Mandates 

F. Applicability of Existing Consensus 

Standards 

List of Subjects in 29 CFR Parts 1910, 1915, 

and 1926 

Authority and Signature 

Amendments to Standards 

B. Glossary 

This glossary specifies the terms 

represented by acronyms, and provides 

definitions of other terms, used 

frequently in the preamble to the final 

rule. This glossary does not change the 

legal requirements in this final rule, nor 

is it intended to impose new regulatory 

requirements on the regulated 

community. 

1. Acronyms 

ACGIH: American Conference of 

Governmental Industrial Hygienists 

AIHA: American Industrial Hygiene 

Association 

ANSI: American National Standards 

Institute 

APF: Assigned Protection Factor 

APR: Air-purifying respirator 

Ci: Concentration measured inside the 

respirator facepiece 

Co: Concentration measured outside the 

respirator 

DOP: Dioctylphthalate (see definition 

below) 

DFM: Dust, fume, and mist filter 

EPF: Effective Protection Factor (see 

definition below under ‘‘Protection 

factor study’’) 

HEPA: High efficiency particulate air 

filter (see definition below) 

IDLH: Immediately dangerous to life or 

health (see definition below) 

LANL: Los Alamos National Laboratory 

LASL: Los Alamos Scientific Laboratory 

LLNL: Lawrence Livermore National 

Laboratory 

MSHA: Mine Safety and Health 

Administration 

MUC: Maximum Use Concentration 

NFPA: National Fire Protection 

Association 

NIOSH: National Institute for 

Occupational Safety and Health 

NRC: Nuclear Regulatory Commission 

OSHA: Occupational Health and Safety 

Administration 

OSH Act: The Occupational Safety and 

Health Act of 1970 (29 U.S.C. 655, 

657, 665). 

PAPR: Powered air-purifying respirator 

(see definition below) 


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PEL: Permissible Exposure Limit 

PPF: Program Protection Factor (see 

definition below under ‘‘Protection 

factor study’’) 

QLFT: Qualitative fit test (see definition 

below) 

QNFT: Quantitative fit test (see 

definition below) 

RDL: Respirator Decision Logic (see 

definition below) 

REL: Recommended Exposure Limit (see 

definition below) 

SAR: Supplied-air (or airline) respirator 

(see definition below) 

SCBA: Self-contained breathing 

apparatus (see definition below) 

WPF: Workplace Protection Factor (see 

definition below under ‘‘Protection 

factor study’’) 

TLV: Threshold Limit Value (see 

definition below) 

SWPF: Simulated Workplace Protection 

Factor (see definition below under 

‘‘Protection factor study’’) 

2. Definitions 

Terms followed by an asterisk (*) refer 

to definitions that can be found in 

paragraph (b) (‘‘Definitions’’) of OSHA’s 

Respiratory Protection Standard (29 CFR 

1910.134). 

Air-purifying respirator*: A respirator 

with an air-purifying filter, cartridge, or 

canister that removes specific air 

contaminants by passing ambient air 

through the air-purifying element. 

Atmosphere-supplying respirator*: A 

respirator that supplies the respirator 

user with breathing air from a source 

independent of the ambient atmosphere, 

and includes SARs and SCBA units. 

Canister or cartridge*: A container 

with a filter, sorbent, or catalyst, or 

combination of these items, which 

removes specific contaminants from the 

air passed through the container. 

Continuous flow respirator: An 

atmosphere-supplying respirator that 

provides a continuous flow of 

breathable air to the respirator 

facepiece. 

Demand respirator*: An atmospheresupplying respirator that admits 

breathing air to the facepiece only when 

a negative pressure is created inside the 

facepiece by inhalation. 

Dioctylphthalate (DOP): An 

aerosolized agent used for quantitative 

fit testing. 

Elastomeric: A respirator facepiece 

made of a natural or synthetic elastic 

material such as natural rubber, 

silicone, or EPDM rubber. 

Filter or air-purifying element*: A 

component used in respirators to 

remove solid or liquid aerosols from the 

inspired air. 

Filtering facepiece (or dust mask)*: A 

negative pressure particulate respirator 

with a filter as an integral part of the 

facepiece or with the entire facepiece 

composed of the filtering medium. 

Fit factor*: A quantitative estimate of 

the fit of a particular respirator to a 

specific individual and typically 

estimates the ratio of the concentration 

of a substance in ambient air to its 

concentration inside the respirator 

when worn. 

Fit test*: The use of a protocol to 

qualitatively or quantitatively evaluate 

the fit of a respirator on an individual. 

Helmet*: A rigid respiratory inlet 

covering that also provides head 

protection against impact and 

penetration. 

High-efficiency particulate air filter 

(HEPA)*: A filter that is at least 99.97% 

efficient in removing monodisperse 

particles of 0.3 micrometers in diameter. 

The equivalent NIOSH 42 CFR part 84 

particulate filters are the N100, R100, 

and P100 filters. 

Hood*: A respiratory inlet covering 

that completely covers the head and 

neck and may also cover portions of the 

shoulders and torso. 

Immediately dangerous to life or 

health (IDLH)*: 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. 

Loose-fitting facepiece*: A respiratory 

inlet covering that is designed to form 

a partial seal with the face. 

Negative pressure respirator (tightfitting)*: A respirator in which the air 

pressure inside the facepiece is negative 

during inhalation with respect to the 

ambient air pressure outside the 

respirator. 

Permissible Exposure Limit (PEL): An 

occupational exposure limit specified 

by OSHA. 

Positive pressure respirator*: A 

respirator in which the pressure inside 

the respiratory inlet covering exceeds 

the ambient air pressure outside the 

respirator. 

Powered air-purifying respirator 

(PAPR)*: An air-purifying respirator that 

uses a blower to force the ambient air 

through air-purifying elements to the 

inlet covering. 

Pressure demand respirator*: A 

positive pressure atmosphere-supplying 

respirator that admits breathing air to 

the facepiece when the positive pressure 

is reduced inside the facepiece by 

inhalation. 

Protection factor study: A study that 

determines the protection provided by a 

respirator during use. This 

determination generally is 

accomplished by measuring the ratio of 

the concentration of an airborne 

contaminant (e.g., hazardous substance) 

outside the respirator (Co) to the 

concentration inside the respirator (Ci) 

(i.e., Co/Ci). Therefore, as the ratio 

between Co and Ci increases, the 

protection factor increases, indicating 

an increase in the level of protection 

provided to employees by the respirator. 

Four types of protection factor studies 

are: 

Effective Protection Factor (EPF) 

study: A study, conducted in the 

workplace, that measures the protection 

provided by a properly selected, fittested, and functioning respirator when 

used intermittently for only some 

fraction of the total workplace exposure 

time (i.e., sampling is conducted during 

periods when respirators are worn and 

not worn). EPFs are not directly 

comparable to WPF values because the 

determinations include both the time 

spent in contaminated atmospheres 

with and without respiratory protection; 

therefore, EPFs usually underestimate 

the protection afforded by a respirator 

that is used continuously in the 

workplace. 

Program Protection Factor (PPF) 

study: A study that estimates the 

protection provided by a respirator 

within a specific respirator program. 

Like the EPF, it is focused not only on 

the respirator’s performance, but also 

the effectiveness of the complete 

respirator program. PPFs are affected by 

all factors of the program, including 

respirator selection and maintenance, 

user training and motivation, work 

activities, and program administration. 

Workplace Protection Factor (WPF) 

study: A study, conducted under actual 

conditions of use in the workplace, that 

measures the protection provided by a 

properly selected, fit-tested, and 

functioning respirator, when the 

respirator is worn correctly and used as 

part of a comprehensive respirator 

program that is in compliance with 

OSHA’s Respiratory Protection Standard 

at 29 CFR 1910.134. Measurements of 

Co and Ci are obtained only while the 

respirator is being worn during 

performance of normal work tasks (i.e., 

samples are not collected when the 

respirator is not being worn). As the 

degree of protection afforded by the 

respirator increases, the WPF increases. 

Simulated Workplace Protection 

Factor (SWPF) study: A study, 

conducted in a controlled laboratory 

setting and in which Co and Ci 

sampling is performed while the 

respirator user performs a series of set 

exercises. The laboratory setting is used 

to control many of the variables found 

in workplace studies, while the 

exercises simulate the work activities of 

respirator users. This type of study is 

designed to determine the optimum 


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performance of respirators by reducing 

the impact of sources of variability 

through maintenance of tightly 

controlled study conditions. 

Qualitative fit test (QLFT)*: A pass/ 

fail fit test to assess the adequacy of 

respirator fit that relies on the 

individual’s response to the test agent. 

Quantitative fit test (QNFT)*: An 

assessment of the adequacy of respirator 

fit by numerically measuring the 

amount of leakage into the respirator. 

Recommended Exposure Limit (REL): 

An occupational exposure level 

recommended by NIOSH. 

Respirator Decision Logic (RDL): 

Respirator selection guidance developed 

by NIOSH that contains a set of 

respirator protection factors. 

Self-contained breathing apparatus 

(SCBA)*: An atmosphere-supplying 

respirator for which the breathing air 

source is designed to be carried by the 

user. 

Supplied-air respirator (or airline) 

respirator (SAR)*: An atmospheresupplying respirator for which the 

source of breathing air is not designed 

to be carried by the user. 

Threshold Limit Value (TLV): An 

occupational exposure level 

recommended by ACGIH. 

Tight-fitting facepiece*: A respiratory 

inlet covering that forms a complete seal 

with the face. 

II. Events Leading to the Final Standard 

A. Regulatory History of APFs 

Congress established the 

Occupational Safety and Health 

Administration (OSHA) in 1970, and 

gave it the responsibility for 

promulgating standards to protect the 

health and safety of American workers. 

As directed by the OSH Act, the Agency 

adopted existing Federal standards and 

national consensus standards developed 

by various organizations such as the 

NFPA and ANSI. The ANSI standard 

Z88.2–1969, ‘‘Practices for Respiratory 

Protection,’’ was the basis of the first six 

sections (permissible practice, minimal 

respirator program, selection of 

respirators, air quality, use, 

maintenance and care) of OSHA’s 

Respiratory Protection Standard (29 CFR 

1910.134) adopted in 1971. The seventh 

section was a direct, complete 

incorporation of ANSI Standard K13.1–

1969, ‘‘Identification of Gas Mask 

Canisters.’’

The Agency promulgated an initial 

respiratory protection standard for the 

construction industry (29 CFR 1926.103) 

in April 1971. On February 9, 1979, 

OSHA formally applied 29 CFR 

1910.134 to the construction industry 

(44 FR 8577). Federal agencies that 

preceded OSHA developed the original 

maritime respiratory protection 

standards in the 1960s (e.g., Section 41 

of the Longshore and Harbor Worker 

Compensation Act). The section 

designations adopted by OSHA for these 

standards, and their original 

promulgation dates, are: Shipyards—29 

CFR 1915.82, February 20, 1960 (25 FR 

1543); Marine Terminals—29 CFR 

1917.82, March 27, 1964 (29 FR 4052); 

and Longshoring—29 CFR 1918.102, 

February 20, 1960 (25 FR 1565). OSHA 

incorporated 29 CFR 1910.134 by 

reference into its Marine Terminal 

standards (Part 1917) on July 5, 1983 (48 

FR 30909). The Agency updated and 

strengthened its Longshoring and 

Marine Terminal standards in 1996 and 

2000, and these standards now 

incorporate 29 CFR 1910.134 by 

reference. 

Under the Respiratory Protection 

Standard that OSHA initially adopted, 

employers were required to follow the 

guidance of the Z88.2–1969 ANSI 

standard to ensure proper selection of 

respirators. Subsequently, OSHA 

published an Advance Notice of 

Proposed Rulemaking (‘‘ANPR’’) to 

revise the Respiratory Protection 

Standard on May 14, 1982 (47 FR 

20803). Part of the impetus for this 

notice was the Agency’s inclusion of 

new respirator requirements in the 

comprehensive substance-specific 

standards promulgated under section 

(6)(b) of the OSH Act, e.g., fit testing 

protocols, respirator selection tables 

with assigned protection factors, use of 

PAPRs, changing filter elements 

whenever an employee detected an 

increase in breathing resistance, and 

referring employees with breathing 

difficulties, either at fit testing or during 

routine respirator use, to a physician 

trained in pulmonary medicine (see, 

e.g., 29 CFR 1910.1025 (OSHA’s Lead 

Standard)). The respirator provisions in 

these substance-specific standards 

reflected advances in respirator 

technology and changes in related 

guidance documents that were state-ofthe-art information at the time when 

OSHA published these substancespecific standards. These standards 

recognized that effective respirator use 

depends on a comprehensive respiratory 

protection program that includes the use 

of APFs. 

In the 1982 ANPR, OSHA sought 

information on the effectiveness of its 

current Respiratory Protection Standard, 

the need to revise the standard, and 

recommendations regarding what 

revisions should be made. The 1982 

ANPR referenced the ANSI Z88.2–1980 

standard on respiratory protection with 

its table of protection factors, the 1976 

report by Ed Hyatt from LASL titled 

‘‘Respiratory Protection Factors’’ (Ex. 2), 

and the RDL developed jointly by OSHA 

and NIOSH, as revised in 1978 (Ex. 9, 

Docket No. H049). The 1982 ANPR 

asked for comments on how OSHA 

should use protection factors. The 

Agency received 81 responses to this 

inquiry. The commenters generally 

supported revising OSHA’s Respiratory 

Protection Standard, and provided 

recommendations regarding approaches 

for including a table of protection 

factors (Ex. 15). 

On September 17, 1985, OSHA 

announced the availability of a 

preliminary draft of the proposed 

Respiratory Protection Standard. This 

preproposal draft standard included a 

discussion of the public comments 

received in response to the 1982 ANPR, 

and OSHA’s analysis of revisions 

needed in the Respiratory Protection 

Standard to address up-to-date 

respiratory protection. The Agency 

received 56 responses from interested 

parties (Ex. 36), which OSHA carefully 

reviewed in developing the proposed 

rule. 

On November 15, 1994, OSHA 

published the proposed rule to revise 29 

CFR 1910.134, and provided notice of 

an informal public hearing on the 

proposal (59 FR 58884). The Agency 

convened the informal public hearing 

on June 6, 1995. In response to the 

comments OSHA received on the 

proposal, the Agency proceeded to 

develop APFs. On June 15, 1995, as part 

of the public hearing, OSHA held a oneday panel discussion by respirator 

experts on APFs. The discussion 

included measuring respirator 

performance in WPF and SWPF studies, 

the variability of data from these 

studies, and setting APFs for various 

types of respirators that protect 

employees across a wide variety of 

workplaces and exposure conditions. 

OSHA also reopened the rulemaking 

record for the revised Respiratory 

Protection Standard on November 7, 

1995 (60 FR 56127), requesting 

comments on a study performed for 

OSHA by Dr. Mark Nicas titled ‘‘The 

Analysis of Workplace Protection Factor 

Data and Derivation of Assigned 

Protection Factors’’ (Ex. 1–156). This 

study, which the Agency placed in the 

rulemaking docket on September 20, 

1995, addressed the use of statistical 

modeling for determining respirator 

APFs. OSHA received 12 comments on 

the Nicas report. This report, and the 

comments received in response to it, 

convinced OSHA that more information 

would be necessary before the Agency 

could resolve the complex issues 

regarding how to establish APFs, 


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including what methodology to use in 

analyzing existing protection factor 

studies. (See Section IV. Methodology 

for Developing Assigned Protection 

Factors in the June 6, 2003 NPRM, 68 

FR 34044, for a detailed discussion of 

the Nicas report and the comments 

OSHA received.) 

OSHA published the final, revised 

Respiratory Protection Standard, 29 CFR 

1910.134, on January 8, 1998 (63 FR 

1152). The standard contains worksitespecific requirements for program 

administration, procedures for 

respirator selection, employee training, 

fit testing, medical evaluation, respirator 

use, and other provisions. However, 

OSHA reserved the sections of the final 

standard related to APFs and MUCs 

pending further rulemaking (see 63 FR 

1182 and 1203). The Agency stated that, 

until a future rulemaking on APFs is 

completed: 

[Employers must] take the best available 

information into account in selecting 

respirators. As it did under the previous 

[Respiratory Protection] standard, OSHA 

itself will continue to refer to the [APFs in 

the 1987 NIOSH RDL] in cases where it has 

not made a different determination in a 

substance specific standard. (63 FR 1163) 

The Agency subsequently established a 

separate docket (i.e., H049C) for the APF 

rulemaking. This docket includes copies 

of material related to APFs that 

previously were placed in the docket 

(H049) for the revised Respiratory 

Protection Standard. The APF 

rulemaking docket also contains other 

APF-related materials, studies, and data 

that OSHA obtained after it promulgated 

the final Respiratory Protection 

Standard in 1998. 

On June 6, 2003, the Agency 

published in the Federal Register an 

NPRM titled ‘‘Assigned Protection 

Factors; Proposed Rule’’ (68 FR 34036) 

that contained proposed definitions for 

APFs and MUCs, a proposed Table 1 

with APFs for the various respirator 

classes, and proposed revisions to the 

APF provisions and tables in OSHA’s 

substance-specific standards. The 

NPRM announced that OSHA would be 

holding an informal public hearing in 

Washington, DC on the proposal. The 

public hearings were held over three 

days, from January 28–30, 2004. OSHA 

received extensive pre-hearing 

comments (Exs. 9–1 through 9–43 and 

10–1 through 10–60), written hearing 

testimony (Exs. 16–1 through 16–25), 

post-hearing comments (Exs. 17–1 

through 17–12), and post-hearing briefs 

(Exs. 18–1 through 18–9 and 19–1 

through 19–8). Transcripts of the public 

hearings also were made and added to 

the APF Docket (Exs. 16–23–1, 16–23–

2, and 16–23–3). It is from these public 

comments, exhibits, hearing transcript, 

and post-hearing submissions that 

OSHA has prepared these final APF and 

MUC provisions and revisions to 

substance-specific standards. 

B. Non-Regulatory History of APFs 

In 1965, the Bureau of Mines 

published ‘‘Respirator Approval 

Schedule 21B,’’ which contained the 

term ‘‘protection factor’’ as part of its 

approval process for half mask 

respirators (for protection up to 10 times 

the TLV) and full facepiece respirators 

(for protection up to 100 times the TLV). 

The Bureau of Mines based these 

protection factors on quantitative fit 

tests, using DOP, that were conducted 

on six male test subjects performing 

simulated work exercises. 

The Atomic Energy Commission 

(AEC) published proposed protection 

factors for respirators in 1967, but later 

withdrew them because quantitative fit 

testing studies, which the AEC used to 

determine APFs, were available for 

some, but not all, types of respirators. 

To address this shortcoming, the AEC 

sponsored respirator performance 

studies at LASL, starting in 1969. 

ANSI standard Z88.2–1969, which 

OSHA adopted by reference in 1971, did 

not contain APFs for respirator 

selection. Nevertheless, this ANSI 

standard recommended that ‘‘due 

consideration be given to potential 

inward leakage in selecting devices,’’

and contained a list of the various 

respirators grouped according to the 

expected quantity of leakage into the 

facepiece during routine use. 

In 1972, NIOSH and the Bureau of 

Mines published new approval 

schedules for respiratory protection 

under 30 CFR 11. However, these new 

approval schedules did not include 

provisions for determining facepiece 

leakage as part of the respirator 

certification process. 

NIOSH sponsored additional 

respirator studies at LASL, beginning in 

1971, that used quantitative test systems 

to measure the overall performance of 

respirators. In a 1976 report titled 

‘‘Respirator Protection Factors’’, Edwin 

C. Hyatt of LASL included a table of 

protection factors for: single-use dust 

respirators; quarter mask, half mask, and 

full facepiece air-purifying respirators; 

and SCBAs (Ex. 2). Hyatt based these 

protection factors on data from DOP and 

sodium chloride quantitative fit test 

studies performed at LASL on these 

respirators between 1970 and 1973. The 

table also contained recommended 

protection factors for respirators that 

had no performance test data. Hyatt 

based these recommended protection 

factors on the judgment and experience 

of LASL researchers, as well as 

extrapolations from available facepiece 

leakage data for similar respirators. For 

example, Hyatt assumed that 

performance data for SCBAs operated in 

the pressure-demand mode could be 

used to represent other (non-tested) 

respirators that maintain positive 

pressure in the facepiece, hood, helmet, 

or suit during inhalation. In addition, 

Hyatt recommended in his report that 

NIOSH continue testing the 

performance of respirators that lacked 

adequate fit test data. To increase the 

database, Hyatt used a representative 

35-person test panel to conduct 

quantitative fit tests from 1974 to 1978 

on all air-purifying particulate 

respirators approved by the Bureau of 

Mines and NIOSH. 

In August 1975, the Joint NIOSH–

OSHA Standards Completion Program 

published the RDL (Ex. 25–4, Appendix 

F, Docket No. H049). The RDL 

contained a table of protection factors 

that were based on quantitative fit 

testing performed at LASL and 

elsewhere, as well as the expert 

judgment of the RDL authors. In 1978, 

NIOSH updated the RDL specifying the 

following protection factors: 

5 for single-use respirators; 

10 for half mask respirators with DFM 

or HEPA filters; 

50 for full facepiece air-purifying 

respirators with HEPA filters or 

chemical cartridges; 

1,000 for PAPRs with HEPA filters; 

1,000 for half mask SARs operated in 

the pressure-demand mode; 

2,000 for full facepiece SARs operated 

in the pressure-demand mode; and 

10,000 for full facepiece SCBAs 

operated in the pressure-demand 

mode. 

ANSI’s Respiratory Protection 

Subcommittee (‘‘Subcommittee’’) 

decided to revise Z88.2–1969 in the late 

1970s. During its deliberations, the 

Subcommittee conducted an extensive 

discussion regarding the role of 

respirator protection factors in an 

effective respiratory protection program. 

As a result, the Subcommittee decided 

to add an APF table to the revised 

standard. In May 1980, ANSI published 

the revision as Z88.2–1980 which 

contained the first ANSI Z88.2 

respirator protection factor table (Ex. 10, 

Docket H049). The ANSI Subcommittee 

based the table on Hyatt’s protection 

factors, which it updated using results 

from fit testing studies performed at 

LANL and elsewhere since 1973. For 

example, the protection factor for full 

facepiece air-purifying particulate 

respirators was 100 when qualitatively 

fit tested, or 1,000 when equipped with 


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HEPA filters and quantitatively fit 

tested. The table consistently gave 

higher protection factors to tight-fitting 

facepiece respirators when employers 

performed quantitative fit testing rather 

than qualitative fit testing. The ANSI 

Subcommittee concluded that PAPRs 

(with any respiratory inlet covering), 

atmosphere-supplied respirators (in 

either a continuous flow or pressuredemand mode), and pressure-demand 

SCBAs required no fit testing because 

they operated in a positive-pressure 

mode. ANSI assigned high protection 

factors to these respirators, but limited 

their use to concentrations below the 

IDLH values. Pressure-demand SCBAs 

and combination continuous flow or 

pressure-demand airline respirators 

with escape provisions for use in IDLH 

atmospheres were assigned protection 

factors of 10,000 plus. 

In response to a complaint to NIOSH 

that the PAPRs used in a workplace did 

not appear to provide the expected 

protection factor of 1,000, Myers and 

Peach of NIOSH conducted a WPF study 

during silica-bagging operations. Myers 

and Peach tested half mask and full 

facepiece PAPRs under these 

conditions, and found protection factors 

that ranged from 16 to 215. They 

published the results of their study in 

1983 (Ex.1–64–46). The results of this 

study led NIOSH and other researchers, 

as well as respirator manufacturers, to 

perform additional WPF studies on 

PAPRs and other respirators. 

NIOSH revised its RDL in 1987 (Ex. 

1–54–437Q) to address advances in 

respirator technology and testing. The 

revision retained many of the provisions 

of the 1978 RDL, but also lowered the 

APFs for other respirators based on 

NIOSH’s WPF studies. For example, the 

APFs were lowered for the following 

respirator classes: PAPRs with a loosefitting hood or helmet (reduced to 25); 

PAPRs with a tight-fitting facepiece and 

a HEPA filter (lowered to 50); suppliedair continuous flow hoods or helmets 

(decreased to 25); and supplied-air 

continuous flow tight-fitting facepiece 

respirators (reduced to 50). 

In August 1992, ANSI again revised 

its Z88.2 Respiratory Protection 

Standard (Ex. 1–50). The ANSI Z88.2–

1992 standard contained a revised APF 

table, based on the Z88.2 

Subcommittee’s review of available 

protection factor studies. In a report 

describing the revised standard (Ex. 1–

64–423), Nelson, Wilmes, and daRoza 

described the rationale used by the 

ANSI Subcommittee in setting APFs: 

If WPF studies were available, they formed 

the basis for the [APF] number assigned. If 

no such studies were available, then 

laboratory studies, design analogies, and 

other information [were] used to decide what 

value to place in the table. In all cases where 

the assigned protection factor changed when 

compared to the 1980 standard, the assigned 

number is lower in the 1992 standard. 

In addition, the 1992 ANSI Z.88.2 

standard abandoned ANSI’s 1980 

practice of giving increased protection 

factors to some respirators when 

quantitative fit testing was performed. 

Thomas Nelson, the co-chair of the 

ANSI Z88.2–1992 Subcommittee, 

published a second report entitled ‘‘The 

Assigned Protection Factor According to 

ANSI’’ (Ex. 135) four years after the 

Z88.2 Subcommittee completed the 

revised 1992 standard. In the report, 

Nelson reviewed the reasoning used by 

the ANSI Subcommittee in setting the 

1992 ANSI APFs. Nelson noted that the 

Z88.2 Subcommittee gave an APF of 10 

to all half mask air-purifying respirators, 

including quarter mask, elastomeric, 

and disposable respirators. The 

Subcommittee also recommended that 

full facepiece air-purifying respirators 

retain an APF of 100 (from the 1980 

ANSI standard) because no new data 

were available to justify another value. 

Nelson noted that the Z88.2 

Subcommittee approved the RDL’s 

reduction to an APF of 25 for loosefitting facepieces and PAPRs with 

helmets or hoods based on their 

performance in WPF studies. For half 

mask PAPRs, the ANSI Subcommittee 

set an APF of 50 based on a WPF study 

by Lenhart (Ex. 1–64–42). The ANSI 

Subcommittee had no WPF data 

available for full facepiece PAPRs, so 

Nelson indicated that the Subcommittee 

selected an APF of 1,000 to be 

consistent with the APF for PAPRs with 

helmets or hoods. The Subcommittee, in 

turn, based its APF of 1,000 for PAPRs 

with helmets or hoods on design 

similarities (i.e., same facepiece designs, 

operation at the same airflow rates) 

between these respirators and airline 

respirators. Nelson noted that the results 

from a subsequent WPF report by Keys 

(Ex. 1–64–40) on PAPRs with helmets or 

hoods were consistent with an APF of 

1,000. According to Nelson, the 

Subcommittee used WPF studies by 

Myers (Exs. 1–64–47 and 1–64–48), 

Gosselink (Ex. 1–64–23), and Que Hee 

and Lawrence (Ex. 1–64–60) to set an 

APF of 25 for PAPRs with loose-fitting 

facepieces. Nelson stated that two WPF 

studies, conducted by Gaboury and 

Burd (Ex. 1–64–24) and Stokes (Ex. 1–

64–66) subsequent to publication of 

ANSI Z88.2–1992, supported the APF of 

25 selected by the Subcommittee for 

PAPRs with loose-fitting facepieces. 

Nelson also stated in his report that 

the ANSI Subcommittee had no new 

information on atmosphere-supplying 

respirators. Therefore, the APFs for 

these respirators were based on 

analogies with other similarly designed 

respirators (Ex. 135). The ANSI 

Subcommittee based the APF of 50 for 

half mask continuous flow atmospheresupplying respirators, and the APF of 25 

for loose-fitting continuous flow 

atmosphere-supplying respirators, on 

the similarities between these 

respirators and PAPRs with the same 

airflow rates. Nelson noted that the 

ANSI Subcommittee set the APF of 

1,000 for full facepiece continuous flow 

atmosphere-supplying respirators 

consistent with the APF for SARs with 

helmets or hoods using the results of 

two earlier studies: a WPF study by 

Johnson (Ex. 1–64–36) and a SWPF 

study by Skaggs (Ex. 1–38–3). The 

Subcommittee used the design analogy 

between PAPRs and continuous flow 

supplied-air respirators to select the 

APF of 50 for half mask pressuredemand SARs and an APF of 1,000 for 

full facepiece pressure-demand SARs. 

Nelson stated, ‘‘The committee believed 

that setting a higher APF because of the 

pressure-demand feature was not 

warranted, but rather that the total 

airflow was critical’’ (Ex. 135). 

Nelson noted in the report that the 

Subcommittee selected no APF for 

SCBAs. In explaining the committee’s 

decision, he stated that ‘‘the 

performance of this type of respirator 

may not be as good as previously 

measured in quantitative fit test 

chambers.’’ Nelson also observed that 

the ANSI Z88.2–1992 standard justified 

this approach in a footnote to the APF 

table. The footnote states: 

A limited number of recent simulated 

workplace studies concluded that all users 

may not achieve protection factors of 10,000. 

Based on [these] limited data, a definitive 

assigned protection factor could not be listed 

for positive pressure SCBAs. For emergency 

planning purposes where hazardous 

concentrations can be estimated, an assigned 

protection factor of no higher than 10,000 

should be used. 

A new ANSI Z88.2 Subcommittee 

recently finished revising the ANSI 

Z88.2–1992 standard, in accordance 

with the ANSI policy specifying that 

each standard receive a periodic review. 

This revised ANSI Z88.2 standard is 

currently under appeal to the ANSI 

Board. 

C. Need for APFs 

When OSHA published the final 

Respiratory Protection Standard in 

January 1998, it noted that the revised 

standard was to ‘‘serve as a ‘building 

block’ standard with respect to future 

standards that may contain respiratory 

protection requirements’’ (63 FR 1265). 


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OSHA’s final Respiratory Protection 

Standard established the minimum 

elements of a comprehensive program 

that are necessary to ensure effective 

performance of a respirator. The only 

parts missing from this building block 

standard are the APF and MUC 

provisions that are being finalized in 

this rulemaking. In the standard the 

Agency recommended that employers in 

the interim ‘‘take the best information 

into account in selecting respirators. As 

it did under the previous standard, 

OSHA itself will continue to refer to the 

NIOSH APFs in cases where it has not 

made specific compliance 

interpretations’’ (63 FR 1203). 

In October 2004, NIOSH published its 

Respirator Selection Logic (RSL), an 

update of the 1987 RDL. The APF tables 

in the new RSL have not changed from 

those in the 1987 RDL. However, NIOSH 

stated in the forward to the 2004 RSL: 

‘‘[w]hen the OSHA standard on APFs is 

finalized NIOSH intends to consider 

revisions to this RSL.’’ (Ex. 20–4.) 

The ANSI Z88.2–1992 APF table also 

has been a source for interim APFs 

while OSHA completed its APF 

rulemaking. However, the ANSI Z88.2–

1992 respiratory protection standard 

was withdrawn by ANSI in 2003. While 

a revised ANSI Z88.2 standard has been 

written, the final ANSI standard has yet 

to be published since it is currently 

under appeal. Therefore, no ANSI 

respiratory protection standard with 

recommended APFs is available at this 

time. The draft APF table from the ANSI 

Z88.2 revision was submitted to the 

OSHA rulemaking docket (Ex.13–7–2), 

and was the subject of discussion during 

the public hearings on APFs. OSHA 

considered the draft ANSI table during 

its deliberations in this rulemaking. 

Throughout the Respiratory 

Protection Standard rulemaking, OSHA 

has emphasized that the APF and MUC 

definitions and the APF table are an 

integral part of the overall standard. A 

careful review of the submitted 

comments and information supports the 

Agency’s conclusion that this final 

standard is necessary to guide 

employers in selecting the appropriate 

class of respirator needed to reduce 

hazardous exposures to acceptable 

levels. The final APF for a class of 

respirators specifies the workplace level 

of protection that a class of respirator 

should provide under an effective 

respiratory protection program. In 

addition, the APFs can be utilized by 

employers to determine a respirator’s 

MUC for a particular chemical exposure 

situation. 

The final APFs must be used in 

conjunction with the existing provisions 

of the Respiratory Protection Standard. 

Integration of the final APF and MUC 

provisions into the reserved provisions 

of paragraph (d) completes that 

standard. With the addition of these 

provisions, appropriate implementation 

of the Respiratory Protection Standard 

by employers in their workplaces 

should afford each affected employee 

the maximum level of respiratory 

protection. 

III. Methodology for Developing APFs 

for Respirators 

A. Introduction 

In the proposed rule for Assigned 

Protection Factors (APFs), OSHA raised 

a number of issues or questions about its 

proposed methodology for deriving 

APFs (68 FR 34112–34113). OSHA 

asked for information on: (1) The 

evidence-based method used by OSHA 

in developing the proposed APFs; (2) 

any additional studies that may be 

useful in determining APFs that were 

not already identified by OSHA in the 

proposal; and, (3) statistical analyses, 

treatments, or approaches, other than 

those described in the proposal, 

available for differentiating between, or 

comparing, the respirator performance 

data. The vast majority of the comments 

in response to the NPRM addressed the 

use of WPF studies for establishing the 

APF for filtering facepiece half mask 

respirators. OSHA also received 

comments on the methodology and data 

it used for determining the filtering 

facepiece APF, and was provided with 

new studies on these respirators for 

consideration. OSHA’s quantitative 

analyses for establishing the APFs for 

other classes of higher performing 

respirators drew little comment, and no 

new studies on these respirators were 

submitted. This section, therefore, 

focuses on methodology and new 

information relative to the APF for half 

mask air-purifying respirators. 

More specifically, Part C of this 

section contains a discussion of the 

comments about OSHA’s proposed 

methodology for determining APFs for 

filtering facepiece half mask respirators, 

including comments on data analysis 

and study selection. In addition, OSHA 

is providing an overview of Dr. Kenny 

Crump’s statistical analyses (Ex. 20–1) 

of the updated half mask database (Ex. 

20–2). Comments about alternative 

approaches are discussed in Part D 

(‘‘Methodology, Data, and Studies on 

Filtering Facepieces and Elastomerics’’). 

The Agency’s overall conclusions on 

methodology, and summaries of new 

studies submitted during the public 

comment process, are presented under 

Part E. Discussion of the comments and 

opinions regarding the APF for half 

mask respirators and the establishment 

of the APFs for higher performing 

respirators is included in Section VI, 

Summary and Explanation of the Final 

Standard. 

B. Background 

The Occupational Safety and Health 

Act of 1970 (‘‘OSH Act’’), 29 U.S.C. 

651–678, enacted to ensure safe and 

healthy working conditions for 

employees, empowers OSHA to 

promulgate standards and provides 

overall guidance on how these 

standards are to be developed. It states: 

(5) The Secretary, in promulgating 

standards dealing with toxic materials or 

harmful physical agents under this 

subsection, shall set the standard which most 

adequately assures, to the extent feasible, on 

the basis of the best available evidence, that 

no employee will suffer material impairment 

of health or functional capacity even if such 

employee has regular exposure to the hazard 

dealt with by such standard for the period of 

his working life. Development of standards 

under this subsection shall be based upon 

research, demonstrations, experiments, and 

such other information as may be 

appropriate. In addition to the attainment of 

the highest degree of health and safety 

protection for the employee, other 

considerations shall be the latest available 

scientific data in the field, the feasibility of 

the standards, and experience gained under 

this and other health and safety laws. 

Whenever practicable, the standard 

promulgated shall be expressed in terms of 

objective criteria and of the performance 

desired. 29 U.S.C. 655(b)(5) [emphasis 

added]. 

A reviewing court will uphold 

standards set under this section when 

they are supported by substantial 

evidence in the record considered as a 

whole (29 U.S.C. 655(f)). In searching 

for the ‘‘best available evidence’’ upon 

which to base its rulemaking, OSHA is 

required to ‘‘identify the relevant factual 

evidence, * * * to state candidly any 

assumptions on which it relies, and to 

present its reasons for rejecting any 

significant contrary evidence or 

argument.’’ Public Citizen Health 

Research Group v. Tyson, 796 F.2d 

1479, 1495 (D.C. Cir. 1986). 

OSHA has retained the multifaceted 

approach it used in the proposal to 

determine the APFs for classes of 

respirators. That is, the Agency 

reviewed all of the available literature, 

including the various analyses by 

respirator authorities, as well as 

quantitative analyses of data from WPF 

and SWPF studies. During revision of 

the overall Respiratory Protection 

Standard, the Agency used a similar 

approach when reviewing protection 

factor studies related to the effectiveness 

and necessity of a comprehensive 

respiratory protection program. 


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50128 Federal Register / Vol. 71, No. 164 / Thursday, August 24, 2006 / Rules and Regulations 

The Agency did not use Effective 

Protection Factor (EPF) and Program 

Protection Factor (PPF) studies in its 

APF analyses since these measure 

deficiencies in respirator program 

practices. More specifically, EPFs are 

not directly comparable to WPF values 

because the determinations include the 

time spent in contaminated atmospheres 

both with and without respiratory 

protection. PPFs are affected by any 

deficient elements of a respirator 

program, including inadequate 

respirator selection and maintenance, 

poor user training and motivation, work 

activities, and inadequate program 

administration. Therefore, OSHA relied 

on WPF and SWPF studies, since they 

focus on the performance characteristics 

of the respirator only. 

During the APF rulemaking, OSHA 

reviewed the extensive literature on 

APFs and developed selection criteria 

for including studies and data in its 

quantitative analysis of respirator 

performance. This procedure ensured 

that only carefully designed and 

executed WPF and SWPF studies were 

included in the analysis. The Agency 

then used these studies to compile the 

NPRM’s original database. The database 

was comprised of 917 data points from 

16 WPF studies for half mask respirators 

(Matrix 1) and 443 data points from 13 

studies for PAPRs and SARs (Matrix 2), 

conducted in a variety of American 

workplaces. OSHA made the studies, its 

selection criteria, the data, and its 

analyses available to the public 

electronically and through the 

rulemaking docket. In addition, the 

Agency encouraged the public to access 

this information and to reanalyze the 

data using methods of their choice. The 

Agency also sought submissions from 

the public of any additional studies for 

inclusion in its database. Four 

additional WPF studies of half masks 

were submitted during the public 

comment period following publication 

of the NPRM. Dr. Kenny Crump updated 

the Matrix 1 half mask database with 

these additional studies (Ex. 20–2) and 

reanalyzed the resulting 1,339 data 

points for half mask respirators (Ex. 20–

1). 

Dr. Crump also performed a second 

quantitative analysis in which the 1,339 

accepted data points (original NPRM 

database updated with data from the 

four new studies) for half mask 

respirators were combined with 403 

data points from 12 studies that the 

Agency originally excluded from the 

analysis. This second analysis 

corroborated the original findings to the 

extent practicable. The results of both of 

these analyses provide compelling 

support of OSHA’s conclusions 

regarding the appropriate APF for half 

mask respirators. The Agency believes 

that the database it constructed 

represents the best available data on 

APFs, and that its conclusions are based 

on substantial evidence. See Texas 

Independent Ginners’ Association v. 

Marshall, 630 F.2d 398, 413 n. 48 (5th 

Cir. 1980), citing Industrial Union Dept., 

AFL–CIO–CIC v. American petroleum 

Institute, 448 U.S. 607, 661 (1980). 

In past rulemakings, OSHA’s 

conclusions as to the best available 

evidence have been upheld as based on 

substantial evidence when it has relied 

on a body of reputable scientific 

evidence. See ASARCO v. Occupational 

Safety and Health Administration, 746 

F.2d 483, 494 (9th Cir. 1984). OSHA 

need not accept all data presented to it 

as long it considers the data and rejects 

it on reasonable grounds. See id. 

Furthermore, each study relied upon by 

the Agency need not be a model of 

textbook scientific inquiry, and OSHA 

need not find one definitive study 

supporting its decision. Public Citizen 

Health Research Group, 796 F.2d at 

1489, 1495. Rather, the Agency is 

justified in adopting a conclusion when 

the cumulative evidence is compelling. 

Id. at 1489, 1491, 1495. OSHA’s 

conclusions are strongest when it has 

relied on multiple data sources that 

support each other, as it has in this 

rulemaking. 

C. Methodology, Data, and Studies on 

Filtering Facepieces and Elastomerics 

1. Comments on the Methodology 

OSHA developed the proposed APFs 

through a multi-faceted approach. As it 

stated in the preamble to the proposal, 

‘‘The Agency reviewed the various 

analyses of respirator authorities, 

available WPF and SWPF studies, and 

other APF literature.’’ It later concluded 

that ‘‘the APFs proposed by OSHA in 

this rulemaking represent the Agency’s 

evaluation of all available data and 

research literature i.e., a composite 

evaluation of all relevant quantitative 

and qualitative information’’ (68 FR 

34050). OSHA then asked the public if 

this method was appropriate to 

determine APFs. The methodology was 

supported by a number of commenters, 

including NIOSH (Ex. 9–13), the 

Department of the Army (Ex. 9–42), 

ALCOA (Ex. 10–31), and others (e.g., 

Exs. 9–1, 9–4, 9–14, 9–16, 9–22, 10–2, 

10–17, 10–18, and 10–59). NIOSH 

stated: 

NIOSH agrees that the APF values resulting 

from this multi-faceted approach are 

reasonable indications of the level of 

protection that should be expected for each 

class of respirators. * * * 

The available data are not ideal because 

there can be considerable model-to-model 

variation and only a few models in each class 

have been evaluated. Given that lack of 

complete data, the approach taken by OSHA 

is the most appropriate currently possible. 

(Ex. 9–13.) 

The United States Army Center for 

Health Promotion and Preventive 

Medicine commented: 

The method of APF development used by 

OSHA is appropriate. OSHA reviewed 

available data, both published and 

unpublished; utilized technical reviews and 

summaries from subject matter experts 

outside-OSHA; weighed study findings and 

conclusions based on study shortfalls, as 

then state-of-the-art technical bias and 

procedural omissions; and used a 

conservative approach to maintain 

confidence that minimal risk of respirator 

selection and use errors will exist in worker 

protection from proposed APF use. (Ex. 9–

42–1.) 

Nevertheless, some commenters did 

not agree with OSHA’s approach. These 

participants included several labor 

organizations (Exs. 9–27, 9–29, 9–34, 9–

40, and 10–37), trade associations (Exs. 

9–24 and 10–27), and individuals (e.g., 

Exs. 9–17, 9–25, 9–33, 9–41, 10–33, and 

10–42). Criticisms of OSHA’s approach 

focused on the Agency’s selection of 

WPF studies for its determination of the 

proposed APFs. Reasons given to 

support these criticisms included: The 

differences between the studies do not 

permit comparison of the studies; the 

study conditions are not representative 

of typical workplaces; the study data are 

too old; the data do not cover all 

configurations of filtering facepieces 

available; and, the analytical method 

employed by some studies was too 

sensitive. 

A few commenters (Exs. 10–34 and 

10–47) recommended that certain 

criteria should be met before a WPF 

study is deemed acceptable for analysis. 

These criteria include: Exposures to 

small particle sizes; work time of at least 

four hours; moderate to heavy work rate; 

and, high temperature and humidity. 

Still others believed that OSHA should 

develop and perform SWPFs on a 

representative subset of all filtering 

facepieces or all configurations of 

filtering facepiece respirators and all 

respirator models, and establish APFs 

for all classes of respirators based on the 

SWPF study results (Exs. 9–41 and 10–

27). A more detailed discussion of data 

issues is presented below. 

2. Comments on Data and Study 

Problems 

Selection bias in WPF studies. Several 

commenters stated that the authors of 

WPF studies ‘‘cherry-picked’’ either the 

workplaces in which the studies were 


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conducted or the individual tasks that 

were performed by workers chosen for 

monitoring (Pascarella, Tr. at 464; 

Faulkner, Tr. at 549 and 564–565). 

‘‘Cherry-picking’’ is a common term for 

‘‘selection bias.’’ Selection bias is a 

matter of concern when either 

workplace study participants or job 

tasks are selected for inclusion in the 

study in a manner that skews the results 

of the study away from the true value. 

Selection bias is a matter of concern 

for all scientific studies, not just WPF 

studies, and peer reviewers typically 

evaluate its effects before a study is 

accepted for publication in a peerreviewed journal. Most of the studies 

included in OSHA’s analysis of WPF 

studies were either published in peerreviewed journals or were presented at 

the AIHCE, and met the criteria for 

respirator research studies accepted by 

the industrial hygiene community. The 

half mask database consists of 16 

studies performed in a variety of 

workplaces over a range of years (from 

1976 to 2004) by many different 

researchers. Therefore, it is highly 

improbable that these studies were 

subject to selection bias. OSHA could 

find no instance of selection bias either 

in its review of the scientific studies or 

its analysis of the data. Finally, OSHA 

repeatedly asked commenters who 

raised concerns about ‘‘cherry-picking’’

for specific studies in which selection 

bias occurred. In no case did the 

commenters provide any details to 

support their allegations. 

Observer effect in WPF studies. 

Several commenters (Shine, Tr. at 644 

and Macaluso, Tr. at 652) stated that 

data from the WPF studies considered 

by OSHA were the result of a condition 

known as the ‘‘observer effect.’’ The 

observer effect occurs when the act of 

observing or monitoring test subjects 

causes their responses to differ from 

their usual (nonobserved) responses. In 

some of the WPF studies used by OSHA, 

the researchers stated that during the 

study, they were present to monitor the 

test equipment to ensure that the 

sampling equipment functioned 

properly, thereby increasing the 

usefulness of the results. In other WPF 

studies, the researchers did not indicate 

their presence during the study. 

The mere presence of an observer 

does not, in and of itself, presume that 

there will be an observer effect. For 

example, if the observer is a researcher 

who is monitoring the test equipment 

instead of a supervisor who is 

monitoring the workers’ practices, the 

workers are unlikely to change their 

practices. 

Although the Agency repeatedly 

asked the commenters who raised this 

concern to identify specific studies in 

which the observer effect may have been 

involved, they could not do so (i.e., in 

no case did the commenters provide any 

example to support their allegations). In 

its own analysis of the WPF studies, the 

Agency was also unable to find any 

evidence of an observer bias. 

Representativeness of the data. A 

number of commenters expressed 

concern that the study data analyzed by 

OSHA were not representative of 

conditions found in the construction 

industry (Ex. 9–29, Building 

Construction Trades Department), or of 

workplace conditions in general (e.g., 

Exs. 9–34, International Union 

Operating Engineers; 9–35, Melissa 

Rich; 9–40, United Steel Workers of 

America; and 10–60, Paul Hewett). The 

bulk of these concerns are represented 

in the comments of Melissa Rich, a 

Department of Energy respirator 

program manager, who stated: 

The selection of the test sites for the cited 

APF proposed rulemaking WPF studies are 

not representative of the worksite for 

American workers. Many test sites chosen for 

these studies were selected on availability 

only. Moreover, key study attributes such as 

hot humid conditions, long work hours, and 

heavy workload were the exception, not the 

norm for most of the cited studies. Most test 

sites had ambient concentrations less than 

the OSHA half mask respirator maximum use 

limit (i.e., ten times the PEL). 

* * * * * 

The various particle sizes, a critical issue 

in a WPF, cited in many of the APF proposed 

rule Workplace Protection Factor studies are 

so large that they do not penetrate the 

faceseal. Many respiratory protection studies 

have indicated that particles larger than two 

microns are less likely to penetrate the most 

important attribute of a respirator, the 

faceseal. Most of the APF proposed rule 

Workplace Protection Factor studies have a 

particle size greater than two microns. (Ex. 9–

35.) 

The studies analyzed by OSHA 

consisted of a varied cross-section of 

workplaces and conditions. For 

example, workplaces included ship 

breaking, asbestos removal, aluminum 

and lead smelters, brass foundries, and 

aircraft painting and manufacturing. 

Two of the four new studies analyzed by 

OSHA involved concrete-block 

manufacturing. The authors of an 

aluminum smelter study (Ex. 1–64–24) 

noted that employees were required to 

rest in a cool area for 50% of each hour 

due to high heat, and a steel mill study 

(Ex. 1–64–50) and a primary lead 

smelter study (Ex. 1–64–42) both were 

conducted in the sinter plant and blast 

furnace areas. The asbestos study (Ex. 

1–64–54) was conducted under high 

humidity conditions. Tasks performed 

by test subjects included welding and 

grinding, torch cutting, pouring molten 

metal, handling concrete blocks, and 

spray painting. Work rates for these 

studies, when provided, ranged from 

low to heavy. 

The purpose of a WPF study is to 

evaluate a respirator’s effectiveness 

under actual workplace use conditions. 

Consequently, the contaminant 

concentrations and particle sizes 

contained in the analyzed studies were 

generated while the workers performed 

their normal job duties. With regard to 

concerns about particle size, Myers et al. 

(Ex.1–64–51) found particles larger than 

10 microns inside the respirator 

facepiece. The Agency believes that 

accepting only WPF studies that are 

conducted at exposure levels close to 10 

times the PEL, with particulates of two 

microns in size or less, would not be 

representative of the conditions found 

in the workplace. Studies based on such 

selective criteria would be more akin to 

a SWPF, rather than a WPF, study. 

OSHA has concluded that the data used 

in its analyses are applicable to other 

American work settings because a range 

of work rates and environmental 

conditions were represented, and many 

of the tasks performed by the test 

subjects are performed in a variety of 

workplaces, including construction. 

Accordingly, the Agency is not 

persuaded by comments suggesting that 

the studies were so narrowly focused 

that the data cannot be applied to other 

work settings. 

Sensitive analytical method. Several 

commenters questioned the use of 

sensitive analytical methods for the 

analyses of workplace exposures, 

sometimes accompanied by a 

recommendation to test respirators 

under controlled laboratory settings, 

and at sufficiently high concentrations 

to obtain inside-the-facepiece 

measurements (Ci) that can be assessed 

by less sensitive methods (e.g., Exs. 9–

32, 9–35, 10–6, 10–37, and 10–49). The 

commenters believed that sensitive 

analytical methods (particularly PIXEA, 

proton-induced x-ray emission analysis) 

permit the determination of low Ci 

concentrations, resulting in high 

protection factors. 

In response to these comments, OSHA 

reviewed the seven half mask studies 

that used the PIXEA analytical method 

(Exs. 1–64–19, 1–64–51, 1–64–52, 1–64–

15, 1–64–16, and 1–64–34) and found 

that six of the studies used the method 

to measure both the Ci and Co 

concentrations. The seventh study (Ex. 

3–12) used PIXEA to measure the Ci 

concentration but used atomic 

absorption (AA) to assess Co 

concentrations because the respirator 

filters were overloaded. However, the 


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Agency does not believe that this study 

provided inaccurate results. Under 

conditions of high Co concentrations, 

the AA method must be used because 

the PIXEA method would exceed its 

maximum measurement limits. 

Therefore, the PIXEA method would be 

unable to provide accurate Co data. 

Based on its review of these seven 

studies, the Agency found that the 

sensitive analytical method (i.e., PIXEA) 

allowed the investigators to quantify 

small amounts of contaminant that 

penetrate a respirator. This method 

permitted accurate assessment of Ci 

concentrations under conditions of low 

ambient concentrations, thereby 

permitting the use of actual Ci values in 

determining WPFs. Less sensitive 

methods would result in penetration 

values that are nondetectable or less 

than the limit of detection (LOD) for the 

analytic method, thereby requiring the 

study to discard these data or to correct 

for nondetected values using 

unvalidated statistical techniques. On 

the other hand, the sensitive analytical 

method was able to quantify low Ci 

concentrations, thereby enhancing the 

validity of the subsequent analysis by 

retaining the actual data and avoiding 

unvalidated statistical corrections. 

Craig Colton of 3M provided the 

following testimony in support of 

OSHA’s conclusions: 

Some commenters also asserted that the 

use of analytical methods with low detection 

limits are a reason to invalidate some of the 

WPF studies. The claim is erroneously made 

that the analytical sensitivity affects the 

results from WPF studies. However, the 

actual amount of contaminant on the Ci 

sample is not changed by the analytical 

method. 

* * * Because the [Ci levels are] typically 

very small in a WPF study, the higher 

sensitivity of [the PIXEA method] is 

necessary to get the best data. 

* * * The WPF protocol from the AIHA 

Respirator Committee recommended the use 

of analytical methods with sensitive 

detection limits. * * * Use of less sensitive 

analytical methods for * * * [Ci] sample[s] 

that result in nondetect values are not 

meaningful for determining true exposure. 

(Tr. at 413–414.) 

In its post-hearing comments, 3M 

illustrated the value of sensitive 

analytical methods using the following 

example: 

[C]onsider three filters ‘‘spiked with 1 μg 

of silicon each and analyzed by three 

different methods [gravimetric, atomic 

absorption (AA), and PIXEA]. In the case of 

gravimetric and AA analyses, it is certain 

only that the silicon mass on the filter is 

between 0 μg and 10 [μg] or 0 μg and 5 μg 

respectively. However, PIXE[A] has sufficient 

analytical sensitivity to ‘‘find’’ the true value 

of 1 μg. Because the mass of contaminants on 

a Ci filter is typically very small in a WPF 

study, the higher sensitivity of PIXE[A] is 

necessary to get the best data. (Ex. 19–3–1.) 

Tom Nelson commented that ‘‘[t]he 

analytical method must be sensitive for 

a WPF study. For a half facepiece 

respirator[,] the detection limit should 

be at least 1⁄100 of the ambient 

concentration’’ (Ex. 18–9). Later in these 

comments, Nelson stated, ‘‘The [lowconcentration Ci] samples are part of the 

distribution of WPF samples collected 

during a study. These represent true 

measures of performance.’’ 

Based on the evidence in the record, 

OSHA concludes that using sensitive 

analytic methods for assessing Ci 

samples is both necessary and 

appropriate. Specifically, the Agency 

sees no scientific basis for excluding 

WPF studies that used PIXEA, 

particularly when using the method to 

determine both Ci and Co. The Agency’s 

review of the record evidence shows 

that a leading national organization 

representing industrial hygienists (i.e., 

the AIHA) recommends using sensitive 

analytic methods for assessing Ci 

samples. Furthermore, using sensitive 

analytic methods improves significantly 

the validity of data analyses by allowing 

studies to retain low Ci values, and by 

reducing substantially the need to use 

unvalidated techniques to correct low Ci 

values. Therefore, OSHA concludes that 

the data from the WPF studies used in 

its analyses are accurate, and that the 

availability of data with low Ci values 

improved the validity of the APFs 

derived from these analyses. 

Large particles. Several commenters 

(e.g., Exs. 9–33, 9–35, 10–6, 10–37, and 

10–41) postulated that larger particles 

(greater than one or two microns) do not 

penetrate a respirator’s faceseal. They 

believed that WPF studies having large 

particles in the Co concentration should 

be excluded from OSHA’s analyses. 

They reasoned that these large particles 

were being measured as part of the Co 

but had no chance of being measured in 

the Ci, and consequently were inflating 

the WPF values. 

These commenters appear to be 

ignoring the possibility that half masks 

(both elastomerics and filtering 

facepieces) with faceseals that 

selectively filter large particles still are 

capable of providing an adequate level 

of protection. Nevertheless, OSHA notes 

that in one of the WPF studies used in 

OSHA’s data analyses, Myers et al. 

found large particles (i.e., 10 microns in 

diameter) inside the facepiece, 

indicating that large particles are 

capable of penetrating a respirator 

faceseal (Ex. 1–64–51). Consistent with 

these results, Tom Nelson stated in his 

comments that ‘‘[t]he particle size of 

contaminants in the various WPF 

studies in the docket range from [about] 

0.5 [microns] to 14 [microns] MMAD,’’ 

and that ‘‘particles much larger than 

those that would be predicted from 

laboratory studies have been found 

inside the facepiece in WPF studies’’ 

(Ex. 18–9). At the hearing, Nelson 

presented data showing that large 

particles enter half mask respirators, 

probably through breaks in the faceseal; 

moreover, these data demonstrate that 

no relationship exists between particle 

size and the WPF obtained for the 

respirator (Tr. at 146–148). The 3M 

Company addressed this point further, 

stating in its comments: 

Laboratory studies have shown that 

particle losses occur through fixed leaks. A 

faceseal leak is not accurately represented by 

a fixed leak, however. To perform these 

studies[,] assumptions were made regarding 

leak size, shape, and the particle size 

penetrating those leaks. These assumptions 

have been shown to be wrong. Myers has 

shown that large particles can be found 

inside the facepiece[,] much larger than 

could have occurred with the fixed leaks 

used by several researchers.[] As shown in 

Figure 1 [of the Myers et al. study], an 

analysis of particle size and the geometric 

mean WPF from a number of studies does not 

show any relationship between particle size 

and WPF. If the size of the particle played 

a role in faceseal leaks, a relationship would 

be evident. (Ex. 9–16.) 

Based on the evidence in the record, 

OSHA concludes that the data in its 

APF analyses for half masks were the 

same as particle sizes found in the 

workplaces represented in the WPF 

studies. Therefore, eliminating the study 

data from the Agency’s analyses would 

be unnecessary and inappropriate. 

Probe bias. Probe bias refers to the 

misplacement of the sampling probe 

when taking measurements inside the 

respirator facepiece. Some commenters 

expressed concern that probe bias may 

have underestimated Ci in the half mask 

WPF studies analyzed by Dr. Brown 

(e.g., Exs. 9–17, 9–30, 9–35, and 10–42). 

These commenters suggested that OSHA 

reanalyze its database after applying a 

correction factor to account for probe 

bias. Tim Roberts provided a specific 

description of this concern when he 

testified: 

Respirator probe error is an issue. It’s been 

better characterized for elastomeric type 

respirators than it has for filtering facepiece 

respirators, and we think that this needs 

some additional work as well, to characterize 

what that means when we put probes in 

different locations in elastomeric facepieces 

(Tr. at 208). 

Later in the hearings, Ching-tsen Bien 

questioned Craig Colton of 3M on 

Colton’s experiences with probe 

location while conducting filtering 


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facepiece WPF studies. Colton 

responded: 

[S]treamlining that you see is similar to 

that in the elastomeric half-facepieces. You 

see it streamlining from the leak up to the 

mouth and nose. And so what Dr. Myers 

indicated in his sampling bias—not really 

probe bias, but the sampling bias—was that 

location becomes important because if your 

probe is flushed with the facepiece, you can 

miss the streamlines. So his recommendation 

was that the probe needs to be ideally on the 

midline, between the mouth and the nose, 

and as close to the face as possible. And so 

that’s what we attempt to do as best as you 

can with the products you end up testing to 

meet his recommendations. (Tr. at 455–456.) 

Colton also noted that, although some 

of his studies may show probes entering 

the side of the filtering facepiece, a 

probe extension was used to place the 

sampling inlet in the nose-mouth area 

(Tr. at 455–456). Tom Nelson explained 

the purpose of the probe location when 

he commented, ‘‘The sampling probe is 

placed so that it is close to the nose and 

mouth. This minimizes sampling bias’’

(Ex. 18–9). Warren Myers testified that, 

in unusual circumstances, the 

configuration of a half mask (including 

some elastomerics) requires placing the 

sampling probe on the side of the mask 

instead of the centerline between the 

nose and the mouth; in these cases, a 

study can control for sampling bias by 

randomly alternating the location of the 

probe on the right and left side of the 

mask (Tr. at 77). 

OSHA also reviewed the 13 half mask 

studies analyzed by Dr. Brown. The 

authors of nine of these studies 

specifically state that the probe was 

located in the area of the nose and 

mouth. While the remaining four 

studies do not specify the probe’s 

location, no evidence from this 

rulemaking indicates that the sampling 

probes were inappropriately placed. 

Therefore, the majority of the WPF 

studies, along with the new studies 

included in the updated database, 

located the sampling probe in the nosemouth area. Of the 1,339 data points in 

the updated database, approximately 

220 of these points (about 16%) are from 

the four studies in which no 

information on probe placement was 

available. OSHA believes the sampling 

methodology that was used in these 

studies was consistent with comments 

indicating that the optimum location for 

a probe is at the centerline between the 

nose and the mouth. At this location, 

the probe will sample any streamlining 

that occurs between a faceseal leak and 

the nose-mouth area, thereby detecting 

the maximum Ci exposure level. In 

addition, no analysis was submitted 

indicating that the data from these 

studies, whether corrected for probe 

bias or excluded altogether, would have 

resulted in APFs that differed from the 

final APFs derived from this 

rulemaking. 

3. Summary and Conclusion 

OSHA considered the comments 

addressing the data and study problems 

identified by commenters, but does not 

find that these comments merit rejection 

of the data or analyses. The studies 

OSHA analyzed were conducted on 

employees in actual workplaces who 

were performing their normal job duties. 

Consequently, the particle sizes, work 

rates, work times, and environmental 

conditions varied among these studies. 

The Agency has concluded that using 

data collected under these various 

conditions presents a more accurate 

picture of workplace use of these 

respirators and is a better measure of the 

protection provided by half mask 

respirators than data collected only from 

SWPF or other highly controlled 

studies. 

D. Alternative Approaches 

1. Alternatives Based on Non-Compliant 

Respirator Programs 

Several commenters suggested 

alternative means for ascertaining APFs. 

While not completely disagreeing with 

OSHA’s approach, Paul Hewett of 

Exposure Assessment Solutions 

Incorporated (Ex. 10–60) stated that 

OSHA should include EPF studies in its 

APF deliberations. He commented that 

EPF studies account for actual use 

conditions in that they factor in the time 

that the employee does not wear the 

respirator but is still exposed to 

atmospheric contaminants. He also 

believed that determination of an 

appropriate APF should represent 

respirator use in hot, strenuous jobs. 

Therefore, he recommended that 

‘‘OSHA should factor in real world 

conditions and not rely exclusively on 

WPF and particularly SWPF studies’’

(Ex. 10–60.) 

OSHA noted in the proposal that the 

Agency would analyze only WPF and 

SWPF studies since they address 

respirator performance exclusively (68 

FR 34045). This alternative approach 

already has been addressed above by the 

Agency in its discussion of the 

usefulness of WPF data. The Agency has 

no data in the record showing that EPF 

studies would improve, or even 

complement, its analyses. Therefore, 

OSHA is not convinced that EPF data 

would increase the validity of the APFs 

derived in this final rule. The 

discussion of an EPF study by Harris et 

al. (Ex. 27–11; 63 FR 1167) substantiates 

these conclusions. 

Ching-tsen Bien of LAO Consulting, 

Inc. (Ex. 18–5) wanted OSHA to enter 

into the record any available 

independent assessment reports (and 

applicable check lists) for the year prior 

to, and for the year of, each WPF study. 

Bien noted that the reports would have 

covered applicable program elements, 

and ensure that OSHA selected studies 

for its analyses that were in compliance 

with appropriate respiratory protection 

standards. He also requested that OSHA 

enter the ‘‘selection criteria, decision 

matrix for each study, and the review 

report for these studies to the H–049C 

Docket’’ (Ex. 18–5.) 

As stated in the NPRM at 68 FR 

34046, the Agency evaluated all studies 

used in its analyses for compliance with 

the requirements of OSHA’s Respiratory 

Protection Standard (29 CFR 1910.134), 

as well as for completeness of the data. 

The Agency also compiled a list of 

criteria (Ex. 5–5) for evaluating each 

study. Accordingly, OSHA evaluated 

each published article or each written 

study report to determine whether the 

test subjects were trained properly, fit 

tested, medically evaluated, and in 

compliance with the requirements of the 

OSHA Respiratory Protection Standard. 

The researchers performing these WPF 

studies ensured that fit testing was 

performed on the test subjects, trained 

them on doffing and donning the 

respirator, as well as the performance of 

user seal checks, on the selection of 

proper-sized respirators, and on the 

other elements of a complete OSHAcompliant respirator program. These 

researchers did not rely on the existing 

workplace respirator program, but 

instead performed the necessary actions 

to ensure that the test subjects in their 

WPF studies met the respirator program 

requirements. 

The WPF studies the Agency 

evaluated were either WPF studies that 

had been published previously, or were 

newly performed studies that were 

submitted during the rulemaking for 

inclusion in the OSHA database. OSHA 

did not perform these studies, and was 

not involved in the selection of the 

worksites being tested. Therefore, the 

Agency could not gather additional 

information on a worksite’s respirator 

program that was in effect when a WPF 

study was performed, as Bien requested. 

Additionally, such information is 

irrelevant to the results of a WPF study 

since the researchers had to demonstrate 

compliance with the required respirator 

program before OSHA included the 

study in its database. 


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2. Alternatives Based on SWPF Studies 

The American Chemistry Council (Ex. 

10–25) stated that OSHA’s APFs should 

be based on SWPF studies, and that the 

APFs derived from this rulemaking 

should be used only as interim values 

until SWPF studies could be performed. 

OSHA notes that basing APFs on SWPF 

studies, rather than on WPF studies, 

was recommended by a number of 

commenters including Organizational 

Resource Counselors Worldwide (ORC) 

(Ex. 10–27), Paper, Allied-Industrial, 

Chemical & Energy Workers 

International Union (PACE) (Ex. 10–37), 

and others (e.g., Exs. 9–32, 9–41, 10–6, 

10–49, 9–33, 9–35, and 18–5). These 

commenters expressed various concerns 

about the WPF studies, and stated that 

SWPF studies permit investigators to 

control a number of variables (e.g., 

particle size, contaminant 

concentration, environmental 

conditions) that cannot be controlled in 

WPF studies. 

SWPF studies use sensitive analytical 

methods, such as PIXEA, to obtain 

measurable Ci information. SWPF 

studies safely test a respirator in a highconcentration atmosphere (i.e., at the 

respirator’s limit of protection) to 

generate enough penetration for the 

analytical method to quantify Ci results. 

OSHA agrees that SWPF testing permits 

an investigator to control factors such as 

particle size, contaminant 

concentration, temperature, and 

humidity. Accordingly, the Agency used 

data generated from all available SWPF 

studies in determining APFs. However, 

OSHA concluded that controlled SWPF 

studies alone are not representative of, 

nor can they be extrapolated readily to, 

typical workplaces. Standardized 

protocols for conducting such testing, or 

a methodology for extrapolating SWPF 

results to protection levels expected in 

the workplace, are not available. ORC 

stated, ‘‘We advocate development of a 

protocol based on a combination of 

laboratory testing and field trials for 

determining expected respirator 

performance’’ (Ex. 10–27). NIOSH also 

supported the use of both SWPF and 

WPF studies, noting, ‘‘NIOSH agrees 

that the APF values resulting from 

OSHA’s multifaceted approach to 

analysis of existing data provide 

reasonable values for the level of 

protection that should be expected for 

each class of respirators’’ (Tr. at 102). 

NIOSH continued, ‘‘Given this lack of 

complete data, the noted model-tomodel variation and the imperfection in 

protection level measurements, the 

approach taken by OSHA is the best 

currently possible based upon available 

data’’ (Tr. at 103). The Agency has 

concluded that its approach in using 

both WPF and SWPF studies is well 

supported by the rulemaking record and 

is appropriate for determining APFs 

specified in this final rule. 

3. Model-Specific APFs 

The Organization Resources 

Counselors Worldwide (Ex. 10–27), the 

American Chemistry Council (Ex. 10–

25), and the Pharmaceutical Research 

and Manufacturers of America (Ex. 9–

24) urged OSHA to develop modelspecific APFs. Under this 

recommendation, each respirator model 

would undergo testing and be assigned 

a unique APF. NIOSH did not support 

this approach. In response to 

questioning by OSHA, NIOSH stated: 

This morning’s expert witnesses and the 

questions I think clearly identified that there 

is variability, and because of this variability, 

we believe that class APFs are more 

appropriate and consistent with the state of 

the art today. In order to achieve more 

precise data, much, much larger data sets, 

including the numbers of test subjects that 

would have to be involved to eliminate this 

variability, seems impractical based upon the 

state of the art today. So we are for these 

reasons supporting class APFs, not modelspecific APFs. (Tr. at 120.) 

OSHA considered the use of SWPF 

studies in developing model-specific 

APFs. The Agency’s review of the ORC 

SWPF study of PAPRs and SARs in the 

proposal (68 FR 34069) stated that ORC 

had recommended that ‘‘the [ORC 

SWPF] study methodology should be 

the basis for determining APFs for all 

respiratory protective equipment 

regulated by OSHA’’ (68 FR 34070). 

However, only a few SWPF studies are 

available that measured the performance 

of a few PAPRs and SARs. Modelspecific SWPF studies for the remaining 

respirator classes have not been 

performed. In addition, the respirator 

protection community has not agreed on 

a standard protocol for conducting 

SWPF studies, or how the results relate 

to APFs. These issues would have to be 

addressed before it would be possible to 

use model-specific APFs. Also, 

insufficient data are available to set 

model-specific APFs, and developing 

the methodology and conducting the 

testing could take years. OSHA believes 

that completing the APF rulemaking 

with the information available now is 

necessary. Delaying this rulemaking to 

develop model-specific APFs will result 

in employers not knowing what 

respirators to select and, consequently, 

employees will not receive adequate 

protection. Based on the rulemaking 

record, the Agency has concluded it will 

determine an APF for each respirator 

class using information from existing 

WPF and SWPF studies. 

4. Nicas-Neuhaus Model 

Several commenters (Paul Hewett, Ex. 

10–60; Bill Kojola, AFL–CIO, Ex. 17–2; 

and NIOSH, Ex. 17–7–1) asked OSHA to 

consider a February 2004 article by 

Nicas and Neuhaus (Ex. 17–7–2) that 

applies a model for analyzing WPF data 

to establish APFs. The Nicas-Neuhaus 

article is based on the variability of 

WPFs (i.e., the variability between 

different test subjects, as well as the 

variability within a test subject resulting 

from repeated donnings of the 

respirator). APFs based on this NicasNeuhaus model require that WPFs for 

95% of all workers be above the APF 

95% of the time. However, the 

established method for deriving APFs 

used by OSHA, NIOSH, and ANSI sets 

the APFs at the 95% percentile of the 

between-subject WPFs. By controlling 

for within-subject variability, APFs 

based on the Nicas-Neuhaus model will 

always be smaller than APFs derived 

using the established method. 

To account for within-subject 

variability, the Nicas-Neuhaus model 

requires repeated measurements on each 

test subject which is not required by the 

established method. Consequently, most 

available WPF studies did not include 

multiple measures on individual test 

subjects, resulting in an extremely 

limited database for applying the NicasNeuhaus model. Nicas and Neuhaus 

were able to analyze only seven half 

mask respirator studies, comprising a 

total of 310 data pairs. In comparison, 

the database established and analyzed 

by OSHA for determining the final APFs 

contains 1,339 data pairs from 16 half 

mask respirator studies. Also, OSHA 

had rejected for its analyses several of 

the WPF studies used by Nicas and 

Neuhaus in developing their model 

because these studies did not meet the 

Agency’s selection criteria. 

The Nicas-Neuhaus model is a 

significant departure from established 

and accepted practices used by the 

respirator research community, The 

Agency has concluded that there are 

insufficient data to fully evaluate the 

proposed model, and to incorporate it in 

setting APFs. 

5. Other Alternative Approaches 

Sheldon Coleman recommended that 

OSHA select a panel from AIHA 

members to review the APF data and 

OSHA’s APF determinations (Ex.10–40). 

OSHA believes this rulemaking has 

provided ample opportunity for 

comment from the public and 

professional associations. Further 

analysis would delay the development 


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of the final APFs, and is unnecessary as 

the rulemaking record is sufficient to 

determine APFs. 

6. Summary and Conclusion 

OSHA is relying on science, data, and 

established quantitative analyses to 

establish the final APFs for filtering 

facepiece and elastomeric half mask 

respirators, and is limiting its statistical 

analyses to those procedures that use 

the selected data to the fullest extent 

possible. Reliance on alternative 

approaches is not supported by the 

evidence in the record. The data to use 

such approaches are not currently 

available, and require either a different 

set of data or a standardized testing 

protocol that requires testing every 

respirator model. OSHA concludes that 

the available data and analytic methods 

used in determining the final APFs are 

appropriate. 

E. Updated Analyses 

1. Review of the Original WPF and 

SWPF Databases 

In developing its proposed rule 

regarding APFs for respirators, OSHA 

contracted with Dr. Kenneth Brown to 

investigate possible approaches for 

evaluating respirator performance data 

from WPF and SWPF studies. To assist 

Dr. Brown in this evaluation, the 

Agency reviewed the available studies 

and created a database from these 

studies. In deciding which WPF studies 

to include in this database, OSHA 

evaluated studies with respect to 

compliance with the requirements of its 

Respiratory Protection Standard (29 CFR 

1910.134) and the completeness of the 

data. In doing so, the Agency excluded 

WPF studies of gas or vapor 

contaminants due to the limited number 

of these studies and the difficulties in 

conducting and interpreting data from 

such studies (68 FR 34046). During the 

rulemaking, OSHA received new WPF 

data on half mask respirators. No new 

SWPF data were submitted for half 

masks, and no new WPF data were 

submitted for higher-performing 

respirators. 

In the NPRM, Dr. Brown initially 

divided negative pressure half mask airpurifying respirators (APRs) into five 

classes. Four classes of filtering 

facepiece half masks were derived based 

on whether a respirator had adjustable 

head straps, an exhalation valve, a 

double-shell construction, or a foamring faceseal. Elastomeric half masks 

were grouped together in a single fifth 

class. (See Ex. 5–1 for details on 

respirator class definitions.) In his 

analyses, Dr. Brown found no clear 

evidence of a difference in WPFs across 

these different classes. In particular, he 

found that elastomeric half masks 

performed substantially the same as 

filtering facepieces. From the original 

database of 917 WPF measurements for 

negative pressure half mask APRs, 36 

WPF measurements (3.9%) were found 

to have an APF less than 10, and 96.1% 

at 10 and above. 

2. Updated OSHA Database on APRs 

In the NPRM, OSHA asked if any 

more WPF or SWPF studies should be 

considered in setting APFs. Data from 

four additional studies were submitted 

for OSHA’s evaluation during the 

comment period, and an updated half 

mask database was compiled using 

these studies (Ex. 20–2). During the 

post-hearing comment period, the 3M 

Company provided OSHA with data 

from two additional WPF studies of 

filtering facepiece respirators. One study 

(Colton and Bidwell, Ex. 9–16–1–1) 

measured the performance of three 

different types of filtering facepiece 

respirators used by 21 workers at a leadbattery manufacturing plant. One 

respirator (3M 8710) was approved 

under 30 CFR part 11, and two 

respirators were N95 particulate 

respirators (3M 8210 and 3M 8510) 

approved under 42 CFR part 84. Up to 

three WPF measurements were made 

with each worker on each respirator 

type, for a total of 143 WPF 

measurements. The data submitted to 

OSHA from this study are provided in 

Appendix A of Dr. Crump’s report on 

the reanalysis of the half mask database 

(Ex. 20–1). 

The second set of WPF data provided 

by 3M Company was from a study by 

Bidwell and Janssen (Ex. 9–16) on the 

performance of a ‘‘flat-fold’’ filtering 

facepiece respirator conducted at a 

concrete-block manufacturing facility. 

Repeated measurements of WPFs were 

made on 19 workers, and each sample 

was analyzed for both silicon and 

calcium. A total of 73 Co and 73 Ci air 

samples were collected, for a total of 

146 WPF measurements. Eleven of the 

146 Ci measurements were nondetectable (all coming from silicon 

exposures). 

The third study added to the database 

was a WPF study by Colton (Ex. 4–10–

4) on the performance of an elastomeric 

half mask respirator. This study had 

been submitted earlier to OSHA, but 

was not included in the NPRM database 

since it was received too late for 

inclusion in Dr. Brown’s original 

analysis. The data from this study, 

conducted in the battery-pasting and 

assembly areas of a battery 

manufacturing plant, have now been 

added to OSHA’s updated database. 

Also, three additional data points from 

a study by Myers and Zhuang (Exs. 1–

64–50 and 3–14) were added to the 

updated database. These data were 

collected in a concrete-block facility 

while elastomeric half mask respirators 

were worn as protection against calcium 

and silicon particulates. 

The updated OSHA half mask 

database (Ex. 20–2), summarized in 

Table III–1, contains 1,339 WPF 

measurements—760 collected from 

filtering facepiece respirators, and 579 

from elastomeric respirators. The 

database originally analyzed by Dr. 

Brown contained 917 WPF 

measurements—471 from filtering 

facepieces, and 446 from elastomerics. 

TABLE III–1.—SUMMARY OF OSHA WPF DATABASE FOR APRS

Respirator 

class Figure 1 No. Constituent sampled Author Exhibit No. 

Number 

samples per 

study 

Number 

samples per 

class 

Filtering Facepiece Respirators 

1 ................................... 1 Asbestos ............................ Dixon ................................. 1–64–54 26 474 

1 ................................... 2 Fe ...................................... Myers ................................. 1–64–50, 3–14 21 ....................

1 ................................... 3 Mn ...................................... Wallis ................................. 1–64–70 69 ....................

1 ................................... 4 Al ....................................... Colton ................................ 1–64–15 23 ....................

1 ................................... 5 Al ....................................... Johnston ............................ 1–64–34 13 ....................

1 ................................... 6 Si ....................................... Johnston ............................ 1–64–34 15 ....................

1 ................................... 7 Ti ........................................ Johnston ............................ 1–64–34 18 ....................

1 ................................... 8 Pb ...................................... Colton & Bidwell ................ 9–16–1–1 143 ....................

1 ................................... 9 Si ....................................... Bidwell & Janssen ............. 9–16 73 ....................


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50134 Federal Register / Vol. 71, No. 164 / Thursday, August 24, 2006 / Rules and Regulations 

TABLE III–1.—SUMMARY OF OSHA WPF DATABASE FOR APRS—Continued 

Respirator 

class Figure 1 No. Constituent sampled Author Exhibit No. 

Number 

samples per 

study 

Number 

samples per 

class 

1 ................................... 10 Ca ...................................... Bidwell & Janssen ............. 9–16 73 ....................

3 ................................... 11 Pb ...................................... Myers ................................. 1–64–51, 3–12 19 162 

3 ................................... 12 Zn ...................................... Myers ................................. 1–64–51, 3–12 20 ....................

3 ................................... 13 Fe ...................................... Colton ................................ 1–146 31 ....................

3 ................................... 14 Mn ...................................... Colton ................................ 1–146 32 ....................

3 ................................... 15 Ti ........................................ Colton ................................ 1–146 28 ....................

3 ................................... 16 Zn ...................................... Colton ................................ 1–146 32 ....................

4 ................................... 17 Pb ...................................... Colton ................................ 1–64–16 62 124 

4 ................................... 18 Zn ...................................... Colton ................................ 1–64–16 62 ....................

Elastomeric Respirators 

5 ................................... 19 Asbestos ............................ Dixon ................................. 1–64–54 46 579 

5 ................................... 20 B(a)Pyrene ........................ Gaboury ............................. 1–64–24 18 ....................

5 ................................... 21 Pb ...................................... Lenhart .............................. 1–64–42 25 ....................

5 ................................... 22 Pb ...................................... Myers ................................. 1–64–51, 3–12 46 ....................

5 ................................... 23 Zn ...................................... Myers ................................. 1–64–51, 3–12 46 ....................

5 ................................... 24 Fe ...................................... Myers ................................. 1–64–50, 3–14 30 ....................

5 ................................... 25 Cr ....................................... Myers ................................. 1–64–52, 4–5 35 ....................

5 ................................... 26 Ti ........................................ Myers ................................. 1–64–52, 4–5 33 ....................

5 ................................... 27 Cd ...................................... Colton ................................ 1–64–13 68 ....................

5 ................................... 28 Pb ...................................... Colton ................................ 1–64–13 57 ....................

5 ................................... 29 Pb ...................................... Dixon & Nelson ................. 1–64–19 42 ....................

5 ................................... 30 Pb ...................................... Colton ................................ 4–10–4 130 ....................

5 ................................... 31 Calcium .............................. Myers ................................. 1–64–50, 3–14 3 ....................

Grand Total ........... .................... ............................................ ............................................ ........................ .................... 1339 

3. Variability of the APF Data 

Several commenters (Faulkner, Ex. 9–

40 and Kojola, Ex. 9–27) criticized WPF 

studies because the studies 

demonstrated what they considered to 

be a high degree of variability of the 

data. However, it is inappropriate to 

describe the variability of the data with 

terms such as ‘‘high’’ or ‘‘low’’ because 

no recognized standard exists by which 

to characterize variability. The 

variability of the data should reflect the 

true variability in respirator fit and 

performance experienced by workers 

who wear respirators. It is reasonable to 

expect variability because respirator 

performance is determined by many 

factors, including: Respirator type, the 

workers’ face shapes, work practices 

and effort levels, and workplace 

conditions such as temperature and 

humidity. Thus, the key issue is not 

whether the data have too much or too 

little variability, but whether the 

variability in the data reflects the true 

variability in respirator performance 

under actual workplace conditions. 

A logarithmic transformation was 

applied to the WPF data set to adjust for 

a skewed distribution and extreme 

outliers, both of which are common 

with ratio-based data. As Figure III–1 

shows, when a logarithmic 

transformation is applied to OSHA’s 

WPF database, the data closely follow a 

standard normal distribution. Therefore, 

OSHA’s analysis of the data, which 

assumes that WPFs are log-normally 

distributed with a geometric mean of 

307 and a geometric standard deviation 

of 7.1, appropriately accounts for the 

variability in the WPF data. 


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Federal Register / Vol. 71, No. 164 / Thursday, August 24, 2006 / Rules and Regulations 50135 

1 Includes four of the five classes originally 

determined in the analysis conducted for OSHA by 

Dr. Ken Brown; no data were available for Class 2. 

Dr. Brown characterized disposable half marks 

according to combinations of the following four 

design characteristics: (1) Adjustable head straps, 

(2) presence of an exhalation valve, (3) double shell 

construction, and (4) foam ring liner. Class 1 has 

none of the four design characteristics. Class 2 has 

design characteristics (1) and (3). Class 3 has design 

characteristics (1) through (3). Class 4 has all four 

of the design characteristics. Class 5 consists of all 

elastomeric half masks. 

4. Analysis of Updated Database on 

APRs 

OSHA proposed an APF of 10 for 

negative pressure half mask APRs, 

including both filtering facepieces and 

elastomerics (68 FR 34096). 

Accordingly, the present analysis 

focuses on estimating this APF, 

particularly the percent of WPFs that are 

less than 10. 

Figure III–2 displays the 1,339 WPF 

values, grouped by respirator class,1

study, and contaminant. Each column of 

data points in the figure corresponds to 

a row number listed in column 2 of 

Table III–1. This figure shows that more 

WPFs for elastomerics are less than 10 

than was the case for filtering 

facepieces, even though a much larger 

proportion of these WPFs are from 

filtering facepieces. 


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Figure III–2 also shows that 

differences exist between WPFs 

measured in different studies, even 

among respirators of the same type. For 

example, both the Colton (Ex. 1–64–15, 

#4 in Figure 2) and the Colton and 

Bidwell (Ex. 9–16–1–1, #8 in Figure 2) 

studies were conducted by some of the 

same investigators, and both studies 

used Class 1 filtering facepieces. 

Nevertheless, all but one of the 23 WPFs 

in the Colton study (Ex. 1–64–15) are 

less than 40, while all 143 of the WPFs 

from the Colton and Bidwell study (Ex. 

9–16–1–1) are at least 58 or higher. 

However, the Colton study evaluated 

respirators approved under 30 CFR part 

11, whereas the Colton and Bidwell 

study evaluated respirators approved 

under 42 CFR part 84. 

Table III–2 shows the percentages of 

WPFs less than 10 by respirator class, 

along with the 90% statistical 

confidence intervals on these 

percentages. The exact confidence 

intervals are based on a binomial 

distribution for counts. The percentage 

of WPFs less than 10 is less than 5% for 

all four classes, and the 90% statistical 

confidence interval on this percentage 

excludes 5% for every class except 

elastomerics. Also, elastomerics had the 

highest percentage of WPFs less than 10 

(4.5%). Over all classes, 38/1339, or 

2.8%, of WPFs were less than 10 (90% 

confidence interval: 2.1%, 3.7%). The 

upper bound of this two-sided 90% 

confidence interval, 3.7%, is equivalent 

to a one-sided 95% upper statistical 

confidence bound on the true 

proportion of WPFs less than 10. This 

bound may be interpreted as follows: 

assuming the database is representative 

of workplace WPFs in general (more 

specifically, that the data approximate a 

random sample of WPFs from all 

workers who use respirators), when the 

true proportion of WPFs less than 10 is 

3.7%, the probability of observing 2.8% 

or less (the observed percentage) would 

be 1 ¥ 0.95 = 0.05. Thus, under these 

assumptions, it is unlikely that the true 

proportion of WPFs less than 10 is as 

high as 3.7% (and extremely unlikely to 

be as high as 5%). 

TABLE III–2.—PERCENT OF WPFS LESS THAN 10 BY RESPIRATOR CLASS

Total n n < 10 Percent (90% Cl) 

Class 1 ..................................................................................................................... 474 11 2.3 (1.3%, 3.8%) 

Class 3 ..................................................................................................................... 162 0 0.0 (0.0%, 1.8%) 

Class 4 ..................................................................................................................... 124 1 0.8 (0.0%, 3.8%) 

Class 1–4 (Filtering Facepieces) ............................................................................. 760 12 1.6 (0.9%, 2.5%) 

Class 5 (Elastomerics) ............................................................................................. 579 26 4.5 (3.2%, 6.2%) 

Total .................................................................................................................. 1339 38 2.8 (2.1%, 3.7%) 


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In the earlier database analyzed by Dr. 

Brown, 3.9% of the WPFs were less than 

10. By comparison, among the 422 

WPFs added to the database, only 2⁄422

(0.5%) were less than 10. Thus, the new 

data indicate a higher level of protection 

by APRs. 

In addition to the 1,339 WPFs in the 

updated OSHA database, an additional 

403 WPFs from 12 studies were coded 

by OSHA but were not included in 

either the present database or the one 

analyzed by Dr. Brown. These data were 

omitted for various reasons, including 

too few WPF measurements in a study 

and problems with the quality of the 

studies (i.e., study did not meet 

requirements of OSHA’s Respiratory 

Protection Standard). In addition, as 

noted earlier, OSHA did not include 

data from studies in which exposures 

were predominantly to a gas or vapor. 

To determine the effect that excluding 

these data had on the results in Table 

III–2, the 403 WPFs were added to the 

updated data base of 1,339 WPFs (for a 

total of 1,742 WPFs), and the overall 

fraction of WPFs less than 10 was 

computed (Table III–3). The percent of 

WPFs less than 10 was 4.0% (90% 

confidence interval: 3.2%, 4.8%). Thus, 

even with no data exclusions, the 

overall percent of WPFs smaller than 10 

is less than 5%, and the 95% statistical 

upper confidence bound is also less 

than 5% (i.e., 4.8%). 

TABLE III–3.—COMPARISON OF PERCENT OF WPFS LESS THAN 10 IN STUDIES USED AND NOT USED BY OSHA 

Total n n < 10 Percent (90% Cl) 

Used ......................................................................................................................... 1339 38 2.8 (2.1%, 3.7%) 

Unused ..................................................................................................................... 403 31 7.7 (5.6%, 10.2%) 

Both Used and Unused ........................................................................................... 1742 69 4.0 (3.2%, 4.8%) 

Consistent with the WPF studies used 

in its analysis, OSHA adopted the point 

estimate of the lower 5th percentile of 

WPF or SWPF data to establish APFs. 

Table III–4 shows the point estimate of 

the 5th percentiles of WPFs for different 

categories of respirators using the 

updated database. The 5th percentile of 

WPFs for filtering facepieces as a whole 

was 18.1, and for elastomerics it was 

12.0. In both cases, the point estimate 

was above the APF of 10 proposed by 

OSHA. Since several commenters 

expressed concern about whether 

sufficient evidence is available to 

support an APF of 10 for filtering 

facepieces, OSHA also calculated 90% 

confidence intervals for each point 

estimate. (As noted earlier, the lower 

limit estimate of a two-sided 90% 

confidence interval is equivalent to a 

one-sided 95% lower confidence 

bound.) The lower 95% confidence 

bounds for the 5th percentile of WPFs 

exceeded 10 for all classes combined, 

and, with the exception of elastomerics, 

for each individual class. The 

confidence limits for the 5th percentiles 

were computed using the method for 

distribution-free confidence intervals of 

Hahn and Meeker (1991), as 

implemented in SAS (2001). Therefore, 

OSHA concludes that sufficient 

statistical evidence is available to justify 

an APF of at least 10 for filtering 

facepieces. 

TABLE III–4.—FIFTH PERCENTILES OF WPFS BY RESPIRATOR CLASS

5th percentile (90% Cl) 

Class 1 ............................................................................................................................................................................. 14.8 (12, 18) 

Class 3 ............................................................................................................................................................................. 19.7 (15, 24) 

Class 4 ............................................................................................................................................................................. 27.0 (22, 49) 

Class 1–4 (Filtering Facepieces) ..................................................................................................................................... 18.1 (15, 22) 

Class 5 (Elastomerics) ..................................................................................................................................................... 12.0 (7, 14) 

Total .......................................................................................................................................................................... 14.7 (13, 18) 

5. Comparison of Respirators Approved 

Under 30 CFR Part 11 Versus 42 CFR 

Part 84 

Several commenters expressed 

concern that the majority of WPF and 

SWPF studies were conducted on 

respirators certified by NIOSH under 

requirements in 30 CFR 11, instead of 

the newer NIOSH certification 

procedure described in 42 CFR 84. 

While these commenters did not explain 

the basis of their concern, two major 

studies were submitted that examined 

the performance of 42 CFR 84-approved 

respirators. The 3M study by Colton and 

Bidwell (Ex. 9–16–1–1) evaluated one 

respirator approved under 30 CFR 11, 

and two respirators approved under 42 

CFR 84. In this study, WPFs were 

measured on up to nine different 

occasions for 21 workers (143 total 

measurements), 17 of whom used each 

type of respirator on at least one 

occasion, with none of them using the 

same type respirator on more than three 

occasions. Thus, this study provides an 

opportunity for comparing the 

performance of respirators approved 

under the two standards. Table III–5 

shows the performance of these three 

respirators using three methods: the 

proportion of samples with Ci nondetects, the distribution of the 30 

smallest WPF values among the three 

respirators, and the geometric mean of 

WPFs. The two 42 CFR 84-approved 

respirators performed similarly with 

each of these methods, and they both 

performed better than the 30 CFR 11- 

approved respirator (see Table III–5). 


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50138 Federal Register / Vol. 71, No. 164 / Thursday, August 24, 2006 / Rules and Regulations 

TABLE III–5.—PERFORMANCE OF THE 30 CFR PART 11 RESPIRATOR (3M 8710) AND THE 42 CFR PART 84 

RESPIRATORS (3M 8511 AND 3M 8210) 

Inside-themask 

non-detects 

Dist. of 30 

smallest 

WPF 

WPF 

geometric 

means 1

3M 8710 ................................................................................................................................................... 5/49 15 792 

3M 8511 ................................................................................................................................................... 23/47 7 2506 

3M 8210 ................................................................................................................................................... 19/47 8 2405 

1 Modeled assuming log-normal distribution with non-detects set at detectin limit. 

The geometric means of WPFs of the 

42 CFR 84 respirators were similar 

(2506 and 2405), and were significantly 

(p < 0.0001) higher than the geometric 

mean of the 30 CFR 11 respirator (792). 

This comparison was made using a 

repeated measures analysis that 

accounted for dependence among 

different samples collected from the 

same worker, assumed log-normally 

distributed WPFs, and set non-detects at 

the detection limit (which should 

minimize differences between the two 

respirator types). All three respirators 

performed well in this study, with the 

smallest of the 143 WPFs being 52, well 

above the APF of 10 proposed by OSHA. 

When the 146 WPF measurements 

from the Bidwell and Janssen study (Ex. 

9–16) (that assessed the 3M 9211 

respirator approved under 42 CFR 84) 

are added to the 94 WPFs from the 

Colton and Bidwell study (Ex. 9–16–1–

1), 240 WPFs in the OSHA database are 

from 42 CFR 84 respirators. None of 

these WPFs was less than 10 (0/240). 

This finding, along with the evidence 

that 42 CFR 84 respirators performed 

better than 30 CFR 11 respirators in the 

same study, suggests that the new 

filtering facepiece respirators certified 

under 42 CFR 84 may perform better 

than the respirators relied on by OSHA 

for its analyses, which consisted mainly 

of respirators approved under 30 CFR 

11. Because the respirators approved 

under 42 CFR 84 outperformed those 

respirators approved under 30 CFR 11, 

which were adequately protective, 

OSHA is confident current workers will 

be well protected by the respirators 

approved under 42 CFR 84. 

6. Methodology of Evaluating 

Overexposure 

Another method to assess the 

appropriateness of an APF is to 

determine whether an overexposure 

occurs (Ex. 10–17). The Agency 

reviewed relevant studies on this 

subject cited by several commenters 

(Exs. 9–16, 9–22, and 10–17–1) to 

determine if such an analysis would 

provide useful information on filtering 

facepiece and elastomeric half mask 

respirators. 

Two major studies (Exs. 9–16–1–9 

and 4–21) address the likelihood that 

half mask respirators will not 

sufficiently reduce occupational 

exposures to airborne contaminants. In 

the first of these two studies (Nelson et 

al., Ex. 9–16–1–9), the authors evaluated 

the risk of overexposure for selected 

APFs using Monte Carlo simulation 

modeling. For a half mask respirator 

with an APF of 10, the calculations 

indicated a low risk of being exposed 

above an occupational exposure limit 

(OEL), with mean exposures being 

controlled well below an OEL. In the 

second article by Drs. Myers and 

Zhuang (Ex. 4–21), ambient (Co) and infacepiece exposure monitoring data (Ci) 

from studies of worker exposures in 

foundry, aircraft-painting, and steelmanufacturing industries were 

compared with the OSHA PEL for 

single-substance exposures. The 5th 

percentiles of the protection factor (Co/ 

Ci) data from each study were 

calculated. The authors used a new 

binomial analysis of likelihood of 

successes (no overexposure) and failures 

(overexposures). Their calculations 

indicate, for both half mask elastomeric 

and filtering facepiece respirators, that 

the <5% of workers who fail to achieve 

an APF of 10 are still being protected. 

OSHA considered Nelson’s analysis 

along with the findings of Myers and 

Zhuang when it conducted its own 

analysis. Accordingly, the Agency was 

persuaded to quantify the probability of 

overexposure by applying the Myers 

and Zhuang binomial analysis to 

OSHA’s updated database. OSHA’s 

expert, Dr. Gerry Wood, performed the 

analysis and presented his results in a 

report (Ex. 20–3) described below. The 

updated OSHA half mask database (Ex. 

20–2) used in this analysis contains 

1,339 WPFs from studies with both 

filtering facepiece half mask respirators 

(760 WPFs) and elastomeric half mask 

respirators with cartridge filters (579 

WPFs). This database also contains Co 

and Ci measurements (expressed in μg/ 

m3), with asbestos fiber counts 

converted as follows: 1 fiber/cm3 = 30 

μg/m3); these measurements permit 

binomial analysis of overexposure 

through calculation of hazard ratios 

(HR). 

The following 8-hour TWA PELs were 

used to calculate HR = Co/PEL for this 

study (see Table III–6). 

TABLE III–6.—8-HOUR TWA PELS

USED TO CALCULATE THE HAZARD

RATIOS

Analyte PEL 

(mg/m3) 

Benzo(a)pyrene ..................... 0.2 

Lead ...................................... 0.05 

Zinc ........................................ 15 

Iron ........................................ 10 

Chromium .............................. 0.5 

Titanium ................................. 15 

Manganese ............................ 5 

Aluminum .............................. 15 

Asbestos ................................ 0.003 (0.1 

fiber/cm3) 

Silica ...................................... 10 

Cadmium ............................... 0.005 

Calcium ................................. 15 

Values for individual WPFs then were 

plotted against HR as illustrated in the 

figures of the Myers and Zhuang 

reference (Ex. 4–21, Figure 1, page 798, 

and Figure 2, page 799). The same 

reference lines and labels were used, but 

the scales were expanded to include all 

data in the OSHA database. 

Figure 1 below shows the plot of all 

data for both filtering facepieces and 

elastomerics. The line labeled CD 

represents WPF = 10; 38 (2.8%) of the 

1,339 data points fell below this line 

and five data points (0.37%) fell within 

the triangle defined by the letters ABK; 

Myers and Zhuang (Ex. 4–21) label this 

triangle as ‘‘Inadequate Protection, 

Overexposure,’’ which corresponds to 

the region in which Ci exceeds the PEL. 


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Federal Register / Vol. 71, No. 164 / Thursday, August 24, 2006 / Rules and Regulations 50139 

Figure 2 shows the same plot for 

studies using filtering facepieces only. 

Twelve data points (1.6%) are below the 

WPF = 10 line. Two of these twelve data 

points equal WPF = 10 when rounded 

off to the nearest whole number. Only 

2 (0.26%) of the points are within the 

ABK overexposure region. The data 

point in the A corner (from a study by 

Colton (Ex. 1–64–16, CL4.15.Pb)) 

represents a Co just above the lead PEL 

(HR = 1.20) that, with a WPF = 1.15 

(almost no protection), gave a Ci = 1.04 

* PEL; this value represents an insidethe-mask exposure just barely higher 

than the PEL. The only other data point 

in the over-exposure region is from the 

asbestos (PEL–0.1 fiber/cm3) study by 

Dixon (Ex. 1–64–54, CL1.2.Asb) which 

corresponds to HR = 77, WPF = 47, and 

a Ci = 1.6 * PEL, (or 0.16 fiber/cm3). 


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If the MUC is defined as MUC = APF 

× PEL, and an APF = 10 is assumed, 

then data points in the triangle labeled 

AHE represent overexposures. With one 

data point in this triangle, filtering 

facepieces are 99.4% effective in 

protecting employees at an APF = 10 

and an MUC = 10 × PEL (i.e., 160 of 161 

data points in the AGFE area, with an 

HR ranging from 1 to 10, are outside the 

triangle (AHE) that represents 

diminished protection). 

Figure 3 shows the same plot for the 

elastomerics. Of these 579 data points, 

26 (4.5%) fall below WPF = 10. Three 

data points (0.5%) in the ABK 

overexposure triangle are from an 

asbestos study by Dixon (Ex. 1–64–54, 

CL5.2.Abs). However, no data points of 

265 in the AGFE area fall within the 

AHE triangle, indicating that all of these 

respirators provided protection at APF = 

10 × PEL. 

Figures 4 and 5 demonstrate that both 

filtering facepiece and elastomeric 

respirators maintain the level of 

employee protection found in Figures 2 

and 3, even when the data are plotted 

using the higher PELs specified by the 

older OSHA asbestos standard (preAugust 1994) and cadmium standard 

(pre-April 1993). The combined data for 

both Figures 4 and 5 show that filtering 

facepieces had only one data point of 

160 (with an HR ratio of 1 to 10) in the 

overexposure area (i.e., the AHE 

triangle), while none of the 241 data 

points for elastomeric respirators fell 

into this area. Therefore, Figures 4 and 

5 and Figures 2 and 3 demonstrate that 

both filtering facepiece and elastomeric 

respirators afford employees effective 

protection against two different 

exposure levels of asbestos and 

cadmium. 

BILLING CODE 4510–26–P 


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BILLING CODE 4510–26–C 

7. Summary of Quantitative Analyses of 

the Updated Database 

First, OSHA’s database includes the 

best available data. As part of the APF 

rulemaking process, the Agency 

conducted a metaanalysis of data 

collected from numerous scientific 

studies related to APFs. OSHA 

established criteria that were used to 

evaluate each study’s design and data 

quality to assure that the database 

included only the most valid data. The 

Agency, at each step in the rulemaking 

process, called on participants to 

identify additional studies to augment 

the dataset or to discuss alternative 

methods of analysis. In response, a 

number of commenters expressed these 

concerns about the data analysis: The 

statistical treatment minimized the true 


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differences between elastomeric and 

filtering facepieces, and there was too 

much variability in the data. In all cases, 

concerns raised by commenters about 

the composition of the dataset used in 

the metaanalysis, or the statistical 

methods used to conduct the analyses, 

were unsubstantiated by evidence 

submitted to the record despite repeated 

requests by OSHA for either specific 

examples or additional evidence. 

Second, the best available data 

support an APF of 10 for half mask 

elastomerics and filtering facepieces. 

The final APF half mask database 

consists of 1,339 data points from 16 

different studies, which represents a 

data increase of 46% over the 917 data 

points initially available for analysis in 

the proposal. The full data set indicates: 

(a) The precise APF for filtering 

facepieces is 18.1, with a 90% 

confidence interval between 15 and 22; 

(b) the precise APF for elastomerics is 

12.0, with a 90% confidence interval 

between 7 and 14; and (c) that a greater 

percentage of elastomerics failed to 

achieve an APF of 10 (4.5%) than 

filtering facepieces (1.6%). In both 

cases, fewer than 5% of the respirators 

failed to achieve an APF of 10, which 

is the maximum failure rate historically 

allowed by both OSHA and other 

standards-setting bodies. 

Third, OSHA substantiated its 

previous analysis by adding to its 

updated database 403 data points that 

were excluded originally because they 

did not meet OSHA’s selection criteria 

and reanalyzing the database. This 

additional analysis also supports an 

APF of 10 for both types of respirators, 

with the results being highly similar to 

the analysis based on the best-available 

data. 

Fourth, new studies submitted during 

the rulemaking allowed OSHA to 

compare the performance of similar 

respirators that were certified under 

both NIOSH’s old (30 CFR 11) and new 

(42 CFR 84) certification standards. The 

42 CFR 84 respirators achieved a WPF 

that was better than the 30 CFR 11 

respirators. This finding is significant 

because the majority of the WPF studies, 

and the only studies in OSHA’s original 

data set, were conducted on respirators 

certified under 30 CFR 11. Thus, the 

improved performance of 42 CFR 84 

respirators indicates that these 

respirators are likely to be even more 

protective of worker health than an APF 

of 10 as provided for in the final rule. 

OSHA also addressed the issue of 

overexposure among workers. In doing 

so, it reviewed the respirator literature 

and performed an analysis of 

overexposure risk using filtering 

facepiece or elastomeric respirators. 

Based on this risk analysis, OSHA 

concluded that workers participating in 

effective respirator programs had an 

extremely low risk of overexposure. 

In conclusion, the extensive 

quantitative analyses of the databases 

clearly indicate that both filtering 

facepieces and elastomeric respirators 

are capable of achieving an APF of 10. 

The results demonstrate that no 

statistical justification exists for 

assigning an APF of less than 10 to 

either of these two types of respirators. 

Finally, the results show that an APF of 

10 is an underestimate of the true 

protection provided by both types of 

respirators. Therefore, the final APF of 

10 determined by this rulemaking 

provides employees who use respirators 

with an extra margin of safety against 

airborne contaminants. 

F. Summary of Studies Submitted 

During the Rulemaking 

1. Additional Studies Used in the 

Updated Analyses 

OSHA found the studies discussed in 

this section to be of sufficient quality for 

inclusion in its APF analyses. 

Bidwell and Janssen study (Exs. 9–16–

1–1 and 9–16). J. O. Bidwell and L. 

Janssen of 3M gave a presentation at the 

May 2003 American Industrial Hygiene 

Conference and Exposition (AIHCE) on 

a workplace protection factor study they 

performed in a concrete-block 

manufacturing plant with workers using 

a NIOSH-approved N95 flatfold filtering 

facepiece respirator. The filtering 

facepiece respirator tested was the 3M 

Particulate Respirator 9211, approved 

by NIOSH under the 42 CFR 84 

respirator certification standards. The 

authors measured silicon and calcium 

exposures to 19 workers in the bagging 

and block-handling areas of the plant. In 

the bagging area, workers placed bags 

over cement-dust chutes for filling, and 

then transferred the bags to pallets. In 

the other areas of the plant sampled by 

the authors, workers handled concrete 

blocks, swept and shoveled dust and 

block pieces into containers, and 

cleaned out mullers with chipping tools. 

The workers were informed of the 

purpose and procedures of, and their 

role in, the study, and were provided 

with instructions on proper donning, 

fitting, and user seal check procedures, 

as well as respirator operation. In 

addition, the workers had to pass a 

Bitrex qualitative fit test that followed 

the fit test protocol described in OSHA’s 

Respiratory Protection Standard prior to 

study participation. They also had to be 

clean shaven. They were observed by 

the authors in the workplace on a oneon-one basis throughout the sampling 

periods. 

The inside-the-facepiece sampling 

train consisted of a 25-mm three-piece 

cassette with a 0.8-micron pore-size 

polycarbonate filter with porous plastic 

back-up pads for collecting the inside 

samples. For sampling purposes, a Liu 

probe was inserted opposite the mouth 

near the midline of the respirator. It 

projected one centimeter into the 

facepiece. The sampling cassette was 

attached directly to the probe, and a 

cassette heater was used to prevent 

condensation of moisture from exhaled 

breath. Outside-the-facepiece samples 

used a 25-mm three-piece cassette with 

a 0.8-micron pore-size mixed celluloseester filter. The outside sample cassette 

also was connected to a Liu probe, and 

this combination was attached in the 

worker’s breathing zone. Inside samples 

and outside samples were collected at a 

flow rate of two liters per minute. 

Respirators were donned and doffed, 

and sampling trains started and 

stopped, in a clean area. Field blanks 

were used to evaluate for samplehandling contamination, and 

manufacturer blanks were collected to 

determine background contamination 

on the filters. 

The inside samples were analyzed 

using proton-induced X-ray emission 

analysis (PIXEA), and the outside 

samples were analyzed by inductively 

coupled plasma (ICP) spectroscopy. For 

both calcium and silicon, the authors 

presented the range of Co, Ci, and the 

associated geometric means and 

standard deviations. Three sets of WPF 

results were determined: One for 

calcium, a second for silicon, and a 

harmonic mean for the combined 

calcium and silicon samples. Silicon 

was not detected on eleven of the Ci 

samples. However, by using 70% of the 

limit of detection as the inside mass, the 

authors were able to include these 

samples in the statistical analysis. No 

field-blank adjustments were made (i.e., 

no calcium or silicon detected), and no 

mention is made of adjusting the data 

for pulmonary retention of particles. In 

addition, three sample sets were 

invalidated as a result of equipment and 

procedural problems. The authors 

reported a mean WPF of 152, with a 5th 

percentile of 13, for the calcium 

samples; a mean WPF of 394, with a 5th 

percentile of 34, for the silicon samples; 

and a harmonic mean of the calcium 

and silicon samples of 206, with a 5th 

percentile of 20. The authors noted a 

difference in the WPFs measured for 

calcium and silicon (using the same 

respirator), and discussed a number of 

possible reasons for the difference (e.g., 

random sampling and analytical errors, 


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possible non-uniformity of the challenge 

aerosol over time). The authors 

concluded, ‘‘The estimated WPF for this 

respirator model based on this study 

exceeds the APF of 10 assigned to this 

respirator class by ANSI Z88.2–1992 

and proposed by OSHA.’’ They also 

stated, ‘‘The respirator provided an 

adequate level of protection and reliably 

provided workplace protection factors 

of at least 10 when properly fitted, 

worn, and used’’ (Ex. 9–16, page 40). 

Colton and Bidwell study (Ex. 4–10–

4). C. Colton and J. Bidwell of 3M made 

a presentation on May 25, 1995 at the 

AIHCE comparing the workplace 

performance of two different types of 

HEPA filters on an elastomeric half 

mask respirator in a battery 

manufacturing plant. The HEPA filters 

and the respirator model tested were 

approved under the 30 CFR 11 

respirator certification standards. The 

half facepiece respirator tested was the 

3M 7000, available in three sizes. The 

HEPA filters tested were the 3M 7255 

high-efficiency (mechanical) filter and 

the 3M 2040 high efficiency (electret) 

filter. The authors measured lead 

exposures for 19 workers in the batterypasting and assembly areas of the plant 

because these areas had the highest lead 

exposures. The workers were informed 

of the purpose and procedures of, and 

their role in, the study, and were 

provided with instructions on proper 

donning and fitting procedures, as well 

as respirator operation. In addition, the 

workers had to pass a saccharin 

qualitative fit test performed using the 

fit test protocol described in OSHA’s 

Lead Standard. Workers had to be clean 

shaven. They were observed in the 

workplace by the authors on a one-onone basis throughout the sampling 

periods. 

For sampling purposes, a Liu probe 

was inserted opposite the mouth near 

the midline of the respirator. It 

projected one centimeter into the 

facepiece. The sampling cassette was 

attached directly to the probe, and a 

cassette heater was used to prevent 

condensation of moisture from exhaled 

breath. A Liu probe was also attached to 

the outside sample to ensure that 

particle loss for the outside samples 

would be similar to that with the inside 

samples. Inside samples and outside 

samples were collected at a flow rate of 

two liters per minute, and sampling 

times ranged from 56 to 200 minutes. 

Up to four samples were collected per 

day on each worker, each worker was 

sampled for two days, field blanks were 

used, and care was taken to avoid 

handling contamination. The filter for 

the first day was assigned randomly, 

with a worker using one filter type on 

the first day and the second filter type 

on the second day. 

The inside- and outside-the-facepiece 

samples were analyzed for lead by ICP 

spectroscopy. The authors presented the 

range of outside and inside lead 

concentrations, and the associated 

geometric means and standard 

deviations. Two sets of WPF results 

were determined: One for the 3M 2040 

filter and a second for the 3M 7255. A 

total of 140 samples were collected—

one sample was eliminated due to low 

mass loading, 10 samples were lost due 

to equipment problems, and 85 samples 

had inside-sample mass values that 

were non-detectable. Of the remaining 

44 samples, one outlier was identified 

in the electret filter data set, leaving 22 

sets for the 3M 2040 filter and 21 sets 

for the 3M 7255 filter. No field blank 

adjustments were reported (i.e., no lead 

was detected on the field blanks). The 

authors reported a mean WPF of 562 

and a 5th percentile of 71 for the 3M 

2040 filter-respirator combination, and a 

mean WPF of 1006 and a 5th percentile 

of 80 for the 3M 7255 filter-respirator 

combination. 

When no lead was detected for the 

inside samples, the WPF results were 

recalculated using the detection limit to 

represent the mass for these samples. 

From these recalculations, the authors 

identified one outlier in the electret 

filter data set and two outliers in the 

mechanical filter data set. They then 

calculated geometric means, geometric 

standard deviations, and 5th percentile 

WPFs for the 67 samples for the 3M 

2040 filter and for the 59 samples for the 

3M 7255 filter. The authors reported a 

mean WPF of 420 and a 5th percentile 

of 101 for the 3M 2040 filter-respirator 

combination, and a mean WPF of 549 

and a 5th percentile of 138 for the 3M 

7255 filter-respirator combination. 

The authors concluded that the 

performance differences between the 

two filter types were not statistically 

significant. Both filters provided 5th 

percentile protection factors above 10. 

No WPFs were less than 30. Under these 

workplace conditions, no difference was 

found in the level of protection 

provided by the electrostatic HEPA filter 

compared to a mechanical HEPA filter. 

Colton and Bidwell study (Ex. 9–16). 

C. Colton and J. Bidwell of 3M 

presented a research paper at the May 

1999 AIHCE on a WPF study they 

performed in a battery manufacturing 

plant with workers using three NIOSHapproved filtering facepiece respirators. 

The filtering facepiece respirators tested 

were the 3M 8210 and 3M 8511, 

approved by NIOSH under the 42 CFR 

84 respirator certification standards, and 

the 3M 8710 filtering facepiece, 

approved by NIOSH under the 30 CFR 

11 respirator certification standards. 

The authors measured lead exposures 

for 21 workers in the batterymanufacturing and assembly areas of 

the plant. The worker job classifications 

tested were stackers, heat sealers, 

burners, and assemblers. The workers 

were informed of the purpose and 

procedures of, and their role in, the 

study, and were provided with 

instructions on proper donning, fitting, 

and user seal check procedures, as well 

as respirator operation. In addition, the 

workers had to pass a Bitrex

qualitative fit test with all three 

respirators, and they had to be clean 

shaven. They were observed in the 

workplace by the authors on a one-onone basis throughout the sampling 

periods. 

The sampling probe was a Liu probe 

that was inserted opposite the mouth 

near the midline of the respirator. It 

projected one centimeter into the 

facepiece. The sampling cassette was 

attached directly to the probe, and a 

cassette heater was used to prevent 

condensation of moisture from exhaled 

breath. Inside and outside samples were 

collected at a flow rate of two liters per 

minute for 79 to 159 minutes. Three 

samples were collected per day for each 

worker. Field blanks were used, and 

care was taken to avoid handling 

contamination. 

The inside samples were analyzed for 

lead using PIXEA. Outside samples 

were analyzed by ICP spectroscopy. The 

authors presented the range of outside 

and inside sample lead concentrations, 

and the associated geometric means and 

standard deviations for each respirator 

model tested. Three sets of WPF results 

were determined: One for the 3M 8710, 

a second for the 3M 8210, and a third 

for the 3M 8511. Lead was not detected 

on five of the inside samples for the 3M 

8710, 19 for the 3M 8210, and 23 for the 

3M 8511. No field blank adjustments 

were reported (i.e., no lead was detected 

on the field blanks). The authors 

reported a mean WPF of 730, with a 5th 

percentile of 105, for the 3M 8710 

respirator; a mean WPF of 955, with a 

5th percentile of 73, for the 3M 8210; 

and a mean WPF of 673, with a 5th 

percentile WPF of 169, for the 3M 8511 

using test samples with detectable lead 

levels. When no lead was detected on 

the inside samples, the WPF results 

were calculated by using 70% of the 

limit of detection as the mass for inside 

samples. The authors reported a mean 

WPF of 804, with a 5th percentile of 

111, for the 3M 8710 respirator; a mean 

WPF of 2210, with a 5th percentile of 

133, for the 3M 8210; and a mean WPF 


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of 1970, with a 5th percentile WPF of 

223, for the 3M 8511. 

The authors stated, ‘‘All respirator 

models provided an equivalent level of 

protection,’’ and that ‘‘[a]ll the 

respirators tested reliably provided 

workplace protection factors of 10 when 

properly fitted, worn, and used.’’ No 

reported WPFs were less than 51, and 

no difference in workplace protection 

was found between workers using 30 

CFR part 11-approved respirators and 

workers using 42 CFR 84-approved 

respirators. The authors concluded that, 

using the 5th percentile WPFs as an 

indicator of performance, the APFs 

should not differ between these 

respirators. 

2. Additional Studies Not Used in the 

Updated Analyses 

The Agency received a number of 

comments on the relationship between 

fit testing and APFs. OSHA regulations 

require that when a respirator user 

cannot pass a fit test with a particular 

respirator model, it cannot be used. 

OSHA does not believe that it is 

appropriate to assign a lower protection 

factor to a respirator (e.g., half the APF) 

when the respirator doesn’t fit. 

However, a number of fit test studies, 

and one study on farm worker 

exposures to bioaerosols, were 

submitted to the record for the Agency 

to evaluate in terms of APFs. OSHA has 

evaluated these studies and determined 

that they do not meet the criteria that 

data must meet to be included in the 

database. These criteria have been 

described above. 

NIOSH agreed (Tr. at 102) that the 

APF values resulting from OSHA’s 

multifaceted approach provide 

reasonable values for the level of 

protection expected for each respirator 

class. Proposed Table 1 (‘‘Assigned 

Protection Factors’’) represents the state 

of the art for each class or respirator. 

However, NIOSH stated that designating 

a specific APF for a respirator class will 

not ensure that a respirator will perform 

as expected. The protection afforded by 

a respirator is contingent on: The 

respirator user adhering to the respirator 

program requirements of OSHA’s 

Respiratory Protection Standard; the use 

of NIOSH-certified respirators in their 

approved configuration; and fit testing 

for each employee that ensures selection 

of a properly fitting respirator. The 

following studies, which OSHA did not 

include in its updated analyses, 

typically violated one or more of these 

three conditions. 

Don-Hee Han study (Ex. 9–13–2). 

NIOSH (Ex. 9–13) submitted a study by 

Don-Hee Han (Ex. 9–13–2) of the 3M 

8511 cup-shaped filtering facepiece, the 

MSA Affinity foldable FR 200, and the 

Willson N95 10FL produced by Dalloz 

Safety in response to OSHA’s request in 

the NPRM for additional studies that 

may be useful in determining APFs. The 

author of the study permitted workers 

who did not pass a fit test with a 

minimum fit factor of 100, as required 

by OSHA’s Respiratory Protection 

Standard, to participate in the study. 

OSHA reviewed this study and did not 

add the data set to its quantitative 

analyses because it was a PPF study that 

is not directly comparable with WFP 

studies used by OSHA in its APF 

determinations. However, the study 

results confirmed that when a worker’s 

filtering facepiece respirator is fit tested 

properly, it is capable of achieving a 

protection factor of at least 10. 

Peacock study (Ex. 9–13–4). This fit 

test research report was submitted to the 

record by NIOSH. In this study, a liquidaerosol QNFT (Large Particle QNFT 

(LPQNFT)) was developed and used to 

evaluate filter penetration of a regular 

N95 respirator. Protection factors 

determined by the LPQNFT were 

compared to fit factors obtained using 

the saccharin QLFT. The sensitivity and 

specificity of the saccharin QLFT were 

evaluated. The results for the specifity 

of the LPQNFT indicated that workers 

who failed the saccharin QLFT also 

failed the LPQNFT when using a 

protection factor ≥ 100. The sensitivity 

was low. Twelve (12) subjects passed 

both the LPQNFT and the saccharin 

QLFT (out of 28 subjects), but another 

16 subjects failed the saccharin test 

while passing the LPQNFT. Peacock 

concluded that the LPQNFT may be 

subject to particle deposition at leakage 

sites, as well as conditions inside the 

facepiece that would lead to sampling 

bias. OSHA did not rely on these fit test 

data for setting APFs because, as 

Peacock noted, further studies should be 

conducted to identify the cause of these 

problems. 

Lee and Nicas study (Ex. 17–7–3). 

NIOSH submitted this study of N95 

respirators used against Mycobacterium 

tuberculosis (TB). In this study, Lee and 

Nicas (Ex. 17–7–3) computed risks of TB 

infection using five medium- or regularsize N95 filtering facepiece respirators. 

Five NIOSH-approved respirators were 

selected for evaluation after reviewing 

manufacturer-provided fit test, comfort, 

and cost data. After extensive 

evaluation, the original five brands were 

rank ordered from highest to lowest fit 

test pass rates, and the authors 

calculated the risk of TB transmission. 

The authors concluded that fit testing is 

necessary to ensure that respirators 

perform as expected. However, OSHA 

did not accept this study for its APF 

analyses because it is not a WPF or 

SWPF study, and addresses only fit 

testing issues. 

Coffey, et al. study (Ex. 17–7–4). 

NIOSH submitted to the record a 

publication by Coffey et al. (Ex. 17–7–

4). In this study, 18 N95 filtering 

facepiece respirators were evaluated. 

The authors determined the following 

measurements from the results: 5th 

percentile SWPF value; the average 

SWPF per shift; the h-value; and the 

assignment error. A SWPF test was used 

to determine respirator performance, 

which was assessed using a Portacount 

Plus with test subjects performing six 

standard fit test exercises. However, the 

generally accepted format for a SWPF 

study involves test subjects performing 

simulated workplace exercises (e.g., 

shoveling pebbles, moving blocks, 

pounding nails). 

Using this procedure, the authors 

found that when properly fit tested, over 

80% of the poorly performing 

respirators achieved a protection factor 

of more than 10. However, OSHA did 

not use this study in its APF 

determinations since this was not a 

WPF or SWPF study. Nevertheless, the 

study supports the requirement that 

APFs apply only when used within the 

context of a comprehensive respirator 

program. 

Reponen et al. study (Exs. 19–8–3 and 

19–8–4). The purpose of this study was 

to further develop a prototype personalsampling system for use with N95 

filtering facepiece respirators. The study 

results were calculated from 30–60 

minute Co and Ci measurements taken 

across multiple agricultural settings, 

tasks, and simulated exposures. The 

data were combined to calculate dust, 

microorganism, and cultured 

microorganism exposures. Descriptions 

of tasks in several workplaces were 

provided. 

The N95 respirators in this study 

performed at or above a WPF of 10 

when evaluated using dust 

measurements. However, the dustexposure measurements counted both 

dust particles and microorganisms 

because the optical-particle counter 

used for this purpose does not 

differentiate between organic and 

nonorganic particles. When they 

calculated WPFs for the microorganism 

samples alone, the WPFs decreased 

somewhat. The authors concluded that 

the geometric mean WPF increased with 

increasing particle size, and that the 

WPFs were smaller for biological 

particles than for dust. The authors 

speculated that differences in WPFs 

may result from the measurement effects 

of particle size or density. They also 

said that even a small variation in the 


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2Preliminary results from the 2001 NIOSH–BLS 

‘‘Survey of Respirator Use and Practices’’ in press. 

NIOSH commissioned the survey to be conducted 

by BLS, who also tabulated the data after 

completing the survey. 

3The survey was conducted between August 

2001 and January 2002. It asked: ‘‘During the past 

12 months, how many of your current employees 

used respirators at your establishment?’’ It excluded 

voluntary use of respirators from detailed followup 

respirator use questions (Ex. 6–3). 

density of particles can have a 

pronounced effect on the loss of dust 

particles through faceseal leaks due to 

impaction. The authors concluded that 

their findings deserve further research. 

OSHA agrees with the authors that 

further research is needed to 

substantiate and explore these findings. 

Also, the Agency has significant 

concern regarding the measurement 

methodology used in this prototype 

study. For example, it is not clear 

whether the WPF differences are valid 

or are simply the result of using 

different measurement methods. 

Therefore, the Agency decided not to 

use this study for developing APFs. 

Summary and conclusions for studies 

not used in the updated database. 

OSHA reviewed the studies submitted 

to the APF rulemaking docket and 

determined that five of them were 

unsuitable for the database used to 

develop APFs. OSHA established a set 

of criteria in the proposal for evaluating 

new studies for inclusion in the APF 

database. The studies by Han (Ex. 9–13–

4), Peacock (Ex. 9–13–4), Lee and Nicas 

(Ex. 17–7–3), Coffey et al. (Ex 17–7–4), 

and Reponen et al. (Exs. 19–8–3 and 19–

8–4) were not used by OSHA in setting 

the final APFs because these studies did 

not follow established WPF or SWPF 

protocols, or required further research to 

substantiate or explore the results. 

IV. Health Effects 

American workers use respirators as a 

means of protection against a multitude 

of respiratory hazards that include 

chemical, biological, and radiological 

agents. Respirators provide protection 

from hazards that are immediately lifethreatening, as well as hazards 

associated with routine operations for 

which engineering controls and work 

practices do not protect employees 

sufficiently. When respirators fail, or do 

not provide the degree of protection 

expected by the user, the user is placed 

at an increased risk of adverse health 

effects that result from exposure to the 

respiratory hazards present. Therefore, 

it is critical that respirators perform 

properly to ensure that users are not at 

an increased risk of experiencing 

adverse effects caused by exposure to 

respiratory hazards. 

In this final rulemaking, OSHA 

defined the minimal level of protection 

a respirator is expected to achieve (i.e., 

the APFs in Table 1), as well as the 

MUCs for the respirators. The Agency 

also is superseding most of the existing 

APF table requirements in its substancespecific standards. By superceding the 

APF tables, the Agency estimates that 

the benefits for the final APFs under the 

Respiratory Protection Standard will be 

available as well to employers who must 

select respirators for employee use 

under the substance-specific standards. 

In addition, the Agency believes that 

harmonizing the APFs of the substancespecific standards with the APFs in the 

Respiratory Protection Standard will 

reduce confusion among the regulated 

community and aids in uniform 

application of APFs, while maintaining 

employee protection at levels at least as 

protective as the existing APF 

requirements. 

V. Summary of the Final Economic 

Analysis and Regulatory Flexibility 

Analysis 

A. Introduction 

OSHA’s Final Economic and 

Regulatory Flexibility Screening 

Analysis (FEA) addresses issues related 

to the costs, benefits, technological and 

economic feasibility, and economic 

impacts (including small business 

impacts) of the Agency’s Assigned 

Protection Factors (APF) rule. The 

Agency has determined that this rule is 

not an economically significant rule 

under Executive Order 12866. The 

economic analysis meets the 

requirements of both Executive Order 

12866 and the Regulatory Flexibility Act 

(RFA; as amended in 1996). The FEA 

presents OSHA’s full economic analysis 

and methodology. The Agency entered 

the complete FEA into the docket as 

Exhibit 11. The remainder of this 

section summarizes the results of that 

analysis. 

The purpose of this FEA is to: 

• Evaluate the costs employers would 

incur to meet the requirements of the 

APF rule; 

• Estimate the benefits of the rule; 

• Assess the economic feasibility of 

the rule for affected industries; and 

• Determine the impacts of the rule 

on small entities and the need for a 

Regulatory Flexibility Analysis. 

B. The Rule and Affected Respirator 

Users 

OSHA’s APF rule would amend 29 

CFR 1910.134(d)(3)(i)(A) of the 

Respiratory Protection Standard by 

specifying a set of APFs for each class 

of respirators. These APFs specify the 

highest multiple of a contaminant’s 

permissible exposure limit (PEL) at 

which an employee can use a respirator 

safely. The APFs would apply to 

respirator use for protection against 

overexposure to any substance regulated 

under 29 CFR 1910.1000. In addition, 

OSHA rules for specific substances 

under subpart Z (regulated under the 

authority of section 6(b)(5) of the OSH 

Act of 1970, 29 U.S.C. 655) specify APFs 

for respirators used for protection 

against these chemicals (hereafter 

referred to as § 6(b)(5) substances). The 

rule would supercede most of these 

protection factors, and harmonize APFs 

for these substances with those for 

general respirator use. 

OSHA based estimates of the number 

of employees using respirators and the 

corresponding number of respiratorusing establishments on the NIOSH-BLS 

survey of respirator use and practices 2

(Ex. 6–3). The NIOSH-BLS survey 

provides up-to-date use estimates by 

two-digit industry sector and respirator 

type for establishments in which 

employees used respirators during the 

previous 12 months.3 As shown in 

Table V–1, an estimated 291,085 

establishments reported respirator use 

in industries covered by OSHA’s 

regulation. Most of these establishments 

(208,528 or 71.6 percent) reported use of 

filtering facepieces. Substantial 

percentages of establishments also 

reported the use of half-mask and full 

facepiece non-powered air-purifying 

respirators (49.0 and 21.4 percent, 

respectively). A smaller number of 

establishments reported use of powered 

air-purifying respirators (PAPRs) and 

supplied-air respirators (SARs). Fifteen 

percent of establishments with 

respirators (43,154) reported using 

PAPRs and 19 percent (56,022) reported 

using SARs. Table V–2 presents 

estimates of the number of respirator 

users by two-digit industry sector. An 

estimated 2.3 million employees used 

filtering facepiece respirators in the last 

12 months, while 1.5 million used half 

masks, and 0.7 million used full 

facepiece non-powered air-purifying 

respirators. Fewer employees reported 

using PAPRs (0.3 million) and SARs (0.4 

million). The industry-specific estimates 

show substantial respirator use in 

several industries, including the 

construction sector, several 

manufacturing industries (SICs 28, 33, 

34, and 37), and Health services (SIC 

80). 

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BILLING CODE 4510–26–C 


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The standard would have different 

impacts on employers using respirators 

to comply with OSHA substancespecific standards than for employers 

using respirators for other purposes. 

Therefore, OSHA used findings from the 

NIOSH–BLS survey of establishments 

that reported respirator use, by general 

respirator class, for protection against 

specific substances (see Table V–3). 

OSHA applied these numbers to all 

respirator users and establishments 

within the industries that make up each 

sector to derive substance-specific 

estimates of respirator use. For those 

§ 6(b)(5) substances not reported by 

NIOSH, OSHA used expert judgments of 

a consultant with experience in the 

respirator industry to estimate the 

percentage of establishments and 

employees that use respirators for 

protection against these chemicals (Ex. 

6–2) (see Table V–3). 

C. Compliance Costs 

The standard does not raise issues of 

technological feasibility because it 

requires only that employers use 

respirators already on the market. 

Further, these respirators are already in 

use and have proven feasible in a wide 

variety of industrial settings. However, 

costs for the APF standard result from 

requiring some users to switch to more 

protective respirators than they 

currently use. When the APF is lower 

than the baseline (current) APF, 

respirator users must upgrade to a more 

protective model. Both the 1992 ANSI 

Z88.2 Respiratory Protection Standard 

and the 1987 NIOSH RDL specify APFs 

for certain classes of respirators. The 

Agency assumed that employers 

currently use the ANSI or NIOSH APFs, 

or the APFs in the OSHA substancespecific standards, as applicable, to 

select respirators. While the Agency 

currently refers to the NIOSH RDL as its 

primary reference for APFs, in the 

absence of an applicable OSHA 

standard, this analysis assumes that, in 

most cases, adhering to the existing 

ANSI APFs fulfills employers’ legal 

obligation for proper respirator selection 

under the existing Respiratory 

Protection Standard. However, in the 

case of full facepiece negative pressure 

respirators, the Agency has established 

that an APF of 50, as opposed to ANSI’s 

APF of 100, is currently acceptable. In 

this regard, all but one of the substancespecific standards with APFs for full 

facepiece negative pressure respirators 

set an APF of 50. In addition, the 

existing respirator rule and its 

supporting preamble require that 

quantitative fit testing of full facepiece 

negative pressure respirators must 

achieve a fit factor of 500 when 

employees use them in atmospheres in 

excess of 10 times the PEL; this 

requirement assumes a safety factor of 

10. Therefore, based on a fit factor of 

500, such respirators are safe to wear in 

atmospheres up to 50 times the PEL, 

consistent with similar requirements 

regarding respirator use found in 

existing standards for § 6(b)(5) 

chemicals. 

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For each respirator type, OSHA 

compared the new and existing 

standards and, where these new APFs 

were lower, identified an incrementally 

more protective respirator model. To be 

adequate, the more protective respirator 

must have an APF greater than the 

current APF. 

1. Number of Users Required To 

Upgrade Respirator Models 

For a given respirator type, the 

number of users required to shift to a 

more protective respirator depends on 

two factors: the total number of users of 

that type, and the percentage of those 

users for whom the ambient exposure 

level is greater than the APF. While 

survey data are available to estimate the 

number of users, virtually no 

information is available in the literature 

that provides a basis for estimating the 

percentage of users required to upgrade 

respirators. The percentage of workers 

switching respirators would depend on 

the profile or frequency distribution of 

users’ exposure to contaminants relative 

to the PEL. For example, the Agency is 

lowering the APFs for full facepiece 

respirators used to protect against cotton 

dust from 100 to 50; accordingly, when 

workers have ambient exposures that 

are greater than 50 times the PEL, 

employers must upgrade the respirator 

from a full facepiece negative pressure 

respirator to a more protective respirator 

(e.g., a PAPR). 

Because of the absence of data on this 

issue, OSHA made several assumptions 

regarding the requirement to upgrade 

respirators. First, OSHA assumed that 

employers use respirators only when 

their employees have exposures above 

the PEL. Second, OSHA assumed 

employers use the most inexpensive 

respirator permitted, taking into 

consideration the employees’ safety and 

compliance with regulatory 

requirements. These assumptions most 

likely overestimate the cost of 

compliance because many employers 

require their employees to use 

respirators when OSHA does not require 

such use, or they require respirators 

with higher APFs than OSHA currently 

requires. As a result, this analysis 

assumes shifts in respirators that 

employers may have implemented 

already. Two commenters on this issue 

agreed that these assumptions 

overestimate the number of employers 

that would need to change respirators as 

a result of this rule (see Exs. 9–16 and 

13–8). One commenter (Ex. 9–16) noted 

that ‘‘For about twenty years, 3M has 

looked for worksites where employers 

were using respirators at concentrations 

at the upper end of the APF range. We 

have not been able to find these 

worksites.’’ This commenter went on to 

note, as a result ‘‘we believe that the 

overall compliance costs associated 

with the proposal, as currently written, 

will likely be even lower than OSHA 

has estimated.’’

The Agency estimated distributions of 

exposures above the PELs based on 

reports from its Integrated Management 

Information System describing 

workplace monitoring of § 6(b)(5) toxic 

substances performed during OSHA 

health inspections. Of the 9,095 samples 

reported above the PELs, 68.0 percent 

reported exposures between one and 

five times the PEL, 13.1 percent found 

exposures between five and 10 times the 

PEL, and 9.5 percent documented 

exposures between 10 and 25 times the 

PEL. Exposures for the remaining 9.4 

percent of the samples were greater than 

25 times the PEL. Based on these data, 

OSHA modeled the current exposure 

distribution for each respirator type. 

2. Incremental Costs of Upgrading 

Respirator Models 

OSHA also analyzed the costs of 

upgrading from the current respirator to 

a more protective alternative. In doing 

so, OSHA estimated the annualized unit 

costs for each respirator type, including 

equipment and accessory costs, and the 

costs for training and fit testing. One 

commenter (Ex. 17–9) noted the 

importance of not just considering the 

initial costs of a respirator, but all 

associated costs. OSHA has considered 


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4These standards regulate cotton dust, coke oven 

emissions, acrylonitrile, arsenic, DBCP, ethylene 

oxide, and lead. 5Paragraph (d)(2) of the Respiratory Protection 

Standard requires employers to provide either a 

pressure demand SCBA or a pressure demand SAR 

with auxiliary SCBA to any employee who works 

in IDLH atmospheres. 

6 In the 1998 rulemaking revising the Respiratory 

Protection Standard, the Final Economic Analysis 

noted that the standard would not directly affect the 

benefits for the estimated 5% of employees who use 

respirators under OSHA’s substance-specific health 

standards (except to the extent that uniformity of 

provisions improve compliance). Therefore, the 

Agency likely over-estimated the benefits of that 

rulemaking since the standard did not affect 

directly the type of respirator used by those 

employees (63 FR 1173). Conversely, this rule 

directly addresses the APF provisions of the 

substance-specific standards; therefore, this rule 

would affect directly the respirators used by 

employees covered by these standards. 

all of these costs, including training, fit 

testing, program development, and 

medical evaluation, as this commenter 

suggested. OSHA then calculated the 

incremental cost for each combination 

of upgrades from an existing model to 

a more protective one, taking into 

account the effect of replacement before 

the end of the respirator’s useful life. 

These annualized costs range from 

$49.98 (for upgrading from a suppliedair, demand mode, full facepiece 

respirator to a supplied-air, continuous 

flow, half-mask respirator) to $963.73 

(for upgrading from a non-powered, airpurifying full facepiece respirator to a 

full facepiece PAPR). 

In certain instances, workers who use 

respirators under the substance-specific 

standards may have to upgrade to a SAR 

with an auxiliary escape SCBA. Several 

substance-specific standards currently 

specify SARs for exposures that exceed 

1,000 times the PEL.4 OSHA believes 

that workers are unlikely to regularly 

use respirators at such extreme exposure 

levels, i.e., they are most likely to use 

them only in exceptional, possibly 

emergency-related situations. 

Furthermore, exposures at levels more 

than 1,000 times the PEL would 

generally be at or above levels deemed 

immediately dangerous to life or health 

(IDLH), so employers already are 

required by the Respiratory Protection 

Standard to provide each worker with a 

respirator that has SCBA capability. For 

these reasons, this PERFSA estimated 

no impacts for these situations.5

3. Aggregate Compliance Costs 

For each respirator type affected by 

the regulation, OSHA combined the 

incremental costs of upgrading to a 

more protective respirator, the estimated 

share of users forecast to upgrade, and 

the number of users involved to 

estimate the compliance costs 

associated with each respirator type. 

Table V–4 shows estimated compliance 

costs for OSHA’s APF rule. The rule 

would require 1,918 users of nonpowered air-purifying respirators to 

upgrade to some respirator more 

expensive than they are now using at a 

cost of $1.8 million. The Agency 

estimates that 22,848 PAPR users would 

upgrade their respirators at a cost of 

$2.3 million. A relatively small number 

of SAR users (5,110) would upgrade to 

more expensive respirators at a cost of 

$0.4 million. Industry-specific 

compliance costs vary according to the 

number of respirator users and the 

proportion of these users affected by the 

rule. Industries with relatively large 

compliance costs include SIC 17, 

Special trade contractors ($0.8 million), 

and SIC 80, Health services ($0.8 

million). 

As discussed previously, the Agency 

believes the actual costs of the standard 

almost certainly are overestimated. The 

cost analysis assumes all respirator 

wearers have levels of exposures that 

require the particular respirator they are 

using. Under this assumption, 15,000 

employees would be allowed to safely 

shift to a less expensive respirator, 

which could lead to cost savings for the 

employer. Such potential cost savings 

are not accounted for in this cost 

analysis. 

In many cases, employers use 

respirators when respirators are not 

required by OSHA, or use respirators 

more protective than required by OSHA. 

As a result, OSHA’s cost analysis 

overestimates the number of employees 

who are affected by the standard, and 

therefore overestimates costs associated 

with the standard. 

D. Benefits 

The benefits that would accrue to 

respirator users and their employers 

take several forms. The standard would 

benefit workers by reducing their 

exposures to respiratory hazards. 

Improved respirator selection would 

augment previous improvements to the 

Respiratory Protection Standard, such as 

better fit-test procedures and improved 

training, contributing substantially to 

greater worker protection. Estimates of 

benefits are difficult to calculate 

because of uncertainties regarding the 

existing state of employer respiratorselection practices and the number of 

covered work-related illnesses. At the 

time of the 1998 revisions to the 

Respiratory Protection Standard, the 

Agency estimated that the standard 

would avert between 843 and 9,282 

work-related injuries and illnesses 

annually, with a best estimate (expected 

value) of 4,046 averted illnesses and 

injuries annually (63 FR 1173). In 

addition, OSHA estimated that the 

standard would prevent between 351 

and 1,626 deaths annually from cancer 

and many other chronic diseases, 

including cardiovascular disease, with a 

best estimate (expected value) of 932 

averted deaths from these causes. The 

APFs in this rulemaking will help 

ensure that these benefits are achieved, 

as well as provide an additional degree 

of protection. These APFs also will 

reduce employee exposures to several 

§ 6(b)(5) chemicals covered by standards 

with outdated APF criteria, thereby 

reducing exposures to chemicals such as 

asbestos, lead, cotton dust, and arsenic.6

While the Agency did not quantify these 

benefits, it estimates that 29,655 

employees would have a higher degree 

of respiratory protection under this APF 

standard. Of these employees, an 

estimated 8,384 have exposure to lead, 

7,287 to asbestos, and 3,747 to cotton 

dust, all substances with substantial 

health risks. 

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7OSHA defines ‘‘affected establishment’’ as any 

facility that uses respirators, as represented in the 

NIOSH–BLS survey data. 

8For some industries, such as SIC 44, data from 

the NIOSH–BLS survey were suppressed due to low 

response rates. In these cases, the Agency, for the 

purposes of assessing economic feasibility, imputed 

broader sector-level data from the survey to form an 

estimate of respirator use. This procedure may 

result in overestimating the impact of the standard 

(proposal) in some industries. See the full FEA (Ex. 

11) for further details. 

In addition to health benefits, OSHA 

believes other benefits result from the 

harmonization of APF specifications, 

thereby making compliance with the 

respirator rule easier for employers. 

Employers also benefit from greater 

administrative ease in proper respirator 

selection. Employers would no longer 

have to consult several sources and 

several OSHA standards to determine 

the best choice of respirator, but could 

make their choices based on a single, 

easily found regulation. Some 

employers who now hire consultants to 

aid in choosing the proper respirator 

should be able to make this choice on 

their own with the aid of this rule. In 

addition to having only one set of 

numbers (i.e., APFs) to assist them with 

respirator selection for nearly all 

substances, some employers may be able 

to streamline their respirator stock by 

using one respirator class to meet their 

respirator needs instead of several 

respirator classes. The increased ease of 

compliance would also yield additional 

health benefits to employees using 

respirators. 

Alternatively, these APFs would 

clarify when employers can safely place 

employees in respirators that impose 

less stress on the cardiovascular system 

(e.g., filtering facepiece respirators). 

Many of these alternative respirators 

may have the additional benefit of being 

less expensive to purchase and operate. 

As previously discussed, OSHA 

estimates that over 15,000 employees 

currently use respirators that fall in this 

group (i.e., shift to a less expensive 

respirator). 

One commenter (Ex. 9–16) agreed that 

the standard would have significant 

benefits, saying: 

3M concurs with OSHA’s conclusion that 

significant health benefits will accrue to 

workers as a result of this rulemaking. 3M 

believes that the majority of these benefits 

will be the result of simplification of the 

respirator selection process for employers. 

This will in turn lead to greater compliance 

with OSHA’s various standards regarding 

exposure to toxic and harmful substances. 

* * * 

In addition to these benefits from increased 

compliance, 3M also concurs with OSHA’s 

determination that the simplification and 

clarification of the APF tables will result in 

lessening of cardiovascular stress, as well as 

other potential stresses, because of the ability 

to select a filtering facepiece respirator. 

E. Economic Feasibility 

OSHA is required to set standards that 

are feasible. To demonstrate that a 

standard is feasible, the courts have 

held that OSHA must ‘‘construct a 

reasonable estimate of compliance costs 

and demonstrate a reasonable likelihood 

that these costs will not threaten the 

existence or competitive structure of an 

industry’’ (United Steelworkers of 

America, AFL–CIO–CLC v. Marshall (the 

‘‘Lead’’ decision), 647 F.2d 1189 (DC 

Cir. 1980)). 

OSHA conducted its analysis of 

economic feasibility on an 

establishment basis. Accordingly, for 

each affected industry, the Agency 

compared estimates of perestablishment annualized compliance 

costs with per-establishment estimates 

of revenues and per-establishment 

estimates of profits. It used two worstcase assumptions regarding the ability 

of employers to pass the costs of 

compliance through to their customers: 

The no-cost-pass-through assumption, 

and the full-cost-pass-through 

assumption. Based on the results of 

these comparisons, which define the 

universe of potential impacts of the 

APFs, OSHA then assessed the 

economic feasibility for all affected 

establishments, i.e., those covered by 

this rule. 

The Agency assumed that 

establishments falling within the scope 

of the standard would have the same 

average sales and profits as other 

establishments in their industries. 

OSHA believes this assumption is 

reasonable because no evidence is 

available showing that the financial 

characteristics of those firms with 

employees who use respirators are 

different from firms that do not use 

respirators. In the absence of such 

evidence, OSHA relied on the best 

available financial data (those from the 

Bureau of the Census (Ex. 6–4) and 

Robert Morris Associates (Ex. 6–5)), 

used a commonly accepted 

methodology to calculate industry 

averages, and based its analysis of the 

significance of the projected economic 

impacts and the feasibility of 

compliance on these data. 

The analysis of the potential impacts 

of this standard on before-tax profits 

and sales shown in Table V–5 is a 

‘‘screening analysis,’’ so called because 

it simply measures costs as a percentage 

of pre-tax profits and sales under the 

worst-case assumptions discussed 

above, but does not predict impacts on 

these before-tax profits or sales. OSHA 

used the screening analysis to determine 

whether the compliance costs 

potentially associated with the standard 

could lead to significant impacts on all 

affected establishments. The actual 

impact of the standard on the profit and 

sales of establishments in a specific 

industry would depend on the price 

elasticity of demand for the products or 

services of these establishments. 

Table V–5 shows the economic 

impacts of these costs. For each 

industry, OSHA constructed the average 

compliance cost per affected 

establishment and compared it to 

average revenues and average profits.7

These costs are quite small, i.e., less 

than 0.005 percent of revenues; the one 

major exception is SIC 44 (Water 

transportation), for which OSHA 

estimated the costs impacts to be 0.16 

percent of revenues. When the Agency 

compared average compliance costs 

with profits, the costs also are small, 

i.e., less than 0.17 percent; again, the 

major exception was SIC 44, which had 

an estimated impact of 2.12 percent of 

profits.8 Based on the very small 

impacts for establishments in all 

industries shown in Table V–5, OSHA 

concludes that the APF standard is 

economically feasible, in the sense of 

being unlikely to close or alter the 

competitive structure of the affected 

industries, for the affected 

establishments. 

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F. Economic Impacts to Small Entities 

OSHA also estimated the economic 

impacts of the rule on affected entities 

with fewer than 20 employees, and for 

affected small entities as defined by the 

Small Business Administration (SBA). 

Table V–6 shows the estimated 

economic impacts for small entities 

with fewer than 20 employees: average 

compliance costs by industry are less 

than 0.005 percent of average revenues, 

and less than 0.19 percent of profits, in 

all industries. Table V–7 presents the 

economic impacts for small entities as a 

whole, as defined by SBA. For these 

firms, average compliance costs are less 

than 0.005 percent of average revenues 

and less than 0.03 percent of average 

profits. Thus, the Agency projects no 

significant impacts from the rule on 

small entities. 

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When costs exceed one percent of 

revenues or five percent of profits, 

OSHA considers the impact on small 

entities significant for the purposes of 

complying with the RFA. For all classes 

of affected small entities, the Agency 

found that the costs were less than one 

percent of revenues and five percent of 

profits. Therefore, OSHA certifies that 

this regulation would not have a 

significant impact on a substantial 

number of small entities. 

VI. Summary and Explanation of the 

Final Standard 

This section of the preamble provides 

a summary and explanation of each 

revision made to OSHA’s Respiratory 

Protection Standard involving APFs. 

A. Definition of Assigned Protection 

Factor 

As part of its 1994 proposed 

rulemaking for the Respiratory 

Protection Standard, OSHA proposed a 

definition for APFs that read as follows: 

‘‘[T]he number assigned by NIOSH [the 

National Institute for Occupational 

Safety and Health] to indicate the 

capability of a respirator to afford a 

certain degree of protection in terms of 

fit and filter/cartridge penetration’’ (59 

FR 58938). OSHA proposed this 

definition on the assumption that 

NIOSH would develop APFs for the 

various respirator classes, building on 

the APFs in the 1987 NIOSH RDL (59 

FR 58901–58903). However, NIOSH 

subsequently decided not to publish a 

list of APFs as part of its 42 CFR 84 

Respirator Certification Standards (60 

FR 30338), and reserved APFs for a 

future NIOSH rulemaking. 

During his opening statement on June 

15, 1995, at an OSHA-sponsored expertpanel discussion on APFs, Adam 

Finkel, then Director of the Agency’s 

Directorate of Health Standards 

Programs, noted that OSHA would 

explore developing its own list of APFs 

(H–049, Ex. 707–X). The Agency then 

announced in the preamble to the final 

Respiratory Protection Standard (63 FR 

1182) that it would propose an APF 

table ‘‘based on a thorough review and 

analysis of all relevant evidence’’ in a 

subsequent rulemaking. In the final 

Respiratory Protection Standard, OSHA 

reserved space for a table for APFs, a 

paragraph ((d)(3)(i)(A)) for APF 

requirements, and a definition of APF 

under paragraph (b). 

In its 1987 RDL, NIOSH defined an 

APF as ‘‘[t]he minimum anticipated 

protection provided by a properly 

functioning respirator or class of 

respirators to a given percentage of 

properly fitted and trained users’’ (Ex. 

1–54–437Q). ANSI subsequently 

developed a definition for an APF in its 

Z88.2–1992 Respiratory Protection 

Standard that reads, ‘‘The expected 

workplace level of respiratory 

protection that would be provided by a 

properly functioning respirator or class 

of respirators to properly fitted and 

trained users’’ (Ex. 1–50). The ANSI 

Z88.2 subcommittee that developed the 

1992 standard used the NIOSH 

definition of an APF as a template for 

its APF definition. However, the Z88.2 

subcommittee revised the phrase 

‘‘minimum anticipated protection’’ in 

the NIOSH definition to ‘‘expected 

workplace level of respiratory 

protection.’’ It also removed the NIOSH 

phrase ‘‘to a given percentage’’ from its 

definition. 

The phrase ‘‘a given percentage’’

implies that some respirator users will 

not achieve the full APF under 

workplace conditions. The ‘‘given 

percentage’’ usually is about five 

percent, which is a percentage derived 

from statistical analyses of results from 

WPF studies. In this regard, five percent 

represents the 5th percentile of the 

geometric distribution of individual 

protection factors in a WPF study. 

Therefore, the 5th percentile is the 

threshold for specifying the APF for the 

respirator tested under those workplace 

conditions. Using the 5th percentile 

means that about five percent of the 

employees who use the respirator under 

these workplace conditions may not 

achieve the level of protection assigned 

to the respirator (or class of respirators), 

even after they receive proper fit testing 

and use the respirator correctly under a 

comprehensive respiratory protection 

program. However, ANSI dropped the 

phrase ‘‘to a given percentage’’ to reduce 

confusion (i.e., the phrase did not 

specify a percentage), and to emphasize 

the level of protection needed by the 

vast majority of employees who use 

respirators in the workplace. See also 

subsection E.4 (‘‘Analysis of Updated 

Database on APRs’’) of Section III 

(‘‘Methodology for Developing APFs for 

Respirators’’) of this preamble. 

The Agency’s review of the available 

data on respirator performance, as well 

as findings from surveys of personal 

protective equipment (Exs. 6–1 and 6–

2), indicate that existing APF definitions 

are confusing to the respirator-using 

public. Accordingly, OSHA has 

developed its own definition in this 

final rule that will reduce confusion 

among employers and employees 

regarding APFs, thereby assisting 

employers in providing their employees 

with effective respirator protection, 

consistent with its Respiratory 

Protection Standard. 

The major revision the Agency made 

to the ANSI APF definition in 

developing the proposed APF definition 

included adding the phrase ‘‘when the 

employer implements a continuing, 

effective respiratory protection program 

as specified by 29 CFR 1910.134.’’ The 

Agency added this phrase to emphasize 

the already existing requirement that 

employers must select a respirator in the 

context of a comprehensive respiratory 

protection program. Also, the Agency 

revised the phrase ‘‘as specified by 29 

CFR 1910.134’’ at the end of the 

proposed APF definition to read ‘‘as 

specified by this section’’ to conform to 

style conventions for referencing an 

entire standard. Therefore, the Agency 

is adopting the APF definition that was 

proposed in the NPRM except for this 

minor revision. OSHA’s final definition 

for APF reads as follows: 

Assigned protection factor (APF) means 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 as specified 

by this section. 

B. APF Provisions 

1. Paragraph (d)(3)(i)(A)—APF 

Provisions 

Paragraph (d)(3)(i)(A) is the provision 

in OSHA’s Respiratory Protection 

Standard that requires employers to use 

the APFs in Table 1 of this final 

standard to select respirators. The 

language of the final provision is the 

same as the language in the proposal. 

Therefore, paragraph (d)(3)(i)(A) in the 

final rule reads as follows: 

(A) Assigned Protection Factors (APFs). 

Employers must use the assigned protection 

factors listed in Table 1 to select a respirator 

that meets or exceeds the required level of 

employee protection. When using a 

combination respirator (e.g., airline 

respirators with an air-purifying filter), 

employers must ensure that the assigned 

protection factor is appropriate to the mode 

of operation in which the respirator is being 

used. 

The proposed language in paragraph 

(d)(3)(i)(A) also contained the following 

note that addressed two issues related to 

APFs: 

Note to paragraph (d)(3)(i)(A): The 

assigned protection factors listed in Table 1 

are effective only when the employer has a 

continuing, effective respiratory protection 

program as specified by 29 CFR 1910.134, 

including training, fit testing, maintenance 

and use requirements. These assigned 

protection factors do not apply to respirators 

used solely for escape. 

The first sentence of the note was 

proposed to remind employers that the 

APFs in Table 1 are effective only when 


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they have a complete respirator program 

that meets the requirements of OSHA’s 

Respiratory Protection Standard. Table 1 

of the final rule already contains a note 

(footnote 2) that essentially repeats this 

language. Therefore, to avoid 

unnecessary duplication, the Agency 

decided to remove this language for the 

final rule. However, the Agency is 

retaining the last part of the note as a 

footnote in Table 1 of the final rule (see 

discussion of footnote 5 in the following 

subsection). 

2. Table 1—APF Table 

The NPRM contained Table 1 

(‘‘Assigned Protection Factors’’), which 

listed the APFs for the various respirator 

classes. The final APFs for these 

respirators are discussed in detail in 

subsection C (‘‘Assigned Protection 

Factors for Specific Respirator Types’’) 

of this section. 

The proposed APF Table also 

contained a set of footnotes that 

informed users regarding the 

application of APFs in the table. In the 

final rule, footnote 1 remains essentially 

unchanged from the proposal. Footnote 

2 has been clarified to explain when 

APFs are effective, rather than when 

APFs apply. All employers who use 

respirators need to comply with the 

Respiratory Protection Standard. The 

language in footnote 3 of the proposed 

table was revised from the proposal. 

Proposed footnote 3 stated ‘‘This APF 

category includes quarter masks, 

filtering facepieces, and half-masks.’’

The reference to quarter masks has been 

removed from this footnote since 

quarter mask respirators have been 

assigned a separate APF in Table 1. 

Also, the phrase ‘‘with elastomeric 

facepieces’’ has been added to the 

description of half masks to clarify that 

elastomeric facepieces are included in 

the half mask respirator class. Final 

footnote 3 reads as follows in the final 

rule: ‘‘This APF category includes 

filtering facepieces, and half masks with 

elastomeric facepieces.’’

Footnote 4 relates to the testing of 

PAPRs with helmets or hoods to 

demonstrate that these respirators can 

perform at the required APF of 1,000 or 

greater for this class. The proposed 

footnote and the changes made to it in 

the final standard are discussed in 

subsection C (‘‘Assigned Protection 

Factors for Specific Respirator Types’’) 

in item 4 (‘‘APF for Powered AirPurifying Respirators (PAPRs)’’) of this 

section. 

Footnote 5 in the proposal described 

limitations for the APF of 10,000 

(maximum) for pressure-demand 

SCBAs. The proposed footnote 5 

described an SWPF study demonstrating 

that, when test subjects used pressuredemand SCBAs under high work rates, 

a few of the study results indicated that 

the respirators may not achieve an APF 

of 10,000. Consequently, the proposed 

footnote cautioned employers not to use 

these respirators under conditions that 

would require protection above this 

level. In discussing this footnote in the 

proposal, OSHA stated that, ‘‘the 

employer must restrict [pressuredemand SCBA] use to conditions in 

which the required level of employee 

protection is at or below an APF of 

10,000’’ (68 FR 34105). While the 

Agency received no comments on the 

proposed footnote, it believes that, 

when employers use these respirators, 

they must assess the exposure 

conditions prior to such use as required 

by paragraph (d)(1)(iii) of OSHA’s 

Respiratory Protection Standard. In 

view of the already existing 

requirement, the Agency decided that 

the information in proposed footnote 5 

was unnecessary, and, therefore, 

removed it from the final rule. 

As noted previously under subsection 

B (‘‘Paragraph (d)(3)(i)(A)—APF 

Provisions’’) of this section, OSHA is 

adding a new footnote 5 to Table 1 in 

the final rule. The new footnote will 

remind employers that they cannot 

apply the APFs specified in Table 1 to 

emergency-escape conditions. OSHA 

believes this footnote is important 

because precise exposures levels, which 

serve as the basis for determining APFs, 

cannot be assessed accurately for 

emergency-escape conditions. Under 

these conditions, the only appropriate 

respirators for employee use are 

respirators designated for escape (i.e., 

escape respirators), consistent with the 

requirements specified by OSHA’s 

Respiratory Protection Standard at 29 

CFR 1910.134(d)(2)(ii). New footnote 5 

is similar to the APF provisions of the 

Agency’s substance-specific standards 

that designate appropriate respirators 

for use under emergency-escape 

conditions. Because both the substancespecific standards and 29 CFR 

1910.134(d)(2)(ii) contain requirements 

for selecting escape respirators, the 

Agency is revising the note slightly to 

ensure that employers refer to the 

appropriate provisions. Therefore, 

footnote 5 to Table 1 in the final rule 

will read as follows: 

These APFs do not apply to respirators 

used solely for escape. For escape respirators 

used in association with specific substances 

covered by 29 CFR part 1910 subpart Z, 

employers must refer to the appropriate 

substance-specific standard in that subpart. 

Escape respirators for other IDLH 

atmospheres are specified by 29 CFR 

1910.134(d)(2)(ii). 

C. Assigned Protection Factors for 

Specific Respirator Types 

OSHA received comments on APFs 

during the public comment period 

following publication of the NPRM, and 

at the public hearing. These comments 

and hearing testimony are addressed in 

the following sections. 

1. APF for Quarter Mask Air-Purifying 

Respirators 

Introduction. OSHA proposed an APF 

of 10 for quarter mask air-purifying 

respirators (i.e., quarter masks/quarter 

mask respirators), including them in the 

same category as filtering facepieces and 

half mask air-purifying respirators (68 

FR 43115). However, the Agency 

specifically requested comment on 

whether this action was appropriate (see 

68 FR 34112). 

The following recommendations 

include all of the issues raised by 

commenters regarding quarter mask 

respirators: assign them an APF of 10; 

assign them an APF of 5; prohibit their 

use altogether; or refrain from assigning 

an APF to them until more studies 

become available. In general, those 

commenters who recommended an APF 

of 10 for quarter mask respirators based 

their recommendations on the 

analogous structural characteristics (i.e., 

similarities in design) of quarter mask 

and half mask respirators. Commenters 

who recommended an APF of 5 pointed 

out that the only available APF data for 

quarter mask respirators were in the 

1976 study by Edwin C. Hyatt entitled 

‘‘Respiratory Protection Factors’’ (i.e., 

the ‘‘Hyatt Study’’ (Ex. 2)). Based on this 

study, Hyatt assigned quarter masks an 

APF of 5. 

Comments regarding quarter mask 

respirators. The commenters who 

advised OSHA to give quarter mask 

respirators an APF of 10 believed that 

when these respirators are used in a 

workplace where the employer has 

implemented a complete respirator 

program as required by 29 CFR 

1910.134, their performance should be 

the same as that of half mask respirators. 

For example, Thomas Nelson of Nelson 

Industrial Hygiene Systems, Inc. 

testified, 

There is no unique property of a quarter 

mask respirator that makes it[s] use different 

from half facepiece respirators provided the 

person using the respirator is trained, fitted 

and maintains the respirator. OSHA should 

include quarter masks in the half facepiece 

category. (Ex. 10–17.) 

Michael Runge of 3M Corporation 

recommended that both half mask and 

quarter mask respirators should receive 

an APF of 10 because of their similarity 


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9As required under Appendix A (Part IA, 

paragraph 13) of 29 CFR 1910.134. 

in performance, which he described as 

follows: 

[L]eakage into a respirator can occur 

through three pathways[:] defects, filter 

penetration or faceseal leakage. Leakage 

through defects is controlled by the respirator 

maintenance program. Quarter facepiece 

respirators are no harder to maintain than 

half facepiece respirators; they have many of 

the same parts * * * Filter leakage is 

controlled by the NIOSH certification process 

* * * Faceseal leakage is controlled through 

fit testing. The same fit tests can be used with 

either type of respirator, hence the same 

maximum face seal leakage would be 

expected for the quarter and half facepiece 

respirator. (See Ex. 9–16.) 

Daniel Shipp and Janice Bradley of 

the International Safety Equipment 

Association and Kenneth V. Bobetich of 

MSA made similar statements (Exs. 9–

22, 9–37, and 16–14). 

Thomas Nelson asserted that the 

Hyatt Study may have underestimated 

the APF for quarter mask respirators 

because the study did not control 

adequately for respirator leakage. His 

comment was based on the fact that the 

authors of the study: (1) Did not 

administer a proper fit test to the test 

subjects prior to measuring particle 

contamination inside the respirator, and 

(2) used a fine particle (sodium 

chloride) as a test aerosol, that may have 

penetrated both the faceseal and filter, 

thereby artificially increasing 

concentrations inside the respirator (Tr. 

at 163 and Ex. 18–9). 

The commenters who recommended 

that OSHA assign quarter mask 

respirators an APF of 5 stressed that no 

studies, including WPF and SWPF 

studies, on quarter mask respirators 

have been performed since the Hyatt 

Study. Few quantitative data are thus 

available on which OSHA can rely to set 

an APF for quarter mask respirators. 

These commenters, who include 

NIOSH, pointed out that NIOSH used 

the Hyatt Study to set the APF for 

quarter mask respirators at 5 in its 1987 

RDL. NIOSH commented further that, 

‘‘quarter mask respirators should be 

separated from half mask respirators 

into a class of their own with an APF 

of 5. The data from Hyatt’s study [1976] 

do not support an APF of 10’’ (Ex. 17–

7–1). Similarly, James S. Johnson stated, 

‘‘We object to the agency’s proposed 

APF of 10 for quarter mask respirators. 

There is no evidence in the record, from 

either WPF or simulated workplace 

protection factor (SWPF) studies that 

support this conclusion’’ (Ex. 16–9–1). 

Johnson’s comments were echoed by the 

AFL–CIO (Exs. 9–27 and 19–1–1). These 

comments indicate that the Hyatt Study 

was not a valid WPF or SWPF study 

because it was a fit test protocol, not an 

experimental study. 

The International Brotherhood of 

Teamsters and the AFL–CIO Building 

and Construction Trades Department 

supported an APF of 5 for quarter mask 

respirators because they believed that 

quarter mask respirators were more 

likely than half mask respirators to 

move around on workers’ faces when 

the workers communicate, or because of 

movement, exertion, or perspiration. 

These commenters stated: 

Since the lower seal of the facepiece in 

quarter mask respirators is on the chin, rather 

than below the chin, the seal is much more 

likely to be compromised than the seal on a 

half face respirator. Additionally, in use 

factors such as movement, exertion, and 

perspiration add to the likelihood that the 

seal of these masks will be compromised in 

the work place. (Exs. 9–12 and 9–29.) 

The Nuclear Regulatory Commission 

commented that its regulations prohibit 

the use of quarter masks because of ‘‘the 

potential lack of stability of fit and the 

availability of acceptable alternatives 

(half-face respirators)’’ (Ex. 10–7). Tracy 

Fletcher of Parsons-Oderbrecht JV 

recommended that OSHA prohibit the 

use of both quarter and half masks, 

stating, ‘‘Employees are required to wear 

eye protection with the respirator, and 

use of the two together is difficult as the 

wearer will find that the glasses rest on 

the nose piece of the respirator creating 

an entry point for an overspray, splash 

or whatever.’’ (Ex. 10–1.) 

A small number of commenters 

expressed the opinion that, because the 

Hyatt Study provides the only data on 

the protection afforded by quarter mask 

respirators, OSHA should reserve its 

decision on the APF for these 

respirators until more studies can be 

completed. ORC Worldwide commented 

that ‘‘[q]uarter masks should be 

evaluated as individual respirator 

models. In the absence of 

comprehensive testing data over the last 

27 years, there is no valid basis for 

giving them an APF of any kind’’ (Ex. 

10–27). David Spence, an industrial 

hygienist, stated: 

We recommend that SWPF studies be 

performed on quarter masks respirators in a 

manner analogous to the ORC SWPF studies 

performed on powered air-purifying 

respirators and supplied-air respirators. To 

not delay publishing APFs for the other 

classes of respirators, the section on APF of 

quarter masks could be reserved pending 

completion of SWPF studies. (Ex. 10–6.) 

Summary and conclusions. In light of 

these comments, the Agency has 

reconsidered the proposed APF of 10 for 

quarter masks. The comments 

recommending an APF of 10 for quarter 

mask respirators are based solely on 

structural analogies between quarter 

masks and half masks, and not on the 

functional characteristics of these 

respirators. Accordingly, the rulemaking 

record contains no quantitative or 

qualitative data or other convincing 

evidence confirming that quarter mask 

and half mask respirators function in a 

similar fashion to provide employees 

with equal levels of respiratory 

protection. No WPF or SWPF studies 

conducted on quarter mask respirators 

were submitted to the record. The Hyatt 

Study, which consisted of testing 

quarter masks using a fit testing 

protocol, provides the only data 

available for quarter mask respirators, 

and it supports an APF of 5. Therefore, 

OSHA has decided to separate quarter 

mask respirators into their own category 

and assign them an APF of 5. 

It is possible that the facepieces of 

quarter masks and half masks are not 

functionally analogous. Some 

commenters noted that half masks rest 

under the chin while quarter masks rest 

on the chin. Consequently, quarter 

masks are more prone than half masks 

to slip and compromise the face seal 

when a worker talks or performs heavy 

work. While the record contains no 

quantitative evidence supporting such 

assertions, there is ample qualitative 

evidence, and OSHA is entitled under 

these circumstances to take a 

conservative approach in weighing the 

available evidence (see, e.g., 29 U.S.C. 

655(b)(5) and United Steelworkers of 

America, AFL–CIO–CLC v. Marshall, 

647 F.2d 1189, 1248 (D.C. Cir. 1980)). 

Moreover, OSHA believes that these 

respirators can be used safely at an APF 

of 5 because properly administered fit 

testing protocols (including 

administering the fit test with glasses 

and other protective equipment worn 

during respirator use),9 as well as 

appropriate respirator training, will 

inform employees of this problem and 

the procedures they can use to prevent 

it. 

In further response to those 

commenters who advised OSHA to 

prohibit quarter masks, OSHA does not 

believe that this approach is reasonable. 

As discussed at the public hearing, 

quarter mask respirators are not widely 

used, but they do have some popularity 

in particular industries (Tr. at 558). All 

existing quarter mask respirators have 

received an N95 rating under NIOSH’s 

certification program, indicating that the 

respirators are designed to prevent at 

least 95% of the challenge agent from 

penetrating the filter. Therefore, these 

certification results, along with the 


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other evidence in the rulemaking 

record, have convinced OSHA that 

employees can use these quarter mask 

respirators safely at an APF of 5 in 

workplaces that implement a respirator 

program that complies with 29 CFR 

1910.134. 

Regarding those commenters who 

advised OSHA to delay the APF 

decision for quarter mask respirators 

until WPF or SWPF studies are 

available, OSHA notes that in the 

intervening 29 years following the Hyatt 

Study, no WPF or SWPF studies have 

been conducted on quarter mask 

respirators. If OSHA was to delay setting 

an APF for quarter mask respirators 

pending further study, it could in effect 

be deciding to delay setting an APF for 

these respirators indefinitely. OSHA has 

not been persuaded by the record to 

delay setting an APF for quarter mask 

respirators. Moreover, as noted in the 

previous paragraph, OSHA has 

concluded that the record evidence 

supports an APF of 5 for quarter mask 

respirators. 

2. APF for Half Mask Air-Purifying 

Respirators 

Introduction. OSHA proposed an APF 

of 10 for both elastomeric and filtering 

facepiece half mask respirators. During 

the public comment period, interested 

parties expressed two divergent views 

on this proposed APF. The healthcare 

industry (Ex. 9–18 to 9–21), NIOSH (Tr. 

107 and 112) and other commenters 

(e.g., Exs. 9–11, 9–22, 9–26, 9–42, and 

10–18) agreed to an APF of 10 for both 

types of respirators, while a number of 

commenters stated that filtering 

facepieces should be assigned a 

protection factor of 5 (e.g., Exs. 9–8, 9–

12, 9–29, and 10–6; AFL–CIO Tr. at 

122–126). The following sections 

discuss this issue in detail. 

A number of reasons were presented 

for limiting filtering facepiece half 

masks to an APF of 5. These reasons can 

be categorized generally into concerns 

related to: (1) WPF studies and 

associated data; (2) design of filtering 

facepiece respirators; (3) respirator use 

in the workplace; and (4) ANSI 

standards. As discussed in Section III 

above, some commenters believed that 

the WPF studies evaluated by OSHA 

suffered from multiple problems (e.g., 

old data, studies not representative of 

typical workplaces). While these points 

are addressed in detail in Section III of 

this preamble, some of these concerns 

warrant further discussion here. 

Some filtering facepieces do not 

achieve an APF of 10. Comment was 

made that the data presented in the 

studies analyzed by OSHA indicate that 

not all filtering facepieces achieved an 

APF of 10. Consequently, these 

commenters argued that the entire class 

of respirators should receive an APF of 

5 (Exs. 9–29, 9–27, and 10–54). The 

AFL–CIO stated: 

An examination of the summary table of 

WPF studies for filtering facepieces and halfmask elastomeric respirators at 68 FR 30495 

of OSHA’s preamble to this proposed rule 

justifies our position. Of the seven respirators 

that had a 5th percentile WPF less than 9, 

five of [the] respirators that failed consisted 

of the filtering facepiece style of respirator. 

Thus [of] the overwhelming majority of the 

half mask respirators that failed, five of the 

seven or 71%, were filtering facepieces. At 

the qualitative level then, this data clearly 

indicates that most of the problem with 

failing to provide adequate protection rests 

with filtering facepieces and not with halfmask elastomerics. (Ex. 9–27.) 

The summary table in the proposal at 

68 FR 34095 contains several studies 

that were reviewed by OSHA, but did 

not meet the selection criteria and were 

excluded from the quantitative analyses. 

The two filtering facepiece respirators 

(one model in each study) evaluated in 

these excluded studies had WPFs less 

than 9 (Cohen, Ex. 1–64–11; and Reed, 

Ex. 1–64–61), while five of the 

respirators included in OSHA’s analyses 

failed to achieve a WPF of 9. Three of 

these five respirators were filtering 

facepiece respirators and the remaining 

two respirators were elastomeric half 

masks. As noted at the hearing, OSHA 

conducted a Chi-square analysis to 

determine if the proportion of filtering 

facepieces having a WPF less than 9 

differed from the proportion of 

elastomerics with a WPF less than 9 

(Trans. at 135–136). This statistical 

comparison showed that these 

proportions did not differ significantly 

from each other, indicating that similar 

proportions of filtering facepiece and 

elastomeric respirators performed at this 

level—i.e., that the filtering facepiece 

respirators did not perform more poorly 

than the elastomeric respirators. 

After updating the proposal’s half 

mask WPF database (Ex. 20–2) with new 

and additional data, Dr. Crump 

reanalyzed the database (Ex. 20–1). 

Plotting the observed protection factors 

for both the elastomeric and the filtering 

facepiece half masks shows that over 

95% of each type of half mask attained 

an APF of at least 10. Moreover, a 

review of these updated analyses reveals 

that more elastomeric than filtering 

facepiece respirators failed to achieve an 

APF of 10 (see Table 2 in Ex. 20–1). 

Even when the data from studies 

excluded from these analyses were 

added to the database, over 95% of the 

WPFs for both types of half mask 

(separately and combined) are still equal 

to or greater than 10. (A detailed 

discussion of Dr. Crump’s analyses can 

be found in section III (Methodology) of 

this preamble.) Therefore, OSHA does 

not agree that the evidence in the record 

supports an APF for filtering facepieces 

of 5 as suggested by these commenters. 

Respirator configuration and 

certification issues. Commenters also 

stated that not all configurations (e.g., 

cups, duckbills, fold flats) of filtering 

facepiece respirators have been studied 

(e.g., Exs. 9–17, 9–34, 9–40, 10–33, and 

10–34; Tr. at 204–205). In addition, 

some commenters mentioned that none 

of the respirators in the studies 

evaluated by the Agency for the 

proposal were certified under NIOSH’s 

new 42 CFR 84 requirements (Exs. 9–33, 

9–34, 10–22, and 10–38). The focus of 

these comments was that OSHA should 

not assume that all filtering facepieces 

perform the same as those filtering 

facepieces that were tested. These 

commenters believed that filtering 

facepiece half masks should be given an 

APF of 5 because, in their view, there 

is a lack of information on 42 CFR 84 

filtering facepieces. 

OSHA recognizes that its analyses do 

not encompass all configurations or 

models of filtering facepiece half masks. 

However, this is true for all types of 

respirators, not just filtering facepiece 

half masks. Since filter efficiency is 

certified by NIOSH, the filter media of 

all filtering facepiece (and elastomeric) 

half mask configurations are equivalent. 

Therefore, any differences in 

performance would arise from 

variations in faceseal leakage among the 

different configurations. OSHA’s 

Respiratory Protection Standard 

requires that all respirator users pass a 

respirator fit test to ensure that a 

minimum acceptable faceseal 

performance is achieved. Therefore, 

because all respirators must be used in 

accordance with the Respiratory 

Protection Standard, the Agency sees no 

reason to conclude that differences in 

configuration will result in performance 

variations. In addition, Section III of this 

preamble discusses two studies that 

compare the workplace performance of 

42 CFR 84 and 30 CFR 11 filtering 

facepiece half masks. The 42 CFR 84 

respirators demonstrated superior 

performance when compared to the 30 

CFR 11 respirators. OSHA concludes 

that, based on the more stringent filter 

efficiency certification requirements and 

these study results, 42 CFR 84 

respirators provide performance at least 

equal to 30 CFR 11 respirators. 

Therefore, the record evidence does not 

support lowering the APF for filtering 

facepieces to 5. 


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Determining faceseal leakage. Several 

commenters mentioned that NIOSH had 

eliminated the fit test portion of its 

certification procedures. They believed 

that as a result of this NIOSH action, 

one could not be sure if a filtering 

facepiece respirator achieves an 

adequate faceseal and provides the 

expected protection (Exs. 9–8, 9–27, 9–

29, 9–34, 9–35, 9–40, 9–41, 10–22, 10–

33, 10–38, 10–50, and 10–55). During 

the public hearing, NIOSH indicated 

that it would establish a new respirator 

certification testing procedure, stating: 

Such changes would result in additional 

certification tests to assure or assess the 

overall performance of every respirator 

model, and thus assure that every model is 

capable of providing a level of protection 

consistent with the class APF. (Tr. at 103.) 

Several commenters supported this 

approach, and indicated that 

implementing such a procedure would 

be beneficial. For example, Tim Roberts 

(Exs. 17–8 and 18–4) stated that the 

procedure would help to identify 

respirators that may not have adequate 

workplace performance. The AFL–CIO 

(Ex. 19–1) believed that while the 

procedure would help assure certified 

filtering facepieces are capable of fitting 

an employee properly, these respirators 

should still be given an APF of 5. 

Two respirator manufacturers also 

addressed this issue. The 3M Company 

commented that no evidence exists 

showing that employee protection 

would be enhanced by adding a fit test 

requirement to NIOSH’s certification 

procedures, and added that proper 

respirator fit must be determined by fit 

testing each wearer (Ex. 18–7). When 

asked by OSHA about the proposed 

NIOSH testing, Jay Parker of Bullard 

responded that he believed such testing 

would be an improvement over the 

current procedures (Tr. at 497). 

OSHA has reviewed this information 

and supports NIOSH’s plans to add 

performance testing to its respirator 

certification procedures. The Agency 

agrees with the 3M Company that 

proper facepiece fit can only be assured 

through individual fit testing. However, 

OSHA also agrees with Tim Roberts that 

performance testing will assist in 

identifying respirators with poor fitting 

characteristics that may not provide 

protection consistent with the 

respirator’s APF. Thus, OSHA 

concludes that performance testing will 

enhance the information needed for 

selecting appropriate respirators, and 

encourages NIOSH to expedite its efforts 

in this area. However, employers and 

respirator users should note that using 

a respirator certified by NIOSH through 

performance tests would not preclude 

individual fit testing as required by 

OSHA’s Respiratory Protection 

Standard. 

Filtering facepiece design problems. 

Several commenters urged an APF of 5 

for filtering facepiece half masks based 

on the design characteristics of these 

respirators. Some commenters 

expressed concern that, in comparison 

to elastomeric half masks, filtering 

facepieces are poorly constructed (e.g., 

non-adjustable head straps, prone to 

crushing or denting, facepiece too stiff 

or too soft) (e.g., Exs. 9–34, 10–37, 10–

38, 10–54, and 12–7–1). For example, 

T.C. Lefford of Fluor Hanford stated: 

Elastomeric half-mask respirators provide a 

better face seal that filtering facepieces 

(Disposable respirators or maintenance-free 

masks). Most elastomeric half-mask 

respirators are made of more pliable silicone 

rubber that provides a much better seal on 

the face. Elastomeric half-mask respirators 

have three sizes with adjustable head straps 

and a head cradle to improve stability while 

the majority of filtering facepieces have one 

or two sizes and the head straps are nonadjustable. (Ex. 9–32.) 

OSHA believes that concerns about 

loose, dented, or crushed filtering 

facepieces are addressed adequately by 

compliance with existing program 

requirements under 29 CFR 1910.134(d) 

and (g). 

In addition, comment was received 

alleging that the 42 CFR 84 

requirements for increased filter 

efficiency result in respirators with stiff 

facepieces, poor face seals, and high 

breathing resistance, thereby producing 

filtering facepieces with increased 

faceseal leakage (e.g., Exs. 9–34, 9–41–

1, 10–46, and 10–50). Mark Haskew, 

Tim Roberts, and Ching-tsen Bien (Exs. 

12–7–1, 16–12, 16–20–3, and 17–5) also 

expressed concern about the increased 

filter efficiency requirements of the new 

42 CFR 84 certification standards and 

their effect on the performance of 

filtering facepiece respirators. In their 

written comments, Mark Haskew and 

Tim Roberts stated that the 42 CFR 84 

filter efficiency requirements ‘‘would 

increase the breathing resistance and in 

turn cause an increase in faceseal 

leakage when compared to 30 CFR part 

11 filtering facepieces’’ (Ex. 12–7–1). 

Haskew, Roberts and Bien also 

questioned the ability of 42 CFR 84 

filtering facepieces to fit the user’s face, 

and the applicability of 30 CFR part 11 

study data to 42 CFR 84 respirators. For 

example, Mark Haskew testified: 

The other problem with the old data is that 

the 30 CFR 11 respirators are significantly 

different in performance, or at least we 

would anticipate that they may be different 

in the performance that they provide. Based 

on the newer filter media with the 95, 99 and 

100 series, there’s an allowance for increased 

breathing resistance. And because the 

efficiency has to be greater, the filter media 

itself tends to be stiffer. And the concern we 

have, of course, which is untested in the 

research as far as we know, is that it may not 

conform as well to a wearer’s face. (Tr. at 

203.) 

Based on their opinion that 

manufacturers would have to produce 

thicker, stiffer filter media to meet the 

new filter efficiency requirements, these 

commenters concluded that the data for 

42 CFR 84 filtering facepieces would 

show a decrease in performance 

compared to the older 30 CFR 11 

respirators. These commenters, based on 

this assumption, concluded that it 

would be inappropriate to set the APF 

for filtering facepieces based on WPF 

studies of the older 30 CFR 11 

respirators. However, they presented no 

data to substantiate this claim. 

When NIOSH published the 42 CFR 

84 respiratory protective devices final 

rule (60 FR 30336), Section 84.180 of 

this rule increased the maximum 

allowable breathing resistance levels 

during inhalation to 35 mm (of water 

pressure), and during exhalation, to 25 

mm. NIOSH explained this increase as 

follows: 

[It will] enable manufacturers to produce 

respirators meeting the new requirements 

more expeditiously and at lower cost. * * * 

This small increase in maximum allowable 

breathing resistance for particulate 

respirators does not add substantially to 

physiologic burden for respirator users, and 

will be compensated for by increased worker 

protection provided by the new filter 

efficiency tests and classification system. (60 

FR 30346.) 

However, when respirator 

manufacturers developed new 

particulate filters to meet the 42 CFR 84 

performance requirements, they were 

able to meet them without increasing 

the breathing resistance levels. For 

example, the 3M Company submitted 

the following table of breathing 

resistance values for several classes of 

42 CFR 84 filters made by different 

manufacturers (Ex. 17–9–1, page 6; 

derived from a paper submitted by 3M 

to the OSHA docket (Ex. 9–16–1–3)). 


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Filter Class Manufacturer A 

(DP mmH2O) 

Manufacturer B 

(DP mmH2O) 

N95 .................................................................... 11.5 ................................................................... 9.7 

R95 .................................................................... No Product ....................................................... 13.6 

P95 .................................................................... 14.9 ................................................................... No Product 

P100 .................................................................. 23.9 ................................................................... 17.3 

No measurement in this table exceeds 

the 30 CFR 11 limit of 30 mm of water 

pressure. As the 3M Company stated, 

‘‘Breathing resistance of 42 CFR 84 

respirators are contained within the 

range of breathing resistances allowed 

for 30 CFR 11 respirators, rather than 

being significantly higher’’ (Ex. 16–25–

2, page 17). 

OSHA also received comments that 

higher breathing resistance leads to 

increased faceseal leakage (Exs. 9–34, 9–

35, 9–41, 10–38, and 10–50). During the 

public hearings, 3M submitted two new 

studies of filtering facepiece respirators 

certified under 42 CFR 84 (Ex. 16–25–

3). The 42 CFR 84 certified filtering 

facepieces used in these studies 

performed better, overall, than 

comparable filtering facepieces certified 

under 30 CFR 11 (see discussion above 

under Section III (‘‘Methodology, etc.’’)). 

These results indicate that faceseal 

leakage, if it existed, did not impair the 

performance of these filtering 

facepieces. 

At the 2004 AIHCE in Atlanta, 

Georgia, Larry Janssen of the 3M 

Company presented the results of a 

recently completed study (Ex. 17–9–1) 

using the OHD FitTester 3000 controlled 

negative pressure (CNP) fit testing 

instrument to measure faceseal leak rate 

(i.e., a drop in pressure inside the 

mask). Leak-rate measurements first 

were made using the negative pressure 

and flow-rate settings listed for the CNP 

fit test in Appendix A of 29 CFR 

1910.134. Without disturbing the fit of 

the respirator, four additional leak-rate 

measurements then were made at four 

different negative pressures and flow 

rates ranging from 5.6 through 20.1 mm 

of water pressure, followed by a final 

measurement at the CNP fit test rates. 

Janssen found that test subjects with a 

fit equal to or greater than a fit factor of 

100: 

[D]id not show any increase in leak rate as 

pressure drop increased. Subjects with a fit 

factor below 100 * * * showed significant 

variability in leakage as the settings were 

changed, but the amount of leakage did not 

correlate with increasing pressure drop, i.e., 

sometimes the leakage was higher and 

sometimes lower. (Ex. 18–7, page 49.) 

The 3M Company concluded that the 

study ‘‘demonstrates the value of fit 

testing: respirators that fit well enough 

to be assigned to a worker do not exhibit 

increased leakage as pressure drop 

increases’’ (Ex. 18–7, page 49). Janssen, 

in a summary of this study that he 

presented at the May 2004 AIHCE 

stated, ‘‘Results of this study do not 

support the concept of increased 

faceseal leakage with increased pressure 

drop.’’

While concern was expressed by some 

commenters about increased filter 

efficiency requirements resulting in 

increased breathing resistance and 

faceseal leakage, no data were submitted 

to support this viewpoint. However, 

studies were submitted that 

demonstrated that 42 CFR 84 filtering 

facepiece respirators perform at least as 

well as 30 CFR 11 filtering facepieces, 

and that increased filter efficiency does 

not result in increased faceseal leakage. 

After reviewing this information, OSHA 

is persuaded that 42 CFR 84 half masks 

are as protective as 30 CFR 11 half 

masks and that increased face seal 

leakage in such respirators has not been 

demonstrated by evidence in the record. 

Therefore, these arguments do not 

support an APF for filtering facepieces 

of 5. 

The efficacy of user seal checks 

provided by respirator manufacturers 

also was questioned by several 

commenters. These commenters stated 

that user seal checks for filtering 

facepieces either could not be 

performed or were more difficult than 

user seal checks with elastomeric 

facepieces (e.g., Exs. 9–27, 9–31, 9–34, 

9–35, 9–40–1, 9–41–1, and 10–54). In 

general, their opinion was that the 

inability to perform an adequate user 

seal check on filtering facepiece 

respirators would lead to decreased 

protection, thereby warranting a 

reduced APF for this type of respirator. 

Bill Kojola of the AFL–CIO (Exs. 9–27 

and 19–1) stated that ‘‘user seal checks 

are rarely performed on filtering 

facepieces in the field and * * * it is 

extremely difficult, if not impossible, to 

perform effective user seal checks on 

filtering facepieces.’’ He stated that it 

was ‘‘easy for wearers to perform 

effective user seal checks on 

elastomerics.’’ Kojola cited this 

difficulty in performing user seal checks 

as a reason for separating filtering 

facepieces from elastomerics, and giving 

filtering facepieces an APF of 5. 

However, he did not provide any data 

to support his experience that filtering 

facepieces demonstrate a difference in 

user seal check performance compared 

to elastomerics. 

Similar concerns were voiced by Mark 

Haskew (Exs. 17–5 and 18–3), Tim 

Roberts (Exs. 9–8, 10–55, and 17–8), and 

Ching-tsen Bien (Exs. 9–43–2 and 18–5). 

In addition, Mark Haskew stated that 

filtering facepieces with adjustable nose 

pieces cannot normally obtain 

repeatable fit factors. However, these 

commenters did not submit any 

supporting data for this contention. In 

his post-hearing submission, Tim 

Roberts (Ex. 18–4) stated that data 

demonstrating this difference in 

performance are not available. 

James Johnson (Exs. 10–33, 16–9–1, 

and 17–10) also stated that filtering 

facepieces cannot be fit checked 

effectively, and presented results from a 

series of fit tests he performed on 

himself with filtering facepieces and 

elastomeric half masks. Three of the 

four elastomeric half masks that he 

tested passed a positive or negative user 

seal check, and consistently achieved a 

fit factor of 1500 or more using the 

Portacount fit test instrument. One 

elastomeric half mask did poorly (fit 

factor of less than 100), and it was 

identified clearly as a failure by a user 

seal check and a subsequent fit test. He 

found that it was difficult to achieve a 

minimum fit factor of 100 or greater 

with filtering facepieces using the 

Portacount Companion fit test 

instrument. However, two of the eight 

filtering facepiece models he tested 

achieved fit factors of 100 or greater. He 

stated that he was able to identify 

obvious leaks with the filtering 

facepieces he tested by exhaling heavily 

and sensing the airflow, but that 

cupping his hands over the facepiece 

was not an effective user seal check for 

him. He stated further that these 

preliminary fit test results demonstrated 

a significant difference in performance 

between elastomeric and filtering 

facepiece half masks, and that OSHA 

should give filtering facepieces an APF 

of 5 based on these results. 

The numerical differences in fit 

factors between filtering facepieces and 

elastomeric half masks reported by 

Johnson may not be significant. 

Achieving a fit factor of 170, as Johnson 

did with the 3M 9211 foldable filtering 


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facepiece using the Portacount 

Companion, is not necessarily worse 

than achieving a fit factor of 2200 with 

a MSA Comfo elastomeric half mask 

using the Portacount alone. In this 

regard, the fit test instruments identified 

the elastomeric half masks and filtering 

facepieces that provided adequate fits 

on Johnson (i.e., they met their required 

fit factor of 100), and he was able to 

perform user seal checks with both 

respirators. Therefore, OSHA finds that 

these fit test measurement differences 

are not a convincing argument for an 

APF for filtering facepiece respirators of 

5. The Agency believes that Johnson’s 

pilot study proves only that some makes 

and models of filtering facepieces are 

not suitable for his face size and shape. 

When he wore a filtering facepiece or 

elastomeric respirator that fit him, an 

APF of at least 10 was achieved. 

In response to these concerns, the 3M 

Company (Ex. 17–9–2) and the Aearo 

Company (Ex. 17–3–1) submitted to the 

record instructions for conducting user 

seal checks on their filtering facepiece 

respirators. The Aearo Company 

instructs users to cup their hands over 

the respirator to test the seal, stating: ‘‘If 

air flows around your nose, tighten the 

nosepiece; if air leaks around the edges, 

reposition the straps to fit better (Ex. 

17–3–1).’’ User seal check instructions 

for 3M filtering facepieces read, ‘‘If air 

leaks between the face and faceseal of 

the respirator, reposition it and readjust 

the nose clip for a more secure seal’’

(Ex. 17–9–2). 

In their post-hearing comments (Exs. 

9–16, 17–9–1, 18–7, and 19–3), 3M 

responded to the comments raised at the 

public hearing regarding the difficulty 

or impossibility of performing user seal 

checks on filtering facepiece respirators. 

The 3M Company pointed out that no 

data were offered to support this 

position, nor was recognition given to 

the methods contained in both the 1980 

and 1992 editions of the ANSI Z88.2 

respirator standard for performing user 

seal checks. The 3M Company also cited 

a study in the docket by Myers et al. (Ex. 

9–16–1–13), which concluded that no 

difference was found in the 

effectiveness of performing user seal 

checks on filtering facepiece respirators 

or elastomeric respirators. This study 

also referenced a comment by Daniel K. 

Shipp of the ISEA (Ex. 9–22) that user 

seal checks can be performed with 

filtering facepieces. A second evaluation 

of user seal checks submitted by 3M (Ex. 

17–9–10) involved the use of a 3M flatfold filtering facepiece by novice 

respirator users. It showed that novice 

respirator users can be trained to 

effectively perform user seal checks, and 

that the use of seal checks improved the 

overall quality of respirator fit. 

The 3M Company also stated that the 

ease or difficulty in performing user seal 

checks is based on many factors. These 

factors include difficulty in performing 

a user seal check on some elastomeric 

respirators when the exhalation valve 

cover must be removed without 

disturbing the fit. Also, it can be 

difficult to perform a user seal check on 

elastomerics by blocking off the filter 

when a respirator user has small hands. 

In addition, 3M cited an analysis from 

its report at the 2001 AIHCE (Ex. 4–10–

7) that showed no significant differences 

in WPF results for filtering facepieces 

measured in the morning and afternoon, 

with repeated redonnings of the 

respirators performed during each of 

these periods. These results indicate 

that the user seal check conducted after 

each redonning was effective in 

ensuring proper respirator fit. 

During the rulemaking, several 

commenters referred to the use of fit 

check cups to perform user seal checks. 

These devices are designed to assist the 

respirator user in performing a positive 

and negative pressure seal check by 

covering the surface of a filtering 

facepiece respirator. For example, Tim 

Roberts stated: 

One of the manufacturers did recognize 

that there was difficulty in doing these types 

of fit checks, and they designed, and 

constructed, and sold a fit-check cup that 

actually fit over the facepiece of a respirator, 

a filtering facepiece respirator, so that it 

would actually check the seal in a more 

conventional manner. We think that that may 

be another alternative approach to assuring 

that these respirators fit properly if there was 

a requirement to do that. (Tr. at 216.) 

Another commenter who discussed 

the use of fit check cups was Donald 

Faulkner of the United Steelworkers, 

who stated during his questioning of 

Warren Myers: 

[W]e don’t see a real good fit with the 

hands-over filtering facepiece. That’s why the 

cups were developed by many 

manufacturers, but we don’t see them being 

utilized, bought, or anything else. (Tr. at 95.) 

He elaborated in his post-hearing 

comment: ‘‘Filtering facepieces do not 

allow seal checks to be performed 

without the assistance of additional 

equipment [i.e., fit check cups] that is 

never provided by the employers, as 

being cost prohibitive.’’ (Ex. 19–2.) 

Bill Kojola of the AFL–CIO (Tr. at 

132) and George Macaluso of the 

Building Construction Trades 

Department of the AFL–CIO (Tr. at 654) 

made similar statements regarding the 

infrequent use of fit check cups, i.e., 

that they are generally not used in the 

workplaces their unions represent. They 

asserted that user seal checks that 

involve cupping the hands over the 

facepiece were not effective, and that 

the use of fit check cups should be 

required by OSHA. They implied that fit 

check cups are a generic device for 

doing user seal checks, and that one 

manufacturer’s fit check cup can be 

used with other types of filtering 

facepieces. On the other hand, Ken 

Wilson of the Ohio Board of Water 

Quality, Division of Safety and Hygiene 

(Ex. 10–3) stated that he has not seen fit 

check cups used in the field, and 

doubted that their use would allow a 

respirator user to achieve a successful fit 

check. 

OSHA has considered carefully the 

opinions presented about fit check cups 

and user seal checks. The Agency 

recognizes that the use of a fit check cup 

is one way of performing a user seal 

check. However, these cups can be 

inconvenient when used in the 

workplace on a daily basis. In this 

regard, each respirator user would need 

ready access to a fit check cup, not only 

to perform the required user seal checks 

when initially donning the respirator, 

but for any repeated respirator donnings 

that occur throughout the workday. The 

fit check cup would be another piece of 

equipment for respirator users to carry 

with them, and it can be misplaced. 

However, most respirator manufacturers 

have not adopted the use of fit check 

cups, and these manufacturers 

recommend cupping the hands over the 

filtering facepiece to perform a user seal 

check. As the 3M Company stated in 

describing the use of fit check cups, 

‘‘Based on our experience, user seal 

checks without cups are effective, more 

convenient, and easier to perform’’ (Ex. 

17–9–1, page 4). 

Since only a few respirator 

manufacturers have fit check cups, it is 

not surprising that they are seldom used 

in the workplace. The fit check cups 

that exist are designed by the respirator 

manufacturer to work with a specific 

facepiece configuration and respirator 

model, and the cups do not necessarily 

work with other models of respirators, 

even models made by the same 

manufacturer. OSHA knows of only one 

series of 42 CFR part 84 filtering 

facepiece respirators that have fit check 

cups available. 

OSHA does not find merit in the 

comments that fit check cups are 

necessary to perform user seal checks 

with filtering facepieces. While a fit 

check cup designed to work with a 

particular model of respirator can be 

used to perform a user seal check, it is 

not the only way to perform this 

function. Accordingly, the Agency 

believes that respirator users can follow 


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a respirator manufacturer’s instructions 

to perform a user seal check, e.g., 

whether the seal check involves 

cupping the hands over the facepiece or 

the use of a fit check cup. 

The OSHA Respiratory Protection 

Standard requires that an employee 

perform a user seal check to use a 

respirator. The WPF database that 

OSHA developed contains over 1,000 

WPF data points for half mask 

respirators collected from workers using 

respirators in programs that included 

user seal checks. Analyses of these data 

showed that the filtering facepiece 

respirators achieved an APF of 10. 

These data are derived from WPF 

studies in which user seal checks were 

performed on filtering facepiece 

respirators by 100s of workers. In 

addition, 3M’s analysis (Ex. 4–10–7) 

indicates that user seal checks 

performed on filtering facepieces ensure 

proper redonning of these respirators. 

When a respirator user cannot perform 

a user seal check with a particular 

respirator model, then that respirator 

cannot be used by that employee, and 

the employer must find another 

respirator model on which a user seal 

check can be performed. This 

requirement applies to all tight-fitting 

facepieces, including filtering facepieces 

and elastomeric half masks. How easy or 

difficult it is for an employee to perform 

a user seal check on a particular type of 

respirator is not an issue that precludes 

other employees from using that 

respirator. Therefore, the comments on 

user seal checks do not provide 

convincing evidence that would support 

decreasing the APF for filtering 

facepieces to 5. 

OSHA argued previously in National 

Cottonseed Products Association v. 

Brock, 825 F.2d 482 (D.C. Cir. 1987) that 

filtering facepieces used to protect 

employees against exposure to cotton 

dust should have an APF of 5 based on 

the difficulty of fit testing, particularly 

fit checking on a daily basis. However, 

the Agency now believes that the record 

evidence for this rulemaking shows that 

the industrial-hygiene research 

community has developed and refined 

qualitative and quantitative fit tests, as 

well as developed sophisticated 

techniques for determining respirator 

leakage. Several commenters (Exs. 16–

25–3 and 17–9–1) provided evidence 

that filtering facepieces could be fit 

tested and then used effectively. Sealcheck techniques and procedures (e.g., 

fit-test cups, manual testing) also have 

been developed to help ensure that 

filtering facepieces maintain their fit 

while being worn in the workplace. 

These new developments allowed the 

Agency to reassess filtering facepieces 

and find that these respirators can be 

reliably fit tested and fit checked. 

The WPF studies provide further 

support for this conclusion. In fact, 

every WPF study of filtering facepieces 

in the OSHA APF database involved fit 

testing the respirator, using the new and 

refined methods, prior to the worker 

using the respirator in the study. 

Researchers used the available fit testing 

and checking technologies and 

methodologies in the studies to be 

assured that employees would be 

protected during the study by the 

respirators when exposed to airborne 

contaminants up to 10 times the PEL, 

and so that they could determine the 

results of the study would be accurate. 

Non-compliance and economic 

incentive issues. Several commenters 

asserted that filtering facepiece half 

masks should be given an APF less than 

10 because employers do not comply 

with the Respiratory Protection 

Standard (e.g., by not performing fit 

testing) (e.g., Exs. 9–40–1, 10–33, and 

10–52; Tr. at 663). In this regard, Donald 

Faulkner of the United Steelworkers of 

America (USWA) stated: 

We observe in many worksites that the 

employers are issuing filtering masks as if 

they were candies. They don’t have 

respiratory protection programs, 

requirements to be clean shaven, and no 

medical or no idea of the MUC of the 

contaminant that the worker needs to be 

protected from. (Ex. 9–40–1.) 

However, the 3M Company 

commented that non-compliance with 

the Respiratory Protection Standard 

should not be a factor in determining 

APFs, noting: 

OSHA has appropriately made the 

proposed APFs contingent upon the 

existence of an effective and well-managed 

respiratory protection program. This is the 

only circumstance under which APFs can be 

used. Setting APFs on assumptions of poor 

fit and lack of training is impossible because 

of the countless variables that exist in the 

workplace and workforce. APFs can only 

apply under properly managed respiratory 

protection programs. This is supported by 

following the American Industrial Hygiene 

Association Respiratory Protection 

Committee definition of APFs: An APF is the 

level of respiratory protection that a properly 

functioning respirator or class of respirators 

would be expected to provide to properly 

fitted and trained users in the workplace. The 

APF takes into account all expected sources 

of facepiece penetration (e.g., face seal 

penetration, filter penetration, valve leakage). 

It is not intended to take into account factors 

that degrade performance such as poor 

maintenance, failure to follow manufacturers’

instructions, and failure to wear the 

respirator during the entire exposure period. 

(Ex. 9–16.) 

Several commenters voiced concern 

that assigning a protection factor of 10 

to both elastomeric and filtering 

facepiece half masks will result in an 

economic incentive for employers to 

provide filtering facepiece respirators to 

employees rather than elastomeric half 

masks. These commenters assumed that 

the less expensive filtering facepiece 

respirators were less protective than the 

more expensive elastomerics (e.g., Exs. 

9–29, 10–38, and 10–54; Tr. at 212–213 

and 659–660). The USWA expressed 

this concern, stating, ‘‘If OSHA gives the 

filtering face piece type of respirator an 

APF of 10, employers would interpret 

this as ‘let’s take the cheap way out.’ It 

will be a dis-incentive to issue to 

workers the proven protection of the 

elastomeric face piece respirator’’ (Ex. 

9–40–1). Responding to an OSHA 

question about this issue, Thomas 

O’Connor of the National Grain and 

Feed Association stated: 

Well, clearly, if [you] had two respirators 

that provided the comfort and fit to the 

employee that’s needed and one was half the 

cost of the other one, obviously anybody 

would select the lower cost respirator. But as 

I noted, that’s not the primary motivation, 

cost. The primary motivation is complying 

with the standard, making sure that the 

employee[s] wear it and it fits properly and 

it’s comfortable. * * * If an employee’s 

wearing a respirator that’s not comfortable, 

there’s going to be an incentive for them 

possibly not to wear that respirator * * * 

when they should be wearing it. So from our 

perspective, comfort is one of the primary 

considerations in selecting a respirator for an 

employee. (Tr. at 684–685.) 

OSHA considered these comments 

and concludes that neither cost nor noncompliance with the Respiratory 

Protection Standard is an appropriate 

basis for determining the final APF for 

half masks. Employers are required to 

comply with all the provisions of the 

Respiratory Protection Standard. Noncompliance is not an option for 

employers. Thus, there is no compliance 

reason to reduce the APF for half masks. 

As to whether assigning a protection 

factor of 10 to filtering facepiece half 

masks will provide an economic 

incentive to use these respirators, OSHA 

concludes that so long as a respirator 

achieves an APF of 10, it doesn’t matter 

what respirator an employer uses. Once 

again, OSHA’s data analyses, as well as 

consensus standards, show that filtering 

facepieces can attain an APF of 10. 

ANSI’s updated APF of 5. Several 

commenters noted that the recent draft 

of the ANSI Z88.2 respirator standard 

gave filtering facepieces an APF of 5 

(e.g., Exs. 9–8, 10–51, and 10–54; Tr. at 

124–125 and 197–201). For example, 

Bill Kojola of the AFL–CIO testified: 

The AFL–CIO’s position that filtering 

facepieces should be given an APF of 5 is 


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also provided by other organizations with 

considerable expertise on respiratory 

protection. Indeed, the ANSI Z88.2 

Committee, charged with the responsibility 

for the American standard for respiratory 

protection, has recently proposed an APF of 

5 for filtering facepiece respirators. We 

believe that OSHA should give serious 

consideration to this ANSI position as well 

when it issues its final rule. (Tr. at 124–125.) 

OSHA considered the draft ANSI 

standard during this APF rulemaking. 

However, this draft standard currently is 

under appeal, and has not been 

designated by ANSI as a final standard 

(Ex. 17–9–10–2). Jill Snyder, Standards 

Coordinator for the AIHA secretariat of 

the ANSI Z88 committee, addressed the 

status of the draft ANSI Z88.2 revised 

respiratory protection standard in an email sent to participants in Roundtable 

228 held at the 2004 AIHCE. This e-mail 

stated: 

Until a standard is approved by ANSI, it 

is not an ANSI standard. Therefore, we 

should not say things like ‘ANSI completed 

drafting * * *’ etc. It is actually the 

Accredited Standards Committee (ASC) Z88 

or Z88.2 that put together what is still the 

DRAFT standard. We also have to make sure 

we call it a draft standard, not a standard at 

this point. (Ex. 17–9–10–2.) 

The method used by ANSI to 

determine the draft APFs also differs 

from OSHA’s approach, which used 

data analyses and expert opinion to 

arrive at the final APF for half masks. 

James Johnson, representing the ANSI 

Z88.2 subcommittee, stated that the 

subcommittee did not perform an 

extensive quantitative analyses similar 

to OSHA’s in determining the draft 

APFs (Tr. at 357). In response to 

questions from Thomas Nelson, ANSI 

subcommittee member George Macaluso 

confirmed that an overall tabulation and 

review of available WPF data was not 

conducted by the ANSI subcommittee in 

determining APFs (Tr. at 663–666). 

With regard to the decision of the 

ANSI subcommittee, James Johnson 

agreed that a subcommittee composed of 

other members may have reached a 

different conclusion regarding the APF 

for filtering facepiece half masks (Tr. at 

354–355). He also stated: 

There’s nothing in the consensus process 

that says every part of the standard has to 

have an absolute defendable, scientific, 

technically traceable base. It doesn’t exist. It’s 

not there. We have tremendous numbers of 

standards that are out there that the 

professionals develop with the best 

knowledge and experience that they have, 

and this is the process. (Tr. at 363.) 

Summary and conclusions. In this 

section, OSHA considered the issue of 

the appropriate APF for filtering 

facepieces. OSHA’s data analyses in the 

record support an APF of 10 for filtering 

facepiece respirators. Moreover, a 

number of commenters supported the 

APF of 10. Some commenters 

recommended a lower APF for filtering 

facepieces than proposed based on the 

poor structural integrity of the mask, the 

availability of additional models of 

respirator protection, poor compliance 

with the respirator program 

requirements, difficulty performing user 

seal checks, increased breathing 

resistance among filtering facepieces 

approved under 42 CFR part 84, and the 

recent ANSI draft APF for filtering 

facepieces. As discussed in the previous 

sections, the evidence in the record with 

regard to these issues justifies retaining 

in this final rulemaking the proposed 

APF of 10 for filtering facepieces. 

3. APF for Full Facepiece Air-Purifying 

Respirators 

Introduction. In a 1976 report, Ed 

Hyatt of LANL developed an APF table 

that included this respirator class (Ex. 

2). In this report, Hyatt used the results 

from quantitative fit testing to assess six 

models of full facepiece negative 

pressure air-purifying respirators 

equipped with HEPA filters. Five of 

these respirators achieved a protection 

factor of at least 100 for 95% of the 

respirator users. The sixth respirator 

attained this level of protection for 70% 

of the users. Based on the results for the 

sixth respirator, Hyatt recommended an 

APF of 50 for the respirator class as a 

whole. 

The 1980 ANSI respirator standard 

listed an APF of 100 for full facepiece 

air-purifying respirators with DFM 

filters (Ex. 7–3). ANSI increased the 

APF for this respirator class from 50 to 

100 because the poorly performing 

respirator in Hyatt’s study was no longer 

in production. Using the 1976 LANL 

quantitative fit testing results, the 1980 

ANSI standard increased this APF to a 

maximum of 1,000 when the respirator 

used HEPA filters and respirator users 

received quantitative fit testing (Ex. 7–

3). 

Based on Hyatt’s 1976 data, the 1987 

NIOSH RDL recommended that this 

respirator class receive an APF of 50 

when equipped with a HEPA filter. 

However, the RDL gave these respirators 

an APF of 10 when using DFM filters. 

NIOSH gave these respirators an APF of 

10 when equipped with DFM filters 

because testing that it conducted 

showed that the filters had relatively 

low efficiency. 

The 1992 ANSI respirator standard 

retained the 1980 ANSI standard’s APF 

of 100 for full facepiece air-purifying 

respirators, but required that respirator 

users perform quantitative fit testing 

and achieve a minimum fit factor of 

1,000 prior to using the respirators. 

QNFTs were necessary because no 

QLFTs could achieve a fit factor of 

1,000. The ANSI standard kept this APF 

because the ANSI committee found, as 

it did in 1980, that no WPF or SWPF 

studies had been performed for this 

respirator class. 

The following table summarizes the 

previous APFs assigned to full facepiece 

air-purifying respirators. 

Fully facepiece air-purifying 

respirators 

APFs 

LANL 

(1976) 

1980 ANSI 

standard 

NIOSH RDL 

(1987) 

1992 ANSI 

standard 

All respirators in the class ....... 50 (with HEPA filter) ............... 10 (with QLFT) ........................ 10 (with DFM filter) ................. 100 

100 maximum (with QNFT) .... 50 (with HEPA filter) ...............

In the proposal, OSHA also discussed 

a WPF study that Colton, Johnston, 

Mullins, and Rhoe (Ex. 1–64–14) 

conducted in a lead smelter. The 

respirator used in this study was a 3M 

7800 full facepiece air-purifying 

respirator equipped with HEPA filters. 

The authors found a 5th percentile 

protection factor of 95 for the sample, 

but concluded that the respirator only 

provided reliable protection at a 

protection factor of 50. In addition, a 

LANL SWPF study by Skaggs, Loibl, 

Carter, and Hyatt (Ex. 1–38–3) measured 

the protection afforded by the MSA 

Ultra Twin respirator with HEPA filters. 

The authors reported fit factors with 

geometric means ranging from 1,000 to 

5,300. However, 23 of the 60 

measurements reported were less than 

1,000, seven were less than 100, and 

three were less than 50. Based on a 

careful review of these studies, OSHA 

proposed an APF of 50 for full facepiece 

air-purifying respirators. 

OSHA requested comment in question 

#7 of the proposal on whether it should 


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limit full facepiece negative pressure 

respirators to an APF of 20 when N95 

filters are used. The NIOSH certification 

tests for 42 CFR part 84 filters are 

conducted using monodisperse aerosols 

of the most penetrating particle size (0.3 

μm) delivered at a high flow rate of 85 

liters per minute. Also, the 42 CFR part 

84 certification standards allow up to 

5% filter leakage with an N95 filter. If 

this level of leakage were to occur in the 

workplace, an APF of 20 would be 

appropriate for a full facepiece 

respirator using N95 filters. However, as 

several commenters noted (Exs. 9–16, 9–

22, 9–23, 9–37, 10–6, 10–17, 10–27, 10–

59, and 10–60), workplace filter 

penetration is always much less than 

filter penetration estimated from 

certification testing. Kenneth Bobetich 

of MSA (Ex. 9–37) stated that while 5% 

leakage is the worst case, such leakage 

does not occur in the workplace. 

Compared to the aerosols used in 

certification testing, workplace aerosols 

are not monodisperse, are many times 

larger, and are delivered through the 

filters at a lower flow rate. In addition, 

the 3M Company (Ex. 9–16) cited 

studies performed by Janssen (Exs. 9–

16–1–3 and 9–16–1–4) that compared 

the performance of N95 and P100 filters 

made by two manufacturers and used 

during grinding operations in a steel 

plant. Workplace performance of both 

filters was equivalent statistically, and 

the study showed that N95 filter 

performance was adequate under these 

conditions. Lisa Brosseau of the 

University of Minnesota (Ex. 10–59) 

stated that it was entirely inappropriate 

for OSHA to consider a 5% leakage 

effect for N95 filters because such 

leakage would only occur when the 

aerosol is monodisperse and of a small 

size, conditions that she said are 

unlikely to occur in most workplaces. 

Bill Kojola of the AFL–CIO (Ex. 9–27), 

Pete Stafford of the Building 

Construction Trades Department of the 

AFL–CIO (Ex. 9–29), and Michael 

Watson of the International Brotherhood 

of Teamsters (Ex. 9–7) supported 

limiting the APF for full facepieces to 20 

when N95 filters are used. Watson 

stated that if OSHA gave these 

respirators an APF higher than 20, 

employees would likely be exposed to 

hazardous levels of workplace 

contaminants. Kojola stated further that 

OSHA should take into account both 

sources of leakage (filter and faceseal), 

and lower the APF accordingly. 

However, neither Watson nor Kojola 

provided any evidence to support these 

misgivings about the performance of 

these respirators. 

NIOSH (Ex. 9–13) recommended that 

OSHA consider the limitations of the 

filter, but did not have any WPF or 

SWPF data on the performance of full 

facepiece respirators certified under 42 

CFR part 84 using N, R, or P95 filters. 

NIOSH stated that because the filters are 

tested at the most penetrating particle 

size, filter efficiency in the workplace 

should exceed certification efficiency. 

However, NIOSH noted that some 

workplace tasks, such as welding and 

grinding, may result in high leakage 

rates through the N95 filter because the 

tasks produce fine or ultra fine particles. 

Loraine Krupa-Greshman of the 

American Chemistry Council (Ex. 10–

25) stated that OSHA could not justify 

using a simplistic, generalized treatment 

of N95 filter efficiency to limit the APF 

to 20. She noted that using N95 or N100 

filters is a matter of professional 

judgment, based on the type and 

concentration of the contaminant. Frank 

White of ORC Worldwide (Ex. 10–27) 

stated that reducing the APF to 20 was 

unnecessary because protection factors 

and filter performance need to be 

considered separately as part of the 

respirator selection process. Ted 

Steichen of the American Petroleum 

Institute (API) (Ex. 9–23) mentioned that 

API believes that OSHA should further 

evaluate the data before assigning, based 

on worst-case assumptions, an APF of 

20 to these respirators. Thomas 

O’Connor of the National Grain & Feed 

Association (Ex. 10–13) commented that 

he was not aware of any scientific 

information that refuted assigning an 

APF of 50 to full facepiece respirators or 

justified lowering the APF for N95 

filters to 20. He supported retaining the 

proposed APF of 50 for this class of 

respirators. Sheldon Coleman of the 

Hanford Site Respiratory Protection 

Committee (Ex. 10–40) stated that, based 

on fit testing data, an APF of 50 for 

these respirators already is conservative. 

OSHA agrees with these commenters 

that full facepiece respirators with N95 

filters provide sufficient protection to 

maintain an APF of 50, and Table 1 of 

the final standard reflects this decision. 

Any effect of filter penetration on 

respiratory protection is best addressed 

during respirator selection, which also 

is the case for half masks and other 

respirator classes using particulate 

filters. In rare cases, when workplace 

exposures consist of a large percentage 

of particles of the most penetrating size, 

this information must be taken into 

account by the employer when selecting 

the appropriate class of particulate filter 

for any respirator, not just for full 

facepieces. 

Summary and conclusions. In the 

proposal, OSHA asked for any 

additional studies of full facepiece airpurifying respirators, but none was 

submitted. After carefully evaluating the 

original studies reviewed in the 

proposal, the Agency is setting an APF 

of 50 for full facepiece air-purifying 

respirators. The final APF agrees with 

the conclusion of Colton, Johnston, 

Mullins, and Rhoe (Ex. 1–64–14) cited 

earlier in this discussion that this class 

of respirators provides reliable 

protection at an APF of 50. Importantly, 

an APF of 50 corresponds with the APF 

previously assigned to full facepiece airpurifying respirators by OSHA in its 

substance-specific standards, and by 

NIOSH in its 1987 RDL. Therefore, 

OSHA is assigning an APF of 50 to full 

facepiece air-purifying respirators based 

on: the results of WPF and SWPF 

studies (which used N95 filters at 

moderate to high contaminant levels); 

The APFs given previously to this 

respirator class by NIOSH and ANSI; 

comments in the record indicating that 

N95 filters function effectively under 

the workplace exposure conditions in 

which they are used; and years of 

experience showing that these 

respirators, when equipped with an N95 

filter, are safe when used in the manner 

prescribed by OSHA’s respiratory 

protection standards. However, as with 

any respirator, if a full facepiece airpurifying respirator is unsuitable for the 

exposure conditions, paragraph (d)(1) of 

OSHA’s Respiratory Protection Standard 

requires that employers select a 

respirator that will protect employees 

from the exposure hazards. 

4. APF for Powered Air-Purifying 

Respirators (PAPRs) 

Half mask tight-fitting PAPRs. In the 

proposal, OSHA assigned an APF of 50 

to tight-fitting half mask PAPRs (68 FR 

34098 and 34115) based on the 1987 

NIOSH RDL and the Z88.2–1992 ANSI 

respirator standard. In arriving at a 

proposed APF of 50 for these 

respirators, the Agency relied heavily on 

the WPF study conducted by Lenhart 

and Campbell (Ex. 1–64–42), instead of 

the WPF study performed by Myers and 

Peach (Ex. 1–64–46) and the SWPF 

studies of Skaggs et al. (Ex. 1–38–3) and 

da Roza et al. (Ex. 1–64–94). In 

explaining its position, OSHA stated: 

[The Lenhart and Campbell] study was 

well controlled and collected data under 

actual workplace conditions; these 

conditions ensure that the results are reliable 

and represent the protection employees 

likely would receive under conditions of 

normal respirator use. The Agency did not 

consider the Myers and Peach WPF study 

* * * for this purpose because of problems 

involving filter assembly leakage and poor 

facepiece fit reported by the authors; 

consequently, the abnormally high levels of 

silica measured inside the mask would most 

likely underestimate the true protection 


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afforded by the respirator. The two SWPF 

studies * * * reported much higher 

geometric mean protection factors than did 

the WPF study performed by Lenhart and 

Campbell. However, OSHA believes that the 

higher protection factors reported for these 

SWPF studies are consistent with the 

proposed APF of 50 based on data obtained 

for this respirator class in the Lenhart and 

Campbell WPF study because SWPF studies 

typically report significantly higher 

protection factors than WPF studies of the 

same respirator. (68 FR 34098.) 

During this rulemaking, OSHA 

received no substantive comments or 

other information regarding the 

proposed APF of 50 for these 

respirators. Nevertheless, OSHA 

believes that the existing WPF and 

SWPF studies on this class proved 

adequate support for OSHA’s 

conclusion that an APF of 50 is an 

appropriate level to predict the 

protection capabilities of this class of 

respirators. 

Full facepiece PAPRs and PAPRs with 

hoods or helmets. In the proposal, 

OSHA assigned an APF of 1,000 to tightfitting full facepiece PAPRs (68 FR 

34099). In support of the proposed APF, 

OSHA cited a WPF study by Colton and 

Mullins that found a corrected 5th 

percentile protection factor of 1,335 for 

these respirators. OSHA received no 

substantive comments or other 

information regarding the proposed APF 

of 1,000 for these respirators. However, 

the ANSI Z88.2–1992 respirator 

standard and the 2004 draft revision to 

the ANSI standard both assign an APF 

of 1,000 to this respirator class. Based 

on its review of these consensus 

standards and the existing WPF research 

literature (see Exs. 1–64–12 and 1–64–

40), and SWPF research studies (Ex. 3–

4), OSHA concludes that this respirator 

class warrants an APF of 1,000. 

In proposing an APF of 1,000 for 

PAPRs with helmets or hoods, the 

Agency stated in footnote 4 of proposed 

Table 1 that ‘‘only helmet/hood 

respirators that ensure the maintenance 

of a positive pressure inside the 

facepiece during use, consistent with 

performance at a level of protection of 

1,000 or greater, receive an APF of 

1,000’’ and that ‘‘[a]ll other helmet/hood 

respirators are treated as loose-fitting 

facepiece respirators and receive an APF 

of 25.’’ (See 68 FR 34115.) OSHA 

proposed this condition because 

available WPF and SWPF studies found 

that some of these hood/helmet 

respirators achieved protection factors 

well below 1,000 (Exs. 3–4 and 3–5). 

Under the proposed condition, the 

burden of conducting any testing likely 

would fall on respirator manufacturers, 

but the employer would be responsible 

for selecting a properly tested respirator. 

According to James Johnson of LLNL, 

simple and effective equipment and 

procedures are available for detecting 

leaks in these respirators. In this regard, 

Johnson noted that LLNL developed 

equipment that monitors and records 

positive pressure in these respirators 

using a commercially available device. 

As he stated at the hearing: 

[T]his is the one we chose, a data logging 

micro manometer, the TSI–DP Calc, with a 

range of –5 to +15 inches of water gauge, and 

data recording intervals of one second and 

longer were chosen. * * * We plan on using 

this technique periodically to monitor actual 

high-contamination work activities to assure 

this PAPR maintains a positive pressure. (Ex. 

16–9–1.) 

A number of commenters provided 

additional support for using positive 

pressure inside the facepiece as the 

criterion for protection. For example, 

Rick Givens of the Atlanta, GA Utilities 

Department stated that ‘‘the 

maintenance of positive pressure is an 

appropriate method for distinguishing 

high-performing hood/helmet 

respirators from others’’ (Ex. 10–2), 

while Sheldon Coleman of the Hanford, 

Washington DOE site asserted: 

In the last three years, our program has 

used approximately 10,000 PAPR hoods. We 

have conducted some limited fit testing using 

particulate fit testers (although the hood 

manufacturer does not recommend using a 

particulate tester due to the extensive dead 

space in the hood). All of our information 

suggests that an APF of 1,000 is appropriate 

for a PAPR hood that maintains positive 

pressure inside of the hood. (Ex. 10–40.) 

Several commenters took exception to 

the positive pressure criterion. Craig 

Colton of 3M stated that ‘‘3M disagrees 

with OSHA’s proposed requirement that 

hoods and helmets demonstrate that 

they maintain positive pressure at all 

times of use to receive an APF of 1,000’’

(Tr. at 390). In this regard, Colton 

argued that the recent study conducted 

on PAPRs with hoods/helmets by ORC 

and LLNL showed that every respirator 

tested in the study ‘‘had two or more 

brief negative pressure spikes within the 

respiratory inlet covering. Under the 

current proposal, all of these respirators, 

except the poorest performing suppliedair respirator would have received an 

APF of 25, even though the 5th 

percentile SWPFs found in the study 

ranged from 86,000 to 250,000’’ (Tr. at 

391). Colton then added, ‘‘This study 

indicates that pressure within the 

respiratory inlet covering is only one of 

a complex set of factors that determine 

the protection provided by PAPRs and 

supplied-air respirators, and should not 

be considered by itself’’ (Tr. at 391). 

John P. Farris of Safe Bridge Consultants 

echoed this concern (Exs. 9–11 and 10–

32). 

Other comments focused either on the 

need for a protocol to determine if the 

respirators could perform at an APF 

level of 1,000, or on design 

characteristics that would permit 

respirator users to select appropriate 

respirators. In advocating the testing 

approach, Stephan Graham of the U.S. 

Army Center for Health Promotion and 

Preventative Medicine noted that 

respirators that have high APFs should 

receive credit for their design and 

performance. Graham recommended 

that manufacturers test their hooded 

and helmeted respirators, and set the 

maximum APF (to a maximum of 1,000) 

based on the results (Ex. 9–42–1). The 

3M Company stated that if OSHA 

retains a testing requirement in the final 

rule, it must specify the testing 

conditions. The 3M Company 

recommended testing at a work rate of 

40 liters per minute, ensuring that 

pressure inside the hood or helmet is 

maintained at a minimum level of one 

atmosphere at this work rate, measuring 

this pressure at the flow rate 

recommended by the manufacturer, and 

maintaining the maximum static 

pressure inside the hood or helmet at 38 

mm of water pressure (Ex. 18–7). 

Similarly, Jay Parker of the Bullard Co. 

stated that ‘‘without oversight and 

guidance, testing performed may not 

achieve such goals. This may lead to the 

use of respirators and an APF of 1,000 

that actually should not be used at that 

level because the testing performed was 

not really capable of ensuring that level 

of performance’’ (Tr. at 492). 

ORC Worldwide stated that ‘‘the 

approach proposed by OSHA would 

hold hood/helmet or loose-fitting 

facepiece PAPRs and SARs to a higher 

standard than that required of other 

respirator classes, based simply on the 

results of one model’’ (Ex. 10–27), a 

point made as well by Alice E. Till of 

the Pharmaceutical Research and 

Manufacturers Association (PhRMA) 

(Ex. 9–24). Nevertheless, ORC 

concluded that, ‘‘[s]hould OSHA retain 

this requirement, the final rule should 

clearly specify acceptable testing criteria 

to which respirator manufacturers must 

conform’’ (Ex. 10–27). PhRMA believed 

that OSHA should consider the 

proposed APF table to be an interim 

step in a transition toward the 

development of a certification protocol 

by NIOSH that provides APFs for each 

respirator model (Ex. 9–24). Thomas 

Nelson of NIHS, Inc. agreed, stating, 

‘‘Specific test conditions and 

performance criteria must be identified’’

(Ex. 10–17). 


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NIOSH provided the following 

information that addressed the concerns 

of these commenters: 

Respirator models should not be assigned 

to the higher APF level following 

promulgation of the proposed APF rule 

unless the respirator manufacturer provides 

evidence that testing of that model 

demonstrates performance at the higher APF 

level. A standard test protocol is needed to 

assure reliable and reproducible results when 

determining if a hood/helmet PAPR * * * 

can consistently achieve a protection factor 

of 1000. NIOSH will assist in developing this 

protocol. With implementation of new 

NIOSH certification criteria, every respirator 

model could be evaluated using this protocol 

as a condition of certification to assure 

overall performance consistent with the 

established APF. Thus, NIOSH will assure 

that approved respirators are capable of 

providing this assigned level of protection so 

that employers have appropriate guidance 

and APF values when selecting respirators 

for their workers. (Ex. 16–4.) 

Proponents of using design criteria, 

instead of testing, to assess the 

protection afforded by these respirators 

recommended that poorer performing 

respirators should be identifiable by 

either their appearance or technical 

specifications. For example, John Ferris 

of Safe Bridge Consultants, stated: 

In my experience, the most important 

factor in achieving workplace protection 

factors of 1,000 or greater with these devices 

is the ability to tuck the inner bib (or shroud) 

into the outer work garment with the outer 

shroud placed over the shoulders on the 

outside of the garment. I support the use of 

a 1000-fold APF for helmet hood PAPRs 

without the footnote. (Ex. 9–11.) 

Robert Barr of Alcoa noted that design 

flaws need to be identified, stating, ‘‘For 

example, flip-front types could be 

designated 25; and helmets with 

shrouds at 1000’’ (Exs. 9–26 and 10–31). 

PhRMA, ORC, and the American 

Chemistry Council argued that OSHA 

should base the APFs for these 

respirators on design and construction 

characteristics that would ‘‘enable a 

more exacting selection process, and 

* * * would be conducive to eventually 

assigning protection factors based on 

individual model performance’’ (Exs. 9–

24 and 10–27). However, Jay Parker of 

the Bullard Co. noted that the latest 

ANSI Z88.2 subcommittee ‘‘was unable 

to agree on the design characteristics of 

a hood or helmet that would lead to a 

performance level equivalent to an APF 

of 25’’ (Tr. at 480). Continuing, Jay 

Parker stated: 

I don’t see that we will ever be able to 

define the performance of a respirator by its 

design. We don’t want to stifle innovation. 

We want to be able to allow respirator 

manufacturers to develop new hoods and 

helmets. If OSHA comes up with a definition 

that limits a hood or helmet to a certain 

design, then that would limit the 

manufacturer’s ability to innovate with new 

designs. (Tr. at 480.) 

After reviewing the comments on 

proposed footnote 4, OSHA concludes 

that: no single parameter (e.g., positive 

pressure inside the facepiece) will 

identify respirators that consistently 

perform at a high APF level; no 

agreement exists on how to determine 

APFs for these respirators based on 

design characteristics alone; no uniform 

testing criteria are available to use in 

determining APFs for these respirators; 

and ample evidence demonstrates that 

WPF or SWPF studies conducted under 

a variety of conditions reliably 

determine reliable and safe protection 

factors for these respirators. Therefore, 

OSHA is revising footnote 4 to Table 1 

in the final standard to read as follows: 

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 WPF or SWPF 

study or equivalent testing. Absent such 

testing, all other PAPRs and SARs with 

helmets/hoods are to be treated as loosefitting facepiece respirators, and receive an 

APF of 25. 

The Agency is setting an APF of 1,000 

for tight-fitting facepiece PAPRs with 

hoods and helmets when the 

manufacturers of these respirators 

conduct testing that demonstrates that 

the respirators provide a level of 

protection of at least 1,000(e.g., 

demonstrating WPFs of at least 10,000 

or greater divided by a safety factor of 

10, or lower fifth percentile SWPFs of at 

least 25,000 divided by a safety factor of 

25). Based on its review of the record 

regarding these respirators, the Agency 

believes that tight-fitting facepiece 

PAPRs with hoods and helmets tested in 

a manner that is consistent with the 

SWPF testing performed previously 

under the ORC–LLNL study of 

respirators in this class (Ex. 3–4–1) will 

provide the required level of protection 

for employees who use these respirators. 

While proposed footnote 4 

emphasized that respirator 

manufacturers have responsibility for 

testing these respirators, it did not 

address who is responsible for selecting 

properly tested respirators. Consistent 

with Section 5 of the OSH Act (29 

U.S.C. 654), which places the 

responsibility for employee protection 

on employers, footnote 4 in the final 

rule now clearly places the 

responsibility for proper respirator 

selection on employers. Accordingly, 

employers may use a respirator at an 

APF of 1,000 only when they have 

appropriate test results provided by the 

respirator manufacturer demonstrating 

that the respirator performs at a 

protection level of 1,000 or greater. 

Evidence in the rulemaking record 

indicates that the technology exists to 

measure any leakage into the facepiece 

from the ambient atmosphere that could 

lessen the protection afforded by a 

PAPR or SAR with a helmet or hood 

(Ex. 16–9–1). This evidence also shows 

that small amounts of leakage measured 

by this technology during testing did 

not reduce the performance of the 

respirator below a level that was 

consistent with an APF of at least 1,000 

(Exs. 3–4–1, 1–38–3, 1–64–12, and 1–

64–40) Based on this evidence, OSHA 

believes that it is important for 

respirator manufacturers to determine, 

using available technology, that leakage 

into a respirator does not compromise 

the respirator’s capability to maintain a 

level of performance throughout testing 

that is consistent with an APF of at least 

1,000. Therefore, the Agency removed 

from footnote 4 in the final rule the 

language in proposed footnote 4 stating 

that ‘‘only helmet/hood respirators that 

ensure the maintenance of positive 

pressure inside the respirator during use 

* * * receive an APF of 1000.’’

Loose-fitting facepiece PAPRs with 

hoods or helmets. OSHA proposed an 

APF of 25 for loose-fitting PAPRs with 

hoods or helmets based on WPF studies 

described in the proposal (68 FR 34100), 

the NIOSH RDL, and the Z88.2–1992 

ANSI respirator standard. In supporting 

the proposed APF, ISEA commented 

that ‘‘as the reports of many WPF 

studies have shown, the performance of 

loose-fitting PAPRs with loose-fitting 

facepieces warrants a lower APF than 

for loose-fitting hoods and helmets’’ (Ex. 

9–24). Additional support came from 

Warren Myers, OSHA’s expert witness 

at the rulemaking hearing, who stated: 

Our summary conclusion was that PAPRs 

were incorrectly considered as positive 

pressure devices by the respirator community 

and that a minimum certification air flow of 

170 liters a minute, at least for the loosefitting class of devices, does not necessarily 

provide a positive pressure operational 

characteristic with the respirator. And then 

finally, that the assigned protection factor for 

these devices with those types of air flows 

would be 25. (Tr. at 69.) 

The WPF studies previously cited (68 

FR 34100) demonstrate that OSHA 

based the proposed APF on valid data 

that were substantiated by the Myers 

study. OSHA concludes that an APF of 

25 is appropriate for loose-fitting 

facepiece PAPRs with hoods or helmets, 

and therefore is retaining this APF for 

this respirator class in the final rule. No 


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adverse comments regarding the 

proposed APF were submitted. 

5. APFs for Supplied-Air Respirators 

(SARs) 

Half mask SARs. The Agency based 

its proposed APF of 10 for this 

respirator class on the analogous 

performance between these respirators 

and negative pressure half mask airpurifying respirators tested in WPF and 

SWPF studies (68 FR 34100). 

Furthermore, the Agency proposed to 

give half mask SARs that function in 

continuous flow or pressure-demand 

modes an APF of 50, consistent with the 

analogous performance between these 

respirators and half mask PAPRs 

operated in a continuous flow mode 

during WPF and SWPF studies. 

Additional support for the proposed 

APFs came from the Z88.2–1992 ANSI 

respirator standard that assigned an APF 

of 10 to half mask airline SARs operated 

in the demand mode, and an APF of 50 

to these respirators when operated in 

the continuous flow or pressure-demand 

modes. The 1987 NIOSH RDL also gave 

half mask demand SARs an APF of 10, 

but recommended an APF of 1,000 for 

these respirators when functioning in 

the pressure-demand or other positivepressure modes. 

OSHA received no comments or other 

information during this rulemaking 

regarding these proposed APFs. 

However, the Agency is confident that 

the available WPF and SWPF studies for 

half mask air-purifying respirators cited 

in the proposal provide sufficient data 

to retain an APF of 10 for half mask 

SARs when operated in the demand 

mode, and an APF of 50 for these 

respirators when operated in the 

continuous flow or pressure-demand 

modes. Therefore, OSHA is retaining 

these APFs in Table 1 of the final rule. 

Full facepiece SARs. OSHA stated in 

the proposal that ‘‘[n]o WPF or SWPF 

studies were available involving tightfitting full facepiece SARs operated in 

the demand mode. Therefore, in the 

absence of any such quantitative data, 

the Agency assigned this respirator class 

an APF of 50’’ (68 FR 34102). OSHA 

based the proposed APF on the 

analogous operational characteristics of 

these respirators and negative pressure 

full facepiece air-purifying respirators 

tested under WPF conditions in the 

demand mode. Also, the proposed APF 

is the same as the APF recommended 

for this respirator class by the 1987 

NIOSH RDL. 

The Agency proposed an APF of 1,000 

for full facepiece SARs operated in 

continuous flow, pressure-demand, or 

other positive-pressure mode (68 FR 

34102). It based the proposed APF on a 

SWPF study (Ex. 1–38–3) in which the 

results for these respirators showed 

geometric mean protection factors 

ranging from 8,500 to 20,000. Further 

justification for the proposed APF came 

from the similarity in operational 

characteristics between these respirators 

and tight-fitting full facepiece 

continuous flow PAPRs, which had a 

proposed APF of 1,000. The proposed 

APF for these respirators also was 

consistent with the APFs of 1,000 

assigned to them under the Z.88.2–1992 

ANSI respirator standard, and was 

substantially lower than the APF of 

2,000 recommended for these 

respirators by the 1987 NIOSH RDL. 

OSHA received no comments on full 

facepiece SARs operated in a demand, 

pressure-demand, or other positivepressure mode. The Agency believes 

that the evidence in the proposal is 

sufficient to support an APF of 50 for 

these respirators when operated in the 

demand mode, and an APF of 1,000 

when the respirators function in a 

pressure-demand or other positivepressure mode, and has included these 

APFs in the final standard. 

SARs with hoods or helmets. Based on 

a number of WPF studies, OSHA 

proposed an APF of 1,000 for 

continuous flow SARs with hoods or 

helmets, contingent on the 

manufacturers’ demonstration that the 

respirators meet the criteria specified in 

Table 1 of the proposed standard (68 FR 

34103). In responding to the proposed 

APF, Paul Schulte of NIOSH noted that 

an APF of 1,000 is appropriate for these 

respirators only when the manufacturer 

demonstrates that the models performed 

at this level (Ex. 9–13). ORC Worldwide 

stated that only SWPF data would give 

employers the assurance that the SAR 

offers the necessary protection for their 

workers (Ex. 10–27). ISEA 

recommended that further testing be 

performed before assigning an APF of 

1,000 for continuous flow SARs with 

hoods and helmets (Ex. 9–22). MSA 

concluded that an APF of 1,000 is 

appropriate (Ex. 16–10) because, it 

asserted, every credible WPF study 

demonstrates that continuous flow 

SARs with hoods and helmets perform 

at an APF of 1,000. 

These commenters generally agree 

that continuous flow SARs with hoods 

or helmets should be assigned an APF 

of 1,000 only after manufacturers 

demonstrate through appropriate WPF 

or SWPF studies that the respirators are 

capable of performing at an APF of 

1000. Therefore, based on the evidence 

cited in the proposal, the comments 

from ORC Worldwide, NIOSH, and 

ISEA, and the absence of any new 

studies or evidence submitted in 

response to the proposal, OSHA is 

assigning these respirators an APF of 

1,000 in the final rule only when the 

employer can provide evidence from the 

respirator manufacturers that 

demonstrates the respirators perform at 

that level; absent such testing, these 

respirators must receive an APF of 25. 

Loose-fitting facepiece SARs. OSHA 

proposed an APF of 25 for this class of 

respirators based on analogous 

performance between these respirators 

and loose-fitting facepiece PAPRs (68 

FR 34104). Additional support cited in 

the proposal included data from NIOSH 

showing that the two types of 

respirators (i.e., loose-fitting facepiece 

SARs and PAPRs) have the same 

minimum airflow rates when evaluated 

under 42 CFR part 84. The proposed 

APF also is consistent with the APF 

specified for respirators in the 1987 

NIOSH RDL and the Z88.2–1992 ANSI 

respirator standard. 

Commenters agreed with OSHA’s 

proposed APF of 25 (Exs. 9–22 and 10–

39; Tr. at 75 and 546). For example, 

Warren Myers stated, ‘‘I believe it is 

reasonable for OSHA to use analogous 

operational characteristics between 

PAPRs and SARs equipped with loosefitting hoods or helmets to set the APF 

for the SARs devices at 25’’ (Tr. at 75). 

ISEA noted that WPF studies conducted 

on loose-fitting facepieces justify an 

APF of 25 for these respirators (Ex. 9–

22). Based on these comments, the 

analogous performance with loosefitting PAPRS, NIOSH certification 

testing at the same minimum flow rates, 

and the APFs given these respirators in 

the 1987 NIOSH RDL and the ANSI 

Z88.2–1992 respirator standard, OSHA 

has concluded that an APF of 25 is 

appropriate for this respirator class. 

Therefore, the final rule will list an APF 

of 25 for SARs with loose-fitting 

facepieces. 

6. APF for Self-Contained Breathing 

Apparatuses (SCBAs) 

Ed Hyatt, in 1976, assigned a 

protection factor of 50 to a full facepiece 

SCBA operated in the demand mode, 

the same protection factor he assigned 

to full facepiece SARs used in this 

mode. Based on results from a panel of 

31 respirator users tested at LANL, he 

gave full facepiece SCBAs used in the 

pressure demand mode an APF of 

10,000+ (Ex. 2). The 1980 ANSI 

respirator standard listed half mask and 

full facepiece SCBAs operated in the 

demand mode with APFs of 10 and 100, 

respectively, when qualitatively fit 

tested. The APFs for half mask or full 

facepiece SCBAs functioning in the 

demand mode were the protection 

factors obtained during quantitative fit 


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testing, with this APF limited to the 

sub-IDLH value. Full facepiece SCBAs 

used in the pressure-demand mode 

received an APF of 10,000+. The 1987 

NIOSH RDL recommended that half 

mask and full facepiece SCBAs operated 

in the demand mode receive APFs of 10 

and 50, respectively, and that the APF 

for full facepiece SCBAs operated in the 

pressure-demand or other positive 

pressure mode be 10,000. 

The Z88.2 subcommittee responsible 

for the 1992 ANSI respirator standard 

could not reach a consensus on an APF 

for full facepiece pressure-demand 

SCBAs. Available WPF and SWPF 

studies reported that, in some cases, the 

respirators did not achieve an APF of 

10,000 (Ex. 1–50). Nevertheless, the 

subcommittee found that a maximum 

APF of 10,000 was appropriate when 

employers use the respirators for 

emergency-planning purposes and 

could estimate levels of hazardous 

substances in the workplace. 

Two respirators equipped with hoods, 

Draeger’s Air Boss Guardian and 

Survivair’s Puma, have operational 

characteristics similar to SCBAs. The 

facepiece of the Draeger respirator 

consists of a hood with an inner nose 

cup and a tight-fitting seal at the neck, 

and an air cylinder that supplies 

breathing air to the facepiece. NIOSH 

reviewed this respirator in accordance 

with its 42 CFR part 84 certification 

requirements, and in January 2001 

certified the respirator as a tight-fitting 

full facepiece demand SCBA when 

equipped with a cylinder having a 30- 

minute service life. NIOSH also 

approved the respirator for use in 

entering and escaping from hazardous 

atmospheres. In a May 16, 2001 letter to 

OSHA’s Directorate of Enforcement 

Programs (Ex. 7–1), Richard Metzler of 

NIOSH justified the classification of the 

Draeger respirator as an SCBA on the 

basis that the neck seal, which is 

integral to the facepiece, forms a gastight or dust-tight fit with the face 

consistent with the definition of a tightfitting facepiece specified by 42 CFR 

84.2(k). This letter also noted that the fit 

testing procedures used for full 

facepiece demand SCBAs apply to the 

Draeger SCBA, and that, as a full 

facepiece demand SCBA, NIOSH 

recommended that the respirator receive 

an APF of 50 in accordance with its 

1987 RDL. 

NIOSH subsequently certified the 

Survivair Puma respirator, which has a 

tight-fitting hood supplied by an air 

cylinder, as a pressure-demand SCBA 

with a tight-fitting facepiece. As part of 

the 42 CFR part 84 certification process, 

NIOSH specified that the fit testing 

requirement for tight-fitting SCBAs 

would apply to this respirator. However, 

Steve Weinstein of Survivair (Ex. 7–2) 

stated that the hood totally encapsulates 

the respirator user’s hair, making 

quantitative fit testing (e.g., with a 

Portacount) impossible. In such cases, 

the fit testing instrument treats dander 

and other material shed by the hair as 

particulates originating from outside the 

respirator, causing the fit factor to be 

artificially low. Nevertheless, qualitative 

fit testing with the hood is possible 

because Survivair provides an adapter 

and P100 filters for this purpose. Such 

fit testing meets the fit-testing 

requirements for tight-fitting SCBAs 

specified in paragraph (f)(8) of OSHA’s 

Respiratory Protection Standard. 

The table below provides a summary 

of APFs given to the half mask and full 

facepiece SCBAs by different groups. 

SCBAs 

APFs 

1992 ANSI 

LANL standard 

(1976) 

1980 ANSI 

standard 

NIOSH RDL 

(1987) 

Tight-fitting half mask 10 (demand) .............. 10 (demand; with QLFT) Same as QNFT 

factor (demand; sub-IDLH value max.).

10 (demand).

Tight-fitting Full facepiece.50 (demand) .............. 100 (demand; with QLFT) Same as QNFT 

factor (demand; sub-IDLH value max.).

50 (demand).

Tight-fitting Full facepiece.10,000 (pressure demand).10,000+ (pressure demand) .......................... 10,000 (pressure demand).10,000 maximum 

(emergency planning purposes only). 

OSHA received no new WPF or SWPF 

studies for tight-fitting half mask SCBAs 

and tight-fitting full facepiece SCBAs 

operated in the demand mode in 

response to the proposal. In the only 

WPF study conducted on full facepiece 

positive-pressure SCBAs, Campbell, 

Noonan, Merinar, and Stobbe of NIOSH 

assessed the performance of two 

different models of full facepiece 

pressure-demand SCBAs that met the 

NFPA 1981 air-flow requirements for 

respirators used by firefighters (Ex. 1–

64–7). While the authors could not 

determine protection factors for these 

respirators because contaminant levels 

measured inside the facepiece were too 

low, pressure measurements taken 

inside the facepiece proved more useful. 

These measurements showed that four 

of the 57 test subjects (i.e., firefighters) 

experienced one or more negative 

pressure incursions inside the facepiece 

while performing firefighting tasks. 

After analyzing the data for these 

firefighters using two different methods, 

the authors estimated that the overall 

protection factor exceeded 10,000. 

In the first of two SWPF studies 

performed on full facepiece SCBAs used 

in the pressure-demand mode, McGee 

and Oestenstad determined the 

protection afforded to members of a 

respirator test panel who used the 

Biopack 60 closed-circuit SCBA (Ex. 1–

64–86). Three members of the panel had 

protection factors of 4,889, 7,038, and 

18,900, with the remaining members 

having protection factors over 20,000. In 

the second study, Johnson, da Roza, and 

McCormack of LLNL (Ex. 1–64–98) 

tested the Survivair Mark 2 SCBA that 

met NFPA 1981 air-flow requirements. 

During testing, a panel of 27 test 

subjects exercised on a treadmill at 80% 

of their cardiac reserve capacity. 

Although the authors found negative 

pressure incursions inside the facepiece 

at high work rates, they concluded that 

the respirator ‘‘provided [a minimum] 

average fit factor of 10,000 [for any 

single subject], with no single subject 

having a fit factor less than 5,000 at a 

high work rate.’’ The tables below 

summarize the results of the WPF and 

SWPF studies performed on full 

facepiece pressure-demand SCBAs. 


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WPF studies for tight-fitting full facepiece pressure demand 

SCBAs (by name of authors and model of respirator tested) Sample size Geometric mean 

Geometric 

standard 

deviation 

5th percentile WPF 

Campbell et al. (Ex. 1–64–7) Unspecified model (with NFPA-compliant airflow).57 .................... .................... >10,000 (estimated). 

SWPF studies for ight-fitting full facepiece pressure demand SCBAs (by name of 

authors & mode of respirator tested) Sample size Geometric mean 

Geometric 

standard 

deviation 

5th percentile WPF 

McGee and Oestenstad (Ex. 1–64–86) Biopack 60 (closed circuit) ............................... 23 >20,000 .................... ....................

Johnson et al. (Ex. 1–64–98) Survivair mark 2 with NFPA-compliant airflow) ............... 27 29,000 1.63 ....................

Janice Bradley (Ex. 9–22) of the 

International Safety Equipment 

Association and Kenneth Bobetich of 

the MSA Company (Ex. 9–37) both 

stated that footnote 5 in the proposed 

OSHA APF Table 1 was not necessary 

because most SCBA models now meet 

the increased air-flow requirements in 

the NFPA 1981 standard. They further 

noted that the study that served as the 

basis of the footnote was more than 15 

years old, and that OSHA should 

remove the footnote. They 

recommended that the APF should be 

10,000 for pressure-demand SCBAs that 

meet the air-flow requirements of NFPA 

1981. Janice Bradley (Tr. at 531) cited 

the WPF study NIOSH performed with 

firefighters (Ex. 1–64–7) as supporting 

the conclusion that SCBAs meeting the 

NFPR 1981 requirements would provide 

APFs of 10,000. 

Summary and conclusions. OSHA is 

setting APFs of 10 and 50, respectively, 

for tight-fitting half mask SCBAs and 

tight-fitting full facepiece SCBAs 

operated in the demand mode. In the 

absence of any new WPF and SWPF 

studies on these respirators, the Agency 

is basing the final APFs on analogous 

operational characteristics between 

these respirators and half mask 

facepiece and full facepiece airpurifying respirators, that have APF 

values of 10 and 50, respectively. In 

addition, the final APFs are consistent 

with the APFs recommended by the 

1987 NIOSH RDL for these respirators. 

(Note that the 1992 ANSI standard did 

not assign APFs for these respirator 

classes.) 

For tight-fitting full facepiece SCBAs 

used in the pressure-demand or other 

positive pressure modes, OSHA is 

setting an APF of 10,000 in the final 

standard, which is consistent with the 

1987 NIOSH RDL and the 1992 ANSI 

respirator standard. Empirical support 

for the final APF comes from the WPF 

study conducted by Campbell, Noonan, 

Merinar, and Stobbe (Ex. 1–64–7). This 

study showed that protection factors for 

these respirators, when operating at 

NFPA-compliant air flows, far exceed 

10,000. While four respirator wearers 

experienced momentary negativepressure spikes inside their facepieces, 

which indicates possible leakage into 

the facepiece under some workplace 

conditions, these spikes did not impair 

overall respirator performance. The 

Agency concludes that these study 

results justify an unrestricted APF of 

10,000 for tight-fitting full facepiece 

SCBAs. 

For the class of respirators designated 

as pressure-demand SCBAs with tightfitting hoods or helmets, including the 

Survivair Puma, OSHA is setting an 

APF of 10,000. The basis for this final 

APF is the analogous operational 

characteristics between these respirators 

and tight-fitting full facepiece pressuredemand SCBAs. 

D. Definition of Maximum Use 

Concentration 

Employers use MUCs to select 

appropriate respirators, especially for 

use against organic vapors and gases. 

MUCs specify the maximum 

atmospheric concentration that an 

employee can experience while wearing 

a specific respirator or class of 

respirators. MUCs are a function of the 

APF determined for a respirator (or class 

of respirators), and the exposure limit of 

the hazardous substance in the 

workplace. 

1. Introduction 

Ed Hyatt, in the 1976 LASL report on 

respiratory protection factors (Ex. 2, 

Docket H049), recounted the early 

history of MUCs, starting with the MUC 

recommendations of the joint AIHA–

ACGIH committee in 1961. This 

committee recommended that, for 

highly toxic compounds, full facepiece 

respirators with HEPA filters use a 

maximum limit of 100 times the TLV. 

Hyatt noted that Dr. Letts in 1961 in the 

United Kingdom, recommended that 

half mask dust respirators provided 

effective protection against airborne 

contaminant levels no greater than 10 

times the TLV. 

In 1974, NIOSH and OSHA started the 

Standards Completion Program to 

develop standards for substances with 

existing PELs. As part of this process, 

the initial respirator decision logic was 

developed and the concept of MUCs 

began to be used. NIOSH Criteria 

Documents also recommended MUCs 

for different types of respirators. The 

information for these MUCs were 

obtained from various sources, 

including NIOSH Current Intelligence 

Bulletins and recognized industrial 

hygiene references. NIOSH later 

published this information in its Pocket 

Guide to Chemical Hazards. Other 

source documents for MUC definitions 

and regulations include the 1987 NIOSH 

RDL, and the ANSI Z88.2–1980 and 

ANSI Z88.2–1992 respiratory protection 

standards. 

OSHA’s 1994 proposed Respiratory 

Protection Standard contained the 

following definition of MUC: 

Maximum use concentration (MUC) means 

the maximum concentration of an air 

contaminant in which a particular respirator 

can be used, based on the respirator’s 

assigned protection factor. The MUC cannot 

exceed the use limitations specified on the 

NIOSH approval label for the cartridge, 

canister, or filter. The MUC can be 

determined by multiplying the assigned 

protection factor for the respirator by the 

permissible exposure limit for the air 

contaminant for which the respirator will be 

used. (59 FR 58884.) 

Several commenters to this 1994 

proposal recommended alternatives to 

this definition. Reynolds Metal 

Company recommended defining MUC 

as ‘‘the maximum concentration of an 

air contaminant in which a particular 

respirator can be used, based on the 

respirator’s assigned protection factor’’

(Ex. 1–54–222). The American 

Petroleum Institute (API) noted NIOSH 

developed the term ‘‘MUC,’’ and that, to 

avoid confusion, OSHA should not use 

the term (Ex. 1–54–330). API proposed 

using the term ‘‘assigned use 

concentration’’ to replace MUC. API 

defined ‘‘assigned use concentration’’ as 

‘‘the maximum concentration of an air 

contaminant in which a particular 


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10For example, when the hazardous substance is 

lead (with a PEL of 50 μg/m3), and the respirator 

used by employees has an APF of 10, then the 

calculated MUC is 500 μg/m3 or 0.5 mg/m3 (i.e., 50 

μg/m3 × 10). 

respirator can be used, based on the 

respirator’s assigned protection factor’’

(Ex. 1–54–330). However, when the 

Agency published the final Respiratory 

Protection Standard in 1998, it reserved 

the definition of MUC in paragraph (b), 

and the MUC requirements in paragraph 

(d)(3)(i)(B), for future rulemaking 

because it reserved the APF provisions 

of the respirator selection section of the 

standard (i.e., MUCs could not be 

determined without knowing the APF 

values). 

In the June 6, 2003 proposal, OSHA 

defined MUC as follows: 

Maximum use concentration (MUC) means 

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 usually can be determined 

mathematically by multiplying the assigned 

protection factor specified for a respirator by 

the permissible exposure limit, short-term 

exposure limit, ceiling limit, peak limit, or 

any other exposure limit used for the 

hazardous substance. (68 FR 34036.) 

Under this definition, MUC represents 

the maximum atmospheric 

concentration of a hazardous substance 

against which a specific respirator or 

class of respirators with a known APF 

can protect employees who use these 

respirators. Accordingly, MUCs are a 

function of the APF determined for a 

respirator (or class of respirators) and 

the exposure limit of the hazardous 

substance in the workplace. 

The last sentence in the definition 

describes the MUC in terms of a 

mathematical calculation, i.e., that 

employers can ‘‘usually’’ determine the 

MUC by multiplying the APF for the 

respirator by the exposure limit used for 

the hazardous substance.10 The last 

sentence of the proposed definition also 

specifies the exposure limits as 

‘‘permissible exposure limit (PEL), 

short-term exposure limit (STEL), 

ceiling limit (CL), peak limit, or any 

other exposure limit used for the 

hazardous substance.’’ Although OSHA 

received no comments on the proposed 

definition, it nevertheless is making 

several minor revisions to the definition 

in the final rule. First, the Agency is 

removing the term ‘‘usually’’ from the 

definition because multiplying the 

assigned protection factor by the 

exposure limit for a hazardous 

substance is the currently accepted 

method used by safety and health 

professionals for calculating MUCs. 

Absent any other accepted method, the 

term ‘‘usually’’ is confusing and 

unnecessary. 

The second revision to the proposed 

MUC definition involves the last part of 

the second sentence, which required 

employers to consider an ‘‘exposure 

limit’’ when determining an MUC. 

OSHA is making two changes to this 

proposed language to make clear its 

intent regarding the information 

employers need to consider when 

making this calculation. First, OSHA is 

clarifying the language to require 

employers to calculate an MUC using an 

OSHA exposure limit in those instances 

where one exists. OSHA was concerned 

that employers could have 

misinterpreted the language in the 

proposed MUC definition as meaning 

that they could use any available 

exposure limit for calculating an MUC 

(and, by implication, for protecting 

employees from hazardous airborne 

contaminants). This revision 

emphasizes the priority that OSHA 

exposure limits have in regulating 

hazardous airborne contaminants. 

Second, OSHA is changing the 

language to make clear the information 

employers need to consider to 

determine an MUC in the absence of an 

OSHA exposure limit. The Agency 

revised the language to require 

employers to use relevant available 

information and informed professional 

judgment when determining an MUC 

when no OSHA exposure limit exists. 

This language more clearly states 

OSHA’s intent that employers can 

utilize a wide range of available 

information in calculating an MUC 

when OSHA has not yet promulgated an 

exposure limit for a hazardous airborne 

contaminant. While not required, some 

employers may choose to conduct 

individualized risk assessments of 

hazards. Others may consult 

information from manufacturers or other 

published exposure limits (e.g., the 

NIOSH RELs or the AIHA WEELs) for 

making MUC determinations. However, 

whatever approach employers choose to 

take, the MUC must provide adequate 

protection for their employees. OSHA 

believes this approach provides 

employers with greater flexibility than 

the proposed MUC definition while still 

maintaining employee protection. 

The Agency also broadened the 

language in this second sentence by 

requiring employers to ‘‘take the best 

available information into account’’

when determining an MUC in the 

absence of an OSHA exposure limit. 

This language is consistent with the 

guidance that the Agency provided to 

employers in the preamble to the 

Respiratory Protection Standard for 

determining APFs in the absence of a 

final APF standard (see, e.g., 63 FR 

1203). OSHA believes this language 

gives employers maximum flexibility to 

develop MUCs that protect their 

employees from hazardous airborne 

contaminants, including the use of other 

exposure limits when appropriate. 

In the proposal to this final rule, 

OSHA requested comments on the 

development of the MUC for substances 

with no OSHA PEL, limiting factors 

such as eye irritation, LELs and IDLHs, 

and mixtures of substances (68 FR 

34112). OSHA received numerous 

comments on these issues, as well as on 

hazard ratios, an issue raised by several 

commenters. These issues are discussed 

in the following sections. 

2. MUCs for Substances With No OSHA 

PEL or Other Limiting Factors 

OSHA received many comments on 

this issue. Some commenters believed 

that in the absence of a PEL it is 

appropriate for the Agency to require 

calculation of MUCs based on other 

information (Exs. 10–54, 9–27, and 10–

3). Other commenters supported using 

any occupational exposure limit for this 

purpose, but some of these commenters 

specified that no other limiting factors 

should be used (Exs. 9–26, 9–42, 10–27). 

Others specified that additional limiting 

factors were needed (Exs. 9–13, 9–15, 9–

29, 10–6, and 10–60). Several 

commenters recommended using only 

the OSHA PELs with limiting factors 

(Ex. 10–17, 10–25, and 9–16) or without 

limiting factors (Exs. 9–22 and 9–23). A 

few commenters addressed limiting 

factors only, either supporting specific 

factors (Exs. 9–12 and 10–1) or stating 

that no limiting factors were needed 

when determining MUCs (Ex. 9–37). 

These comments are discussed in the 

following paragraphs. 

W.M. Parris of Alabama Power (Ex. 9–

15) proposed the following generic 

definition of MUC that would include 

all possible MUCs: 

Maximum use concentration (MUC) means 

the maximum atmospheric concentration of a 

hazardous substance from which an 

employee can be expected to be protected 

when wearing a respirator. The MUC will be 

the lowest of the following: (1) IDLH value 

for the substance, (2) the LEL value, (3) 

limitations set by manufacturer, or (4) 

mathematically determined by multiplying 

the assigned protection factor specified for 

the respirator by the permissible exposure 

limit, short term exposure limit, ceiling limit, 

peak, or another occupational exposure limit 

used for the hazardous substance. 

Paul Schulte of NIOSH (Exs. 9–13, 

13–11–1, and 16–4) recommended that 


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employers use the RELs, or in the 

absence of a REL, another appropriate 

exposure limit. Schulte also stated that, 

for both regulated and non-regulated 

substances, the MUC for any respirator 

other than a pressure-demand SCBA 

should never exceed the IDLH value. 

Schulte noted further that NIOSH did 

not agree with the use of the LEL as an 

appropriate respirator-selection factor 

for MUCs unless the respirator is the 

source of an ignition hazard (e.g., 

respirators with communication 

systems). Accordingly, Schulte (Ex. 9–

13) proposed revising the MUC 

definition to read as follows: 

Maximum use concentration (MUC) means 

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 lesser of 

• APF times (x) exposure limit 

• The respirator manufacturer’s maximum 

use concentration for a hazardous substance 

(if any) 

• The IDLH, unless the respirator is a 

positive-pressure, full facepiece SCBA 

Daniel K. Shipp of the International 

Safety Equipment Association (ISEA) 

(Ex. 9–22) commented that ISEA 

believed that OSHA should not expand 

the MUC definition to include MUCs for 

hazardous substances not regulated by 

OSHA, and that the definition should 

not involve limiting factors. He 

indicated that employers should have 

the flexibility to determine what to do 

in these situations. Shipp also stated 

that the NIOSH approval labels on 

chemical cartridges already read ‘‘Do 

not exceed maximum use 

concentrations established by regulatory 

standards.’’ In this regard, he suggested 

that OSHA rewrite the MUC definition 

to require that MUCs used to select 

respirators shall not be exceeded. 

Michael Sprinker of the International 

Chemical Workers Union Council of the 

United Food and Commercial Workers 

Union (Ex. 10–54) believed that OSHA’s 

definition of MUC should be revised 

because it is unclear whether the MUC 

is a concentration never to be exceeded 

or a time weighted average. He also 

stated that OSHA should require 

employers to determine MUCs for 

substances for which no OSHA PEL is 

available, and that these MUCs can be 

derived from occupational exposure 

limits issued by NIOSH, ACGIH, EPA, 

or the manufacturer. 

Robert W. Barr and Linda M. Maillet 

of Alcoa, Inc. (Exs. 9–26 and 10–31) said 

that OSHA should not expand the 

definition and application of MUCs to 

hazardous substances it does not 

regulate because that would constitute 

adoption of these exposure limits as 

OSHA rules. The Alcoa representatives 

said that employers should be free to 

select the criteria for calculating MUCs 

based on their own risk assessments. 

Also, they did not want the lower 

NIOSH RELs to replace OSHA PELs in 

calculating MUCs. They did not believe 

that OSHA should specify the LEL or 

10% of the LEL as a limiting factor 

because LEL is an independent 

indicator of a physical hazard. They 

asserted that respirator users who could 

be exposed to an explosive level of a 

substance must not enter such an area 

because of the physical hazard—the 

characteristics of their respirators are 

irrelevant in such situations. Similarly, 

Daniel P. Adley and William L. Shoup 

of the Society for Protective Coatings 

(Ex. 9–10) did not agree with the ‘‘or 

any other exposure limit’’ in the 

definition of MUC, which would give 

regulatory authority to TLVs, RELs, and 

other industry—established exposure 

limits. 

Bill Kojola of the AFL–CIO (Exs. 9–27 

and 16–5) believed that OSHA should 

expand the definition and application of 

MUC to include substances it does not 

regulate, and that the exposure limits 

issued by NIOSH, ACGIH, EPA, or the 

manufacturer should be used when 

available. Pete Stafford of the Building 

and Construction Trades Department, 

AFL–CIO (Ex. 9–29) recommended that 

OSHA expand the definition of MUC to 

include appropriate exposure values 

because thousands of harmful and 

potentially harmful chemicals used in 

the workplace are not regulated by 

OSHA. He indicated that alternative 

MUCs calculated for chemicals using a 

non-OSHA exposure limit should be 

used when these MUCs are lower than 

the MUCs determined from using PELs. 

He also recommended that OSHA 

specify 10% of the LEL as a limiting 

factor for MUCs. 

Stephan C. Graham of the United 

States Army Center for Health 

Promotion and Preventive Medicine 

(Exs. 9–42, 9–42–1, and 9–42–2) 

indicated that OSHA should expand the 

MUC definition to include hazardous 

substances it does not regulate. 

However, he did not believe that NIOSH 

MUCs should be used when they are 

lower than the MUCs calculated using 

OSHA PELs. Rick N. Givens of Augusta 

Utilities Department (Ex. 10–2) also 

agreed that OSHA should require 

employers to calculate MUCs for 

substances that do not have OSHA 

PELs. Ken M. Wilson of the Division of 

Safety & Hygiene, Ohio Board of Water 

Control (Ex. 10–3) stated that OSHA 

should require employers to determine 

MUCs for substances that have no 

OSHA PEL because many of these 

substances can harm employees. 

David L. Spelce (Ex. 10–6) stated that 

the PELs in 29 CFR 1910.1000 were 

adopted by OSHA in 1971 and came 

mostly from the 1968 ACGIH TLVs. He 

recommended that OSHA require 

employers to use the ACGIH TLVs and 

AIHA Workplace Environmental 

Exposure Levels when no OSHA PEL 

exists. He indicated that these 

alternative values also should be used 

when they are more stringent than the 

OSHA PELs. He agreed with OSHA that 

when the IDLH level is lower than the 

calculated MUC, the IDLH 

concentration must take precedence. In 

such circumstances, only the most 

protective atmosphere-supplying 

respirators should be used. He also 

stated that IDLH limits should be 

established based on toxicological data, 

but, in the absence of toxicological data, 

10% of the LEL should be used as the 

limiting factor (i.e., having the same 

weight as the IDLH for flammable 

substances). 

Thomas C. O’Connor of the National 

Grain and Feed Association (NGFA) 

(Exs.10–13 and 16–19) recommended a 

revised MUC definition that would read 

as follows: 

Maximum use concentration (MUC) * * * 

usually can be determined mathematically by 

multiplying the assigned protection factor 

specified for a respirator by the permissible 

exposure limit or ceiling value as 

appropriate. In a situation when such 

regulatory limits have not been set by OSHA, 

the employer may rely on limits established 

by non-regulatory organizations based on 

professional judgment and the working 

environment. 

However, he (Ex. 10–13) said that 

NGFA strongly opposes requiring 

employers to determine MUCs for 

substances for which no OSHA PELs are 

available. The NGFA also opposed any 

requirement that employers rely on 

MUCs developed by NIOSH, but 

supported the use of non-OSHA 

exposure limits as aids employers can 

use in establishing MUCs. 

Thomas Nelson of NIHS, Inc. (Ex. 10–

17) indicated that OSHA should not 

require employers to determine MUCs 

for substances that have no OSHA PELs. 

Nelson said that OSHA first must 

determine when a need for such 

exposure limits exists, and then issue 

new PELs. Furthermore, Nelson stated 

that OSHA cannot rely on other groups 

to establish limits for OSHA’s use. He 

also said that the only limiting factors 

that should be used in calculating MUCs 

are APFs and IDLHs, and that the 

Agency should specify the LEL, or a 

value close to the LEL (e.g., 90% of the 


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LEL), when no IDLH exists for a 

substance. 

Lorraine Krupa-Greshman of the 

American Chemistry Council (ACC) (Ex. 

10–25) indicated that NIOSH MUCs 

should not be adopted as a specific 

requirement, but should remain 

available for guidance. The ACC also 

does not support requiring compliance 

with NIOSH MUCs when they are lower 

than OSHA’s MUCs. The ACC 

recommends a requirement for 

employers to determine the appropriate 

MUCs for substances that do not have 

an OSHA PEL. However, employers 

should be allowed to designate and 

document the basis for these MUCs 

using either the OSHA formula or other 

criteria. She stated that the IDLH is a 

reasonable limit on the MUC for some 

types of respirators, and that an IDLH 

should be based on health effects. She 

noted that using the LEL or a percentage 

of the LEL to limit MUCs is confusing 

and inappropriate because an LEL is 

used to determine whether an employee 

can safely enter an area with a fire 

hazard, not for selecting respirators. 

Frank A. White of ORC Worldwide 

(Ex. 10–27) stated that OSHA should not 

require employers to calculate MUCs for 

substances that have no OSHA PEL, but 

that employers should have the freedom 

to select the occupational exposure 

limits used for calculating MUCs based 

on their own risk assessments. He 

emphasized that it is important that 

employers be able to show the 

documented evidence used to support 

their MUC decisions. ORC Worldwide 

also indicated that OSHA should not 

expand the application of MUCs to 

hazardous substances it does not 

regulate because these exposure limits 

(e.g., developed by chemical 

manufacturers, ACGIH, NIOSH, EPA) 

would become OSHA regulations. He 

also stated that OSHA should not 

enforce the 1994 NIOSH IDLHs, but 

instead should continue to rely on those 

IDLHs that NIOSH developed in 1990. 

OSHA should not use either the LEL or 

10% of the LEL as a limiting factor 

because these factors are not healthbased, and are used as indicators of a 

physical hazard. 

Ted Steichen of the American 

Petroleum Institute (Ex. 9–23) believed 

that the determination of MUCs for 

substances with no OSHA PELs should 

be left to the good practices of the 

employer. He stated that OSHA would 

be exceeding its authority if it expanded 

the definition and application of MUC 

to hazardous substances that it does not 

regulate. Steichen said that the use of 

the LEL to limit the MUC is confusing 

and inappropriate. He stated that the 

LEL has no relationship to the 

protection provided by a respirator, but 

is an essential factor to consider when 

working with flammable or combustible 

materials. 

Paul Hewett of Exposure Assessment 

Solutions, Inc. (Ex. 10–60) believed that 

OSHA should require employers to 

determine MUCs for those substances 

that have no OSHA PEL. He pointed out 

that employers already are required to 

consider all hazardous substances, 

including those substances without an 

OSHA PEL, under the ‘‘recognized 

hazards’’ provision of the general-duty 

clause of the OSH Act. He 

recommended that OSHA indicate, 

either by regulation or by repeated 

emphasis in the preamble of this final 

standard and in all respirator 

guidelines, that these requirements also 

apply to overexposures involving 

unregulated substances. Hewett also 

stated that OSHA should not require 

employers to comply with MUCs 

calculated using NIOSH RELs when 

these MUCs are lower than the MUCs 

calculated using OSHA PELs. He 

recommended as well that OSHA 

should specify an upper bound on 

MUCs that is a percentage of the IDLH 

for a substance, e.g., the MUC is no 

more than 25% of the IDLH. 

Michael Watson of the International 

Brotherhood of Teamsters, AFL–CIO 

(Ex. 9–12), Pete Stafford of the Building 

and Construction Trades Department, 

AFL–CIO (Ex. 9–29), and Rick N. Givens 

of the Augusta Utilities Department (Ex. 

10–2) agreed with using the IDLH as a 

limiting factor for MUCs. Givens also 

recommended that OSHA specify 10% 

of the LEL as an additional limiting 

factor for MUCs. 

Michael Runge of the 3M Company 

(Exs. 9–16, 16–25, and 16–25–2) said 

that only APFs and IDLHs should be 

used to calculate MUCs. The LEL and 

eye irritation, as well as all other 

limitations, already are considered in 

the respirator selection process, and do 

not necessarily need to be considered 

when establishing specific MUCs. He 

did not support use of 10% of the LEL 

as a limiting factor, but stated that 

OSHA should specify the LEL when no 

IDLH is available for a chemical. He also 

stated that when employers use the REL 

for an unregulated contaminant to select 

a respirator, the APF and MUC 

principles specified in the proposal 

should apply. 

Kenneth Bobetich of Mine Safety 

Appliances (Ex. 9–37) believed that 

OSHA’s definition of MUC is sufficient 

to cover the limitations, and that MUCs 

should not be based on eye irritation. 

Tracy C. Fletcher of Parsons-Odebrecht 

JV (Ex. 10–1) recommended that OSHA 

use 10% of the LEL as an MUC-limiting 

factor. Accordingly, when the 

atmosphere reaches 10% of the LEL, the 

employee should be removed and steps 

taken to make the work area safe (e.g., 

ventilate the area). When the area 

cannot be made safe, the employer 

should provide the employee with a 

fire-retardant suit and supplied air. 

3. Summary and Conclusions 

As noted above in the discussion of 

the MUC definition, the final standard 

will require employers to use an OSHA 

exposure limit when available. 

However, absent an OSHA exposure 

limit, employers must use relevant 

available information combined with 

informed professional judgment to 

determine MUCs. The purpose of this 

approach is to permit employers to rely 

on existing data sources and 

professional judgment when 

determining an MUC that will provide 

adequate protection for their employees 

from hazardous airborne contaminants 

that have no OSHA exposure limit. 

E. MUCs for Mixtures and Hazard Ratios 

1. MUCs for Mixtures 

Paragraph (d)(3)(i)(B)(1) requires 

employers to select respirators for 

employee use that maintains the 

employees exposure to the hazardous 

substance at or below the MUC. 

However, a question arises regarding 

how to make these calculations for 

mixtures. Question 12 in Section VIII. 

(‘‘Issues’’) of the proposal addressed this 

issue by requesting comments on the 

proposed MUC for mixtures., About half 

of the commenters supported the MUC 

provisions as proposed, but believed 

that insufficient data were available to 

perform the calculations for mixtures 

(Exs. 9–23, 9–37, 10–17, 10–25, and 10–

59). Another group of commenters 

supported performing the calculations 

based on information that each 

component of a mixture has a nonadditive effect on independent organ 

systems. In this case, the commenters 

suggested either a separate MUC for 

each component, or lowering the MUC 

according to the proportion of each 

component in the mixture (Exs. 9–12, 9–

13, 9–22, 9–29, and 9–37). Still others 

recommended lowering the MUC by an 

unspecified proportion when individual 

components of the mixture have 

synergistic effects on organ systems (Ex. 

9–42), or simply requiring employers to 

use supplied-air respirators when 

employees are exposed to mixtures (Ex. 

10–1). 

Daniel K. Shipp of the International 

Safety Equipment Association (Ex. 9–

22) pointed out that the effect of the 

mixture on canister/cartridge service life 


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must be evaluated, and an appropriate 

change schedule established for a 

mixture of gases or vapors. Shipp 

indicated that no MUC equation is 

available for mixtures. He suggested that 

when the health effects of a mixture’s 

components are not additive, then each 

component should be evaluated 

separately, and the respirator must be 

appropriate for the sum of the 

individual chemical concentrations. 

Kenneth Bobetich of Mine Safety 

Appliances (Ex. 9–37) noted that no 

evidence exists to indicate that 

respirator performance is different when 

the exposure is to a mixture of 

particulates versus a single particulate. 

However, the effect of a mixture of gases 

or vapors on canister/cartridge service 

life must be evaluated, and an 

appropriate change schedule 

established. He further mentioned that 

Dr. Gerry Wood of LANL is conducting 

a study to evaluate the effect of mixtures 

on service life, and is developing a 

model to predict cartridge service life. 

Bobetich indicated that when the health 

effects of the mixture components are 

on the same organ system and these 

effects are additive, an additive formula 

can be used to establish the PEL for the 

mixture. However, when the health 

effects are not additive, then each 

component should be evaluated 

individually and the respirator must be 

appropriate for the sum of the 

individual chemical concentrations. 

Thomas Nelson of NIHS, Inc. (Ex. 10–

17) said that, because exposures to 

multiple organic vapors will affect the 

service life of a cartridge, the employer 

already is required to consider multiple 

contaminants in setting a cartridge 

change schedule. He recommended that, 

to determine the MUC for a mixture that 

affects the same organ system, 

employers should assume that the 

health effects of each component are 

additive. 

Frank A. White of ORC Worldwide 

(Ex. 10–27) indicated that exposure to 

multiple gas or vapor contaminants may 

affect the service life of respirator filters 

and cartridges differently than exposure 

to a single contaminant. He, too, 

mentioned that Dr. Gerry Wood is 

working on this issue with NIOSH, and 

that a service life calculation model for 

multiple contaminants will soon be 

available. He emphasized that the more 

important consideration in determining 

MUCs for mixtures is the health effects 

of multiple contaminants. He stated that 

the employers are in the best position to 

apply recommendations from chemical 

manufacturers and information on 

health effects to their specific 

workplaces. He noted that industrial 

hygienists should determine if the 

contaminants have additive health 

effects, and they should use the additive 

mixture formula set by ACGIH and 

OSHA to calculate the MUC. 

Michael Watson of International 

Brotherhood of Teamsters, AFL-CIO (Ex. 

9–12) and Pete Stafford of the Building 

and Construction Trades Department, A 

FL-CIO (Ex. 9–29) stated: 

The presence of multiple contaminants in 

the workplace should be taken into 

consideration when the employer determines 

the MUC and respirator change schedules for 

gases and vapors. Mixtures may have similar 

effects on chemical cartridge loading, so the 

MUC of each component of a mixture should 

be lowered in proportion to its percentage of 

the total concentration of contaminants in 

air. 

Paul Schulte of NIOSH (Exs. 9–13, 

13–11–1, and 16–4) recommended that 

the equation C1/MUC1 + C2/MUC2 + 

* * * + Cn/MUCn = 1 should be used to 

determine MUCs for mixtures. He 

asserted that the MUC would be safe 

only when the result is ≥1. Schulte also 

stated that the rated service life of the 

cartridge may be shortened during 

exposure to a mixture (i.e., one or more 

of the mixture’s components may break 

through before the rated end-of-servicelife). 

Ted Steichen of American Petroleum 

Institute (Ex. 9–23) indicated that no 

data are available comparing respirator 

performance during exposure to 

multiple contaminants and exposure to 

single contaminants, and that it is 

impractical to discuss establishing 

different MUCs for mixtures. Stephan C. 

Graham of the United States Army 

Center for Health Promotion and 

Preventive Medicine (Exs. 9–42, 9–42–

1, and 9–42–2) stated that MUCs for 

mixtures should differ from MUCs for 

single compounds depending on 

whether the health effects are additive 

or synergistic. 

Tracy C. Fletcher of ParsonsOdebrecht JV (Ex. 10–1) believed that 

supplied-air respirators should be used 

to eliminate the risk of filter failure 

caused by chemical reactions that may 

occur among the components of a 

mixture. Lorraine Krupa-Greshman of 

the American Chemistry Council (ACC) 

(Ex. 10–25) indicated that by addressing 

contaminants with additive effects, 29 

CFR 1910.1000(d)(2)(i) and the proposal 

provide adequate means of achieving 

suitable protection. Also, she said that 

MUCs can be developed for multiple 

contaminants that have independent 

health effects by using the change 

schedule provisions of 

1910.134(d)(3)(iii)(B)(2). The ACC does 

not believe that adequate information 

and data are available to develop MUCs 

for mixtures with synergistic effects. 

Lisa M. Brosseau of the University of 

Minnesota (Ex. 10–59) believed that the 

issue of mixtures, as addressed in the 

proposal, is confusing and incorrect. 

She stated that the only requirements 

needed are to assure that respirators 

have the required filters and that gases 

and vapors have appropriate cartridges. 

2. Use of Hazard Ratios 

Michael Runge of the 3M Company 

(Ex. 9–16), Daniel K. Shipp of the 

International Safety Equipment 

Association (Ex. 9–22), and Lisa M. 

Brosseau of the University of Minnesota 

(Ex. 10’59) supported another method 

for selecting respirators, the hazard ratio 

(HR). The HR is defined as the ratio of 

the workplace concentration of an 

airborne contaminant divided by the 

occupational exposure limit (e.g., PEL). 

Any respirator that has an APF equal to 

or greater than the HR may be selected. 

They stated that the HR is more useful 

to employers than MUCs because 

employers likely will have information 

on airborne concentrations and 

occupational exposure limits when 

selecting respirators. Both Runge and 

Shipp said that the HR is similar to the 

MUC. Brosseau noted that it makes 

more sense to use the HR rather than the 

MUC to select respirators, and she 

recommended that OSHA require the 

HR method, and use the MUC as 

guidance. 

OSHA is not adopting hazard ratios 

under this final rulemaking because it 

was not addressed in the notice of 

proposed rulemaking. Accordingly, 

OSHA would have to provide the public 

with notice and an opportunity for 

comment on this issue before taking 

such action. 

3. Summary and Conclusions 

OSHA agrees with the commenters 

who stated that the data on mixtures are 

limited, and that no revision is needed 

for OSHA’s proposed singlecontaminant MUC definition (Exs. 9–23, 

9–37, 10–17, 10–25, and 10–59). The 

existing requirement for setting change 

schedules for respirator cartridges and 

canisters specified in 29 CFR 1910.134 

(d)(3)(iii)(B)(2) already requires that 

employers consider the effects of each 

component in organic vapor mixtures 

when they develop change schedules. 

The Agency recognizes that reliable 

methods are not available to develop 

MUCs for mixtures based on whether 

the components of the mixture act 

additively or synergistically, and 

whether they affect the same organ or 

different organs. Therefore, OSHA will 

rely on the provisions at 29 CFR 

1910.1000(d)(2)(i) to assist employers in 

calculating MUCs. 


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While the determination of MUCs and 

service life are both necessary for 

respirator selection, they should not be 

confused. MUCs can be used to decide 

if a certain type of respirator even 

qualifies for consideration for use in 

defined workplace concentrations. 

Service life estimation identifies how 

long a properly selected respirator can 

be expected to provide worker 

protection and, therefore, is useful for 

setting change schedules. 

OSHA has established at 29 CFR 

1910.1000(d)(2)(i) an equivalent 

exposure requirement for mixtures of air 

contaminants. Accordingly, MUCs for 

respirators used in a mixture of 

contaminants must satisfy the following 

equation: 

Em = (C1 ÷ L1 + C2 ÷ L2) + * * * + (Cn

÷ Ln) 

Where: 

Em is the equivalent exposure for the 

mixture 

C is the concentration of a particular 

contaminant 

L is the exposure limit for that 

substance 

The value of Em shall not exceed unity 

(1). 

OSHA is maintaining the MUC as a 

requirement in the final standard for 

determining the maximum 

concentration of an airborne 

contaminant from which a respirator 

will protect an employee. In addition, 

the Agency cannot revise the final rule 

to mandate the use of hazard ratios 

because the regulated community must 

have adequate notice of, and an 

opportunity to comment on, any such 

revision to the standard. 

F. MUC Provisions 

1. Paragraph (d)(3)(i)(B)—MUC 

Provisions 

These final requirements consist of 

three separate paragraphs ((d)(3)(i)(B)(1) 

through (d)(3)(i)(B)(3)). Paragraph 

(d)(3)(i)(B)(1), which sets the 

requirements for the use and application 

of MUCs, reads, ‘‘The employer must 

select a respirator for employee use that 

maintains the employee’s exposure to 

the hazardous substance, when 

measured outside the respirator, at or 

below the MUC.’’ This paragraph, which 

has the same designation in the 

proposal, requires employers to select 

respirators for employee protection that 

are appropriate to the ambient levels of 

the hazardous substance found in the 

workplace, i.e., that the ambient level of 

the hazardous substance must never 

exceed the MUC, which is the exposure 

limit specified for the hazardous 

substance multiplied by the respirator’s 

APF. Accordingly, this provision 

ensures that employers maintain 

employees’ direct exposure to 

hazardous substances (i.e., inside the 

respirator) below levels specified by 

OSHA’s Z tables and substance-specific 

standards, and, when OSHA has no 

standards, below exposure levels 

determined by the employer. Therefore, 

this provision provides employee 

protection consistent with existing 

regulatory requirements and prevailing 

industrial-hygiene practice. 

In the MUC provision following 

paragraph (d)(3)(i)(B)(1) in the proposal, 

OSHA had incorporated a note that 

stated: ‘‘MUCs are effective only when 

the employer has a continuing, effective 

respiratory protection program as 

specified by 29 CFR 1910.134, including 

training, fit testing, maintenance and 

use requirements.’’ The Agency is 

removing this note because the program 

already is required under its Respiratory 

Protection Standard for all employers 

using respirators, and OSHA believes 

that duplicating this information in a 

note is unnecessary. 

The second MUC provision in the 

proposal, paragraph (d)(3)(i)(B)(2), 

required employers to use MUCs 

determined by respirator manufacturers 

when those MUCs were lower than the 

MUCs determined using the general 

calculation (i.e., MUC = APF × PEL). 

Several commenters objected to the 

proposed provision, stating that it gave 

regulatory status to manufacturer’s 

MUCs (e.g., Exs. 9–10, 9–22, 9–23, 9–24, 

9–26, and 10–13). However, the Agency 

often defers in its rules to instructions 

and other documents published by 

manufacturers (e.g., no fewer than seven 

provisions of OSHA’s Respiratory 

Protection Standard refer to 

manufacturers’ instructions or 

recommendations). Nevertheless, the 

Agency believes that the proposed 

provision is unnecessary because using 

the general calculation specified in the 

MUC definition is an accepted safe 

practice in the industrial-hygiene 

community. 

Paragraph (d)(3)(i)(B)(2) of the final 

MUC provisions (which was designated 

as paragraph (d)(3)(i)(B)(3) in the 

proposal) specifies that employers must 

not use MUCs to select respirators for 

employees who are entering an IDLH 

atmosphere. OSHA previously specified 

the requirements for selecting 

respirators for use in IDLH atmospheres 

in paragraph (d)(2) of its Respiratory 

Protection Standard. Paragraph (d)(2) 

requires employers to select for this 

purpose a full facepiece pressuredemand SCBA certified by NIOSH to 

have a service life of at least 30 minutes, 

or a combination full facepiece 

pressure-demand supplied-air respirator 

with an auxiliary self-contained air 

supply. In the preamble to the final 

Respiratory Protection Standard, the 

Agency justified selecting these 

respirators as follows: ‘‘In [IDLH] 

atmospheres there is no tolerance for 

respirator failure. This record supported 

OSHA’s preamble statement that IDLH 

atmospheres ‘require the most 

protective types of respirators for 

workers’ ’’ (59 FR 58896). Commenters 

to the APF proposal, including NIOSH, 

ANSI, and representatives of both labor 

and management, agreed that employees 

should use these respirators, which are 

the most protective respirators available, 

when exposed to IDLH atmospheres. 

(See 63 FR 1201 for a more complete 

discussion of these comments.) 

Ted Steichen of the American 

Petroleum Institute (Ex. 9–23) requested 

that OSHA clarify that a pressuredemand full facepiece SAR with 

auxiliary SCBA can be used at an APF 

higher than 1,000. He said that positivepressure SARs with auxiliary SCBAs 

often are used by the petroleum 

industry for non-emergency work in 

high-hazard operations (e.g., cleaning 

refinery flare systems) that may involve 

potential exposures greater than 1,000 

times the PEL. Under proposed Table 1, 

he questioned whether OSHA would 

consider this use of SARs with auxiliary 

SCBAs to be acceptable. The Agency 

notes that paragraph (d)(2)(i)(B) of its 

Respiratory Protection Standard already 

permits employers to use a combination 

full facepiece pressure-demand 

supplied-air respirator (SAR) with 

auxiliary self-contained air supply in 

IDLH atmospheres. Also, paragraph 

(d)(3)(i)(A) of this final standard states, 

‘‘When using a combination respirator 

* * * employers must ensure that the 

assigned protection factor is appropriate 

to the mode of operation in which the 

respirator is being used.’’ In this case, 

the combination pressure-demand full 

facepiece SAR with auxiliary SCBA 

respirator is equivalent to an SCBA, 

and, therefore, the APF for an SCBA 

applies. 

The last MUC provision, proposed 

paragraph (d)(3)(i)(B)(4), would have 

required that ‘‘[w]hen the calculated 

MUC exceeds another limiting factor 

such as the IDLH level for a hazardous 

substance, the lower explosive limit 

(LEL), or the performance limits of the 

cartridge or canister, then employers 

must set the maximum MUC at that 

lower limit.’’ Accordingly, the IDLH 

limits for hazardous substances would 

take precedence over the calculated 

MUC when the IDLH limits result in 

lower employee exposures to the 

hazardous substances. Consequently, 


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this provision increases employee 

protection against these hazardous 

substances. OSHA is retaining a revised 

version of this proposed provision in 

the final rule (redesignated as paragraph 

(d)(3)(i)(B)(3)). The remaining 

paragraphs of this subsection discuss 

the revisions. 

The previous discussion of MUCs for 

substances with no OSHA PEL or other 

limiting factors (see subsection 2 

(‘‘MUCs for Substances with No OSHA 

PEL or Other Limiting Factor’’) of this 

section) addressed the use of the LEL as 

a limiting factor to be considered when 

calculating the MUC. NIOSH did not 

agree with the use of the LEL as a 

limiting factor for MUCs in respirator 

selection unless the respirator is the 

source of an ignition hazard (Ex. 9–13). 

Alcoa, Inc. did not believe OSHA 

should use the LEL as a limiting factor 

for MUCs since the LEL ‘‘is not healthbased, rather it is an independent 

indicator of a physical hazard’’ (Ex. 10–

31). The American Chemical Council 

commented using the LEL to set MUCs 

was confusing and inappropriate, 

because the LEL is used to determine 

whether an employee can safely enter 

an area with a fire hazard, not for 

selecting respirators (Ex. 10–25). The 

American Petroleum Institute also 

questioned the use of the LEL to limit 

the MUC because the LEL has no 

relationship to the protection provided 

by a respirator, but is a factor to 

consider when working with flammable 

or combustible substances (Ex. 9–23). 

The 3M Company stated that the LEL 

already is required under the 

Respiratory Protection Standard when 

selecting respirators, and does not need 

to be taken into account when 

establishing specific MUCs (Ex. 9–16). 

The Agency agrees with these 

commenters that the LEL is not 

appropriate as a limiting factor in 

setting MUCs. Therefore, OSHA 

removed from paragraph (d)(3)(i)(B)(3) 

in the final rule the language that 

identified the LEL as a limiting factor in 

setting MUCs. The Agency made this 

revision to the proposal because the LEL 

is not related to the performance of the 

respirator, but is an independent 

indicator of a physical hazard (i.e., the 

flammability or combustibility of a 

substance) that already must be 

considered when determining whether 

an employee can safely enter a 

hazardous area. 

The revised and redesignated final 

paragraph (d)(3)(i)(B)(3) now reads as 

follows: 

(3) When the calculated MUC exceeds the 

IDLH level for a hazardous substance, or the 

performance limits of the cartridge or 

canister, then employers must set the 

maximum MUC at that lower limit. 

G. Superseding the Respirator Selection 

Provisions of Substance-Specific 

Standards in Parts 1910, 1915, and 1926 

1. Introduction 

OSHA proposed to revise the 

provisions in its substance-specific 

standards under 29 CFR parts 1910, 

1915, and 1926 that regulate APFs 

(except the APF requirements for the 

1,3-Butadiene Standard at 29 CFR 

1910.1051). These substance-specific 

standards specify numerous 

requirements for regulating employee 

exposure to toxic substances. The 

proposed revisions would have removed 

the APF tables from these standards, as 

well as any references to these tables, 

and would have replaced them with a 

reference to the APF and MUC 

provisions specified by proposed 

paragraphs (d)(3)(i)(A) and (d)(3)(i)(B) of 

the Respiratory Protection Standard at 

29 CFR 1910.134. In justifying these 

proposed revisions, the Agency stated 

that the proposed revisions would 

simplify compliance for employers by 

removing many APF requirements 

across its substance-specific standards. 

The proposed revisions would enhance 

consolidation and uniformity of these 

requirements, and conform them to each 

other and to the general APF and MUC 

requirements specified by 29 CFR 

1910.134 (68 FR 34107). 

As noted elsewhere in this preamble 

to the final APF rule, OSHA developed 

the final APFs using the best available 

evidence. The development of these 

final APFs included a careful review of 

the comments, testimony, data, and 

other evidence submitted to the 

rulemaking record, a quantitative (i.e., 

statistical) analysis of the results from 

WPF studies performed among workers 

wearing air-purifying half mask 

respirators (both filtering facepieces and 

elastomerics) discussed above in this 

preamble, and a thorough quantitative 

and qualitative review of existing WPF 

and SWPF studies performed with other 

types of respirators. Using the best data 

and analytic techniques available, as 

well as the extensive comments and 

testimony provided to the rulemaking 

record, lends a high degree of reliability 

and validity to the final APF 

determinations. 

The Agency believes that the final 

APFs developed under this rulemaking 

will improve the substance-specific 

standards. The final APFs will provide 

employers with confidence that their 

employees will receive the level of 

protection from airborne contaminants 

signified by these APFs when they 

implement a respiratory protection 

program that complies with the 

requirements of 29 CFR 1910.134. In 

addition, applying the final APFs to the 

substance-specific standards is 

consistent with OSHA’s goal of bringing 

uniformity to its respiratory protection 

requirements. Moreover, protection for 

workers likely will be increased because 

the final APFs result in regulatory 

consistency, enhanced employer 

compliance, and reduced the 

compliance burden on the regulated 

community, and, consequently, further 

increases the protection afforded to 

employees who use respirators. 

In its Respiratory Protection Standard, 

OSHA noted that the revised standard 

was to ‘‘serve as a ‘‘building block’’

standard with respect to future 

standards that may contain respiratory 

protection requirements.’’ (See 63 FR 

1265, 1998.) However, in the proposed 

APF rulemaking that would provide 

generic APFs and MUCs as part of the 

Respiratory Protection Standard, the 

Agency decided to retain former 

respirator selection provisions in the 

existing substance-specific standards 

that it found supplemented or 

supplanted the proposed APFs and 

MUCs (e.g., organic vapor cartridge and 

canister procedures, prohibiting use of 

filtering facepieces or half mask 

respirators). OSHA did so because these 

provisions enhance the respirator 

protection afforded to employees. 

2. Comments Regarding the Respirator 

Selection Provisions of the 1,3- 

Butadiene Standard 

The former respirator selection 

provisions being retained in this final 

rule include those provisions in the 1,3- 

Butadiene (BD) Standard. In issue 13 of 

the proposed APF rule (68 FR 34112), 

OSHA asked if exclusion of this 

standard was warranted. The responses 

to this question addressed only the 

service life requirement for cartridges 

used to absorb atmospheric BD. Typical 

of these responses is the following 

comment from the 3M Company: 

A short service life does not affect the 

ability of a specific respirator to reduce a 

concentration of a contaminant below the 

PEL. * * * [W]ith the cartridge change 

requirements in 1910.134 there is no need to 

limit the use of organic vapor cartridges or 

canisters to specific levels of BD. The 

employer is required to determine a useful 

service life. If that service life is very short, 

the employer will need to determine if the 

replacement schedule is realistic. (Ex. 18–7.) 

However, two other commenters 

made important observations. First, the 

American Chemistry Council 

representative noted that ‘‘[E]xclusion of 

[the BD] standard is reasonable since 

this standard has a more comprehensive 


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respirator section that includes end of 

service life specifications’ (Ex. 10–25). 

Second, ORC Worldwide stated, 

‘‘Excluding [BD] is warranted. 

Additional verbiage relative to service 

lives developed under a negotiated 

rulemaking process should not be 

changed’’ (Ex. 10–27). 

Commenters who recommended 

adopting the change-out schedule 

provisions of 29 CFR 1910.134 provided 

no compelling rationale for disturbing 

the extensive change-out schedules 

developed for the BD Standard on the 

recommendation of industry and labor 

representatives . Substituting the 

performance-based provisions that 

regulate change schedules under 29 CFR 

1910.134 for the existing BD Standard’s 

change schedule provisions for the sake 

of convenience is insufficient 

justification for revisiting these 

relatively recently promulgated 

provisions. In this regard, the latter two 

commenters clearly recognized the 

importance of the process that resulted 

in the existing change schedule 

requirements. 

In the preamble to the final BD 

Standard, the Agency reviewed test data 

that demonstrated short breakthrough 

times for BD concentrations above 50 

ppm. Accordingly, these short 

breakthrough times justified setting at 

50 ppm the upper limit at which 

employees can use air-purifying 

respirators for protection against BD 

exposures. The Agency used these data 

to develop change schedules for 

cartridges and canisters that are unique 

for BD exposures (see Table 1 of the BD 

Standard). OSHA reviewed the test data 

when it published the final standard in 

1996 and found that these conclusions 

remain valid. The Agency believes that 

it would impose an unnecessary burden 

on employers who are subject to the BD 

Standard to require them to repeat the 

review already conducted by OSHA on 

BD breakthrough times, and then 

develop their own change-out schedules 

under 29 CFR 1910.134. Moreover, 

employee protection from exposure to 

BD is unlikely to be increased. 

The Agency acknowledged in the 

preamble to the final BD Standard that 

it took a conservative approach to 

employee protection. In this regard, 

OSHA noted that its ‘‘decision to rely on 

the more protective NIOSH APFs is 

based on evidence showing that organic 

vapor cartridges and canisters have 

limited capacity for adsorbing BD and 

may have too short a service life when 

used in environments containing greater 

than 50 ppm BD.’’ (See 61 FR 56816.) 

With regard to the change-out 

schedules, the Agency concluded: 

Allowing for a reasonable margin of 

protection, and given that test data were 

available only for a few makes of cartridges 

and canisters, OSHA believes that airpurifying devices should not be used for 

protection against BD present in 

concentrations greater than 50 ppm, or 50 

times the 1 ppm PEL. Thus, OSHA finds that 

the ANSI APFs of 100 for full facepiece, airpurifying respirators and 1,000 for PAPRs 

equipped with tight-fitting facepieces are 

inappropriate for selecting respirators for BD. 

Accordingly, OSHA is retaining the 

respirator selection provisions of the BD 

Standard to avoid imposing on 

employers the new burden of 

developing their own change-out 

schedules, and to ensure maximum 

protection for employees exposed to BD. 

3. Comments Regarding the Respirator 

Selection Provisions of Other 

Substance-Specific Standards 

The Agency proposed to retain a 

number of special respirator selection 

provisions in the existing substancespecific standards. In this regard, OSHA 

noted that the respirator selection 

requirements proposed for retention 

were developed in rulemakings to 

provide protection against a hazardous 

characteristic or condition that is 

unique to the regulated substance. 

Additionally, the Agency stated that 

retaining these requirements would not 

increase the existing employer burden 

because they already must comply with 

these requirements. Consequently, 

retaining these provisions would 

maintain the level of respiratory 

protection currently afforded to 

employees. These provisions were in 

the substance-specific standards 

regulating employee exposure to vinyl 

chloride, inorganic arsenic, asbestos, 

benzene, coke oven emissions, cotton 

dust, ethylene oxide, and formaldehyde. 

Under issue 13 in the proposal, OSHA 

requested comments on the need to 

standardize the respirator selection 

provisions being proposed for retention. 

The Agency received numerous 

comments and hearing testimony on 

this issue. Most of these comments and 

testimony encouraged OSHA not to 

retain these provisions in their existing 

form, but instead to subsume these 

provisions under the Respiratory 

Protection Standard at 29 CFR 1910.134. 

An example of such a recommendation 

was provided by the 3M Company (3M) 

when it stated, in its hearing testimony, 

‘‘It is neither necessary nor justified to 

retain any of the specific requirements 

in the substance-specific standards. 

* * * They do not reflect the changes 

in science and technology, respirator 

design, respirator certification, or 

respirator regulation under 29 CFR 

1910.134’’ (Tr. at 393). In subsequent 

testimony, a representative from 3M 

stated, ‘‘We contend that requiring 

separate respirator APFs and selection 

requirements in the substance-specific 

standards as proposed would only add 

confusion to the respirator selection 

process, and is not justified by any 

scientific or practical evidence’’ (Tr. at 

394). Thomas Nelson of NIHS, Inc., 

provided similar rationale in support of 

standardizing these provisions, stating: 

The proposal would retain information 

[on] cartridge change schedules, filter 

selection and some specific respirator 

selection requirements in the substance 

specific standards. None of these 

requirements are necessary in the substance 

specific standard[s]. The current 1910.134 

with the addition of an assigned protection 

factor table contains requirements that are 

protective. (Ex. 18–9.) 

Many of these comments addressed 

issues involving single substancespecific standards, including their 

cartridge, canister, and filter 

requirements. The following paragraphs 

provide a summary of the comments 

that pertain to individual substancespecific standards, as well as OSHA’s 

response to these comments. 

• Inorganic Arsenic (29 CFR 

1910.1018). A commenter wanted 

OSHA to ‘‘[c]larify if filtering facepieces 

will be acceptable [under this 

standard],’’ and asserted that requiring 

‘‘gas masks or SARs for exposures above 

the PEL is unnecessary (Ex. 9–5). Two 

commenters, the Mine Safety 

Appliances Co., and the 3M Company, 

questioned the need to require a HEPA 

filter when using a cartridge or canister 

for exposures above a specified limit 

(Exs. 9–37, 18–7), while one of these 

commenters claimed that any filter 

approved by NIOSH under 42 CFR part 

84 would provide the required level of 

filter efficiency (Ex. 18–7). 

The Agency did not address, as part 

of this rulemaking, the use of filtering 

facepieces during inorganic arsenic 

exposures. This question deals with 

compliance. The other two commenters 

provided no basis for questioning the 

requirement for HEPA filters, while the 

issue of filters approved under 42 CFR 

part 84 is addressed below (see section 

entitled ‘‘Substituting N95 Filters for 

HEPA Filters’’). 

• Asbestos (29 CFR 1910.1001 and 29 

CFR 1926.1101). The 3M Company (3M) 

objected to the provision in this 

standard that prohibits the use of 

disposable half masks, but permits the 

use of elastomeric respirators, at 

asbestos concentrations that are 10 

times the PEL (Ex. 18–7). In these 

comments 3M stated that this disparity 

‘‘is counter to OSHA’s analysis of WPF 

data that does not show a difference 


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between filtering facepieces and 

elastomeric facepieces.’’ The 3M 

Company continued by noting that 

NIOSH stated that the aerosol size used 

in its respirator certification test ensures 

that filter performance will be at least as 

efficient ‘‘for essentially all other 

aerosol sizes’’ (see 60 FR 30344). While 

this comment implies that NIOSH 

would accept filtering facepieces for 

protection against asbestos, another 

commenter observed that the 1997 

NIOSH Pocket Guide to Chemical 

Hazards expressly prohibits such use 

(Ex. 18–5). 

The rebuttal made by the last 

commenter indicates that 3M’s concerns 

regarding the use of disposable 

respirators are controversial. 

Consequently, revision would require a 

new rulemaking. 

• Coke Oven Emissions (29 CFR 

1910.1029). A 3M representative 

asserted that OSHA made an error when 

it proposed to revise the term ‘‘singleuse respirator’’ to ‘‘filtering facepiece 

respirators’’ in item (b)(1) of Table 1 in 

paragraph (g)(3) of this standard (Ex. 

18–7). This commenter supported this 

assertion by noting that ‘‘[t]he ‘single 

use type’ respirator was a term that 

NIOSH started after promulgation of the 

coke oven emission standard,’’ and that 

‘‘[d]isposable dust/mist respirators are 

not prohibited from use under the * * * 

standard.’’ In conclusion, this 

commenter remarked that, by revising 

the term ‘‘single-use respirator’’ to 

‘‘filtering facepiece respirators,’’ the 

Agency is ‘‘prohibiting disposable 

particulate respirators from being used, 

which was not the intent of the original 

standard.’’ However, another 

commenter took exception to removing 

the proposed prohibition against all 

filtering facepiece respirators (Ex. 18–5), 

claiming that the particle size of coke 

oven emissions is unknown, and that 

coke oven fumes may degrade the 

electrostatic filters used in filtering 

facepieces. This commenter asserted 

that employers should use only HEPA 

filter cartridges, or P100 filtering 

facepieces that respirator manufacturers 

demonstrate will not degrade when 

exposed to coke oven fumes. 

The Agency agrees with the first 

commenter that the term ‘‘single-use 

respirator’’ is outdated. It believes that 

the regulated community now 

designates these respirators as filtering 

facepiece respirators. Accordingly, the 

definition of filtering facepiece 

respirators in paragraph (b) of 29 CFR 

1910.134 consists of three key 

characteristics—they function under 

negative pressure, are used against 

particulates and vapors, and consist of 

a filtering medium that is an integral 

part of the facepiece or that constitutes 

the entire facepiece. These 

characteristics also describe single-use 

respirators. This definition does not 

specify the functional characteristics of 

filtering facepieces, only their structural 

features. In this regard, both filtering 

facepiece and single-use respirators 

generally are considered disposable, 

with the period of effectiveness 

determined by the functional 

characteristics of either respirator. 

Therefore, because single-use and 

filtering facepiece respirators are 

identical with regard to their structural 

characteristics, OSHA is retaining the 

proposed terminology in the final APF 

standard. However, while paragraph 

(b)(1) of the Table I in the Coke Oven 

Emissions Standard prohibits using a 

single-use, filtering facepiece respirator, 

paragraph (b)(2) of this table permits its 

use when it functions as a ‘‘particulate 

filter respirator.’’ Accordingly, 

employers may select filtering facepiece 

respirators when employees are exposed 

to coke oven emissions and those 

emissions (1) consist solely of 

particulates, and (2) the exposure 

conditions are no more than 10 times 

the PEL for coke oven emissions. 

Finally, OSHA simply cannot adopt the 

recommendation of the second 

commenter to use only P100 filtering 

facepieces under these conditions as 

this issue was not part of this 

rulemaking. 

• Cotton Dust (29 CFR 1910.1043). 

The comments concerning this standard 

addressed whether filtering facepieces 

used to protect employees against cotton 

dust exposure should retain the current 

APF of 5 or be upgraded to an APF of 

10. In this regard, one commenter 

believed that revising this standard to 

upgrade the APF of filtering facepieces 

to 10 would be consistent with the 

results of OSHA’s statistical analysis of 

WPF studies for filtering facepiece 

respirators (Ex. 18–7). This commenter 

stated, ‘‘[F]iltering facepieces should 

have the same APF of 10 for cotton dust 

as they would for all other dusts. 

Filtering facepieces do not show 

selective performance to cotton dust 

versus other aerosols.’’ Three additional 

commenters echoed a similar concern 

with regard to filtering facepieces used 

against cotton dust. Two of these 

commenters noted that no technical 

reason exists ‘‘to reduce the APF to 5 for 

filtering facepieces’’ (Exs. 9–22 and 9–

37), while the third commenter stated 

that ‘‘[n]ot allowing filtering facepieces 

for greater than 5 times the PEL is 

inconsistent with an APF of 10 

indicated in [proposed] Table 1’’ (Ex. 9–

42). 

Several commenters responded 

negatively to the recommendations to 

raise the APF from 5 to 10 for filtering 

facepieces used for protection against 

cotton dust (Exs. 12–7–1 and 18–5; Tr. 

at 41–43). However, these commenters 

provided no technical or safety-andhealth rationale for their position. 

Typical of these comments was the 

following statement made at the 

rulemaking hearing by one of the 

participants: ‘‘If OSHA goes ahead and 

assigns a 10 * * * for [filtering 

facepieces] for the cotton dust standard 

* * *, you’re going against what was 

established way back when and settled 

by the court [at] an APF of 5.’’ (Tr. at 

43.) 

The first set of commenters 

recommended revising this standard to 

raise the APF for filtering facepieces 

from 5 to 10, consistent with the APF 

for filtering facepieces proposed for 29 

CFR 1910.134. However, the Agency did 

not propose to raise the APF for filtering 

facepieces used against cotton dust, and 

the record is inadequate to make that 

decision at this time. The second set of 

comments noted that revising the APF 

from 5 to 10 for filtering facepieces used 

during exposures to cotton dust would 

be foreclosed by the court’s decision in 

Minnesota Mining and Manufacturing 

Co. v. OSHA, 825 F.2d 482 (D.C. Cir. 

1987); this decision upheld the Cotton 

Dust Standard’s assignment of an APF 

of 5 for disposable respirators. While 

OSHA is not revising the APF for 

filtering facepieces used against cotton 

dust at this time, the Agency notes that 

the court’s decision in this case does not 

preclude it from revising the Cotton 

Dust Standard in the future based on an 

appropriate rulemaking record. 

4. Change-Out Schedules for Vinyl 

Chloride (29 CFR 1910.1017), Benzene 

(29 CFR 1910.1028), Formaldehyde (29 

CFR 1910.1048), and Ethylene Oxide (29 

CFR 1910.1047) 

The International Safety Equipment 

Association (ISEA), the Mine Safety 

Appliances Co., and the 3M Company 

(3M) requested OSHA to remove the 

existing cartridge change-out schedules 

under the Vinyl Chloride Standard and 

replace them with the change-out 

schedule provisions of 29 CFR 1910.134 

(Exs. 9–22, 9–37, and 18–7). In its 

comments on this issue, 3M stated that 

‘‘the nature of toxicity of any analyte 

does not affect the service life of a 

chemical cartridge’’ (Ex. 18–7). ISEA 

and 3M submitted similar comments 

regarding the existing cartridge changeout schedules in the Benzene Standard 

(Exs. 9–22 and 18–7). Accordingly, 3M 

noted that the Agency should not limit 

cartridge selection to only organic vapor 


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11OSHA published this decision at 44 FR 5446 

(January 26, 1979). 

cartridges specified for benzene 

absorption, but should expand the 

permitted cartridges to organic vapor 

cartridges for acid gas or formaldehyde 

absorption, as well as multi-gas 

cartridges (Ex. 18–7). The three 

commenters also recommended that 

OSHA remove the requirements for 

cartridges, filters, and the cartridge 

change-out schedules in the Ethylene 

Oxide Standard, as well as the 

specifications for cartridges/canisters 

and change-out schedules in the 

Formaldehyde Standard, asserting that 

employers could refer to 29 CFR 

1910.134 to obtain the necessary 

information (Exs. 9–22, 9–37, and 18–7). 

In response to these commenters, the 

Agency notes that it believes that the 

minimum change-out schedules 

specified by these standards ensure that 

employers use the designated 

respirators at appropriate concentration 

levels of the regulated substance. OSHA 

also recognizes that retaining these 

specifications may limit employers’

flexibility in adopting change-out 

schedules. However, it considers this 

limitation justified because the specified 

change-out schedules provide a high 

level of protection for employees against 

the dangerous properties of these 

substances. In addition, adopting the 

change-out schedule provisions of 29 

CFR 1910.134 for current OSHA health 

standards is beyond the scope of this 

APF rulemaking. The Agency cannot 

make revisions to this final rule based 

on these comments because the 

regulated community must have 

adequate notice of, and an opportunity 

to comment on, any proposed revisions. 

5. Miscellaneous Comments Regarding 

Superseding Other Substance-Specific 

Standards 

A number of comments were general, 

and did not address a single substancespecific standard. These comments 

centered on respirator selection issues 

that involved two or more of the 

substance-specific standards, such as 

HEPA filters and training. The following 

paragraphs identify the issues addressed 

in these comments, and provide a 

summary of the comments that address 

these general issues, including OSHA s 

response to them. 

• Skin absorption and eye irritation. 

Three commenters argued that it was 

unnecessary to preclude the use of half 

masks against eye irritants in the 

Ethylene Oxide, Methylene Chloride, 

and Formaldehyde standards when 

employees wear appropriate eye 

protection with half masks (Exs. 9–22, 

9–37, and 9–42). A fourth commenter 

made a similar statement regarding 

protection against eye irritants, but did 

not identify any specific substances (Ex. 

9–59). One of these commenters asked, 

‘‘Why make it a requirement to wear eye 

protection unless the concentrations are 

at irritant levels?’’ (See Ex. 9–42.) This 

commenter also noted that OSHA does 

not permit the use of half mask 

respirators during exposure to arsenic 

trichloride, but did not apply this 

prohibition to other chemicals that 

employees may absorb rapidly through 

the skin. This commenter recommended 

that the Agency ‘‘[p]rovide consistent 

recommendations that involve 

chemicals that can be absorbed through 

the skin in significant amounts (e.g., 

chemicals with PEL or TLV with ‘skin’

notations).’’ Another commenter took a 

different approach to this issue, 

proposing that OSHA should ‘‘[r]emove 

all references to [the] use of respirators 

for protection from substances that can 

be absorbed through the skin or irritate 

the skin or eyes. There are other ways 

that the skin can be protected’’ (Ex. 10–

59). 

The purpose of this rulemaking was to 

provide the regulated community with 

notice of, and an opportunity to 

comment on, specific respirator 

selection provisions that the Agency 

proposed for revision. In this regard, 

OSHA proposed no revisions to any 

requirements in the substance-specific 

standards that addressed protection 

against eye or skin irritants. 

Accordingly, these provisions will 

remain intact. The Agency believes that 

the requirements of existing substancespecific standards that specify the use of 

protective clothing and the other 

personal protective equipment 

requirements of 29 CFR 1910 subpart D 

will prevent serious skin absorption of 

toxic substances. Moreover, provisions 

in the substance-specific standards that 

require the use of full facepiece 

respirators and other high-end 

respirators for eye protection will 

provide employees with an integrated 

protection system that assures 

maximum respiratory and eye 

protection. 

• HEPA Filters. Several commenters 

took exception to requirements in many 

substance-specific standards that some 

respirators use HEPA filters. For 

example, one commenter stated that 

NIOSH’s updated respirator testing 

protocol in 42 CFR 84 eliminated the 

need for HEPA filters (Ex. 9–22). 

Similarly, a second commenter noted 

that HEPA filters were no longer listed 

in the NIOSH certification categories, 

and that OSHA should update the 

language in the Respiratory Protection 

Standard to be consistent with these 

categories (Ex. 10–59). A third 

commenter recommended that the 

Agency remove references to HEPA 

filters from a number of its substancespecific standards because ‘‘[p]article 

properties such as size and form are no 

longer needed in filter selection’’ (Ex. 9–

37). Another commenter stated that 

P100 filters were equivalent to HEPA 

filters, and that OSHA should 

‘‘[p]rovide clear generic guidance on 

when HEPA or P100 filters should be 

used, as opposed to another less 

efficient filter’’(Ex. 9–42). 

In addressing other issues, one 

commenter stated that OSHA would be 

breaching an earlier decision if it 

superseded dust-mist-fume respirators 

with respirators using HEPA filters at 

lead levels that are equal to or below 0.5 

mg/m3 (Ex. 10–4).11 Another commenter 

recommended limiting the use of all 

electrostatic (fiber) filters (Ex. 18–5). 

This commenter based this 

recommendation on evidence presented 

at the 1994 NIOSH hearing on the 

proposed filter certification 

requirements of 42 CFR 84. This 

commenter stated that the evidence 

showed, when tested with a heated 

DEHP aerosol challenge agent, the 

average filter efficiency for electrostatic 

P100 filters was less than the average 

filter efficiency for respirators that used 

a mechanical filter media. In one of 

these tests, the average filter efficiency 

for a P100 electrostatic filter was as low 

as 84.5%. 

While it is beyond the scope of this 

rulemaking to make the revisions 

recommended by these commenters, the 

Agency notes that the definition of 

HEPA filters in paragraph (b) of 29 CFR 

1910.134 equates these filters with highend filters tested under the NIOSH 

certification scheme specified by 42 

CFR 84. In this regard, the definition 

notes that, under 42 CFR 84, HEPA 

filters are equivalent to the N100, R100, 

and P100 particulate filters certified by 

NIOSH. Therefore, the Respiratory 

Protection Standard already describes 

HEPA filters in language that equates 

them to N100, R100, and P100 filters 

certified by NIOSH (i.e., the terms are 

interchangeable). OSHA Directive No. 

CPL 2–0.120 of September 25, 1998 

(‘‘Inspection Procedures for the 

Respiratory Protection Standard’’) also 

states, ‘‘When HEPA filters are required 

by an OSHA standard, N100, R100, and 

P100 filters can be used to replace 

them.’’ In addition, an Agency letter of 

interpretation to Neoterik Health 

Technologies, Inc. dated March 18, 1996 

concludes that, ‘‘when any OSHA 

standard requires the use of HEPA 

filters[,] then the employer may satisfy 


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the requirement by choosing to use a 

P100, N100, or R100 filter certified 

under 42 CFR 84, since such filters 

would exhibit minimum leakage.’’

Therefore, for over eight years, OSHA 

has consistently equated HEPA filters to 

the high-end filters certified by NIOSH 

under 42 CFR 84. 

OSHA believes that this definition is 

sufficient to meet the recommendations 

of these commenters regarding the need 

to update the description of HEPA 

filters consistent with the NIOSH 

certification program, including the 

need to provide the ‘‘clear generic 

guidance’’ requested by one of the 

commenters (Ex. 9–42). As noted by 

another commenter (Ex. 9–37), the 

definition of HEPA filters contained in 

the Respiratory Protection Standard also 

specifies the filtering criterion that these 

filters must meet in terms of particulate 

size. The definition recognizes that the 

N100, R100, and P100 filters meet this 

criterion, thereby updating the HEPA 

definition as recommended by this 

commenter. 

Contrary to the assertions made by 

one of the commenters (Ex. 10–4), the 

Agency is not breaching its earlier 

decision to permit the use of dust-mistfume respirators (instead of respirators 

configured with HEPA filters) when 

employees are exposed to lead levels 

that are equal to or below 0.5 mg/m3. 

Although this commenter mentioned 

that the decision covered N95 

respirators as well, N95 respirators were 

not even available in 1979 when the 

Agency published the decision and, 

therefore, were never part of the 

decision. The remarks of the last 

commenter (Ex. 18–5) described special 

testing conditions (using a heated DEHP 

aerosol challenge agent) that appeared 

to degrade specific types of filters. 

While this information may be of 

interest to NIOSH in determining the 

efficacy of its filter certification 

program, it is unclear how useful this 

information would be in selecting 

respirators for use in workplaces that 

vary substantially from these 

specialized testing conditions. 

• Substituting N95 Filters for HEPA 

Filters. A representative for the 3M 

Company (3M) argued strongly that 

OSHA should require only N95 

particulate filters for respirators, noting 

that OSHA based the existing 

requirement to use HEPA filters under 

some exposure conditions on NIOSH’s 

outdated filter certification process 

specified in 30 CFR 11 (Tr. at 396). The 

3M Company then described a WPF 

study conducted by Jensen et al. in a 

steel foundry on employees who 

performed a grinding operation 

involving a heavy work load (i.e., as 

shown by high airflow rates through the 

filters) and exposure to an iron aerosol. 

The 3M Company claimed that under 

these conditions, no significant 

difference existed between P95 and 

P100 particulate filters used by these 

employees with regard to the percentage 

of workplace iron penetration inside the 

filter. In addition, they asserted that 

neither type of filter permitted any 

detectable oil mist penetration (Ex. 18–

7; Tr. at 397). 

Later in the hearing, when asked 

about the test conditions under which 

NIOSH certifies filter efficiency, the 3M 

representative stated: 

NIOSH’s testimony yesterday, which I 

agree with, is that they’ve got a worst case, 

or close to worst case, testing, and, as they’ve 

stated, * * * they expect performance in the 

workplace to be better than that rating. * * * 

So I believe that in the N95 filter[s], while 

you see a difference in their performance in 

the laboratory, when they’re used against 

workplace aerosols, there is no difference. 

(Tr. at 429.) 

In his testimony the previous day, the 

NIOSH representative made the 

following statement: 

Well, NIOSH does not accept the premise 

that efficiency levels for filters that we test 

should be considered at higher efficiency 

levels. The approval program designates an 

efficiency level for the filters, which is well 

known to be tested with a near-worst case 

aerosol. However, this is done so that every 

workplace does not have to conduct sizing 

tests before they selected proper filters in the 

workplace. We think that this is a proper way 

to go, and we also do not think that assuming 

particle sizes and greater efficiencies on the 

filters is a very wise approach for protecting 

workers. (Tr. at 121.) 

The 3M Company also mentioned that 

another justification for substituting 

N95 filters for N100 filters is that 

‘‘increased breathing resistance caused 

by use of a 100 filter may decrease 

overall respirator effectiveness by 

reducing user comfort and thereby 

reducing the time the respirator is 

worn’’ (Ex. 18–7). 

In its post-hearing comments, NIOSH 

acknowledged, ‘‘It is possible that a 

specific NIOSH certified 95-level filter 

may have filter penetration less than 5% 

in a specific workplace. However, this 

type of workplace-specific result may 

not be generalized to all 95-level filters 

in all workplace settings’’’ (Ex. 17–7–1). 

Later in these comments it stated, 

‘‘NIOSH has included rigorous 

certification tests to help assure that 

filter performance in the workplace will 

be maintained at least at the 

certification level even under severe 

conditions,’’ and ‘‘the NIOSH 

certification criteria are designed to 

assure that filters meet minimum 

performance requirements. NIOSH does 

not certify that they will perform any 

better than these criteria.’’

Revising the existing respirator 

selection requirements for HEPA filters, 

or for filters certified by NIOSH as 

N100, R100, and P100 under 42 CFR 

part 84, is beyond the scope of the 

present rulemaking. Additionally, the 

commenters did not provide any 

evidence demonstrating that 95-level 

filters would protect employees when 

used under the worst-case conditions 

simulated during the NIOSH 

certification tests. However, from the 

evidence presented here, OSHA believes 

that NIOSH’s filter certification program 

provides a substantial margin of 

protection to employees who use 

respirators. In addition, it is unclear 

from the study discussed by these 

commenters whether the results are 

applicable to the extreme range of 

exposure conditions used by NIOSH in 

its filter certification testing. 

Consequently, the Agency believes that 

adopting the recommendations made by 

these commenters may enable 

employers to purchase respirators that 

do not perform at the designated level 

of efficiency under extreme workplace 

exposure conditions, thereby 

jeopardizing seriously the health of their 

employees. Absent data demonstrating 

that 95-level filters perform effectively 

under near worst-case experienced 

conditions, OSHA is retaining its 

existing HEPA filter requirements. 

• Mixed-Versus Single-Substance 

Contaminants. Several commenters 

recommended superseding the 

individualized canister/cartridge 

change-out schedules in the substancespecific standards with the 

performance-based provisions for 

developing change-out schedules 

described in OSHA’s Respiratory 

Protection Standard. Their rationale for 

this recommendation is that schedules 

developed using the Respiratory 

Protection Standard provisions are 

capable of accommodating employee 

exposure to multiple contaminants, 

while the schedules provided in the 

substance-specific standards are limited 

to a single atmospheric contaminant. 

For example, 3M noted that: 

[T]he benzene standard requires the 

cartridges be changed before the beginning of 

the next shift. In a refinery, workers may be 

exposed to benzene along with [toluene] and 

[x]ylene. The change schedule should be 

based on the exposure to the mixture as 

required by 29 CFR 1910.134, not just the 

benzene, because the mixture may result in 

requiring the cartridge to be changed sooner 

than eight hours. By following the 

requirements of 134, a change schedule 

would be established resulting in changing 


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the cartridge before loss of service life, 

thereby, increasing worker protection. (Tr. at 

396.) 

The International Safety Equipment 

Association and Thomas Nelson of 

NIHS, Inc., made similar statements (Tr. 

at 518 and Ex. 18–9). In further 

justification, 3M remarked that 

‘‘[r]espirator program administrators 

may not be aware that the cartridge 

change schedules contained in the 

substance specific [standards] may not 

be protective if multiple contaminants 

are present’’ (Ex. 18–7). 

These comments are a variation of the 

comments cited earlier in this section 

that recommended removing the 

change-out schedules specified for 

substance-specific standards and 

replacing them with the provisions of 29 

CFR 1910.134 governing change-out 

schedules. This recommendation 

involves a major revision to these 

standards, and, therefore, is beyond the 

scope of this rulemaking. However, such 

a revision likely is unnecessary because 

change-out schedules involving 

multiple-contaminant exposures would 

not be covered under the substancespecific standards. Instead, employers 

must develop these change-out 

schedules for air-purifying respirators 

not equipped with an end-of-service-life 

indicator according to the requirements 

of the Respiratory Protection Standard, 

notably paragraph (d)(3)(iii)(B)(2). 

• Retaining APF Tables for Lead and 

Asbestos. Several unions requested that 

OSHA retain the revised APF tables in 

the construction standards for lead and 

asbestos. During the hearing, a 

representative from the Building 

Construction Trades Department of the 

AFL–CIO (BCTD) stated that unionmanagement training centers ‘‘conduct a 

great deal of worker training on lead and 

asbestos,’’ and that ‘‘these tables * * * 

greatly facilitate the understanding of 

appropriate respirator selection’’ (Tr. at 

615). This representative stated further: 

It is much more usable for these parties to 

go directly to the substance-specific standard 

with the air-monitoring results and choose 

the appropriate type of respirator. If 

employers had to do calculations to 

determine the appropriate type of respirator 

to select, that is simply an added barrier to 

compliance. Additionally, the tables are of 

great help when communicating the need for 

respirators to employers who may not 

normally be engaged in lead and asbestos 

work. (Tr. at 615.) 

The BCTD representative later noted 

that ‘‘[i]t’s the idea of jumping from [the 

respiratory protection] standard to [the 

lead/asbestos construction] standard, 

that’s why we don’t want the table 

[removed]’’ (Tr. at 647). The BCTD posthearing comments expanded on this 

testimony, stating, ‘‘Calculations to 

determine appropriate respirator add [a] 

barrier to compliance * * *’’ (Ex. 9–29). 

A representative of the Insulators and 

Asbestos Workers International 

(‘‘IAWI’’) found the tables to be 

invaluable as a teaching aid, and added 

that: 

I am asked by all types of people, 

regulators, legislators, facility engineers, 

owners of companies, [and] consultants 

where to find the information [about APFs]. 

I just tell them [to] look in the tables. * * * 

The common worker knows where to find 

this. It is where it should be. There are no 

OSHA libraries on the job sites. * * * I am 

asked by a lot of people in charge of sites 

where these [APFs] are in writing. If it is 

taken out of the rules, if it is not written, it 

will not be adhered to. (Tr. at 623.) 

However, this representative later 

admitted that ‘‘[e]very one of our 

supervisors gets a copy of an updated 

[construction] standard,’’ and ‘‘[h]e gets 

the 1910.134 [i.e., the Respiratory 

Protection Standard]’’ (Tr. at 645.) 

Similarly, another commenter remarked 

that ‘‘[e]mployers covered by 

[substance-]specific standards are 

already required to refer to 29 CFR 

1910.134 for most respirator program 

elements including fit testing, 

inspection and cleaning, and program 

evaluation,’’ and that ‘‘[i]f some 

employers would not bother to consult 

29 CFR 1910.134 for APFs, these same 

employers are most likely not 

complying with other necessary 

program elements’’(Ex. 18–7). 

The Agency believes that employers 

know they are required to use the 

Respiratory Protection Standard. 

Retaining the APF tables in the 

construction standards for lead and 

asbestos is unlikely to result in any 

savings or convenience to employers or 

other parties because these tables cannot 

be used safely and effectively without 

consulting the requirements of 29 CFR 

1910.134. Even one of the union 

representatives recognized this 

necessity when stating that supervisors 

must have access to both the 

construction standards and the 

Respiratory Protection Standard at the 

job site (Tr. at 646). In addition, OSHA 

believes that any respirator selection 

requirements that are unique to a 

substance-specific standard (i.e., not 

subsumed by this rulemaking under the 

Respirator Protection Standard) will 

remain available for easy access under 

the particular standard. In this regard, 

the Agency concludes that it is 

unnecessary to retain the APF tables for 

the lead and asbestos standards in the 

construction standards because the 

required APF tables can be assembled 

readily for training purposes from the 

available information in the revised 

substance-specific standards and the 

Respiratory Protection Standard. 

• Upgrading Respirator Type at 

Employee Request. At the hearing, the 

BCTD representative mentioned that 

several of the substance-specific 

standards required employers to 

upgrade respirators when requested to 

do so by employees. The representative 

encouraged the Agency to include such 

a requirement in current and future 

substance-specific standards (Tr. at 

616). The IAWI representative 

commented: 

[S]ome of our members, for a variety of 

reasons, like working in PAPRs. * * * Some 

people work in them, feel comfortable in 

them. They want them. And it makes them 

more at ease at doing their work. * * * It 

makes the person more productive, cools 

them down; there’s a variety of reasons. (Tr. 

at 648.) 

When asked how often employers 

upgrade respirators when doing so is 

discretionary, this representative 

replied, ‘‘I wouldn’t say it’s 100 percent. 

I’d say a portion of them would allow 

somebody that activity’’ (Tr. at 649). 

Placing a burden on employers to 

upgrade respirators at an employee’s 

request is beyond the scope of this 

rulemaking. However, the Agency 

recognizes the advantages, as well as 

disadvantages, to upgrading a respirator 

at an employee’s request. As it stated in 

the preamble to the Respiratory 

Protection Standard with regard to 

PAPRs: 

OSHA continues to believe that under 

some circumstances PAPRs provide superior 

acceptability. These include situations where 

employees wear respirators for full shifts, 

where employees frequently readjust their 

negative pressure respirators to achieve what 

they consider a more comfortable or tighter 

fit, and where the air flow provided by a 

PAPR reduces the employee’s psychological 

and physiological discomfort. However, 

where ambient temperatures are extremely 

high or low, PAPRs are often unacceptable 

because of the temperature of the airstream 

in the facepiece. * * * (63 FR 1201.) 

OSHA noted further, ‘‘The Agency 

continues to believe that it is good 

industrial hygiene practice to provide a 

respirator that the employee considers 

acceptable’’ (63 FR 1201). Therefore, 

employers are free to upgrade 

respirators voluntarily at an employee’s 

request when the employee meets the 

medical qualifications for using the 

respirator and receives the necessary 

training. 

5. Summary of Superseding Actions 

The following table summarizes final 

revisions to the existing respirator 

selection provisions of OSHA’s 


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substance-specific standards. Section 

VIII (‘‘Amendments to Standards’’) of 

this rulemaking notice provides the full, 

plain-language regulatory text of these 

final revisions. 

SUMMARY OF SUPERSEDING ACTIONS FOR SUBSTANCE-SPECIFIC STANDARDS

Existing provisions Final action 

29 CFR 1910.1001(g)(2)(ii) ....................................................................... Revise. 

.1001(g)(3) ................................................................................................ Remove Table 1 and revise. 

.1001(l)(3)(ii) .............................................................................................. Redesignate Table 2 as Table 1. 

.1017(g)(3)(i) ............................................................................................. Remove table and revise. 

.1017(g)(3)(iii) ............................................................................................ Remove. 

.1018 (Tables I and II) .............................................................................. Remove. 

.1018(h)(3)(i) ............................................................................................. Revise. 

.1018(h)(3)(ii) ............................................................................................ Remove. 

.1018(h)(3)(iii) ............................................................................................ Redesignate as .1018 (h)(3)(ii). 

.1025(f)(2)(ii) ............................................................................................. Remove Table II. 

.1025(f)(3)(i) .............................................................................................. Revise. 

.1027(g)(3)(i) ............................................................................................. Remove Table 2 and revise. 

.1028(g)(3)(ii) ............................................................................................ Remove Table 1. 

.1028(g)(2)(i) ............................................................................................. Revise. 

.1028(g)(3)(i) ............................................................................................. Revise. 

.1029(g)(3) ................................................................................................ Remove Table I and revise. 

.1043(f)(3)(i) .............................................................................................. Remove Table I and revise. 

.1043(f)(3)(ii) ............................................................................................. Revise. 

.1044(h)(3) ................................................................................................ Remove Table 1 and revise. 

.1045(h)(2)(i) ............................................................................................. Revise. 

.1045(h)(3) ................................................................................................ Remove Table I and revise. 

.1047(g)(3) ................................................................................................ Remove Table 1 and revise. 

.1048(g)(2) ................................................................................................ Revise. 

.1048(g)(3) ................................................................................................ Remove Table 1 and revise. 

.1050(h)(3)(i) ............................................................................................. Remove Table 1 and revise. 

.1052(g)(3) ................................................................................................ Remove Table 2 and revise. 

29 CFR 1915.1001(h)(2)(i) through (h)(2)(v) ............................................ Remove Table 1 and revise. 

29 CFR 1926.60(i)(3)(i) ............................................................................. Remove Table 1 and revise. 

.62 (f)(3)(i) ................................................................................................. Remove Table 1 and revise. 

.1101(h)(3)(i) through (h)(3)(iv) ................................................................. Remove Table 1 and revise. 

.1127(g)(3)(i) ............................................................................................. Remove Table 1 and revise. 

6. Use of Plain Language 

In the proposal, OSHA rewrote into 

plain language the respirator-selection 

provisions of the substance-specific 

standards retained in this final rule. The 

Agency received no comments on these 

proposed revisions. OSHA believes that 

using plain language will improve the 

uniformity and comprehensibility of 

these provisions. These improvements 

will, in turn, enhance employer 

compliance with the provisions and, 

concomitantly, increase the protection 

afforded to employees. The Agency also 

found that rewriting the respiratorselection provisions of the existing 

substance-specific standards into plainlanguage provisions did not alter the 

substantive requirements of the existing 

provisions. (The following table lists the 

plain-language provisions in the final 

rule and the corresponding provisions 

in the existing standards.) Therefore, 

OSHA is retaining these plain-language 

revisions in the final rule. 

PLAIN-LANGUAGE PROVISIONS IN THE FINAL RULE AND CORRESPONDING PROVISIONS IN THE EXISTING STANDARDS

Plain-language provisions Existing provisions 

§ 1910.1001(g)(2)(ii) .................................................................................. § 1910.1001(g)(2)(ii). 

§ 1910.1001(g)(3)(i) ................................................................................... § 1910.1001(g)(3); Table 1. 

§ 1910.1001(g)(3)(ii) .................................................................................. § 1910.1001(g)(3); Table 1. 

§ 1910.1017(g)(3)(i)(B) .............................................................................. § 1910.1017(g)(3)(i); undesignated table. 

§ 1910.1017(g)(3)(i)(C) .............................................................................. § 1910.1017(g)(3)(i); undesignated table. 

§ 1910.1018(h)(3)(i)(B) .............................................................................. § 1910.1018(h)(3)(i); Table II (footnote 2). 

§ 1910.1018(h)(3)(i)(C) .............................................................................. § 1910.1018(h)(3)(i); Table I and Table II. 

§ 1910.1018(h)(3)(i)(D)(1) ......................................................................... § 1910.1018(h)(3)(ii). 

§ 1910.1018(h)(3)(i)(D)(2) ......................................................................... § 1910.1018(h)(3)(i); Table II. 

§ 1910.1025(f)(3)(i)(B) ............................................................................... § 1910.1025(f)(3)(i); Table II (footnote 2). 

§ 1910.1025(f)(3)(i)(C) ............................................................................... § 1910.1025(f)(3)(i); Table II. 

§ 1910.1025(f)(3)(ii) ................................................................................... § 1910.1025(f)(3)(ii). 

§ 1910.1027(g)(3)(i)(B) .............................................................................. § 1910.1027(g)(3)(i)(B); Table 2 (footnote b). 

§ 1910.1027(g)(3)(i)(C) .............................................................................. § 1910.1027(g)(3)(i)(B); Table 2. 

§ 1910.1028(g)(3)(i)(B) .............................................................................. § 1910.1028(g)(3)(i); Table 1. 

§ 1910.1028(g)(3)(i)(C) .............................................................................. § 1910.1028(g)(3)(i); Table 1. 

§ 1910.1028(g)(3)(i)(D) .............................................................................. § 1910.1028(g)(3)(i); Table 1 (footnote 1). 

§ 1910.1029(g)(3) ...................................................................................... § 1910.1029(g)(3); Table I. 

§ 1910.1043(f)(3)(i)(A) ............................................................................... § 1910.1043(f)(3)(i); Table I. 


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PLAIN-LANGUAGE PROVISIONS IN THE FINAL RULE AND CORRESPONDING PROVISIONS IN THE EXISTING STANDARDS—

Continued 

Plain-language provisions Existing provisions 

§ 1910.1043(f)(3)(i)(B) ............................................................................... § 1910.1043(f)(3)(i); Table I. 

§ 1910.1043(f)(3)(ii) ................................................................................... § 1910.1043(f)(3)(ii). 

§ 1910.1044(h)(3)(ii) .................................................................................. § 1910.1044(h)(3); Table 1. 

§ 1910.1045(h)(3)(ii) .................................................................................. § 1910.1045(h)(3); Table I. 

§ 1910.1047(g)(3)(i) ................................................................................... No provision of the original ethylene oxide standard contains this text. 

However, the only respirators designated for selection are either full 

facepiece respirators or respirators with hoods and helmets. Also, 

§ 1910.1047(g)(4) (‘‘Protective clothing and equipment’’) states, 

‘‘When employees could have eye or skin contact with EtO or EtO 

solutions, the employer must select and provide * * * appropriate 

protective clothing or other equipment * * * to protect any area of 

the employee’s body that may come in contact with the EtO or EtO 

solution * * *.’’

§ 1910.1047(g)(3)(ii) .................................................................................. § 1910.1047(g)(3); Table 1. 

§ 1910.1047(g)(3)(iii) ................................................................................. § 1910.1047(g)(3); Table 1. 

§ 1910.1048(g)(2)(ii) .................................................................................. § 1910.1048(g)(2)(ii). 

§ 1910.1048(g)(3)(i)(B) .............................................................................. § 1910.1048(g)(3)(i); Table 1. 

§ 1910.1048(g)(3)(i)(C) .............................................................................. § 1910.1048(g)(3)(i); Table 1. 

§ 1910.1048(g)(3)(ii) .................................................................................. § 1910.1048(g)(3)(i); Table 1 (footnote 2). 

§ 1910.1048(g)(3)(iii) ................................................................................. § 1910.1048(g)(3)(ii). 

§ 1910.1050(h)(3)(i)(B) .............................................................................. § 1910.1050(h)(3)(i); Table 1. 

§ 1910.1050(h)(3)(i)(C) .............................................................................. § 1910.1050(h)(3)(i); Table 1. 

§ 1910.1050(h)(3)(i)(D) .............................................................................. § 1910.1050(h)(3)(i); Table 1 (footnote 2). 

§ 1910.1052(g)(3)(i) ................................................................................... No provision of the original methylene chloride standard contains this 

text. However, the only respirators designated for selection are either full facepiece respirators or respirators with hoods and helmets. 

Also, § 1910.1052(h)(1) (‘‘Protective work clothing and equipment’’) 

states, ‘‘Where needed to prevent MC-induced skin and eye irritation, the employer shall provide clean protective clothing and equipment which is resistant to MC * * *.’’

§ 1910.1052(g)(3)(ii) .................................................................................. § 1910.1052(g)(3); Table 2. 

§ 1915.1001(h)(2)(i) ................................................................................... § 1915.1001(h)(2)(i); Table 1. 

§ 1915.1001(h)(2)(ii) .................................................................................. § 1915.1001(h)(2)(i); Table 1. 

§ 1915.1001(h)(2)(iii) ................................................................................. § 1915.1001(h)(2)(iii)(A). 

§ 1915.1001(h)(2)(iv) ................................................................................. § 1915.1001(h)(2)(iv). 

§ 1915.1001(h)(2)(v) .................................................................................. § 1915.1001(h)(2)(v). 

§ 1926.60(i)(3)(i)(B) ................................................................................... § 1926.60(i)(3)(i); Table 1. 

§ 1926.60(i)(3)(i)(C) ................................................................................... § 1926.60(i)(3)(i); Table 1. 

§ 1926.60(i)(3)(i)(D) ................................................................................... § 1926.60(i)(3)(i); Table 1 (footnote 2). 

§ 1926.62(f)(3)(i)(B) ................................................................................... § 1926.62(f)(3)(i); Table 1 (footnote 2). 

§ 1926.62(f)(3)(i)(C) ................................................................................... § 1926.62(f)(3)(i); Table 1. 

§ 1926.1101(h)(3)(i)(A) .............................................................................. § 1926.1101(h)(3)(i); Table 1. 

§ 1926.1101(h)(3)(i)(B) .............................................................................. § 1926.1101(h)(3)(i); Table 1. 

§ 1926.1101(h)(3)(ii) .................................................................................. § 1926.1101(h)(3)(ii). 

§ 1926.1101(h)(3)(iii) ................................................................................. § 1926.1101(h)(3)(iii). 

§ 1926.1101(h)(3)(iv) ................................................................................. § 1926.1101(h)(3)(iv). 

§ 1926.1127(g)(3)(i)(B) .............................................................................. § 1926.1127(g)(3)(i); Table 1 (footnote b). 

§ 1926.1127(g)(3)(i)(C) .............................................................................. § 1926.1127(g)(3)(i); Table 1. 

VII. Procedural Determinations 

A. Legal Considerations 

The purpose of the Occupational 

Safety and Health Act, 29 U.S.C. 651 et 

seq. (‘‘the Act’’) is to ‘‘assure so far as 

possible every working man and woman 

in the Nation safe and healthful working 

conditions and to preserve our human 

resources’’ (29 U.S.C. 651(b)). To 

achieve this goal, Congress authorized 

the Secretary of Labor to promulgate 

and enforce occupational safety and 

health standards (see 29 U.S.C. 654(b) 

(requiring employers to comply with 

OSHA standards) and 29 U.S.C. 655(b) 

(authorizing promulgation of standards 

pursuant to notice and comment)). 

A safety or health standard is a 

standard ‘‘which requires conditions, or 

the adoption or use of one or more 

practices, means, methods, operations, 

or processes, reasonably necessary or 

appropriate to provide safe or healthful 

employment or places of employment.’’

(29 U.S.C. 652(8)). A standard is 

reasonably necessary or appropriate 

within the meaning of Section 652(8) of 

the Act when it substantially reduces or 

eliminates significant risk, and is 

technologically and economically 

feasible, cost effective, consistent with 

prior Agency action or supported by a 

reasoned justification for departing from 

prior Agency action, and supported by 

substantial evidence; it also must 

effectuate the Act’s purposes better than 

any national consensus standard it 

supersedes (see International Union, 

UAW v. OSHA (LOTO II), 37 F.3d 665 

(DC Cir. 1994; and 58 FR 16612–16616 

(March 30, 1993)). 

The APFs specified by this final rule 

are an integral part of OSHA’s 

Respiratory Protection Standard. This 

standard ensures that respirators reduce 

or eliminate the significant risk to 

employee health resulting from 

exposure to hazardous airborne 

substances. Accordingly, employers 

need the APFs provided in this final 

rule to select appropriate respirators for 

employees use when the employers 


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must rely on respirators to maintain 

hazardous substances at safe levels in 

the workplace. The APFs in this final 

rule will help ensure that the 

Respiratory Protection Standard 

achieves the annual health benefits 

estimated for that standard (i.e., 932 

averted work-related deaths (best 

estimate) and 4,046 work-related 

illnesses (best estimate)) (see 63 FR 

1173). 

In this rulemaking, OSHA also is 

superseding the existing APF 

requirements in its substance-specific 

standards. As noted in section V of this 

preamble (‘‘Summary of the Final 

Economic Analysis and Regulatory 

Flexibility Analysis’’), the Agency 

estimates that the final APFs will reduce 

significantly employee exposures to the 

hazardous airborne substances regulated 

by these substance-specific standards, 

especially asbestos, lead, cotton dust, 

and arsenic. Consequently, employees 

will receive additional protection 

against the chronic illnesses resulting 

from exposure to these hazardous 

substances, notably a variety of cancers 

and cardiovascular diseases. 

The Agency believes that a standard 

is technologically feasible when the 

protective measures it requires already 

exist, can be brought into existence with 

available technology, or can be 

developed using technology that can 

reasonably be expected to be available 

(see American Textile Mfrs. Institute v. 

OSHA (Cotton Dust), 452 U.S. 490, 513 

(1981); American Iron and Steel 

Institute v. OSHA (Lead II), 939 F.2d 

975, 980 (DC Cir. 1991)). A standard is 

economically feasible when industry 

can absorb or pass on the costs of 

compliance without threatening the 

industry’s long-term profitability or 

competitive structure (see Cotton Dust, 

452 U.S. at 530 n. 55; Lead II, 939 F.2d 

at 980), and a standard is cost effective 

when the protective measures it requires 

are the least costly of the available 

alternatives that achieve the same level 

of protection (see Cotton Dust, 452 U.S. 

at 514 n. 32; International Union, UAW 

v. OSHA (LOTO III), 37 F.3d 665, 668 

(DC Cir. 1994)). 

All standards must be highly 

protective (see 58 FR 16612, 16614–15 

(March 30, 1993); LOTO III, 37 F.3d at 

669). Accordingly, section 8(g)(2) of the 

Act authorizes OSHA ‘‘to prescribe such 

rules and regulations as [it] may deem 

necessary to carry out its 

responsibilities under the Act’’ (see 29 

U.S.C. 657(g)(2)). However, health 

standards also must meet the 

‘‘feasibility mandate’’ of section 6(b)(5) 

of the OSH Act, 29 U.S.C. 655(b)(5). 

Section 6(b)(5) of the Act requires 

OSHA to select ‘‘the most protective 

standard consistent with feasibility’’

needed to reduce significant risk when 

regulating health hazards (see Cotton 

Dust, 452 U.S. at 509). Section 6(b)(5) 

also directs OSHA to base health 

standards on ‘‘the best available 

evidence,’’ including research, 

demonstrations, and experiments (see 

29 U.S.C. 655(b)(5)). In this regard, 

OSHA must consider ‘‘in addition to the 

attainment of the highest degree of 

health and safety protection * * * the 

latest scientific data * * * feasibility 

and experience gained under this and 

other health and safety laws’’ (Id.). 

Furthermore, section 6(b)(5) of the Act 

specifies that standards must ‘‘be 

expressed in terms of objective criteria 

and of the performance desired’’ (see 29 

U.S.C. 655(b)(7)). 

The APF and MUC provisions in this 

final rule are integral components of an 

effective respiratory protection program. 

Respiratory protection is a supplemental 

method used by employers to protect 

employees against airborne 

contaminants in workplaces when 

feasible engineering controls and work 

practices are not available, have not yet 

been implemented, or are not in 

themselves sufficient to protect 

employee health. Employers also use 

respiratory protection under emergency 

conditions involving, for example, the 

accidental release of airborne 

contaminants. The amendments to 

OSHA’s Respiratory Protection 

Standard, and the Agency’s substancespecific standards, specified in this final 

rule will provide employers with 

critical information to use when 

selecting respirators for employees 

exposed to airborne contaminants found 

in general industry, construction, 

shipyard, longshoring, and marine 

terminal workplaces. Since it is 

generally recognized that different types 

of respiratory protective equipment 

provide different degrees of protection 

against hazardous exposures, proper 

respirator selection is of critical 

importance. Failure to select the proper 

respirator for use against exposure to 

hazardous substances may result in 

employees being overexposed to these 

substances, thereby resulting in an 

increased incidence of cancer, 

cardiovascular disease, and other 

illnesses. The APF and MUC provisions 

in this final rule will greatly enhance an 

employer’s ability to select a respirator 

that will adequately protect employees. 

The Agency also developed the 

provisions of this final rule to be 

feasible and cost effective, and is 

specifying them in terms of objective 

criteria and the level of performance 

desired. In this regard, section V of this 

preamble (‘‘Summary of the Final 

Economic Analysis and Regulatory 

Flexibility Screening Analysis’’) 

provides the benefits and costs of the 

final rule, and describes several other 

alternatives as required by section 205 

of the Unfunded Mandates Reform Act 

of 1995 (2 U.S.C. 1535). Based on this 

information, OSHA concludes that the 

APF and MUC provisions of the final 

rule constitute the most cost-effective 

alternative for meeting its statutory 

objective of reducing risk of adverse 

health effects to the extent feasible. 

Several benefits will accrue to 

respirator users and their employers 

from this rulemaking. First, the standard 

benefits workers by reducing their 

exposures to respiratory hazards. 

Improved respirator selection augments 

previous improvements to the 

Respiratory Protection Standard, such as 

better fit-test procedures and improved 

training, contributing substantially to 

greater worker protection. At the time of 

the 1998 revisions to the Respiratory 

Protection Standard, the Agency 

estimated that the standard would avert 

between 843 and 9,282 work-related 

injuries and illnesses annually, with a 

best estimate (expected value) of 4,046 

averted illnesses and injuries annually 

(63 FR 1173). In addition, OSHA 

estimated that the standard would 

prevent between 351 and 1,626 deaths 

annually from cancer and many other 

chronic diseases, including 

cardiovascular disease, with a best 

estimate (expected value) of 932 averted 

deaths from these causes. The APFs in 

this rulemaking will help ensure that 

these benefits are achieved, as well as 

provide an additional degree of 

protection. These APFs also will reduce 

employee exposures to several § 6(b)(5) 

chemicals covered by standards with 

outdated APF criteria, thereby reducing 

exposures to chemicals such as asbestos, 

lead, cotton dust, and arsenic. While the 

Agency did not quantify these benefits, 

it estimates that 29,655 employees 

would have a higher degree of 

respiratory protection under this APF 

standard. Of these employees, an 

estimated 8,384 have exposure to lead, 

7,287 to asbestos, and 3,747 to cotton 

dust, all substances with substantial 

health risks. 

In addition to health benefits, OSHA 

believes other benefits result from the 

harmonization of APF specifications, 

thereby making compliance with the 

respirator rule easier for employers. 

Employers also benefit from greater 

administrative ease in proper respirator 

selection. Employers no longer have to 

consult several sources and several 

OSHA standards to determine the best 

choice of respirator, but can make their 

choices based on a single, easily found 


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standard. Some employers who now 

hire consultants to aid in choosing the 

proper respirator should be able to make 

this choice on their own with the aid of 

this rule. In addition to having only one 

set of numbers (i.e., APFs) to assist them 

with respirator selection for nearly all 

substances, some employers may be able 

to streamline their respirator stock by 

using one respirator type to meet their 

respirator needs instead of several 

respirator types. The increased ease of 

compliance also yields additional health 

benefits to employees using respirators. 

B. Paperwork Reduction Act 

After a thorough analysis of the final 

provisions, OSHA believes that these 

provisions do not add to the existing 

collection-of-information (i.e., 

paperwork) requirements regarding 

respirator selection. OSHA determined 

that its existing Respiratory Protection 

Standard at 29 CFR 1910.134 has two 

provisions that involve APFs and also 

impose paperwork requirements on 

employers. These provisions require 

employers to: Include respirator 

selection in their written respiratory 

protection program (29 CFR 

1910.134(c)(1)(i)); and inform 

employees regarding proper respirator 

selection (29 CFR 1910.(k)(ii)). The 

information on respirator selection 

addressed by these two provisions must 

include a brief discussion of the 

purpose of APFs, and how to use them 

in selecting a respirator that affords an 

employee protection from airborne 

contaminants. The burden imposed by 

this requirement remains the same 

whether employers currently use the 

APFs published in the 1987 NIOSH RDL 

or the ANSI Z88.2–1992 Respiratory 

Protection Standard, or implement the 

final APFs in this rulemaking. 

Therefore, the use of APFs in the 

context of these two existing respirator 

selection provisions does not require an 

additional paperwork-burden 

determination because OSHA already 

accounted for this burden under its 

existing Respiratory Protection Standard 

(see 63 FR 1152–1154; OMB Control 

Number 1218–0099). 

Both OSHA’s existing Respiratory 

Protection Standard and the final APF 

provisions require employers to use 

APFs as part of the respirator selection 

process. This process includes obtaining 

information about workplace exposure 

to an airborne contaminant, identifying 

the exposure limit (e.g., permissible 

exposure limit) for the contaminant, 

using this information to calculate the 

required level of protection (i.e., the 

APF), and referring to an APF table to 

determine which respirator to select. 

Admittedly, this process involves the 

collection and use of information, but it 

does not require employers to inform 

others, either orally or in writing, about 

the process they use to select respirators 

for individual employees, or the 

outcomes of this process. By not 

requiring employers to communicate 

this information to others, OSHA 

removed this process from the ambit of 

the Paperwork Reduction Act of 1995 

(PRA–95) (44 U.S.C. 3506(c)(2)(A)). In 

the alternative, even if PRA–95 applies, 

the final provisions involve the same 

information collection and use 

requirements with regard to APFs as the 

existing standard (see paragraphs (d)(1) 

and (d)(3)(i) of 29 CFR 1910.134, and 

the rationale for the existing APF 

requirements in the preamble to the 

final Respiratory Protection Standard, 

63 FR 1163 and 1203–1204). 

Accordingly, the paperwork burden 

imposed by the final standard would be 

equivalent to the burden already 

imposed under the existing standard. 

C. Federalism 

The Agency reviewed the final APF 

provisions according to the most recent 

Executive Order on Federalism 

(Executive Order 13132, 64 FR 43225, 

August 10, 1999). This Executive Order 

requires that federal agencies, to the 

extent possible, refrain from limiting 

state policy options, consult with states 

before taking actions that restrict their 

policy options, and take such actions 

only when clear constitutional authority 

exists and the problem is of national 

scope. The Executive Order allows 

federal agencies to preempt state law 

only with the expressed consent of 

Congress. In such cases, federal agencies 

must limit preemption of state law to 

the extent possible. 

Under section 18 of the Occupational 

Safety and Health Act (‘‘the Act’’), 

Congress expressly provides OSHA with 

authority to preempt state occupational 

safety and health standards to the extent 

that the Agency promulgates a federal 

standard under section 6 of the Act. 

Accordingly, section 18 of the Act 

authorizes the Agency to preempt state 

promulgation and enforcement of 

requirements dealing with occupational 

safety and health issues covered by 

OSHA standards unless the state has an 

OSHA-approved occupational safety 

and health plan (i.e., is a state-plan 

state) (see Gade v. National Solid 

Wastes Management Association, 112 S. 

Ct. 2374 (1992)). Therefore, with respect 

to states that do not have OSHAapproved plans, the Agency concludes 

that this final rule conforms to the 

preemption provisions of the Act. 

Additionally, section 18 of the Act 

prohibits states without approved plans 

from issuing citations for violations of 

OSHA standards; the Agency finds that 

this final rulemaking does not expand 

this limitation. 

OSHA asserts that it has authority 

under Executive Order 13132 to issue 

final APF requirements because the 

problems addressed by these 

requirements are national in scope. As 

noted in section V (‘‘Summary of the 

Final Economic Analysis and 

Regulatory Flexibility Screening 

Analysis’’) of this preamble, hundreds 

of thousands of employers must select 

appropriate respirators for millions of 

employees. These employees are 

exposed to many different types and 

levels of airborne contaminants found in 

general industry (including healthcare), 

construction, shipyard, longshoring, and 

marine terminal workplaces. 

Accordingly, OSHA concludes that the 

requirements in this final rule will 

provide all covered employers in every 

state with critical information to use 

when selecting respirators to protect 

their employees from the risks of 

exposure to airborne contaminants. 

However, while OSHA drafted the final 

APF and MUC requirements to protect 

employees in every state, section 

18(c)(2) of the Act permits state-plan 

states to develop their own 

requirements to deal with any special 

workplace problems or conditions, 

provided these requirements are at least 

as effective as the requirements 

specified by this final rule. 

D. State Plans 

The 26 states and territories with their 

own OSHA-approved occupational 

safety and health plans must adopt 

provisions comparable to the provisions 

in this final rule within six months after 

the Agency publishes the rule. These 

State-Plan states and territories are: 

Alaska, Arizona, California, Hawaii, 

Indiana, Iowa, Kentucky, Maryland, 

Michigan, Minnesota, Nevada, New 

Mexico, North Carolina, Oregon, Puerto 

Rico, South Carolina, Tennessee, Utah, 

Vermont, Virginia, Washington, and 

Wyoming. Connecticut, New Jersey, 

New York, and the Virgin Islands have 

OSHA-approved State Plans that apply 

to state and local government employees 

only. Until a state-plan state 

promulgates its own comparable 

provisions, federal OSHA will provide 

the state with interim enforcement 

assistance, as appropriate. 

E. Unfunded Mandates 

The Agency reviewed the final APF 

and MUC provisions according to the 

Unfunded Mandates Reform Act of 1995 

(UMRA) (2 U.S.C. 1501 et seq.) and 

Executive Order 12875. As discussed in 


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section V (‘‘Summary of the Final 

Economic Analysis and Regulatory 

Flexibility Screening Analysis’’) of this 

preamble, OSHA estimates that 

compliance with this final rule will 

require private-sector employers to 

expend about $4.6 million each year. 

However, while this final rule 

establishes a federal mandate in the 

private sector, it is not a significant 

regulatory action within the meaning of 

section 202 of the UMRA (2 U.S.C. 

1532). 

OSHA standards do not apply to state 

and local governments, except in states 

that have voluntarily elected to adopt an 

OSHA-approved state occupational 

safety and health plan. Consequently, 

the provisions of this final rule do not 

meet the definition of a ‘‘Federal 

intergovernmental mandate’’(see section 

421(5) of the UMRA (2 U.S.C. 658(5)). 

Therefore, based on a review of the 

rulemaking record, the Agency believes 

that few, if any, of the affected 

employers are state, local, and tribal 

governments. Therefore, the 

requirements of this final rule do not 

impose unfunded mandates on state, 

local, and tribal governments. 

F. Applicability of Existing Consensus 

Standards 

Section 6(b)(8) of the Occupational 

Safety and Health Act (29 U.S.C. 

655(b)(8)) requires OSHA to explain 

‘‘why a rule promulgated by the 

Secretary differs substantially from an 

existing national consensus standard,’’

by publishing ‘‘a statement of the 

reasons why the rule as adopted will 

better effectuate the purposes of the Act 

than the national consensus standard.’’

Regarding APFs, the American National 

Standard Institute (ANSI) issued in 1992 

is the only publicly available consensus 

standard (i.e., ANSI Z88.2–1992, 

‘‘Respiratory Protection’’) that provided 

APFs for the various respirators covered 

by this final rule (i.e., ‘‘the 1992 ANSI 

APFs’’) (Ex. 1–50). However, ANSI 

withdrew this consensus standard in 

2003, and it has yet to officially adopt 

a replacement standard. 

The Agency relied heavily on the 

1992 ANSI APFs in developing this 

final standard. Nevertheless, the APFs 

specified in this final rule differ in 

important ways from the 1992 ANSI 

APFs. For example, the APFs for full 

facepiece air-purifying respirators differ 

substantially between the two 

standards. Additionally, the APF of 

1,000 for powered air-purifying 

respirators with helmets or hoods listed 

in Table 1 of this final rule is based on 

achieving specific test results, while the 

1992 ANSI APF for this respirator class 

is not contingent on any test results. As 

noted above in section VI of the 

preamble to this final rule (‘‘Summary 

and Explanation of the Final 

Standard’’), OSHA has determined that 

the differences between the APFs 

specified in this final rule and the 1992 

ANSI APFs will afford employees 

increased protection when they are 

exposed to hazardous airborne 

contaminants. Therefore, the Agency 

did not adopt outright the 1992 ANSI 

APFs under this final rule. 

In addition to the differences between 

the APF standards described in the 

previous paragraph, use of the 1992 

ANSI APFs depends on meeting six 

other respirator-selection provisions, 

several of which differ substantially 

from the respirator-selection provisions 

specified in OSHA’s Respiratory 

Protection Standard. In this regard, use 

of the 1992 ANSI APFs is contingent on 

‘‘the nature of the hazardous operation 

or process,’’ ‘‘the location of the 

hazardous area in relation to the nearest 

area having respirable air,’’ ‘‘the 

activities of workers in hazardous 

areas,’’ and ‘‘the physical characteristics 

and functional capabilities and 

limitations of the various types of 

respirators’’; none of these conditions is 

specified in this manner in the Agency’s 

Respiratory Protection Standard. 

Revising OSHA’s Respiratory Protection 

Standard to accommodate the six 

respirator-selection provisions that are 

an integral part of the 1992 ANSI APFs 

is beyond the scope of this rulemaking, 

which provides additional justification 

for the Agency not adopting directly the 

1992 ANSI APFs. 

Finally, the APFs adopted here 

represent a clear enforceable 

requirement, not merely a 

recommendation. When employers and 

employees can easily determine what 

respirator is appropriately protective, 

compliance is simplified and enhanced. 

List of Subjects in 29 CFR Parts 1910, 

1915, and 1926 

Assigned protection factors, Airborne 

contaminants, Health, Occupational 

safety and health, Respirators, 

Respirator selection. 

Authority and Signature 

Edwin G. Foulke, Jr., Assistant 

Secretary of Labor for Occupational 

Safety and Health, U.S. Department of 

Labor, 200 Constitution Ave., NW., 

Washington, DC 20210, directed the 

preparation of this notice. The Agency 

issues these final sections under the 

following authorities: Sections 4, 6(b), 

8(c), and 8(g) of the Occupational Safety 

and Health Act of 1970 (29 U.S.C. 653, 

655, 657); Section 3704 of the Contract 

Work Hours and Safety Standards Act 

(the Construction Safety Act) (40 U.S.C. 

3701 et seq.); Section 41, the Longshore 

and Harbor Worker’s Compensation Act 

(33 U.S.C. 941); Secretary of Labor’s 

Order No. 5–2002 (67 FR 65008); and 29 

CFR part 1911. 

Signed at Washington, DC on August 9, 

2006. 

Edwin G. Foulke, Jr., 

Assistant Secretary of Labor. 

VIII. Amendments to Standards 

■ For the reasons stated in the preamble 

of this final rule, the Agency is 

amending 29 CFR parts 1910, 1915, and 

1926 to read as follows: 

PART 1910—[AMENDED] 

Subpart I—[Amended] 

■ 1. Revise the authority citation for 

subpart I of part 1910 to read as follows: 

Authority: Sections 4, 6, and 8 of the 

Occupational Safety and Health Act of 1970 

(29 U.S.C. 653, 655, and 657); and Secretary 

of Labor’s Order No. 12–71 (36 FR 8754), 8–

76 (41 FR 25059), 9–83 (48 FR 35736), 1–90 

(55 FR 9033), 6–96 (62 FR 111), 3–2000 (62 

FR 50017), or 5–2002 (67 FR 65008), as 

applicable. 

Sections 1910.132, 1910.134, and 1910.138 

of 29 CFR also issued under 29 CFR part 

1911. 

Sections 1910.133, 1910.135, and 1910.136 

of 29 CFR also issued under 29 CFR part 

1911 and 5 U.S.C. 553. 

■ 2. Amend § 1910.134 as follows: 

■ a. Add the text of the definitions for 

‘‘Assigned protection factor (APF)’’ and 

‘‘Maximum use concentration (MUC)’’

to paragraph (b); 

■ b. Add the text of paragraphs 

(d)(3)(i)(A), including Table 1, and 

(d)(3)(i)(B); and 

■ c. Revise paragraph (n). 

The added and revised text reads as 

follows: 

§ 1910.134 Respiratory protection. 

* * * * * 

(b) * * * 

Assigned protection factor (APF) 

means 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 as 

specified by this section. 

* * * * * 

Maximum use concentration (MUC) 

means 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 


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exposure limit of the hazardous 

substance. The MUC can be determined 

mathematically by multiplying the 

assigned protection factor specified for 

a respirator by the required OSHA 

permissible exposure limit, short-term 

exposure limit, or ceiling limit. When 

no OSHA exposure limit is available for 

a hazardous substance, an employer 

must determine an MUC on the basis of 

relevant available information and 

informed professional judgment. 

* * * * * 

(d) * * * 

(3) * * * 

(i) * * * 

(A) Assigned Protection Factors 

(APFs). Employers must use the 

assigned protection factors listed in 

Table 1 to select a respirator that meets 

or exceeds the required level of 

employee protection. When using a 

combination respirator (e.g., airline 

respirators with an air-purifying filter), 

employers must ensure that the assigned 

protection factor is appropriate to the 

mode of operation in which the 

respirator is being used. 

TABLE 1.—ASSIGNED PROTECTION FACTORS 5

Type of respirator 1,2 Quarter 

mask Half mask Full facepiece 

Helmet/ 

hood 

Loose-fitting 

facepiece 

1. Air-Purifying Respirator ........................................................................ 5 3 10 50 .................... ....................

2. Powered Air-Purifying Respirator (PAPR) ........................................... .................... 50 1,000 4 25/1,000 25 

3. Supplied-Air Respirator (SAR) or Airline Respirator 

• Demand mode .............................................................................. .................... 10 50 .................... ....................

• Continuous flow mode .................................................................. .................... 50 1,000 4 25/1,000 25 

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

4. Self-Contained Breathing Apparatus (SCBA) 

• Demand mode .............................................................................. .................... 10 50 50 ....................

• Pressure-demand or other positive-pressure mode (e.g., open/ 

closed circuit) ................................................................................ .................... .................... 10,000 10,000 ....................

Notes: 

1Employers 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. 2The 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. 3This APF category includes filtering facepieces, and half masks with elastomeric facepieces. 

4The 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 WPF or 

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. 5These 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). 

(B) Maximum Use Concentration 

(MUC). (1) The employer must select a 

respirator for employee use that 

maintains the employee’s exposure to 

the hazardous substance, when 

measured outside the respirator, at or 

below the MUC. 

(2) Employers must not apply MUCs 

to conditions that are immediately 

dangerous to life or health (IDLH); 

instead, they must use respirators listed 

for IDLH conditions in paragraph (d)(2) 

of this standard. 

(3) When the calculated MUC exceeds 

the IDLH level for a hazardous 

substance, or the performance limits of 

the cartridge or canister, then employers 

must set the maximum MUC at that 

lower limit. 

* * * * * 

(n) Effective date. Paragraphs 

(d)(3)(i)(A) and (d)(3)(i)(B) of this 

section become effective November 22, 

2006. 

* * * * * 

Subpart Z—[Amended] 

■ 3. Revise the authority citation for 

subpart Z of part 1910 to read as 

follows: 

Authority: Sections 4, 6, and 8 of the 

Occupational Safety and Health Act of 1970 

(29 U.S.C. 653, 655, and 657); Secretary of 

Labor’s Orders 12–71 (36 FR 8754), 8–76 (41 

FR 25059), 9–83 (48 FR 35736), 1–90 (55 FR 

9033), 6–96 (62 FR 111), or 3–2000 (62 FR 

50017); and 29 CFR part 1911. 

* * * * * 

■ 4. Amend § 1910.1001 by: 

■ a. Removing Table 1 in paragraph 

(g)(3); 

■ b. Redesignating Table 2 in paragraph 

(l)(3)(ii) as Table 1; 

■ c. Removing the reference to ‘‘Table 

2’’ in paragraph (l)(3)(ii) and adding 

‘‘Table 1’’ in its place; and 

■ d. Revising paragraphs (g)(2)(ii) and 

(g)(3). 

The revisions read as follows: 

§ 1910.1001 Asbestos. 

* * * * * 

(g) * * * 

(2) * * * 

(ii) Employers must provide an 

employee with a tight-fitting, powered 

air-purifying respirator (PAPR) instead 

of a negative pressure respirator selected 

according to paragraph (g)(3) of this 

standard when the employee chooses to 

use a PAPR and it provides adequate 

protection to the employee. 

* * * * * 

(3) Respirator selection. Employers 

must: 

(i) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134; however, employers must not 

select or use filtering facepiece 

respirators for protection against 

asbestos fibers. 

(ii) Provide HEPA filters for powered 

and non-powered air-purifying 

respirators. 

* * * * * 

■ 5. In § 1910.1017, remove the table in 

paragraph (g)(3)(i), remove paragraph 

(g)(3)(iii), and revise paragraph (g)(3)(i) 

to read as follows: 

§ 1910.1017 Vinyl chloride. 

* * * * * 

(g) * * * 

(3) * * * 

(i) Employers must: 

(A) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134. 


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(B) Provide an organic vapor cartridge 

that has a service life of at least one 

hour when using a chemical cartridge 

respirator at vinyl chloride 

concentrations up to 10 ppm. 

(C) 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 backmounted canister, at vinyl chloride 

concentrations up to 25 ppm. 

* * * * * 

■ 6. In § 1910.1018, remove Tables I and 

II and paragraph (h)(3)(ii), redesignate 

paragraph (h) (3)(iii) as paragraph 

(h)(3)(ii), and revise paragraph (h)(3)(i) 

to read as follows: 

§ 1910.1018 Inorganic arsenic. 

* * * * * 

(h) * * * 

(3) * * * 

(i) Employers must: 

(A) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134. 

(B) Ensure that employees do not use 

half mask respirators for protection 

against arsenic trichloride because it is 

absorbed rapidly through the skin. 

(C) Provide HEPA filters for powered 

and non-powered air-purifying 

respirators. 

(D) Select for employee use: 

(1) 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 suppliedair respirators when the inorganic 

arsenic concentration is at or below 500 

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 μg/m3. 

* * * * * 

■ 7. In § 1910.1025, remove Table II in 

paragraph (f)(2)(ii) and revise 

paragraphs (f)(3)(i) and (f)(3)(ii) to read 

as follows: 

§ 1910.1025 Lead. 

* * * * * 

(f) * * * 

(3) * * * 

(i) Employers must: 

(A) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134. 

(B) Provide employees with full 

facepiece respirators instead of half 

mask respirators for protection against 

lead aerosols that cause eye or skin 

irritation at the use concentrations. 

(C) Provide HEPA filters for powered 

and non-powered air-purifying 

respirators. 

(ii) Employers must provide 

employees with a powered air-purifying 

respirator (PAPR) instead of a negative 

pressure respirator selected according to 

paragraph (f)(3)(i) of this standard when 

an employee chooses to use a PAPR and 

it provides adequate protection to the 

employee as specified by paragraph 

(f)(3)(i) of this standard. 

* * * * * 

■ 8. In § 1910.1027, remove Table 2 in 

paragraph (g)(3)(i) and revise paragraph 

(g)(3)(i) to read as follows: 

§ 1910.1027 Cadmium. 

* * * * * 

(g) * * * 

(3) * * * 

(i) Employers must: 

(A) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134. 

(B) Provide employees with full 

facepiece respirators when they 

experience eye irritation. 

(C) Provide HEPA filters for powered 

and non-powered air-purifying 

respirators. 

* * * * * 

■ 9. In § 1910.1028, remove Table 1 in 

paragraph (g)(3)(ii) and revise 

paragraphs (g)(2)(i) and (g)(3)(i) to read 

as follows: 

§ 1910.1028 Benzene. 

* * * * * 

(g) * * * 

(2) * * * 

(i) Employers must implement a 

respiratory protection program in 

accordance with 29 CFR 1910.134 (b) 

through (d) (except (d)(1)(iii)), and (f) 

through (m). 

* * * * * 

(3) * * * 

(i) Employers must: 

(A) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134. 

(B) Provide employees with any 

organic vapor gas mask or any selfcontained breathing apparatus with a 

full facepiece to use for escape. 

(C) Use an organic vapor cartridge or 

canister with powered and non-powered 

air-purifying respirators, and a chinstyle canister with full facepiece gas 

masks. 

(D) Ensure that canisters used with 

non-powered air-purifying respirators 

have a minimum service life of four 

hours when tested at 150 ppm benzene 

at a flow rate of 64 liters per minute 

(LPM), a temperature of 25 °C, and a 

relative humidity of 85%; for canisters 

used with tight-fitting or loose-fitting 

powered air-purifying respirators, the 

flow rates for testing must be 115 LPM 

and 170 LPM, respectively. 

* * * * * 

■ 10. In § 1910.1029, remove Table I in 

paragraph (g)(3) and revise paragraph 

(g)(3) to read as follows: 

§ 1910.1029 Coke oven emissions. 

* * * * * 

(g) * * * 

(3) Respirator selection. Employers 

must select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134; however, employers may use 

a filtering facepiece respirator only 

when it functions as a filter respirator 

for coke oven emissions particulates. 

* * * * * 

■ 11. In § 1910.1043, remove Table I in 

paragraph (f)(3)(i) and revise paragraphs 

(f)(3)(i) and (f)(3)(ii) to read as follows: 

§ 1910.1043 Cotton dust. 

* * * * * 

(f) * * * 

(3) * * * 

(i) Employers must: 

(A) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134; however, employers must not 

select or use filtering facepieces for 

protection against cotton dust 

concentrations greater than five times 

(5 ×) the PEL. 

(B) Provide HEPA filters for powered 

and non-powered air-purifying 

respirators used at cotton dust 

concentrations greater than ten times 

(10 ×) the PEL. 

(ii) Employers must provide an 

employee with a powered air-purifying 

respirator (PAPR) instead of a nonpowered air-purifying respirator 

selected according to paragraph (f)(3)(i) 

of this standard when the employee 

chooses to use a PAPR and it provides 

adequate protection to the employee as 

specified by paragraph (f)(3)(i) of this 

standard. 

* * * * * 

■ 12. In § 1910.1044, remove Table 1 in 

paragraph (h)(3) and revise paragraph 

(h)(3) to read as follows: § 1910.1044 

1,2-Dibromo-3-chloropropane. 

* * * * * 

(h) * * * 


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(3) Respirator selection. Employers 

must: 

(i) Select, and provide to employees, 

the appropriate atmosphere-supplying 

respirator specified in paragraph 

(d)(3)(i)(A) of 29 CFR 1910.134. 

(ii) Provide employees with one of the 

following respirator options to use for 

entry into, or escape from, unknown 

DBCP concentrations: 

(A) A combination respirator that 

includes a supplied-air respirator with a 

full facepiece operated in a pressuredemand 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. 

(B) An SCBA with a full facepiece 

operated in a pressure-demand or other 

positive-pressure mode. 

* * * * * 

■ 13. In § 1910.1045, remove Table I in 

paragraph (h)(3) and revise paragraphs 

(h)(2)(i) and (h)(3) to read as follows: 

§ 1910.1045 Acrylonitrile. 

* * * * * 

(h) * * * 

(2) * * * 

(i) Employers must implement a 

respiratory protection program in 

accordance with 29 CFR 1910.134 (b) 

through (d) (except (d)(1)(iii)), and (f) 

through (m). 

* * * * * 

(3) Respirator selection. Employers 

must: 

(i) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134. 

(ii) For escape, provide employees 

with any organic vapor respirator or any 

self-contained breathing apparatus 

permitted for use under paragraph 

(h)(3)(i) of this standard. 

* * * * * 

■ 14. In § 1910.1047, remove Table 1 in 

paragraph (g)(3) and revise paragraph 

(g)(3) to read as follows: 

§ 1910.1047 Ethylene oxide. 

* * * * * 

(g) * * * 

(3) Respirator selection. Employers 

must: 

(i) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134; however, employers must not 

select or use half masks of any type 

because EtO may cause eye irritation or 

injury. 

(ii) Equip each air-purifying, full 

facepiece respirator with a front-or backmounted canister approved for 

protection against ethylene oxide. 

(iii) For escape, provide employees 

with any respirator permitted for use 

under paragraphs (g)(3)(i) and (ii) of this 

standard. 

* * * * * 

■ 15. In § 1910.1048, remove Table 1 in 

paragraph (g)(3)(i) and revise paragraphs 

(g)(2) and (g)(3) to read as follows: 

§ 1910.1048 Formaldehyde. 

* * * * * 

(g) * * * 

(2) Respirator program. (i) Employers 

must implement a respiratory protection 

program in accordance with 29 CFR 

1910.134 (b) through (d) (except 

(d)(1)(iii)), and (f) through (m). 

(ii) When employees use air-purifying 

respirators with chemical cartridges or 

canisters that do not contain end-ofservice-life indicators approved by the 

National Institute for Occupational 

Safety and Health, employers must 

replace these cartridges or canisters as 

specified by paragraphs (d)(3)(iii)(B)(1) 

and (B)(2) of 29 CFR 1910.134, or at the 

end of the workshift, whichever 

condition occurs first. 

(3) Respirator selection. (i) Employers 

must: 

(A) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134. 

(B) Equip each air-purifying, full 

facepiece respirator with a canister or 

cartridge approved for protection 

against formaldehyde. 

(C) For escape, provide employees 

with one of the following respirator 

options: A self-contained breathing 

apparatus operated in the demand or 

pressure-demand mode; or a full 

facepiece respirator having a chin-style, 

or a front-or back-mounted industrialsize, canister or cartridge approved for 

protection against formaldehyde. 

(ii) Employers may substitute an airpurifying, half mask respirator for an 

air-purifying, full facepiece respirator 

when they equip the half mask 

respirator with a cartridge approved for 

protection against formaldehyde and 

provide the affected employee with 

effective gas-proof goggles. 

(iii) Employers must provide 

employees who have difficulty using 

negative pressure respirators with 

powered air-purifying respirators 

permitted for use under paragraph 

(g)(3)(i)(A) of this standard and that 

affords adequate protection against 

formaldehyde exposures. 

* * * * * 

■ 16. In § 1910.1050, remove Table 1 in 

paragraph (h)(3)(i) and revise paragraph 

(h)(3)(i) to read as follows: 

§ 1910.1050 Methylenedianiline. 

* * * * * 

(h) * * * 

(3) * * * 

(i) Employers must: 

(A) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134. 

(B) Provide HEPA filters for powered 

and non-powered air-purifying 

respirators. 

(C) For escape, provide employees 

with one of the following respirator 

options: Any self-contained breathing 

apparatus with a full facepiece or hood 

operated in the positive-pressure or 

continuous-flow mode; or a full 

facepiece air-purifying respirator. 

(D) Provide a combination HEPA filter 

and organic vapor canister or cartridge 

with powered or non-powered airpurifying respirators when MDA is in 

liquid form or used as part of a process 

requiring heat. 

* * * * * 

■ 17. In § 1910.1052, remove Table 2 in 

paragraph (g)(3) and revise paragraph 

(g)(3) to read as follows: 

§ 1910.1052 Methylene chloride. 

* * * * * 

(g) * * * 

(3) Respirator selection. Employers 

must: 

(i) Select, and provide to employees, 

the appropriate atmosphere-supplying 

respirator specified in paragraph 

(d)(3)(i)(A) of 29 CFR 1910.134; 

however, employers must not select or 

use half masks of any type because MC 

may cause eye irritation or damage. 

(ii) For emergency escape, provide 

employees with one of the following 

respirator options: A self-contained 

breathing apparatus operated in the 

continuous-flow or pressure-demand 

mode; or a gas mask with an organic 

vapor canister. 

* * * * * 

PART 1915—[AMENDED] 

■ 18. Revise the authority citation for 

part 1915 to read as follows: 

Authority: Section 41, Longshore and 

Harbor Workers’ Compensation Act (33 

U.S.C. 941); Sections 4, 6, and 8 of the 

Occupational Safety and Health Act of 1970 

(20 U.S.C. 653, 655, and 687); and Secretary 

of Labor’s Order No. 12–71 (36 FR 8754), 8–

76 (41 FR 25059), 9–83 (48 FR 35736), 1–90 

(55 FR 9033), 6–96 (62 FR 111), 3–2000 (62 

FR 50017), or 5–2002 (67 FR 65008) as 

applicable. 

Sections 1915.120 and 1915.152 of 29 CFR 

also issued under 29 CFR part 1911. 


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Federal Register / Vol. 71, No. 164 / Thursday, August 24, 2006 / Rules and Regulations 50191 

Subpart Z—[Amended] 

■ 19. In § 1915.1001, remove Table 1 in 

paragraph (h)(2)(iii) and revise 

paragraph (h)(2) to read as follows: 

§ 1915.1001 Asbestos. 

* * * * * 

(h) * * * 

(2) Respirator selection. (i) Employers 

must select, and provide to employees 

at no cost, the appropriate respirators 

specified in paragraph (d)(3)(i)(A) of 29 

CFR 1910.134; however, employers 

must not select or use filtering facepiece 

respirators for use against asbestos 

fibers. 

(ii) Employers are to provide HEPA 

filters for powered and non-powered 

air-purifying respirators. 

(iii) Employers must: 

(A) Inform employees that they may 

require the employer to provide a tightfitting, powered air-purifying respirator 

(PAPR) permitted for use under 

paragraph (h)(2)(i) of this standard 

instead of a negative pressure respirator. 

(B) Provide employees with a tightfitting PAPR instead of a negative 

pressure respirator when the employees 

choose to use a tight-fitting PAPR and 

it provides them with the required 

protection against asbestos. 

(iv) Employers must provide 

employees with an air-purifying, half 

mask respirator, other than a filtering 

facepiece respirator, whenever the 

employees perform: 

(A) Class II or Class III asbestos work 

for which no negative exposure 

assessment is available. 

(B) Class III asbestos work involving 

disturbance of TSI or surfacing ACM or 

PACM. 

(v) Employers must provide 

employees with: 

(A) A tight-fitting, powered airpurifying respirator or a full facepiece, 

supplied-air respirator operated in the 

pressure-demand mode and equipped 

with either HEPA egress cartridges or an 

auxiliary positive-pressure, selfcontained breathing apparatus (SCBA) 

whenever the employees are in a 

regulated area performing Class I 

asbestos work for which a negative 

exposure assessment is not available 

and the exposure assessment indicates 

that the exposure level will be at or 

below 1 f/cc as an 8-hour time-weighted 

average (TWA). 

(B) A full facepiece, supplied-air 

respirator operated in the pressuredemand mode and equipped with an 

auxiliary positive-pressure SCBA 

whenever the employees are in a 

regulated area performing Class I 

asbestos work for which a negative 

exposure assessment is not available 

and the exposure assessment indicates 

that the exposure level will be above 1 

f/cc as an 8-hour TWA. 

* * * * * 

PART 1926—[AMENDED] 

Subpart D—[Amended] 

■ 20. Revise the authority citation for 

subpart D of part 1926 to read as 

follows: 

Authority: Section 3704 of the Contract 

Work Hours and Safety Standards Act (40 

U.S.C. 3701 et seq.); Sections 4, 6, and 8 of 

the Occupational Safety and Health Act of 

1970 (29 U.S.C. 653, 655, and 657); Secretary 

of Labor’s Orders 12–71 (36 FR 8754), 8–76 

(41 FR 25059), 9–83 (48 FR 35736), 1–90 (55 

FR 9033), 6–96 (62 FR 111), 3–2000 (62 FR 

50017), or 5.2002 (67 FR 650008); as 

applicable; and 29 CFR part 11. 

Sections 1926.58, 1926.59, 1926.60, and 

1926.65 also issued under 5 U.S.C. 553 and 

29 CFR part 1911. 

Section 1926.62 of 29 CFR also issued 

under section 1031 of the Housing and 

Community Development Act of 1992 (42 

U.S.C. 4853). 

Section 1926.65 of 29 CFR also issued 

under section 126 of the Superfund 

Amendments and Reauthorization Act of 

1986, as amended (29 U.S.C. 655 note), and 

5 U.S.C. 553. 

■ 21. In § 1926.60, remove Table 1 and 

revise paragraph (i)(3)(i) to read as 

follows: 

§ 1926.60 Methylenedianiline. 

* * * * * 

(i) * * * 

(3) * * * 

(i) Employers must: 

(A) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134. 

(B) Provide HEPA filters for powered 

and non-powered air-purifying 

respirators. 

(C) For escape, provide employees 

with one of the following respirator 

options: Any self-contained breathing 

apparatus with a full facepiece or hood 

operated in the positive-pressure or 

continuous-flow mode; or a full 

facepiece air-purifying respirator. 

(D) Provide a combination HEPA filter 

and organic vapor canister or cartridge 

with air-purifying respirators when 

MDA is in liquid form or used as part 

of a process requiring heat. 

* * * * * 

■ 22. In § 1926.62, remove Table 1 in 

paragraph (f)(3)(ii) and revise paragraph 

(f)(3)(i) to read as follows: 

§ 1926.62 Lead. 

* * * * * 

(f) * * * 

(3) * * * 

(i) Employers must: 

(A) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134. 

(B) Provide employees with a full 

facepiece respirator instead of a half 

mask respirator for protection against 

lead aerosols that may cause eye or skin 

irritation at the use concentrations. 

(C) Provide HEPA filters for powered 

and non-powered air-purifying 

respirators. 

* * * * * 

Subpart Z—[Amended] 

■ 23. Revise the authority citation for 

subpart Z of part 1926 to read as 

follows: 

Authority: Section 3704 of the Contract 

Work Hours and Safety Standards Act (40 

U.S.C. 3701 et seq.); Sections 4, 6, and 8 of 

the Occupational Safety and Health Act of 

1970 (29 U.S.C. 653, 655, 657); Secretary of 

Labor’s Orders 12–71 (36 FR 8754), 8–76 (41 

FR 25059), 9–83 (48 FR 35736), 1–90 (55 FR 

9033), 6–96 (62 FR 111), 3–2000 (62 FR 

50017), or 5–2002 (67 FR 65008) as 

applicable; and 29 CFR part 11. 

Section 1926.1102 of 29 CFR not issued 

under 29 U.S.C. 655 or 29 CFR part 1911; 

also issued under 5 U.S.C. 553. 

■ 24. In § 1926.1101, remove Table 1 in 

paragraph (h)(3)(i) and revise paragraph 

(h)(3) to read as follows: 

§ 1926.1101 Asbestos. 

* * * * * 

(h) * * * 

(3) Respirator selection. (i) Employers 

must: 

(A) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134; however, employers must not 

select or use filtering facepiece 

respirators for use against asbestos 

fibers. 

(B) Provide HEPA filters for powered 

and non-powered air-purifying 

respirators. 

(ii) Employers must provide an 

employee with tight-fitting, powered 

air-purifying respirator (PAPR) instead 

of a negative pressure respirator selected 

according to paragraph (h)(3)(i)(A) of 

this standard when the employee 

chooses to use a PAPR and it provides 

adequate protection to the employee. 

(iii) Employers must provide 

employees with an air-purifying half 

mask respirator, other than a filtering 

facepiece respirator, whenever the 

employees perform: 

(A) Class II or Class III asbestos work 

for which no negative exposure 

assessment is available. 


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50192 Federal Register / Vol. 71, No. 164 / Thursday, August 24, 2006 / Rules and Regulations 

(B) Class III asbestos work involving 

disturbance of TSI or surfacing ACM or 

PACM. 

(iv) Employers must provide 

employees with: 

(A) A tight-fitting powered airpurifying respirator or a full facepiece, 

supplied-air respirator operated in the 

pressure-demand mode and equipped 

with either HEPA egress cartridges or an 

auxiliary positive-pressure, selfcontained breathing apparatus (SCBA) 

whenever the employees are in a 

regulated area performing Class I 

asbestos work for which a negative 

exposure assessment is not available 

and the exposure assessment indicates 

that the exposure level will be at or 

below 1 f/cc as an 8-hour time-weighted 

average (TWA). 

(B) A full facepiece supplied-air 

respirator operated in the pressuredemand mode and equipped with an 

auxiliary positive-pressure SCBA 

whenever the employees are in a 

regulated area performing Class I 

asbestos work for which a negative 

exposure assessment is not available 

and the exposure assessment indicates 

that the exposure level will be above 1 

f/cc as an 8-hour TWA. 

* * * * * 

■ 25. In § 1926.1127, remove Table 1 in 

paragraph (g)(3)(i) and revise paragraph 

(g)(3)(i) to read as follows: 

§ 1926.1127 Cadmium. 

* * * * * 

(g) * * * 

(3) * * * 

(i) Employers must: 

(A) Select, and provide to employees, 

the appropriate respirators specified in 

paragraph (d)(3)(i)(A) of 29 CFR 

1910.134. 

(B) Provide employees with full 

facepiece respirators when they 

experience eye irritation. 

(C) Provide HEPA filters for powered 

and non-powered air-purifying 

respirators. 

* * * * * 

[FR Doc. 06–6942 Filed 8–23–06; 8:45 am] 

BILLING CODE 4510–26–P 


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