Volume 14 Number 2 1996

By Alan Johnston, C.I.H.

The OSHA Office of Health Compliance has received numerous questions about respirator fit testing, fit checking and the reuse of new particulate respirators certified under the NIOSH 42 CFR 84 procedures. The proposed changes to 29 CFR 1910.134 and the new respirator certification procedures appear to have prompted these questions.

In response to these inquiries, OSHA's Directorate of Compliance Programs issued a March 6, 1996 memorandum to OSHA Regional Administrators providing information and guidance on current Agency respirator requirements. This memorandum replaced a February 26, 1996 memorandum
on the same subject.

Respirator fit testing and fit checking requirements

The OSHA memo states that the procedures and requirements for fit testing particulate respirators certified under 42 CFR 84 have not changed from those that are currently required by the Agency. Although 1910.134 does not specify the fit tests and protocols that are to be used, the new memo states that qualitative fit testing with Bitrex is acceptable, along with those methods published in OSHA's substance specific standard.

In addition, the new memo reconfirms OSHA's enforcement policy allowing the use of CNC (condensation nuclei counting, i.e., the Portacount manufactured by TSI) and CNP (controlled-negative pressure, i.e., the Dynatech Nevada Fit-Tester 3000) quantitative fit testing methods. The CNP method can be used for respirators with replaceable filters but is not applicable for filtering facepiece respirators.

Protection factors and QNFT

In the new enforcement policy, OSHA acknowledges that ANSI (American National Standards Institute) and NIOSH (National Institute for Occupational Safety and Health) assign an Assigned Protection Factor (APF) of 10 to maintenance-free filtering facepiece half-face respirators. OSHA then indicates that wearers must achieve
a minimum fit factor of 100 when performing a quantitative fit test (QNFT) with these respirators.
It is acceptable, however, to use
a qualitative fit test method.

The Agency states it has not formally assigned an APF to the Type 95, 99 or 100 respirators certified under 42 CFR 84, but will "take a formal position on the APFs" when the final respiratory protection standard is issued. Meanwhile, OSHA will continue to require a minimum fit factor of 100 for Type 95, 99 and 100 maintenance-free respirators when they are quantitatively fit tested.

OSHA specifically addresses
the use of 42 CFR 84 certified respirators for protection against occupational exposure to tuberculosis. The Agency reiterates that a fit factor of 100 must be obtained during QNFT, not a fit factor of 10 as the pass/fail point
for quantitative fit testing.

Qualitative fit testing

This protocol was developed by members of the 3M OH&ESD Laboratory. The memo also indicates that all QLFT protocols will be reviewed during revision of the respiratory protection standard.

Fit checking procedures

Reuse of maintenance-free filtering
facepiece respirators

In this final section of the new policy, OSHA accepts the NIOSH position on reuse of 42 CFR 84 respirators: Reuse is permitted, provided the respirators have not been damaged or soiled, the breathing resistance has not become great enough to cause discomfort
to the wearer (i.e., the respirator is not overloaded), and the integrity
of the respirator has not
been compromised.

For further information

Copies of the OSHA policy may be obtained by contacting your OSHA Regional Office or checking the OSHA Home Page on the Worldwide Web.

References

Bitrex is a trademark of MacFarlan Smith, Ltd.

By Lauri Alvarez

Background

In 42 CFR 84, NIOSH established not only new performance criteria but new categories for non-powered particulate filter, air-purifying respirators. The categories of dust, mist, fume and radionuclides, as well as paint spray and pesticide prefilters, have been eliminated and replaced with nine new classes of filters. These classes include three categories or series (N, R, P), each with three levels of filter efficiency against 0.3 micrometer (mass median aerodynamic diameter or MMAD) particles: 95%, 99% and 99.97%. N-series filters are restricted to non-oil aerosol particles (i.e., solid and water-based particles), while R- and P-series filters can be used if either oil or non-oil aerosols are present. Table 1 provides more detailed information about the N-, R- and P-series filters.

Since July 10, 1995, all new particulate filter respirators submitted to NIOSH for certification have been tested under the 42 CFR 84 requirements. However, NIOSH has allowed a three-year transition period (until July 10, 1998) for complete implementation of the new regulation, during which existing respirators certified under 30 CFR 11 can be sold by respirator manufacturers. This transition period also allows users time to evaluate their workplace contaminants, respiratory protection programs and work practices with respect to these new classes of particulate respirators.

The NIOSH User's Guide

In developing 42 CFR 84, NIOSH introduced "worst case" testing criteria, including use of test aerosols in the most penetrating size range. In doing this, NIOSH stated that 42 CFR-certified filters can be used against particles of any size in the workplace. In the User's Guide, therefore, particle size is not a criteria for selection of 42 CFR 84 products.

In order to properly select a respirator, NIOSH emphasizes there are several conditions that must be known, such as the identity and concentration of airborne particles in the workplace and the occupational exposure limit for
the contaminant (e.g., PEL). In addition, NIOSH notes that the hazard ratio (i.e., the airborne particulate concentration found
in the air divided by the OSHA permissible exposure limit), the respirator's assigned protection factor, and immediately dangerous to life and health (IDLH) concentrations still need to be considered. In fact, this information is needed—and has always been needed—prior to making any decision about respirator selection. It is not unique to selection of 42 CFR 84 products. What 42 CFR 84 does however, is necessitate that employers re-evaluate their workplaces in order to make a proper selection from the nine new classes of particulate filters. The selection of N-, R- and P-series filters depends on the presence or absence of oil particles.

In Appendix C to the User's Guide, NIOSH proposes the following criteria for selecting
42 CFR 84 particulate filters:

According to NIOSH, selection of filter efficiency depends on how much filter leakage can be accepted. How one actually decides on an acceptable level of filter leakage is not defined. Although higher filter efficiency obviously means lower filter leakage, filter efficiency in the actual workplace will essentially be higher than stated by NIOSH certification.
The efficiency rating is based
on laboratory testing against
0.3 micrometer particles. In actual workplace settings, the vast majority of operations generate particle sizes in excess of 0.3 micrometer (mass median aerodynamic diameter or MMAD), so the efficiency of the filters are often much greater than the
42 CFR 84 rating indicates.

3M experience indicates that other, more human variables actually have a greater impact on worker protection. These variables include face seal leakage, worker comfort and wear time. Facepiece leakage from poorly-fitting or improperly-maintained respirators often far exceeds filter penetration. Issues such as worker comfort, the ability to communicate and the need for facepiece cleaning, which directly affect respirator wear time, are also important to address during the selection process. These human variables will have greater impact on protection than the difference in filter efficiency.

In applications that previously required dust/mist and dust/fume/ mist approved respirators, NIOSH suggests that an N95 filter would provide an acceptable level of performance if workplace testing
has shown the environment to be free of oil aerosols. The User's Guide indicates that an N95-series filter provides appropriate respiratory protection for metal fumes generated by welding, for pesticides that are solid particles with low vapor pressure, for tuberculosis, and as a prefilter used in paint spray applications. However, if a work setting contains or may contain oil aerosols, an R95- or P95-series filter must be selected as the minimum level of performance.

For users of existing dust, mist, fume and HEPA filters, as well as paint spray and pesticide prefilters that have been properly selected, NIOSH makes the suggestions shown in Table 2. In situations where a HEPA respirator was previously required, the NIOSH User's Guide suggests that an N100 filter provides adequate protection for a worker, if the environment is free of all oil aerosols. If the work setting contains or may contain oils, NIOSH recommends an R100 or P100 filter be selected.

NIOSH also states, however, that this approach to selection may result in a recommendation that exceeds requirements since there may be instances where the 99% or 95% filters are appropriate substitutes for a HEPA filter. But these guidelines may not allow workers to take full advantage of the benefits of the new 95% efficient filters.

The selection of N-, R- and
P-series filters depends on whether oil aerosols are present. N-series filters are restricted to use only with non-oil aerosols, such as solid and water-based particles. R- and
P-series filters can be used for both oil and non-oil aerosols. If the work environment may contain oil particles or if it is uncertain whether oil particles are present, then the R- or P-series filters should be used. NIOSH suggests using the following guide to help remember the filter series:

The examples of oil-based aerosols that NIOSH provides include lubricants, cutting fluids and glycerin. These might be found in machine shops or operations involving plasticizers. Currently,
it is not clear which other aerosols should be treated as oils. For example, coke oven emissions contain a tar-like liquid particle that may behave like an oil aerosol.

According to the NIOSH selection logic, the R- or P-series filters will also need to be selected when oil mist is present, even though it is not the respiratory hazard. In textile mills, for example, mineral oil is used to provide lubrication in spinning, twisting and winding processes. Respirators may be used for cotton dust, but due to the oil mist present, R- or P-series filters may be selected even though oil mist levels are less than the exposure limits.

As is true for filters certified under 30 CFR 11, N-, R-, and
P-series filters should be disposed of if the filter is damaged, soiled
or difficult to breathe through. In addition, NIOSH has established the following time use limitations:

Conclusions

Although the NIOSH User's Guide does provide some guidance for selection of particulate respirators certified under
42 CFR 84, there are still many aspects of respirator selection that remain unknown. These include selecting the appropriate efficiency level and expanding the definition of oil aerosols.

It is important to remember that regulatory agencies (OSHA, MSHA) have not indicated procedures for selection of filters approved under 42 CFR 84. OSHA is currently revising its respiratory protection use standard 1910.134. While the Agency is allowing continued use of particulate filters and respirators approved under
30 CFR 11, its enforcement policy for new respirators approved under 42 CFR 84 is not complete.

However, particulate respirators and filters currently approved under 30 CFR 11, if properly selected and worn, are still effective and can be purchased during the NIOSH three-year transition period. This transition period also allows users time to evaluate their workplace contaminants and properly select new particulate respirators as more information becomes available.

Obtaining a copy
of the User's Guide

To get a copy of the User's Guide,
as well as other NIOSH documents,
call 1-800-35-NIOSH or write to National Institute for Occupational Safety and Health, Publications Dissemination,
4676 Columbia Parkway, Cincinnati, OH 45226-1998 and request NIOSH Publ.
#96-101. You can also check the NIOSH Home Page on the Worldwide Web at http://www.cdc.gov/niosh/homepage.htm1.

Reference

By Larry Janssen, C.I.H.

Introduction

Proper respirator selection requires a thorough hazard analysis. An important element of this analysis is the air contaminant concentration that is considered to be immediately dangerous to life or health (IDLH). When exposures are at or above this concentration, only a self-contained breathing apparatus (SCBA) or a combination airline respirator with auxiliary SCBA (Type C/SCBA) may be selected. Respirator approvals for other respirator types do not allow their use in IDLH atmospheres. Published respirator selection procedures, such as those found in ANSI Z88.2-1992 and the 3M Respirator Selection Guide, recognize this limitation on respirator use. For many years, the most convenient source listing IDLH concentrations has been the NIOSH Pocket Guide to Chemical Hazards. However, recent changes to the NIOSH IDLH values have been a source of confusion for those selecting respirators.

Background

The NIOSH IDLH values were
a product of a joint effort by the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) to develop occupational health standards in the mid-1970s. This "Standards Completion Program" resulted in 383 draft standards (which were not implemented) and the first version of the NIOSH Pocket Guide to Chemical Hazards, which was published in 1978. The IDLH concentrations, published in the Pocket Guide, were set to allow a worker without a respirator to escape without loss of life, irreversible health effects, severe eye or respiratory irritation, or other effects that might impair escape (e.g., disorientation). As a margin of safety, the values assumed an escape time of 30 minutes.

Since there was no other listing of IDLH concentrations available, most organizations, including OSHA, began to refer to the NIOSH Pocket Guide when IDLH information was needed to properly select a respirator. In the years that followed, new OSHA regulations, such as 29 CFR 1910.146, Permit Required Confined Spaces, and 29 CFR 1910.120, Hazardous Waste Operations and Emergency Response, imposed specific legal requirements if IDLH conditions exist or may be present. As a consequence, because nearly everyone was using the NIOSH values to make IDLH determinations, the NIOSH IDLH values essentially gained regulatory status without ever being the subject of OSHA rulemaking.

On December 1, 1993, NIOSH published a notice in the Federal Register requesting public comment on a number of issues related to the IDLH values. The notice stated that the information received would "assist NIOSH in evaluating the scientific adequacy of the criteria and procedures originally used for establishing IDLH values and proceeding with establishment and revision of IDLH values." Much of the information NIOSH requested had to do with the specific definition of IDLH and the type of data that should be considered in setting IDLH values. For example, NIOSH asked whether latent effects such as carcinogenicity should be considered in determining IDLH values. The public comment period closed on May 2, 1994.

Surprisingly, in May 1994, NIOSH published Documentation for Immediately Dangerous to Life or Health Concentrations (IDLHS). This publication mentioned the Federal Register notice as a part of an ongoing process to evaluate the criteria used to establish the original IDLH values. It went on to say that the original values had already been reviewed using new criteria, and had been revised where appropriate. The Documentation reviewed the IDLH concentrations for 387 substances. IDLH values for 272 substances were lowered, values for 57 substances were unchanged, and values were established for 58 substances that did not originally have IDLH values listed.

Because the criteria used to revise the IDLH values were very conservative, some of the values were drastically reduced. For example, the IDLH for ethyl ether was lowered from 19,000 ppm (the lower explosive limit) to 1,900 ppm (10% of the lower explosive limit). There are also some substances for which the revised IDLH value is at or below an OSHA permissible exposure limit. For example, the revised IDLH value for perchloroethylene is 150 ppm; OSHA's peak exposure limit is 300 ppm. It is interesting that the Documentation cites the same studies as the basis for both the original and revised IDLH values for perchloroethylene and a number of other substances. In other words, even in the absence of new toxicological data, the revised criteria resulted in lower IDLH values.

In June 1994, the revised IDLH values were published in a new version of the NIOSH Pocket Guide to Chemical Hazards. The Pocket Guide stated that the values had been revised using "interim criteria," and that a new strategy
for revising and developing IDLH values was being planned.

Discussion

The timing of NIOSH's revision of the IDLH values is puzzling. The 1993 Federal Register notice did not describe an immediate need to revise the IDLH values. NIOSH did not say, for instance, that illnesses, injuries, or deaths had occurred because the original IDLH values were too high. In fact, the Federal Register notice cited only one article that questioned "whether all of the IDLH values provide adequate worker protection." Secondly, the Documentation does not explain why NIOSH proceeded with the review and revision of the IDLH values before the public comments on the Federal Register notice were evaluated. It simply states that NIOSH decided to do it.

The revision of the IDLH
values has had significant legal implications. A December 1995 memorandum from the OSHA Directorate of Compliance Programs instructed OSHA regional and area offices to use the revised IDLHs in enforcement activities.
In effect, regulatory requirements had been changed without public comment. In some workplaces, use of the revised IDLH values would have required actions (e.g., use of SCBA, emergency procedures) that were not necessary when the original IDLH values were used.

Affected industry groups disputed some of the revised
IDLH values, based on their own experience and data that NIOSH did not consider. Because of these concerns and NIOSH's statement that the revised values were based on interim criteria, OSHA decided that the revised IDLH values would not be used for enforcement. On May 21, 1996, a memorandum from the Directorate of Compliance Programs instructed the field to return to the use of the original IDLH values, last published by NIOSH in the 1990 version of the Pocket Guide to Chemical Hazards. The memorandum allows for use of the revised (1994) values only
if they can be "fully supported"
and the compliance officer can establish industry recognition
of the revised IDLH.

Users of the 1996 3M Respirator Selection Guide must be aware of OSHA's recent change in policy regarding the use of the revised IDLH values. The Selection Guide was published before OSHA reverted to the use of the original IDLH values, and therefore lists the revised values. The selection logic described on pages 11 and 12 directs the user to select SCBA or combination Type C/SCBA whenever an IDLH value is exceeded. Obviously, this situation occurs frequently when the revised IDLH values are used.

For example, acetone exposures above the revised IDLH value of 2,500 ppm would require SCBA or Type C/SCBA. This concentration is less than four times the TLV, and well below the original IDLH value of 20,000 ppm. In addition, organic vapor cartridges are known to perform well at acetone concentrations up to 10 times the TLV. 3M concurs with OSHA's decision to return to the use of the original IDLH values, which were published in the 1995 and earlier versions of the 3M Respirator Selection Guide. The 1997 Selection Guide will incorporate whichever IDLH values are enforced by OSHA at the time it goes to press.

• 42 CFR 84 changing regulations

• Respirator capabilities and limitations

• Contaminant identification

• Fit testing

• Records administration

• Program evaluation

• Respirator maintenance

• Medical evaluation of
respirator users

• Breathing air quality for atmosphere supplying respirators

• Setting up a respiratory protection program

• OSHA requirements

3M also offers courses on current issues, such as filter testing and approval regulations, that can be scheduled and customized to meet specific needs.

Course participants qualify for Continuing Education credits. Courses are offered in cities around the United States and in Canada.

To register or request further information, call 1-800-659-0151,
ext. 275.

Tech line

To reach 3M's Technical Service staff with questions regarding our products, you can call 1-800-243-4630. If you wish to contact your local sales representative, you can leave a message by calling 1-800-896-4223.