Appendix
NIOSH Respirator Use Policy Approved: August 4, 1999
Background. OSHA’s new respiratory protection standard, 29 CFR
1910.134, became effective on April 8, 1998, with complete compliance
required by October 5, 1998. The new regulation is an upgrade in many
ways and is a significant advance for respirator wearers. The NIOSH
Respirator Use Policy (RUP) Workgroup has carefully reviewed the new
regulation and determined that it is generally consistent with previous
NIOSH policy. The Workgroup identified only five differences between
the previous NIOSH policy and the new 1910.134. The Workgroup reviewed
these differences to determine if it would be appropriate for NIOSH
to modify its policies to be in harmony with OSHA. The consistency
between NIOSH and OSHA that would result from such harmonization was
considered an advantage to respirator users in that it would tend
to minimize confusion in the workplace. At the same time, the Workgroup
recognized that the rulemaking process placed restrictions on OSHA
that do not apply to NIOSH in making its public health recommendations.
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NIOSH Respirator Policy Statement: |
NIOSH endorses all provisions of OSHA’s 29 CFR Part
1910.134, as published on January 8, 1998, except that
NIOSH does not recommend (a) the use of irritant smoke
for qualitative respirator fit testing, or (b) unsupervised
medical evaluations conducted by health care professionals
who are not licensed for independent practice to perform
or supervise medical evaluations. |
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Discussion. Both NIOSH policy and the new OSHA regulation
are in fundamental agreement that the primary means to prevent occupational
diseases caused by breathing contaminated air is through the use of
feasible engineering controls such as enclosures, confinement of operations,
ventilation, or substitution with less toxic materials. Only when
effective engineering controls are not
feasible, or while they are being installed or maintained, should
respirators be utilized as the primary means of worker protection.
The differences between the previous NIOSH respirator use recommendations
and OSHA’s 1910.134 are discussed below along with the basis
of the new NIOSH recommendations.
1. Change Schedules. Chemical-cartridge respirators
typically use activated charcoal as a sorbent to filter toxic gases
and vapors. They are essentially 100% efficient filters until the
gas or vapor "breaks through." To use these respirators
safely, the user must have some way of knowing when "breakthrough"
has occurred and the chemical cartridge has to be replaced. This breakthrough
can be identified in three ways. First, if the substance has good
warning properties (smell, taste, irritation), the wearer detects
breakthrough and knows to replace the cartridge (or canister). Second,
an end-of-service-life-indicator (ESLI) for the specific gas or vapor
of concern signals the wearer to replace the cartridge. Third, a cartridge
"change schedule" is established to assure the cartridge
is replaced well before breakthrough occurs. These change schedules
must be specific for each workplace situation because the service
life of a cartridge depends on many variables including: the contaminant
concentration, humidity, temperature, interference from other gases
and vapors, patterns of use (continuous or intermittent), and characteristics
of each respirator model. Previously, OSHA and NIOSH recognized only
the first two methods. The new 1910.134 now recognizes only the second
and third (ESLIs and change schedules) and no longer recognizes the
first (warning properties). Based on the recommendations of the RUP
Workgroup, NIOSH has updated its policy to be consistent with OSHA
by recognizing the use of change schedules and by recommending against
reliance on warning properties.
Developing cartridge change schedules is a new exercise for most respirator
users; because standard approaches to setting a change schedule have
not been developed and validated, there is uncertainty about their
efficacy. Endorsing the use of cartridge change schedules is done
with the full knowledge of the uncertainty and problems associated
with this approach. It is believed, however, that the uncertainties
of change schedules present less of a public health problem than would
the continued reliance on warning properties. Further, the new OSHA
regulation will likely, over time, cause the development of improved
methods of establishing cartridge change schedules. However, there
is the possibility that some employers may develop and follow inadequate
change schedules that can result in chronic overexposure. Research
to develop and validate clear and practical methods for employers
to establish change schedules is, therefore, critically needed.
Reliance on warning properties has long been recognized as problematic.
The 1987 NIOSH Respirator Decision Logic described the typical wide
variation of odor threshold in the general population (greater than
two orders of magnitude). The recommendation made in that publication
was for "screening tests for workers who wear air-purifying gas
or vapor respirators to determine their ability to detect the odor
below the exposure limit for that gas or vapor." However, NIOSH
does not know of any employer who has tried to do this screening nor
any established procedures for doing this screening. Even if screening
were performed, other problems would remain: shift in odor threshold
due to extended low exposures, shifts due to simple colds and other
illnesses, failure to recognize odor because of distraction of the
workplace competing for worker attention, and inaccuracies in the
screening test itself.
Of the five differences between NIOSH and OSHA, this is the only one
where following the previous NIOSH recommendation would preclude following
the OSHA regulation and would therefore be in violation of OSHA’s
regulations.
2. Irritant Smoke Fit Testing. This qualitative respirator
fit test is conducted by directing the smoke stream from ventilation
smoke tubes (intended to study building ventilation systems) at the
respirator face seal. An inadequate face seal is indicated by an involuntary
reaction (coughing or gagging) of the worker. The involuntary nature
of the reaction is the reason many prefer this test over other qualitative
fit tests.
NIOSH, in its formal comments to OSHA on the proposed revision of
29 CFR 1910, 1915, and 1926, strongly recommended against the use
of this fit test method because of the health risk associated with
exposure to the irritant smoke. That recommendation was primarily
based on studies conducted as part of a NIOSH HHE (HETA 93-040-2315)
and described in Appendix A of the NIOSH comments to OSHA dated May
15, 1995 (docket H-049). NIOSH continues to recommend against the
use of irritant smoke fit testing for these same reasons.
A person's involuntary reaction after breathing irritant smoke is
caused by a white hydrochloric acid fume produced by ventilation smoke
tubes containing stannic chloride. Hydrogen chloride is immediately
irritating at air concentrations of 5 parts per million (ppm) or more.
Therefore, the NIOSH recommended exposure limit, the OSHA permissible
exposure limit, and the ACGIH TLV® for hydrogen chloride are all
ceiling limits of 5 ppm. (A ceiling limit is an air concentration
that should not be exceeded during any part of a workday.) Air sampling
has shown that ventilation smoke tubes can produce highly variable
and unpredictable hydrogen chloride concentrations far exceeding 5
ppm. The NIOSH HHE included measurements of the hydrogen chloride
concentrations emitted from smoke tubes measured at a distance of
12 inches from the tube and generated from a single squeeze of an
aspirator bulb. These concentrations ranged from near the ceiling
limit (1 ppm, 4 ppm, and 9 ppm) in a room with low relative humidity
to 100 times the ceiling limit (460 ppm, 520 ppm, and 1700 ppm) in
a room with high relative humidity.
NIOSH reviewed the revised protocol for the irritant smoke test in
OSHA's final respiratory protection standard and concluded that a
risk still exists for overexposure to hydrogen chloride during a facepiece
fit test. To check their sensitivity, test subjects are required to
breathe irritant smoke both before and after a successful fit test.
Generated concentrations to which test subjects are subjected are
not measured in the test protocol. A concentration of 5 ppm is the
accepted threshold level at which a response is evoked from most persons.
A fit test is a failure when a test subject experiences an involuntary
cough or irritation. Retesting requires repeating the sensitivity
check. In each case, the responses of coughing and irritation are
the adverse health effects for which hydrogen chloride's exposure
limits are intended to protect against. Consequently, NIOSH maintains
its recommendation against the use of irritant smoke as a fit testing
agent.
3. Saccharin qualitative fit testing. This test is
conducted with an inexpensive, commercially available kit that challenges
the respirator wearer with a sweet tasting saccharin aerosol. After
previously having been screened to assure that he/she can taste saccharin
at the required concentration, the respirator wearer is asked to report
if saccharin is tasted during fit testing. If so, the respirator is
considered to have an inadequate fit and fails the fit test.
NIOSH has previously recommended against the saccharin fit test because
of its classification as a potential carcinogen [NTP 1981; IARC 1987;
Niemeier 1991]. However, NIOSH recently re-examined the potential
risk to workers that would be posed by saccharin used in fit testing
[NIOSH 1999]. Finding that the risk to workers from use of saccharin
in respirator fit testing is extremely small and may be zero, and
in accordance with the new REL policy [NIOSH 1995], NIOSH recommends
both saccharin or Bitrex® for use in qualitative respirator fit
testing, consistent with OSHA’s respiratory protection standard
(29 CFR 1910.134).
NIOSH intends to include the saccharin fit test in its ongoing research
program to assess the efficacy of fit test methods in general. That
is, NIOSH plans to evaluate the ability of the saccharin fit test
to identify those individuals who will achieve a fit sufficient to
assure adequate protection when the respirator is worn in the workplace.
NIOSH researchers have conducted, and are conducting, such studies
of a variety of fit test methods.
4. Voluntary Respirator Use. Previously, NIOSH recommended,
and OSHA required, a full-blown respirator program whenever a respirator
was used. Thus, for example, employees having a workplace exposure
below the exposure limit but wanting to further reduce their exposure
with voluntary respirator use could not do so unless the employer
implemented a complete respirator program with all its elements (fit
testing, written program, medical evaluation, record keeping, etc.).
This tended to discourage the use of respirators to further reduce
exposure to levels well below maximum exposure limits.
The new OSHA regulations require a complete respirator program whenever
respirator use is required by the employer. However, when respirators
are used voluntarily by employees, the employer needs only to establish
those respirator program elements necessary to assure the respirator
itself is not a hazard. The exception is that filtering facepiece
respirators can be used without any respirator program when used voluntarily.
Although there are no known studies of such voluntary respirator use,
NIOSH supports OSHA’s voluntary use provisions because they
provide safe ways not previously available to use respirators to reduce
exposure well below established exposure limits.
5. Medical Evaluation Responsible Person. The previous
OSHA 1910.134 stated: "Persons should not be assigned to tasks
requiring use of respirators unless it has been determined that they
are physically able to perform the work and use the equipment. The
local physician shall determine what health and physical conditions
are pertinent."
The new 1910.134 states: "The employer shall identify a physician
or other licensed health care professional (PLHCP) to perform medial
evaluations...." In the definitions section, OSHA states: Physician
or other licensed health care professional (PLHCP) means an individual
whose legally permitted scope of practice (i.e., license, registration,
or certification) allows him or her to independently provide, or be
delegated the responsibility to provide, some or all of the health
care services required by paragraph (e) of this section."
Thus the new OSHA regulation allows a non-physician, under certain
conditions, to be the responsible person who determines medical fitness
to wear a respirator. However, the definition in 1910.134(b) of a
"physician or other licensed health care professional" does
not limit the non-physician responsible person to those who are licensed
for independent practice in all the health care services required
by 1910.134(e). NIOSH recommends that the only non-physicians responsible
for medical surveillance and medical clearance (either conducting
the examinations or supervising them) should be nurse practitioners
and physician assistants in those states where they are licensed for
independent practice.
signed:\ Linda Rosenstock, M.D., M.P.H. _August 4, 1999_____
Director, NIOSH Date
REFERENCES for Appendix
IARC [1987]. IARC monographs on the evaluation
of carcinogenic risks to humans; overall evaluations of carcinogenicity:
an updating of IARC monographs, volumes 1-42, supplement 7. Lyon,
France: World Health Organization, International Agency for Research
on Cancer, pp. 334-339.
Niemeier RW [1991]. Letter of April 19, 1991, from
R.W. Niemeier, Division of Standards Development and Technology
Transfer, National Institute for Occupational Safety and Health,
Centers for Disease Control and Prevention, Public Health Service,
U.S. Department of Health and Human Services to Donald Wilmes, 3M.
NIOSH [1995]. NIOSH Recommended Exposure Limit
Policy, September 1995. In: NIOSH policy statements. Cincinnati,
OH: U.S. Department of Health and Human Services, Public Health
Service, Centers for Disease Control and Prevention, National Institute
for Occupational Safety and Health.
NIOSH [1999]. NIOSH Saccharin Use for Respirator
Fit Testing Policy, July 1999. In: NIOSH policy statements. Cincinnati,
OH: U.S. Department of Health and Human Services, Public Health
Service, Centers for Disease Control and Prevention, National Institute
for Occupational Safety and Health.
NTP [1981]. Second annual report on carcinogens.
Research Triangle Park, NC: U.S. Department of Health and Human
Services, Public Health Service, National Toxicology Program, NTP
Publication No. 81-43.
Schulte PA [1999]. Memorandum of February 23, 1999, from
P.A. Schulte, Education and Information Division, to Don Campbell,
Chairperson, Respirator Use Policy Committee, National Institute
for Occupational Safety and Health, Centers for Disease Control
and Prevention, Public Health Service, U.S. Department of Health
and Human Services.
Wilmes D [1994]. Letter of May 18, 1994, from Don
Wilmes, 3M, to Richard W. Niemeier, Division of Standards Development
and Technology Transfer, National Institute for Occupational Safety
and Health, Centers for Disease Control and Prevention, Public Health
Service, U.S. Department of Health and Human Services.
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