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. | |
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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