Chapter III.
Respirator Selection Logic Sequence
After all criteria have been identified and evaluated and after
the requirements and restrictions of the respiratory protection
program have been met, the following sequence of questions can be
used to identify the class of respirators that should provide adequate
respiratory protection. Note that if OSHA has promulgated a substance
– specific standard for a contaminant found in your workplace,
respirator selection must meet or exceed the respirators required
in that standard. (OSHA General Industry Air Contaminants Standard,
29 CFR 1910.1000).
Step 1. Is the respirator intended for use during
fire fighting?
a. If yes, only a full-facepiece, pressure-demand,
self-contained breathing apparatus (SCBA) meeting the requirement
of the NFPA 1981, Standard on Open-circuit Self-contained Breathing
Apparatus for Fire and Emergency Services (2002 edition) is required.
Information on NFPA 1981 can be found at http://www.nfpa.org.
b. If no, proceed to Step 2.
Step 2. Is the respirator intended for use in
an oxygen-deficient atmosphere, i.e., less than 19.5% oxygen?
a. If yes, any type of SCBA other than escape
only, or supplied-air respirator (SAR) with an auxiliary SCBA is
required. Auxiliary SCBA must be of sufficient duration to permit
escape to safety if the air supply is interrupted.
If yes, and contaminants are also present, proceed to Step
3 to determine if the hazard requires the SCBA or SAR/SCBA to meet
a specific APF level.
b. If no, proceed to Step 3.
Step 3. Is the respirator intended for entry into
unknown or IDLH atmospheres (e.g., an emergency situation)?
a. If yes, one of two types of respirators are
required: a pressure-demand SCBA with a full facepiece or a pressure-demand
SAR with a full facepiece in combination with an auxiliary pressure-demand
SCBA. Auxiliary SCBA must be of sufficient duration to permit escape
to safety if the air supply is interrupted.
b. If no, proceed to Step 4.
Step 4. Is the exposure concentration of the contaminants,
as determined by acceptable industrial hygiene methods, less than
the NIOSH REL or other applicable exposure limit?
a. If yes, a respirator is not required for routine
work. For escape respirators, determine the potential for generation
of a hazardous condition caused by an accident, spill or equipment
failure. See Section IV. Page 17, for a discussion and selection
of escape respirators. Proceed to Step 6.*
b. If no, proceed to Step 5.
* If respirators are required by the employer
to be worn (even if below the occupational exposure limit), OSHA
requires that the employer establish and implement a written respiratory
protection program with worksite specific procedures. If an employer
provides respirators at the request of employees or permits employees
to use their own respirators when exposure levels are below the
applicable limits, this is considered voluntary respirator use.
OSHA requires that employers provide to their employees the information
contained in Appendix D of 29 CFR 1910.134, that they establish
and implement those elements of a written program necessary to ensure
that any employee using a respirator voluntarily is medically able
to wear the respirator (except that medical evaluation is not required
for voluntary use of filtering facepieces) and that the respirator
is cleaned, stored, and maintained so that it does not represent
a health hazard to the wearer.
Step 5. Are conditions such that a worker who
is required to wear a respirator can escape from the work area and
not suffer loss of life or immediate or delayed irreversible health
effects if the respirator fails, i.e., are the conditions not immediately
dangerous to life or health (IDLH)? IDLH values for certain compounds
can be found in the NIOSH Pocket Guide for Chemical Hazards. This
document can be accessed at http://www.cdc.gov/niosh/npg/npg.html.
IDLH values for some substances can also be found on the NIOSH internet
at
http://www.cdc.gov/niosh/idlh/idlh-1.html.
a. If yes, conditions are not considered to be
IDLH. Proceed to Step 6.
b. If no, conditions are considered to be IDLH.
Two types of respirators are recommended: a pressure-demand, full-facepiece
SCBA or a pressure-demand, full-facepiece SAR in combination with
an auxiliary pressure-demand, full-facepiece SCBA. The auxiliary
SCBA must be of sufficient duration to permit escape to safety if
the air supply is interrupted. An auxiliary unit means that the
SAR unit includes a separate air bottle to provide a reserve source
of air should the airline become damaged. The auxiliary unit shares
the same mask and regulator, and enables the SAR to function as
an SCBA if needed.
Step 6. Is the contaminant an eye irritant, or
can the contaminant cause eye damage at the workplace concentration?
Information on eye irritation is included in the International Programme
on Chemical Safety, International Chemical Safety Cards which can
be accessed at http://www.cdc.gov/niosh/ipcs/nicstart.html.
a. If yes, a respirator equipped with a full facepiece,
helmet, or hood is recommended. Proceed to Step 7.
b. If no, a half-mask or quarter-mask respirator
may still be an option, depending on the exposure concentration.
Proceed to Step 7.
Step 7. Determine the maximum hazard ratio (HR)
by the following:
• Divide the time-weighted average (TWA) exposure
concentration for the contaminant determined in Step 4 by
the NIOSH REL or other applicable exposure limit. If the exposure
limit is an 8 hour limit the TWA used must be on 8 hour average.
If the exposure limit is based on 10 hours, use a 10 hour
TWA.
• If the contaminant has a ceiling limit, divide the
maximum
exposure concentration for the contaminant determined in Step
4 by the ceiling limit.
• If the contaminant has a short term exposure limit
(STEL),
divide the maximum 15 min TWA exposure concentration for the
contaminant determined in Step 4 by the STEL.
• For escape respirators, determine the potential for
generation of a hazardous condition caused by an accident
or equipment failure.
• If a potentially hazardous condition could occur
or a hazard ratio greater than 1 has been calculated, proceed
to Step 8.
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Step 8. If the physical state of the contaminant
is:
• a particulate (solid or liquid aerosol) during periods of respirator
use, proceed to Step 9;
• a gas or vapor, proceed to Step 10;
• a combination of gas or vapor and particulate, proceed
to Step 11.
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Step 9. Particulate Respirators
9.1. Is the particulate respirator intended only
for escape purposes?
a. If yes, see Section IV (page 17), for a discussion
and selection of escape respirators.
b. If no, the particulate respirator is intended
for use during normal work activities. Proceed to Step 9.2.
9.2. A filter series (N, R or P) that will provide
protection against exposure to the particulate in question is recommended.
a. The selection of N-, R-, and P-series filters
depends on the presence or absence of oil particles, as follows:
• If no oil particles are present in
the work environment, use a filter of any series (i.e., N-,
R-, or P-series).
• If oil particles (e.g., lubricants, cutting fluids,
glycerine, etc.) are present, use an R- or P-series filter.
Note: N-series filters cannot be used if oil particles are
present.
• If oil particles are present and the filter is to
be used for more than one work shift, use only a P-series
filter
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Note: To help
you remember the filter series, use the following guide: |
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N for Not resistant
to oil,
R for Resistant to oil
P for oil Proof |
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b. Selection of filter efficiency (i.e., 95%,
99%, or 99.97%) depends on how much filter leakage can be accepted.
Higher filter efficiency means lower filter leakage.
Additional information on selecting the appropriate filter certified
under 42CFR84 can be found at http://www.cdc.gov/NIOSH/userguid.html.
Proceed to Step 9.3.
9.3. Respirators that have not been eliminated
from Table 1 by the previous steps and that have APFs equal to,
or greater than, the maximum hazard ratio determined in Step 7 are
recommended. Note, however, that the maximum use concentration (MUC)
is the maximum atmospheric concentration of a hazardous substance
from which an employee can be expected to be protected by a class
of respirator and is determined by the lesser of:
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• APF X exposure limit
• The respirator manufacturer’s MUC for a hazardous
substance (if any) |
1 If the respirator is intended for use in an oxygen-deficient
atmosphere, only SCBA or SAR with an auxiliary SCBA, can be selected
from the Table.
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• The IDLH, unless the respirator
is a pressure-demand, full-facepiece SCBA or combination pressure-demand
SAR with a full facepiece in combination with an auxiliary pressure-demand
SCBA. |
For multi-component mixtures the MUC can be calculated by:
C1/MUC1 + C2/MUC2 +…Cn/MUCn=
1
Step 10. Gas/Vapor Respirators
10.1. Is the gas/vapor respirator intended
only for escape?
a. If yes, refer to escape respirators Section
IV (page 17).
b. If no, the gas/vapor respirator is intended
for use during normal work activities. Proceed to Step 10.2.
10.2. An air-purifying chemical cartridge/canister
respirator is recommended that has a sorbent suitable for
the chemical properties of the anticipated gas/vapor contaminant(s)
and for the anticipated exposure levels. Information on cartridges
or canisters approved for use for classes of chemicals or
for specific gases or vapors can be found in the NIOSH Certified
Equipment List http://www.cdc.gov/NIOSH/npptl/topics/respirators/cel/.
Proceed to Step 10.3.
10.3. Respirators that have not been eliminated
from Table 2 by the previous steps and that have APFs equal
to, or greater than, the maximum hazard ratio determined in
Step 7 are recommended. Note, however, that the maximum use
concentration (MUC) is the maximum atmospheric concentration
of a hazardous substance from which an employee can be expected
to be protected by a class of respirator and is determined
by the lesser of:
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• APF X exposure limit • The respirator
manufacturer’s MUC for a hazardous substance (if any)
• The IDLH, unless the respirator is a pressure-demand,
full-facepiece SCBA or combination pressure-demand SAR with
a full facepiece in combination with an auxiliary pressure-demand
SCBA. |
For multi-component mixtures the MUC can be calculated
by:
C1/MUC1 + C2/MUC2
+…Cn/MUCn= 1 |
1 If the respirator is intended for use in an oxygen-deficient
atmosphere, only SCBA or SAR with an auxiliary SCBA, can be
selected from the Table. Step 11.
Combination Particulate and Gas/Vapor Respirators
11.1. Is the combination respirator intended
for "escape only" purposes?
a. If yes, refer to escape respirators on
page 17, for a discussion and selection of "escape only"
respirators.
b. If no, the combination respirator is
intended for use during normal work activities. Proceed to
Step 11.2.
11.2 From Table 3, select a respirator type,
not eliminated by the previous steps, and have APFs equal
to, or greater than, the maximum hazard ratio determined in
Step 7. are recommended. Note, however, that the maximum use
concentration (MUC) is the maximum atmospheric concentration
of a hazardous substance from which an employee can be expected
to be protected by a class of respirator and is determined
by the lesser of: |
• APF X exposure limit
• The respirator manufacturer’s MUC for a hazardous
substance (if any)
• The IDLH, unless the respirator is a pressure-demand,
full-facepiece SCBA or combination pressure-demand SAR with
a full facepiece in combination with an auxiliary pressure-demand
SCBA.
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For multi-component mixtures the MUC can be calculated
by:
C1/MUC1 + C2/MUC2
+…Cn/MUCn= 1 |
1 If the respirator is intended for use in an oxygen-deficient
atmosphere, only SCBA or SAR with an auxiliary SCBA, can be selected
from the Table.
Table 1. Particulate Respirators
Assigned protection1
factor |
Type of Respirator |
5 |
Quarter mask respirator
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10 |
Any air-purifying elastomeric half-mask respirator equipped
with appropriate type of particulate filter.2
Appropriate filtering facepiece respirator.2,3
Any air-purifying full facepiece respirator equipped with
appropriate type of particulate filter.2
Any negative pressure (demand) supplied-air respirator
equipped with a half-mask.
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25 |
Any powered air-purifying respirator equipped with a hood
or helmet and a high efficiency (HEPA) filter.
Any continuous flow supplied-air respirator equipped with
a hood or helmet.
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50 |
Any air-purifying full facepiece respirator equipped with
N-100, R-100, or P-100 filter(s).
Any powered air-purifying respirator equipped with a tight-fitting
facepiece (half or full facepiece) and a high-efficiency
filter.
Any negative pressure (demand) supplied-air respirator
equipped with a full facepiece.
Any continuous flow supplied-air respirator equipped with
a tight-fitting facepiece (half or full facepiece).
Any negative pressure (demand) self-contained respirator
equipped with a full facepiece.
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1,000 |
Any pressure-demand supplied-air respirator equipped with
a half-mask.
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2,000 |
Any pressure-demand supplied-air respirator equipped with
a full facepiece.
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10,000 |
Any pressure-demand self-contained respirator equipped with
a full facepiece.
Any pressure-demand supplied-air respirator equipped with
a full facepiece in combination with an auxiliary pressure-demand
self-contained breathing apparatus.
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1 The protection offered by a given respirator is contingent upon
(1) the respirator user adhering to complete program requirements
(such as the ones required by OSHA in 29CFR1910.134), (2) the use
of NIOSH-certified respirators in their approved configuration, and
(3) individual fit testing to rule out those respirators that cannot
achieve a good fit on individual workers.
2 Appropriate means that the filter medium will provide protection
against the particulate in question. See step 9.2 for information
on the presence or absence of oil particulates.
3 An APF of 10 can only be achieved if the respirator is qualitatively
or quantitatively fit tested on individual workers.
Table 2. Gas/Vapor Respirators
Assigned protection1
factor |
Type of Respirator |
10 |
Any air-purifying half mask respirator equipped with appropriate
gas/vapor cartridges.2
Any negative pressure (demand) supplied-air respirator
equipped with a half mask.
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25 |
Any powered air-purifying respirator with a loose-fitting
hood or helmet equipped with appropriate gas/vapor cartridges.2
Any continuous flow supplied-air respirator equipped with
a hood or helmet.
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50 |
Any air-purifying full facepiece respirator equipped with
appropriate gas/vapor cartridges2 or gas mask
(canister respirator).2
Any powered air-purifying respirator equipped with a tight-fitting
facepiece (half or full facepiece) and appropriate gas/vapor
cartridges or canisters.2
Any negative pressure (demand) supplied-air respirator
equipped with a full facepiece.
Any continuous flow supplied-air respirator equipped with
a tight-fitting facepiece (half or full facepiece).
Any negative pressure (demand) self-contained respirator
equipped with a full facepiece.
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1,000 |
Any pressure-demand supplied-air respirator equipped with
a half-mask.
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2,000 |
Any pressure-demand supplied-air respirator equipped with
a full facepiece.
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10,000 |
Any pressure-demand self-contained respirator equipped with
a full facepiece.
Any pressure-demand supplied-air respirator equipped with
a full facepiece in combination with an auxiliary pressure-demand
self-contained breathing apparatus.
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1 The protection offered by a given respirator is
contingent upon (1) the respirator user adhering to complete program
requirements (such as the ones required by OSHA in 29CFR1910.134),
(2) the use of NIOSH-certified respirators in their approved configuration,
and (3) individual fit testing to rule out those respirators that
cannot achieve a good fit on individual workers.
2 Select a cartridge/canister certified to be
used for the specific class of chemicals or the specific gas/vapor
found in your workplace.
Table 3. Combination Gas/Vapor
and Particulate Respirators
Assigned protection1
factor |
Type of Respirator |
10 |
Any air-purifying half-mask respirator equipped with appropriate
gas/vapor cartridges2 in combination with appropriate
type of particulate filter.3
Any full facepiece respirator with appropriate gas/vapor
cartridges2 in combination with appropriate type
of particulate filter.3
Any negative pressure (demand) supplied-air respirator
equipped with a half-mask.
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25 |
Any powered air-purifying respirator with a loose-fitting
hood or helmet that is equipped with an appropriate gas/vapor
cartridge2 in combination with a high-efficiency particulate
filter .
Any continuous flow supplied-air respirator equipped with
a hood or helmet.
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50 |
Any air-purifying full facepiece respirator equipped with
appropriate gas/vapor cartridges2 in combination
with an N-100, R-100 or P-100 filter or an appropriate canister2
incorporating an N-100, P-100 or R-100 filter.
Any powered air-purifying respirator with a tight-fitting
facepiece (half or full facepiece) equipped with appropriate
gas/vapor cartridges2 in combination with a high-efficiency
filter or an appropriate canister2 incorporating
a high-efficiency filter.
Any negative pressure (demand) supplied-air respirator
equipped with a full facepiece.
Any continuous flow supplied-air respirator equipped with
a tight-fitting facepiece (half or full facepiece).
Any negative pressure (demand) self-contained respirator
equipped with a full facepiece.
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1,000 |
Any pressure-demand supplied-air respirator equipped with
a half-mask.
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2,000 |
Any pressure-demand supplied-air respirator equipped with
a full facepiece.
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10,000 |
Any pressure-demand self-contained respirator equipped with
a full facepiece.
Any pressure-demand supplied-air respirator equipped with
a full facepiece in combination with an auxiliary pressure-demand
self-contained breathing apparatus.
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1 The protection offered by a given respirator is
contingent upon (1) the respirator user adhering to complete program
requirements (such as the ones required by OSHA in 29CFR1910.134),
(2) the use of NIOSH-certified respirators in their approved configuration,
and (3) individual fit testing to rule out those respirators that
cannot achieve a good fit on individual workers.
2 Select a cartridge/canister certified to be
used for the specific class of chemicals or the specific gas/vapor
found in your workplace.
3 Appropriate means that the filter medium will
provide protection against the particulate in question. See step
9.2 for information on the presence or absence of oil particulates.
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