Industrial Hygienists (ACGIH)
— Occupational Safety and Health
Administration (OSHA)
— National Institute for Occupational Safety
and Health (NIOSH)
— American Industrial Hygiene Association
(AIHA)
Exposure Limits for Mixtures
The American Conference of Governmental
Industrial Hygienists (ACGIH) publishes the
following information to determine the TLV of
a mixture.
First determine the total concentration of the
chemical mixture (C Mixture ) from the individ-
ual contaminant concentrations (C 1 , C 2 ,
C 3 ...) using the following formula:
C Mixture = C 1 +C 2 +C 3 +...
The TLV of the mixture is found by using the
following formula where T 1 , T 2 , T 3 , ... are
the individual contaminant TLVs and C 1 , C 2 ,
C 3 ... are the individual contaminant concen-
trations:
T
=
Mixture
Only use these equations if the contami-
nants present are actually mixed. Some sub-
stances do not mix and may be present
separately, for example, in pockets or at dif-
ferent levels. In that case, the lowest TLV of
the substances present must be used to
determine the appropriate respirator catego-
ry for protection against all contaminants
present. See MSA's Response Respirator
Selector for additional information.
RESPIRATOR FIT TEST
A qualitative or quantitative respirator fit test
must be carried out for each wearer of this
respirator to determine the amount of pro-
tection it will provide.
DESCRIPTION
C
Mixture
C
C
C
1
2
3
+
+
T
T
T
1
2
3
Respirator fit tests are explained fully in the
American National Standard for Respiratory
Protection, ANSI Z88.2, which is published by
the American National Standards Institute, 11
West 42nd Street, New York, New York,
10036.
QUANTITATIVE TEST – If a Quantitative Fit
Test is used, a fit factor that is at least 100
shall be obtained before that respirator is
assigned to an individual.
QUALITATIVE TEST - If a Qualitative Fit
Test is used, only validated protocols are
acceptable. The individual must pass a test
designed to assess a fit factor of at least 100.
Regardless of facial dimensions and respira-
tor sizing charts, respirator fit testing, either
qualitative or quantitative, must be per-
formed to ensure the respirator selected
provides an adequate fit.
The user must perform a respirator fit
test and follow all warnings and limita-
tions specified. Failure to do so can result
in serious personal injury or death.
PREPARATIONS FOR USE
The following inspection points must be
checked before donning the respirator. A
respirator that fails the inspection must not
be used. The respirator must be repaired or
replaced.
1. Neck strap/Headband: Check to see that
the headband and neck strap still have
their elasticity. Inspect for breaks or tears
and make sure all adjusters are in place
and working properly.
2. Facepiece: Check facepiece for dirt,
cracks, tears, or holes. Inspect the shape
of the facepiece for possible distortion
that may occur from improper storage
and make sure the rubber is flexible, not
stiff. Also check the yoke for cracks.
3. Inhalation and exhalation valves: Check
for cracks, tears, distortion, dirt, build-up
5
WARNING