(5) The terms "substance" and "air contaminant" are equivalent in meaning for purposes
of these rules.
History: 1990 AACS; 2001 AACS; 2017 AACS.
R 325.51103 Exposure limits.
Rule 3. An employer shall ensure that an employee exposure to any substance listed in
tables G-1-A or G-2 in R 325.51108 is limited in accordance with the requirements of all
of the following provisions:
(a) With respect to table G-1-A, all of the following provisions apply:
(i) Removed (May 9, 2001).
(ii) Removed (May 20, 2001).
(iii) An employee's exposure to any substance listed in table G-1-A shall not exceed the
time-weighted average (TWA) limit, short-term exposure limit (STEL) and ceiling limit
specified for that substance in table G-1-A.
(iv) To prevent or reduce skin absorption, an employee's skin exposure to substances
listed in table G-1-A with an "X" in the skin designation column following the substance
name shall be prevented or reduced to the extent necessary through the use of gloves,
coveralls, goggles, or other appropriate personal protective equipment, engineering
controls, or work practices.
(v) An employee shall not be exposed to air concentrations between the TWA and
STEL limits more than 4 times in a workshift and such exposures shall be no less than 60
minutes apart.
(b) With respect to table G-2, all of the following provisions apply:
(i) An employee's exposure to any substance listed in table G-2 in any 8-hour workshift
of a 40-hour workweek shall not exceed the 8-hour, time-weighted average limit given
for that substance in table G-2.
(ii) An employee's exposure to a substance listed in table G-2 shall not exceed, at any
time during an 8-hour workshift, the acceptable ceiling concentration limit given for the
substance in the table, except for a period of time and up to a concentration that does not
exceed the maximum duration and concentration allowed in the column under
"Acceptable maximum peak above the ceiling concentration for an 8-hour workshift."
For example, during an 8-hour workshift, an employee may be exposed to a
concentration of Substance A (with a 10 parts of the substance per million parts of air
(ppm) TWA, 25 ppm ceiling and 50 ppm peak) above 25 ppm (but not above 50 ppm)
only for a maximum period of 10 minutes. Such an exposure shall be compensated for by
exposures to concentrations less than 10 ppm so the cumulative exposure for the entire 8-
hour workshift does not exceed a time-weighted average of 10 ppm.
(iii) If a substance is preceded by an "S", then an employer shall take the necessary
precautions to prevent an employee from absorbing the substance through his or her skin.
History: 1990 AACS; 2001 AACS; 2017 AACS.
R 325.51104 Computation formulae.
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