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. Author manuscript; available in PMC: 2015 Jun 23.
Published in final edited form as: J Occup Environ Med. 2014 Mar;56(3):313–318. doi: 10.1097/JOM.0000000000000095

TABLE 6.

Heat Strain Measurements in Acclimatized and Unacclimatized Employees

Acclimatized
(n = 48–50)		 Unacclimatized
(n = 8)		 P
Tc, average, °F 99.6 99.7 0.68
Peak Tc, average (range), °F 100.7 (99.0–102.8) 101.0 (99.5–102.4) 0.34
HR, average (range), BPM 107 (84–127) 118 (105–134) <0.01
Tc > criterion,* n (%) 10 (20) 7 (88) <0.01
  Minutes above criterion, median (range) 28 (6–112) 46 (11–597)
  Period monitored above criterion, average, % 9 22
Sustained† HR > (180 − age), n (%) 19 (40) 5 (63) 0.27
  Minutes above criterion, average 53 53
  Period monitored above criterion, average, % 13 12
Average HR > 115, n (%) 8 (17) 3 (38) 0.18
*

American Conference of Governmental Industrial Hygienists heat strain criteria: Tc greater than 101.3°F for acclimatized employees or greater than 100.4°F for unacclimatized employees.

†

Values sustained for greater than or equal to 5 continuous minutes.

BPM, beats per minute; HR, heart rate; Tc, core body temperature.