Heat Stress

Standards

There is no specific standard that applies to heat stress. The only citation option is a General Duty, 5(a)(1).

Sampling

Methods

Refer to the OSHA Technical Manual (OTM), Section III, Chapter 4, Sub-section IV, for heat stress sampling methods. Here are some key points:

• The wick of the natural wet bulb thermometer should be kept wet with distilled water for at least one-half hour before the temperature reading is made. It is not enough to immerse the other end of the wick into a reservoir of distilled water and wait until the whole wick becomes wet by capillarity. The wick must be wetted by direct application of water from a syringe one-half hour before each reading.
• The wick should always be clean, and new wicks should be washed before using.
• The globe thermometer should be exposed at least 25 minutes before it is read.
• A stand should be used [. . .] so that [. . .] the wet-bulb and globe thermometer are not shaded.

• Wet Bulb Globe Temperature Indexes (WBGI): Here is some information on how the different temperature indices are calculated. This will help to understand the differences between the various readings on the heat monitor:
  • Indoor or outdoors with no solar load: WBGT = 0.7NWB + 0.3GT
  • Outdoors with solar load: WBGT = 0.7NWB + 0.2GT + 0.1DB
  • where:
    • WBGT = Wet Bulb Globe Temperature Index
    • NWB = Natural Wet-Bulb Temperature
    • DB = Dry-Bulb (air) Temperature
    • GT = Globe Thermometer Temperature

Substance Codes

[Honestly, I'm not sure which of these we need to enter on the sampling sheets. I have yet to find anything in IMIS or a CPL that indicate which IMIS codes to use. -kbh]

8320 Heat Stress - Dry

• Do not use anything involving the Wet Bulb (WB)

8330 Heat Stress

• The IMIS description indicates that this is for inside heat monitoring. Therefore, use the WBGT_i value. [???]

8891 Humidity, Relative

Unless told otherwise, enter all of these values into the sampling forms and into OSHA Express. Additionally, after yours truly contacted a former KYOSH CSHO who now works with federal OSHA in Ohio, this was basically how the feds in his region do it — the "shotgun approach."

Equipment

NEEDS INFORMATION ON QUESTEMP 34

QuesTemp 34 Manual