The globe is covered by a black cloth that is kept moist by water kept in a
metallic cylinder surrounding the stem of the thermometer.
The Botsball is hung in an appropriate location, and the WGT index is
read directly from the dial.
The Botsball device is used only in certain areas such as jungle type
If humidity is greater than 30 percent and there is little or no wind, the
Botsball device is acceptable for use.
However, there is a need to periodically correlate the WGT with the
In most areas, the WGT index is not as accurate an indicator of heat
injury hazard as the WBGT index.
b. Heat Category Number. The heat category number is used to indicate the
general degree of heat injury hazard.
Often, the heat category number is used instead of the WBGT when
informing troops about the present risk of heat injury.
Table 4-2 shows the heat category numbers with the matching WBGT
4-27. USE OF THE WBGT INDEX
The proponents of the WBGT index have proposed the following as a standard for
application of the index.