The advantages of the Botsball (BB) over other methods for determining wet bulb globe temperature (WBGT) were considered. A BB, combining the effects of air temperature, humidity, wind speed and radiation into a single reading, and an electronic instrument for measuring WBGT, were used to measure the climatic conditions of work stations in two industrial facilities. A mathematical formula to express the relationship between the WBGT and BB, based on a year of twice daily data collection, was found to have a high correlation coefficient. Permissible heat exposure threshold limit values (TLV) were established in BB units equivalent to the TLV of WBGT units. The major advantages of the BB related to its small size which allowed it to be hung directly in work stations and thus more accurately evaluate the heat stress to which workers were exposed. The BB was easier to read and less expensive than the WBGT. The major disadvantages of the BB were its leakage in the water reservoir and the black cotton cover was not removable. The authors advise the use of the BB as a replacement for WBGT in determining thermal TLVs.