Oral/rectal temperature differences during work and heat stress

¹ Human Sciences Laboratory and Mathematical-Statistical Division, Transvaal and Orange Free State Chamber of Mines, Johannesburg, South Africa

Fifty-two groups of about 20 men each were exposed for 5 hr to various combinations of work rate, environmental temperature, and wind velocity. Hourly observations were made of oxygen intake and oral and rectal temperatures. Oral/rectal temperature differences increased significantly with time only under those conditions where steady-state responses were not achieved. Increasing wind velocity from 50 to 400 cm/sec, raising air temperatures from 27 to 36 C, and combinations of these factors had no significant influence on the difference between the recorded temperatures. The main contributing factor to oral/rectal temperature difference is work rate. Increasing energy consumption from 2.5 to 9.0 Cal/min resulted in a rectilinear increase in average difference from 0.5 to 1.1 C. A warning is expressed against the indiscriminate use of oral temperatures in work and heat studies.

Submitted on May 18, 1964