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EHS > Occupational Safety > Programs & Guidelines > Heat Stress > Heat Stress Manual >

II. Heat Hazard Assessment

The potential for an employee who works in a hot environment to be affected by heat stress depends on heat combined with physical labor, loss of fluids and fatigue, in addition to the factors listed below. An assessment of each job with these factors can assist in developing a strategy to prevent heat related problems.

A. Temperature and Humidity

Ambient temperature and humidity levels must be taken into consideration when assessing the potential for heat stress hazards. There are several different ways to evaluate heat index based on temperature and relative humidity. EHS has purchased a Wet Bulb Globe Temperature (WBGT) index direct read out insturment. This temperature accounts for the effects of ambient temperature, humidity and radiant heat, and is an accepted measure of heat stress on an individual in the monitored environement. EHS is compling data of WBGT for commonly preformed hot jobs on campus, and will provide heat stress monitoring as needed.

A commonly used "quick and easy" approach to determining heat stress index was developed by the National Weather Service and is known as the "General Heat Stress Index". A copy of this index is provided in Appendix B. This index can be used to determine danger levels based on temperature and humidity.

The ACGIH has established various Threshold Limit Values (TLVs) for hot environments, as expressed in WBGT. A TLV is an average level for an eight-hour work day and a 40-hour work week, to which it is believed that nearly all workers may be repeatedly exposed, day after day, without adverse effect (See Appendix C). These TLVs are valid for workers dressed in light summer clothing only. Extra caution must be exercised in establishing work practices for employees wearing personal protective equipment (PPE) that poses as a barrier to heat loss. (See Appendix C, table C2)

B. Employee Work Rate

The rate at which an employee works and the activities being performed will have a direct effect on their potential to experience heat stress. This work rate must be taken into consideration when establishing safe work practices for employees working in hot environments. See Appendix D for guidance in determining an employee's work rate based on the activities they perform.

C. Location of Heat Sources

An employee who works in an environment which is generally cool, but in close proximity to hot objects may be at risk for heat stress. Sources of heat must be identified and their location in relation to the employee considered when assessing potential for heat stress.

D. Individual Risk Factors for Heat Stress

Certain factors can put employees at greater risk for heat stress. Employees will be made aware of these risk factors, and given the opportunity for medical consolation if those risk factors apply to them. Training will consist of a video and review of this written program.

E. Physical Barriers to Heat Loss

Extra caution must be exercised in establishing work practices for employees wearing personal protective equipment (PPE) that poses as a barrier to heat loss. This equipment could include coveralls, gloves and respirators, and chemical protective clothing. Guidelines for work-rest regimens for employees wearing PPE is provided in Appendix E.

Employee Health Evaluations

Heat Stress Manual Table of Contents


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