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25.1 Introduction #
Work operations involving high air temperatures, radiant heat sources, high humidity, direct physical contact with hot objects, or strenuous physical activities have a high potential for inducing heat stress in employees engaged in such operations. These activities are often conducted in the following locations: steam tunnels; sections of the Central Power Plant; pipe chases; some mechanical rooms; some kitchens; outdoor construction activities, particularly on roofs; and outdoor construction activities that require the use of protective clothing.
The risk of heat-induced illnesses and injuries may be increased and productivity reduced in situations when the total heat load exceeds the capacities of the body to maintain normal body functions. The purpose of this program is to assist departments in eliminating or reducing heat stress risk factors.
MIOSHA Guidance: Heat-Related Illness State Emphasis Program (SEP)
25.2 Heat Stress Evaluation #
The incidence of heat stress is the result of a variety of factors. For heat stress evaluations, contact EHS. Factors to be evaluated when considering the need for a Heat Stress Program include the following:
- Wet Bulb Globe Temperature (WBGT)
- Work location and air movement for cooling
- Type of work required – the metabolic heat generated during heavy, moderate or light work
- Required work clothing and safety equipment (impermeable work clothing increases the potential for heat stress)
- Employee symptoms and/or complaints
- Employee conditioning and/or acclimatization
25.3 Heat Stress Control Measures #
To control heat stress situations follow the procedures outlined in this section. Implement the appropriate control measures for the specific work condition from among the following possible control methods.
Engineering Controls #
Ventilation, air cooling, fans, shielding, and insulation are the five major types of engineering controls used to reduce heat stress in hot work environments.
Heat reduction can also be achieved by using power assists and tools that reduce the physical demands placed on a worker. However, for this approach to be successful, these devices must require less effort than would be required without them.
Where feasible, eliminate steam leaks and shut down hot machinery and equipment.
Administrative Controls #
Workers should be allowed to take frequent rest breaks in a cooler environment. The higher the heat stress conditions, the longer the rest period should be. EHS can help determine a work rest ratio based on the heat stress conditions. Rotation of workers may be one feasible alternative.
Employees shall be given work schedules in advance, made aware of break times, shown where to receive a means of hydration, and given weather information if requested.
Protective Clothing #
If working outside, wear loose fitting, light colored, porous clothing which allows free air circulation over the body. Wear a well-ventilated broad brimmed hat. If working inside, wear as little clothing as necessary.
Work Practices #
Cool water (50-60 degrees F) or any cool liquid (except alcoholic beverages) should be made available to workers to encourage them to drink small amounts frequently (e.g., one cup every 20 minutes). An ample supply of liquids should be placed close to the work area. Although some commercial replacement drinks contain salt, this is not necessary for acclimatized individuals because most people add enough salt to their diets.
In some situations, a buddy system (no less than two employees) may be appropriate so the employees can observe each other for early signs of heat strain. Establish a means of communication so that employees can call for assistance when necessary. EHS can assist supervisors in determining when a buddy system and communications would be appropriate.
Training #
Heat stress training is the key to good work practices for both employees and supervisory personnel. All affected employees need to understand the reasons for using appropriate work practices to prevent heat stress and ensure a successful program.
Employees who work in hot environments and their supervisors will attend heat stress training conducted by EHS prior to being assigned work tasks in a hot environment. The training will cover the following topics below:
- Statistics of Heat-related Illnesses
- Health Effects and Long-Term Conditions caused by Heat-Related Illnesses
- Risk Factors for Heat Stress
- Preventive Measures and Controls
Training records will be kept by EHS.
Medical Surveillance #
Employees identified by EHS as performing strenuous physical work in an environment with high air temperature, high humidity, radiant heat or direct contact with hot objects that exceeds the ACGIH TLV for Heat Stress Exposure and cannot adhere to a work/rest ratio will be enrolled in the heat stress medical surveillance evaluation. Examples include emergency work, Tunnel workers and DPSS riot control with ballistic vests, and Hazmat workers. The Medical Surveillance Program is administered by EHS. For more information, contact EHS at 615-2140.
