Heat Stress

As we enter the hottest months of the year, OSHA is ramping up its enforcement of heat-related hazards. While OSHA is working on a new Heat Injury and Illness Prevention rule, they have implemented a National Emphasis Program (NEP) addressing outdoor and indoor heat-related hazards. One industry that OSHA focuses on with their NEP and the proposed rule is construction. The construction industry poses risk factors for heat illness, including heavy physical activity, hot work environment conditions, clothing that holds in body heat, and the potential for changing temperatures.

Heat conditions on a job site can change rapidly, especially in New England. In these types of environments, the body has a hard time trying to acclimate to the heat. A “toolbox” of heat stress controls that can be implemented as the conditions change is critical to preventing heat illness. Three of the leading prevention tools are water, rest, and shade. 

Workers should be encouraged to drink electrolyte-containing beverages such as sports drinks. Workers lose salt and other electrolytes when they sweat. Substantial loss of electrolytes can cause muscle cramps and other dangerous health problems. Water cannot replace electrolytes; different types of beverages are needed. Water or other fluids provided by the employer should not only be cool but should also be provided in a location that is familiar to the workers, near the work, easy to access, and in sufficient quantity for the duration of the work. Workers should not rely on feeling thirsty to prompt them to drink. They should be reminded to drink regularly to maintain hydration throughout their shift.

When heat stress is high, employers should require workers to take breaks. The length and frequency of rest breaks should increase as heat stress rises. Breaks should last long enough for workers to recover from the heat. How long is long enough? That depends on several factors, including environmental heat (WBGT), the worker’s physical activity level, and the individual worker’s risk factors. The location of the breaks also matters. If workers rest in a cooler area, they will be ready to resume work more quickly. Breaks should last longer if workers have no cool location to rest. Workers should be given a cool place to take breaks and recover from the heat. Outdoors might mean a shady area, an air-conditioned vehicle, a nearby building or tent, or an area with fans and misting devices.

Employers should create a written plan to prevent heat-related illness. The plan should address the following elements:

  • Who will provide oversight daily?
  • How will new workers gradually develop heat tolerance?
  • Temporary workers may be more susceptible to heat and require closer supervision.
  • Workers returning from extended leave (typically defined as more than two weeks) may also be at increased risk.
  • How will the employer ensure that first aid is adequate and that the protocol for summoning medical assistance in situations beyond first aid is effective?
  • What engineering controls and work practices will be used to reduce heat stress?
  • How will heat stress be measured?
  • How to respond when the National Weather Service issues a heat advisory or heat warning?
  • How will we determine if the total heat stress is hazardous?
  • What training will be provided to workers and supervisors?

Several heat-related illnesses can affect workers. Some of the symptoms are non-specific. This means that when a worker is performing physical labor in a warm environment, any unusual symptom can be a sign of overheating. Employers and workers should become familiar with the heat symptoms. When any of these symptoms are present, promptly provide first aid. Do not try to diagnose which illness is occurring. Diagnosis is often difficult because symptoms of multiple heat-related illnesses can occur together. Time is of the essence. These conditions can worsen quickly and result in fatalities. The following table lists the signs and symptoms of heat-related illness.

Heat-Related IllnessSymptoms and Signs
Heat strokeConfusion Slurred speech Unconsciousness Seizures Heavy sweating or hot, dry skin Very high body temperature Rapid heart rate
Heat exhaustionFatigue Irritability Thirst Nausea or vomiting Dizziness or lightheadedness Heavy sweating Elevated body temperature or fast heart rate
Heat crampsMuscle spasms or pain Usually in the legs, arms, or trunk
Heat syncopeFainting Dizziness
Heat rashClusters of red bumps on the skin Often appear on the neck, upper chest, and skin folds
Rhabdomyolysis (muscle breakdown)Muscle pain Dark urine or reduced urine output Weakness

Leave a Comment