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Heat Stress

10 Key Elements for a Workplace Heat Safety Program

July 19, 2022
Roughly half of the workforce is at an increased risk for heat illness—make sure you’re properly protecting the health of your workers.

Globally, extreme heat waves have been increasing in their frequency, duration and magnitude and are expected to continue to rise, according to the World Health Organization. Employers must therefore be prepared to respond to more frequent occurrences of excessive heat to protect the health of their employees.

Heat illness can occur indoors or outdoorsand in any season. Employees may experience heat illness at temperatures much lower than heat advisories because physical labor increases heat stress. Limiting exposure to high temperatures, properly managing work activities and staying hydrated can help prevent heat illness.

When the body cannot stay cool, the inner core temperature rises too high and body systems break down, resulting in heat illness. Heat illness can range in severity from minor heat rash, sunburn and heat cramps to heat syncope (fainting), heat exhaustion, Rhabdomyolysis (loss of muscle tissue) and heat stroke, which can be fatal. Heat can also be an underlying cause of other types of workplace injuries, such as falls and equipment accidents.

Anyone, regardless of age or physical fitness, can experience heat illness. However, some people may have more difficultly shedding excess body heat and are at a higher risk, such as those who are older, overweight or obese, have diabetes, have heart disease and have hypertension or high blood pressure. The Centers for Disease Control and Prevention estimates that 48% of U.S. adults have hypertension and 40% are obese, making it likely that at least half of the workforce is at an increased risk for heat illness.

OSHA is focusing on heat safety in the workplace and will be conducting more worksite audits under its National Emphasis Program for Outdoor and Indoor Heat-Related Hazards. You need to make sure your workplace is prepared to keep employees safe while working in heat. Here are 10 key elements for a workplace heat safety program.

1. Monitoring Heat Hazards

Managers must be trained to monitor the conditions in the workplace and respond to excessive heat. There are many factors that have a role in creating an occupational heat stress risk to employees, including:

  • Environmental conditions (e.g., temperature, humidity, sunlight and air speed), especially over sequential days.
  • Worksite heat sources (e.g., heavy equipment, hot tar, ovens, furnaces).
  • Level of physical activity/strenuous workloads.
  • Heavy or synthetic clothing or personal protective equipment (PPE).
  • Individual risk factors and high-risk conditions.

With the help of an occupational health advisor, consider installation of wet bulb globe temperature (WBGT) monitoring devices—the gold standard for precisely measuring heat stress. WBGT measures heat stress in direct sunlight, taking into account temperature, humidity, wind speed, sun angle and cloud cover. If WBGT is not available, continuously monitor the local heat index and accordingly plan heat safety precautions.

2. Medical Monitoring of Employees Working in Heat

Medical monitoring for all employees exposed to heat stress should include pre-placement and periodic medical evaluations to assess personal risk factors for heat illness. Continuous medical monitoring may be recommended for employees working in high levels of heat stress (e.g., core temperature, hydration, pulse and/or blood pressure). An occupational health advisor should be engaged to develop a medical monitoring program specific to the worksite.

3. Emergency Action Plan

Establish a worksite emergency action plan that outlines how to recognize the signs of heat illness, administer first aid, provide immediate cooling measures and contact emergency medical services. Ensure all employees know the emergency action plan and conduct regular refresher training, especially during heat advisories.

4. Heat Safety Education

Educate all employees about heat safety before they begin work in a hot environment. Provide educational materials in a language and literacy level that employees can understand. Heat safety education programs should include:

  • The importance and process of acclimatization and how to follow the plan.
  • How to recognize the signs and symptoms of heat illness.
  • Clear procedures to follow when someone has symptoms of heat illness, including first aid and how to call for medical assistance.
  • What causes heat illness (e.g., temperature, humidity, sun/wind exposure, workloads).
  • How to minimize risk from heat illness (e.g., hydration, rest cycles, monitoring for symptoms).
  • How to use heat-protective PPE (e.g., sunscreen, hats, cooling vests).
  • Effects of lifestyle factors on risk for heat illness (e.g., use of drugs and alcohol, obesity).

Encourage employees to download apps, such as the OSHA-NIOSH Heat Safety Tool Appthat monitor local weather conditions and notify users of heat advisories. OSHA also has a Heat Illness Prevention Training Guide available in English and Spanish.

Managers should receive additional training on how to implement the acclimatization plan, respond to weather advisories, and monitor and encourage hydration and rest breaks.

5. Acclimatization

Acclimatization is a physiological process that improves the body’s tolerance to heat by gradually increasing the duration of heat exposure. It can take anywhere from several days to two weeks to adjust. Some acclimatization factors to consider: 

  • Most heat-related fatalities occur in the first few days of exposure because the body isn’t acclimatized.
  • Acclimatization can be lost in just a few days away from the hot environment.
  • Non-physically fit employees may require more time to acclimatize.
  • Training and education are critical for both managers and employees.

Benefits of acclimatization include:

  • Increased sweating efficiency (greater sweat production, reduced electrolyte loss in sweat).
  • Work is performed at lower core temperature and heart rate.
  • Increased blood flow to the skin to lose heat.

CDC/NIOSH recommend that employees new to hot environments work 20% of the usual workday and gradually increase their time by 20% every day thereafter. Employees returning to the hot environment after an absence should start at 50% of the usual workday and gradually increase their time by 10% every day thereafter. This is a general timeframe, which may need to be altered based on the individual’s risk profile.

6. Engineering Controls

Use engineering controls to reduce heat stress on employees, including:

  • Reduce physical demands of the job by using powered devices for heavy tasks, such as forklifts.
  • Use air conditioning, fans or misters; however, ensure any moisture generated is not a safety risk.
  • Provide tents, shades or canopies.

7. Hydration Plan

Provide an adequate and accessible supply of cool, potable water with individual drinking cups or bottles. Managers should encourage and monitor employee hydration. Employees should drink 1 cup of water every 15-20 minutes (32 oz./1 liter of fluid per hour). During prolonged sweating over several hours, they should drink sports drinks with balanced electrolytes and eat regular light meals to replace salt lost in sweat.

Provide convenient access to adequate toilet facilities. This will ensure employees do not avoid drinking water to delay bathroom use during work.

8. Work/Rest Cycles and Reschedule Work

Managers should consider shifting work schedules to early or later in the day during excessive heat conditions. Employees should take regular rest breaks in a cool/shady area to allow the body to cool down. In general, employees should have mandatory 15-minute rest breaks every hour. Rest periods may need to be longer or more frequent during extreme heat conditions.

Shorten work periods and increase rest periods based on the following conditions:

  • As temperature, humidity and sunshine increase (WBGT).
  • When there is little or no wind or air flow.
  • If employees are wearing heavy protective clothing or equipment.
  • If workload is heavy or strenuous.

9. Use the Buddy System

Heat illness can make people confused and unaware they are experiencing symptoms. Assign work buddies to monitor each other for signs of heat illness and ensure they are following the hydration and work/rest cycle plan. If employees must work alone, conduct regular remote wellness checks with the employee.

10. PPE and Clothing for Heat Safety

PPE for prevention of heat illness may include wide-brimmed hats, sunscreen or cooling vests that circulate cool liquid or have ice packs. If safe to do, employees working in heat may also want to sprinkle water over their skin or clothing or keep a damp cloth on the back of the neck.

When the job does not require specialized clothing to protect against other hazards (e.g., flame resistant and arc rated clothing), encourage employees to choose clothing made from cotton or natural fibers rather than clothing made from synthetic material. Avoid dark-colored, heavier clothing and opt for light-colored, lightweight cotton clothing.

Courtney Mindzak, MPH, M.Ed., is public health program manager with International SOS and an adjunct instructor for the College of Healthcare Sciences at Alvernia University. Myles Druckman, MD, is vice president of medical services with International SOS. Nicolau Chamma, MD, is an occupational health medical advisor with International SOS. The International SOS Group of Companies provides customized health, security, risk management and well-being solutions.

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