10 Key Elements for a Workplace Thermal Safety Program

Globally, extreme heat waves have increased in frequency, duration and magnitude and are expected to continue to increase, 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 sickness can occur indoors or outdoors, and in any season. Employees can experience heat illness at temperatures well below heat advisories, as physical labor increases heat stress. Limiting exposure to high temperatures, managing work activities properly, and staying hydrated can help prevent heat-related illnesses.

When the body cannot stay cool, the internal core temperature rises too much and bodily systems break down, leading to heat illness. The severity of heat illness can vary from a minor 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 condition, can experience heat stroke. However, some people may have more difficulty removing excess body heat and are at greater risk, such as the elderly, overweight or obese, with diabetes, heart disease, and hypertension or high blood pressure. The Centers for Disease Control and Prevention estimates that 48% of American adults have high blood pressure and 40% are obese, making it likely that at least half of the workforce is at increased risk of disease from heat.

OSHA is focusing on thermal safety in the workplace and will conduct more job site audits as part of its national outdoor and indoor heat hazard focus program. You need to make sure your workplace is prepared to keep employees safe when working in the heat. Here are 10 key elements for a workplace thermal safety program.

1. Heat Risk Monitoring

Managers must be trained to monitor workplace conditions and respond to excessive heat. Many factors play a role in creating occupational heat stress risk for employees, including:

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

With the help of an occupational health consultant, consider installing Wet Bulb Temperature (WBGT) monitors, the gold standard for accurate measurement of heat stress. The 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 plan thermal safety precautions accordingly.

2. Medical monitoring of employees working in the heat

Medical follow-up for all employees exposed to heat stress should include pre-employment and periodic medical assessments to assess personal risk factors for heat illness. Ongoing medical supervision may be recommended for employees working under conditions of high heat stress (eg, core temperature, hydration, pulse, and/or blood pressure). An occupational health advisor should be engaged to develop a workplace-specific medical surveillance program.

3. Emergency Action Plan

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

4. Thermal safety education

Educate all employees on thermal safety before they start working in a hot environment. Provide educational materials in a language and literacy level that employees can understand. Thermal 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.
  • Clear procedures to follow when someone shows symptoms of heat illness, including first aid and how to call for medical assistance.
  • What are the causes of heat illnesses (e.g. temperature, humidity, sun/wind exposure, workloads).
  • How to minimize the risk of heat illness (eg, hydration, rest cycles, symptom monitoring).
  • How to use heat protection PPE (e.g. sunscreen, hats, cooling vests).
  • Effects of lifestyle factors on the risk of heat-related illnesses (eg, drug and alcohol use, obesity).

Encourage employees to download apps, such as the OSHA-NIOSH Heat Safety Tool app, that monitor local weather conditions and notify users of heat advisories. OSHA also offers 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 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 may take several days to two weeks to adjust. Some acclimatization factors to consider:

  • Most heat-related deaths occur within the first few days of exposure because the body is not acclimatized.
  • Acclimatization can be lost in just a few days away from the hot environment.
  • Employees who are not in good physical shape may need more time to acclimatize.
  • Training and education are essential for both managers and employees.

The benefits of acclimatization include:

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

The CDC/NIOSH recommends new employees in hot environments to work 20% of the usual work day and gradually increase their time by 20% each day thereafter. Employees returning to the warm environment after an absence should start at 50% of the usual work day and gradually increase their time by 10% each day thereafter. This is a general timeframe, which may need to be modified depending on the risk profile of the individual.

6. Technical checks

Use engineering controls to reduce employee heat stress, including:

  • Reduce the physical demands of the job by using electrical devices for heavy duty tasks, such as forklifts.
  • Use air conditioning, fans or foggers; however, ensure that the moisture generated does not constitute a safety hazard.
  • Provide tents, shadehouses or awnings.

7. Hydration program

Provide an adequate and accessible supply of fresh drinking water with individual 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 of several hours, they should drink sports drinks with balanced electrolytes and eat small meals regularly to replace the salt lost in sweat.

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

8. Work/rest cycles and work rescheduling

Managers should consider moving work schedules to earlier or later in the day in the event of excessive heat. Employees should take regular breaks in a cool/shaded area to allow the body to cool down. In general, employees should have mandatory breaks of 15 minutes every hour. Rest periods may need to be longer or more frequent in extreme heat conditions.

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

  • When temperature, humidity and sunlight increase (WBGT).
  • When there is little or no wind or air circulation.
  • If employees wear heavy protective clothing or equipment.
  • If the workload is heavy or intense.

9. Use the buddy system

Heat illness can make people confused and unaware that they are experiencing symptoms. Assign co-workers to watch for signs of heat and ensure they follow the hydration and work/rest cycle plan. If employees must work alone, perform regular remote wellness checks with the employee.

10. PPE and clothing for thermal safety

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

When the job does not require specialized clothing to protect against other hazards (for example, flame and arc resistant clothing), encourage employees to choose cotton or natural fiber clothing over clothing made of synthetic. Avoid dark colored and heavier clothes and opt for lightweight cotton clothes in light colors.

Courtney Mindzak, MPH, M.Ed., is a public health program manager at International SOS and an assistant instructor in the College of Health Sciences at Alvernia University. Myles Druckman, MD, is vice president of medical services at International SOS. Nicolau Chamma, MD, is an Occupational Health Medical Advisor at International SOS. The International SOS Group of Companies provides tailored health, safety, risk management and wellness solutions.

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