10 Key Elements for a Workplace Thermal Safety Program

Globally, extreme heat waves have increased in frequency, duration and magnitude and are expected to keep going up, according to the World Health Organization. Employers must 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 high and the body’s systems break down, leading to heat illness. Heat illnesses can range in severity from minor rashes, sunburn and heat cramps, to heat fainting (fainting), heat exhaustion, rhabdomyolysis ( loss of muscle tissue) and heatstroke, 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 heatstroke. 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 hypertension and 40% are obesemaking it likely that at least half of the workforce is at increased risk of heat illness.

OSHA is focusing on thermal safety in the workplace and will be performing more audits on job sites under its National Outdoor and Indoor Heat Hazard Emphasis 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

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 protective gear.
  • Individual risk factors and high-risk conditions.

Managers must be trained to monitor workplace conditions and respond to excessive heat.

With the help of an Occupational Health Advisor, consider installing Wet Bulb Temperature (WBGT) monitoring devices – the gold standard for precise 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 accordingly heat safety precautions.

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. Continuous medical surveillance 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 construction site emergency plan which explains how to recognize the 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. To assure educational material use language and a level of literacy 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 PPE and heat protection equipment (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 (for example, OSHA-NIOSH Thermal Safety Tool Application) that monitor local weather conditions and notify users of heat advisories.

OSHA 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 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 or up 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.

CDC/NIOSH recommend that new employees in hot environments 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, for example:

  • Reduce the physical demands of the job: Use 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. Drink 1 cup of water every 15-20 minutes (32 oz/1 liter of fluid per hour). During prolonged sweating over several hours, drink sports drinks with balanced electrolytes and eat small meals regularly to replace the salt lost in sweat.

Provide convenient access to adequate toilets. 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 15-minute breaks 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 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 (e.g. flame and arc resistant clothing), encourage employees to choose clothes made from cotton or natural fibers rather than synthetic material garments. 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 with International SOS and an Adjunct Instructor for 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.

Ryan H. Bowman