The Heat Is On: Understanding Heat Stress and How to Manage It Effectively 

As summer approaches, we know that rising temperatures and humidity are coming, which also means a potential rise in heat stress incidents is on the way. Working in extreme heat may cause a variety of health complications—such as heat strokes, heat exhaustion, heat cramps, heat syncope, heat rash, rhabdomyolysis, or an acute kidney injury—if one isn’t properly prepared. Now is the time to start taking the necessary precautions to protect your personnel and prevent heat-related injuries and illnesses.  

Employees who work outside are exposed to direct sunlight, higher ambient temperatures, and high humidity for longer periods of the day than those who work indoors, and as such, employees working outside are at greater risk of developing and even succumbing to any one of the illnesses mentioned. The U.S. Department of Labor’s Bureau of Labor Statistics (BLS) reports that 43 work-related deaths in 2022 were due to heat exposure, which is up from 36 deaths in 2021.1 BLS also states that since 2011 479 work-related deaths have resulted from excessive heat exposure. 2

In response to this increase, the Occupational Safety and Health Administration (OSHA) has developed a National Emphasis Program (NEP)3 to prioritize on-site responses for heat-related inspections in industries that expose employees to indoor and outdoor heat-related hazards. The following industries have the highest numbers of heat-related illnesses:

  1. Cattle ranching and farming 
  2. Support activities for crop productio
  3. Support activities for mining 
  4. Bakeries and tortilla manufacturing 
  5. Sawmills and wood preservation 

A full list of the target industries can be found in Appendix A of OSHA Directive CPL 03-00-024: National Emphasis Program – Outdoor and Indoor Heat-Related Hazards.3

The goal of OSHA’s NEP is to decrease or end employee exposure to heat-related hazards. The NEP states that OSHA will accomplish this by: 

  • Increasing planned and unplanned inspections, including industry-targeting inspections; 
  • Providing employer outreach opportunities; and 
  • Providing employer compliance assistance. 

OSHA has instructed compliance officers to expand the scope of current inspections to include heat-related inspections and to open or refer for a heat-related inspection when: 

  • A heat-related hazard is present; 
  • A heat-related injury or illness has been documented on the OSHA 300 logs or 301 Incident Reports; or 
  • An employee alerts the compliance officer of a heat-related hazard existing at the job site. 

Heat-related hazards may include employees being exposed to elevated temperatures without adequate safety training or proper acclimatization or employees not having access to adequate amounts of water, breaks, or shade.  

OSHA has also instructed compliance officers to request copies of any heat-related hazard prevention programs during heat priority days. A heat priority day is a day when the heat index is expected to be 80°F or higher.  

Understanding the working conditions that may put your employees at risk and how to prevent heat-related illnesses will help you to ensure that your employees remain safe during the warmest of days this summer.  

What are some work activities that may put my employees at risk for a heat-related illness? 

Activities that may expose your employees to heat-related hazards include, but are not limited to, the following:

  • Working in direct sunlight
  • Performing work near heat sources (e.g., kilns, dryers, gas engines, furnaces, boilers, or steam lines) 
  • Wearing heavy or bulky clothing or equipment, including personal protective equipment (PPE) 
  • Performing moderate-, heavy-, or very-heavy-intensity job tasks  
  • Remaining exposed to extreme heat conditions for extended periods 

How can I help prevent heat-related illnesses for my employees? 

Employees rely on their employers to protect them from all hazards associated with their jobs, including extreme heat. Following is a list of five actions you can take to reduce or eliminate your employees’ exposure to extreme heat and heat-related hazards. 

1. Provide Training   

Educate all employees about the following:

  • Hazards that may increase their risk for developing heat-related illnesses, such as but not limited to personal risks factors, health conditions, the effects of precipitation, and the effects of over-the-counter medications, caffeine intake, and alcohol consumption
  • How to avoid conditions that may lead to heat-related illnesses 
  • The signs and symptoms of heat-related illnesses 
  • First-aid procedures to administer during heat-related incidents 
  • The employer policies and procedures to prevent heat-related illness 

Supervisors and/or team leaders should also be trained on how to monitor weather conditions and the steps to take when a hot weather advisory has been issued. 

2. Establish a Written Medical Monitoring and Heat Prevention Program  

This program should address the following: 

  • How employees will be trained on the program and heat-related prevention strategies
  • How the weather and workplace conditions will be monitored and by whom 
  • How a heat hazard assessment will be conducted at the workplace 
  • The heat acclimatization plan for new and experienced employees 
  • Control measures that will be taken to protect employees (i.e., engineering, administrative, and work practice controls and the PPE that will be provided) 
  • How heat-related medical emergencies will be handled How to implement a medical monitoring program that includes preplacement and periodic medical evaluations by a licensed healthcare provider to assist with identifying early signs or symptoms for employees as recommended by the National Institute for Occupational Health and Safety (NIOSH) 

3. Establish and Implement Engineering, Administrative, and Work Practice Controls 

Stress factors from extreme heat can be decreased when you implement engineering, administrative, and work practice controls. Engineering controls might include increasing air flow with portable air conditioners or cooling/misting fans, providing heat-reflective or heat-absorbing shields, or providing shade to the work site.  

Administrative and work practice controls might include: 

  • Scheduling work to be completed during a cooler part of the day, 
  • Providing shaded areas and adequate amounts of cool water near each work area and encouraging employees to drink, 
  • Reducing the physical demands of the job, 
  • Implementing a job rotation schedule, and  
  • Increasing the number of breaks throughout the day.  

Another way to prevent heat-related illnesses is to implement a buddy system so employees can monitor each other and identify early signs and symptoms of heat stress.  

4. Provide Appropriate Personal Protective Clothing and Equipment 

The National Weather Service uses heat index (often known as the “feels like” temperature) as a tool to classify environmental heat into four categories:4

CAUTION — 80°F–90°F

EXTREME CAUTION — 91°F–103°F

DANGER — 103°F–124°F

EXTREME DANGER — 126°F or higher

To help employers find the forecasted and current heat index at job sites, OSHA and NIOSH developed the OSHA-NIOSH Heat Safety Tool App, which can be downloaded on any phone. This app helps indicate if the immediate area is under a CAUTION, EXTREME CAUTION, DANGER, EXTREME DANGER advisory.  

When a heat index of 80°F or higher has been issued, occupational heat-related illnesses and injuries are more prevalent. Therefore, PPE should be provided to anyone who works outdoors. Those who perform strenuous manual labor—such as carrying, pushing or pulling heavy loads, shoveling or digging, and sawing—are especially vulnerable to heat-related incidents, as are others such as sawmill workers or loader operators who spend extended periods outside. 

PPE includes hats for outdoor workers; loose, reflective clothing designed to divert radiant heat; water-cooled garment; dermal patches to monitor core temperature; or ice-packed garments. OSHA states that caution should be used while wearing water-cooled or ice-packed garments, as they may become insulators when they warm to an employee’s body temperature.  

5. Provide Acclimatization Opportunities 

Acclimatization is a process by which an employee gradually increases their exposure to a hot environment to properly regulate their body temperature and minimize the potential for heat-related illnesses. Acclimatization is beneficial to physiological adaptations because it helps to: 

  • Increase sweating efficiency, 
  • Stabilize circulation, 
  • Increase blood flow in the skin, and 
  • Increase the ability to perform work with a lower core temperature and heart rate. 

A heat acclimatization plan should be developed prior to the hotter months of the year to reduce the potential for heat-related illnesses.  

OSHA’s NEP recommends the following:5

  • New employees should be allowed a 7- to 14-day acclimation period that consists of no more than 20 percent of the duration and workload for day 1 and no more than an increase of 20 percent on subsequent days until they are safely able to perform a full day of work. New employees should be closely supervised during the first 14 days to ensure they are taking the required breaks and hydrating properly.  
  • Experienced employees should be allowed no more than 50 percent of the duration and workload for day 1, 60 percent on day 2, 80 percent on day 3, and 100 percent on day 4.  
  • Employees who have been absent from work for more than 3 days will need to gradually reacclimate to the heat by starting at the beginning of the “experienced employee” acclimation plan.  

The risks to employees who work in excessive heat conditions are great. It is the responsibility of all employers to ensure that their employees are provided with the proper equipment and training to keep them safe at work. Planning ahead is critical to ensuring that no one falls victim to preventable heat-related illnesses and injuries, so don’t wait! 

For more information about heat stress and OSHA’s NEP, visit our website, or contact Kelly Bergeron, Health and Safety Specialist, at 412-742-0796 or kelly.bergeron@ehs-support.com. Also, please explore the links below to additional OSHA resources.  


1   Bureau of Labor Statistics, U.S. Department of Labor (BLS). 2023, December 19“National Census of Fatal Occupational Injuries in 2022. News Release (USDL-23-2615). Accessed at https://www.bls.gov/news.release/pdf/cfoi.pdf

2   BLS. 2023, June 5. 36 work-related deaths due to environmental heat exposure in 2021 TED: The Economics Daily. Accessed at https://www.bls.gov/opub/ted/2023/36-work-related-deaths-due-to-environmental-heat-exposure-in-2021.htm.

OSHA, U.S. Department of Labor. 2022, April 8. “National Emphasis Program – Outdoor and Indoor Heat-Related Hazards (Directive Number: CPL 03-00-024). Accessed at https://www.osha.gov/sites/default/files/enforcement/directives/CPL_03-00-024.pdf  

4   National Weather Service, “Heat Forecast Tools.” Accessed at https://www.weather.gov/safety/heat-index

5    OSHA, “Appendix A: Target Industries for Heat NEP.” 

Resources:  

Centers for Disease Control and Prevention (CDC). 2016, February. Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments. DHHS (NIOSH) Publication 2016-106. Accessed at: https://www.cdc.gov/niosh/docs/2016-106/ 

OSHA “Heat – Overview: Working in Outdoor and Indoor Heat Environments.” Accessed at:  https://www.osha.gov/heat-exposure 

OSHA. 2021, July. Model Heat-Illness Prevention Plan. Available at: https://www.osha.gov/sites/default/files/2021-07/Model%20Heat%20Illness%20Prevention%20Plan.pdf 

 

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