Industrial Maintenance and Construction/Support Services Safety Manual - Heat Stress Policy


Industrial Maintenance and Construction/Support Services Safety Manual - Heat Stress Policy



The University of North Carolina at Chapel Hill (UNC) is committed to the health and safety of our students, faculty, staff and visitors. The goal of this Policy is to minimize the detrimental effects of excessive heat on UNC employees who are required to work outdoors or within indoor environments with elevated temperatures. Background information is also included. Effective measures to prevent heat stress vary by work unit, job duties and the work environment. 

The University of North Carolina at Chapel Hill (“UNC-Chapel Hill” or “University”) is committed to the health and safety of our students, faculty, staff, and visitors. The goal of this Policy is to minimize the harm of excessive heat on University employees who are required to work:

  • Outdoors, or
  • Indoors with unconditioned spaces or heat-generating equipment.

This Policy addresses effective measures to prevent heat stress because studies show a link between signs of heat stress and increased workplace accidents. (National Institute for Occupational Safety and Health (“NIOSH”)) Effective measures vary by work unit, activities, and environment. Work activities that could expose our employees to these hazards include landscaping, roof work, mail and package delivery, warehousing, and outdoor construction.


This Policy applies to all University employees who are required to work in excessive heat and are at risk of developing heat-related disorders.

Policy Statement

Heat Stress Risk Factors

Heat-related disorders may occur when a person has or is exposed to certain heat stress risk factors:

  1. Environmental conditions that affect the risk of heat-related disorders are air temperature and humidity, air movement, and the temperature of surrounding surfaces, which affect radiant heat exchange.
  2. Work conditions influence the stress on the temperature regulation system. Individual responses to a given workload vary, but the body’s internal metabolic heat production rises as an employee expends more energy. This increases stress on the cardiovascular system, which regulates body temperature (i.e., by increasing blood flow to the skin). Work-related factors that influence heat stress include work rate, level of physical effort, and duration of activity. Working in an environment with heat stress increases the risk for specific heat-related disorders such as heat exhaustion and heat stroke and increases the risk for other adverse events like workplace accidents.
  3. Clothing characteristics such as insulation, permeability, weight, fit, and ventilation affect the body’s ability to regulate internal temperatures. Other factors that may increase the risk of heat-related disorders include additional equipment, the use of a respirator, or other personal protective equipment (PPE).
  4. Personal characteristics such as age, weight, previous heat stress injury, underlying medical conditions (e.g., diabetes, cardiovascular disorders, chronic pulmonary disease, and thyroid disorders), medication use, and overall health and physical fitness contribute to an employee’s susceptibility of contracting a heat-related illness.

How to Identify Heat-Related Disorders

The chart below illustrates some signs and symptoms associated with heat-related disorders. If supervisors or coworkers observe signs of heat stress or the employee experiences any of these symptoms (excluding heat rash), the supervisor is responsible for ensuring that the employee receives prompt medical treatment by taking the affected employee to the emergency room or calling 911. The supervisor or another person must accompany the employee to the emergency room. The affected employee must be escorted to seek medical attention.  If 911 is called while waiting for emergency personnel to arrive, escort the affected employee to a cool area as soon as possible, cool the employee with water or ice, and remove outer layers of clothing, especially PPE.

Heat-Related Disorders Signs and Symptoms
Heat stroke
  • Confusion
  • Slurred speech
  • Unconsciousness
  • Seizures
  • Heavy sweating or hot, dry skin
  • Very high body temperature
  • Rapid heart rate
Heat exhaustion
  • Fatigue
  • Irritability
  • Nausea or vomiting
  • Dizziness or lightheadedness
  • Heavy sweating
  • Elevated body temperature or fast heart rate
Heat cramps
  • Muscle spasms or pain
  • Usually in legs, arms, or trunk
Heat syncope
  • Fainting
  • Dizziness
Heat rash
  • Clusters of red bumps on the skin
  • Often appears on neck, upper chest, and skin folds
Rhabdomyolysis (muscle breakdown)
  • Muscle pain
  • Dark urine or reduced urine output
  • Weakness

Source: Occupational Safety and Health Administration (OSHA) National Emphasis Program – Outdoor and Indoor Heat-Related Hazards

Any questions regarding heat-related health disorders (signs, symptoms, prevention, or treatment) should be directed to the University Employee Occupational Health Clinic (UEOHC) at 919-966-9119.

How to Prevent Heat Stress

A control is a mechanism to minimize or eliminate exposure to a hazard, such as heat. Three types of controls can be implemented to reduce exposure to excessive heat:

  • Administrative,
  • Engineering and
  • PPE.

Each person and situation is unique, so controls and their application will vary. The best combination of ways to prevent heat stress depends on the work, the environment in which it must be done, and the employees doing the work. Contact EHS for help selecting the most appropriate preventive measures for your work.

Administrative Controls

Administrative Controls, also known as work strategy controls, are strategies supervisors use to limit exposure to a hazard. For example, changes to the work schedule (i.e., when and how the job is performed) can limit the time an employee is exposed to excessive heat. Guidance for implementing administrative controls is provided below:

Rest and Cool Down Breaks

Consider changes to your break practices to lower the risk of heat stress. Possible changes during heat-stressed conditions include:

  • Changing the work/rest schedule based on air temperature and work intensity.
  • Taking breaks in a shaded area or air-conditioned building.
  • Encouraging employees to hydrate regularly and at any time they feel necessary (i.e., 1 quart each hour at the beginning of the shift; 12 ounces every 20 minutes during the heat of the day).

Pacing the job to allow more frequent breaks for fluid intake and sufficient recovery time.

Work Schedule Changes

Consider changes to your work schedule to lower the risk of heat stress. Possible changes include:

  • Scheduling routine maintenance and repair work during cooler periods of the day or cooler seasons. This limits sun exposure during midday hours.
  • Implementing a worker rotation schedule every hour or sooner for jobs essential to continuing University operations.
  • Implementing summer work schedules (e.g., 6:00 a.m. to 2:00 p.m.).
  • Allowing heavy work, such as heavy material handling, only before 9:00 a.m.
  • Scheduling all jobs requiring extensive PPE for the coolest parts of the day (i.e., early mornings).
  • Allowing sufficient recovery time for each worker.

Engineering Controls

Engineering Controls are physical changes made to the work environment, such as adding fans or air conditioning to an indoor environment. 

To minimize the risk of heat-related disorders with Engineering Controls, consider the following:

  • Opening windows and adding fans to increase air movement, provide air cooling, and ventilate heat.
  • Shielding radiant heat sources or local exhaust at the point of heat generation.
  • Providing shaded areas during remote outdoor work (e.g., constructing temporary shelters using tarps).
  • Equipping tractors, lawnmowers, and other outdoor equipment with cabs or canopies. 

Personal Protective Equipment

There is a limited selection of PPE to reduce the risk of heat stress. To reduce heat stress, consider:

  • Wearing hats and loose-fitting clothing;
  • Wearing sunglasses; and
  • Applying sunscreen (SPF 15 or higher).

In some cases, PPE, such as impermeable protective clothing and respirators, may increase the risk of developing a heat-related disorder. Administrative and Engineering Controls may be necessary to allow work in heat-risk environments with appropriate PPE.

Contact EHS for help in evaluating the necessity and effectiveness of available PPE.

Roles and Responsibilities

Supervisor's Responsibility
Developing a Heat Stress Plan

Every University work unit classified as an Industrial, Maintenance, Construction, or Support Services work environment must prepare, maintain, and submit a Hazards Management Plan (HMP) to EHS. Every University work unit with employees who must work outdoors or in environments with excessive heat must develop a Heat Stress Plan, which is included in the HMP.

Supervisors must provide detailed information to their employees on preventive measures that will be used during exposure to excessive heat in the Heat Stress Plan. EHS will provide a template for documenting preventive measures. The choice of effective preventive controls will depend on the following:

  • The work being done,
  • The work environment, and
  • The people doing the work.

Supervisors are required to review their work unit’s Heat Stress Plan with their staff annually or whenever relevant work procedures change.

Developing an Acclimatization Plan

Supervisors should include an acclimatization plan in the Heat Stress Plan.  Workers new to working outdoors or in environments with excessive heat may not be used to this heat. Their bodies need time to adapt to working in excessive heat.  The acclimatization plan gradually increases exposure time to excessive heat over a period of 7 to 14 working days. This plan should target the following groups:

  1. New, temporary, or existing employees who start new work activities:
    • in excessive heat;
    • while wearing additional clothing (e.g., chemical PPE); and/or
    • with increased physical activity.
  2. Workers returning to work environments with potential exposure to heat hazards after an absence of one week or more (e.g., returning from any extended leave).
  3. Workers who continue working through seasonal changes when temperatures first increase in the spring or early summer.
  4. Workers who work when the weather is significantly warmer than on previous days (i.e., heat wave).

The U.S. Occupational Safety and Health Administration (OSHA) and NIOSH recommend the "Rule of 20 percent (%)" for building heat tolerance (see table below):

  • New workers should work only 20% of the normal duration on their first day in the heat.
  • New workers should increase the time they work in the heat by 20% each subsequent day until they perform a regular schedule.

By following the Rule of 20%, new workers will be working a full schedule by the end of their first week. The Rule of 20% should protect the most physically fit workers with no medical problems. Other workers may sometimes require more time to adapt to heat – up to 14 days. When in doubt, give workers more days to adapt. Workers should perform tasks similar in intensity to their expected work.

For employees returning from a week or more absence from work, the adaptation schedule should be no more than 50% of the normal duration on day 1 in the heat, 60% on day 2, 80% on day 3, and 100% on day 4 (see table below).

Day Percent of the Work Shift Spent Working in the Heat for New Workers Percent of the Work Shift Spent Working in the Heat After One Week Absence
1 20% 50%
2 40% 60%
3 60% 80%
4 80% 100%
5 100%  
Monitoring for Signs of Heat Stress

Supervisors, coworkers, and employees are all responsible for monitoring the signs and symptoms of heat-related disorders. See the above table for information on recognizing the signs and symptoms of impending heat stress.

Supervisors should do the following:

  • Regularly check workers (by observation and questions) for signs and symptoms of heat stress when risks are present.
  • Take extra care to monitor those at high risk, such as employees who are older or overweight, employees who overexert themselves, and employees with chronic medical conditions, including diabetes, heart or lung disease, thyroid disease, or high blood pressure. Employees who take certain medications may also be at increased risk and need to check with their physician.
  • Supervisors should check to ensure that employees self-monitor and ask for their determinations.
  • During the excessive heat season, closely monitor staff to ensure that the work units’ Heat Stress Plan is followed and evaluate if additional measures are needed.
Providing Heat Stress Training

Supervisors must provide initial heat stress training for employees working outdoors or in environments with excessive heat. Supervisors must submit documentation of this initial training to EHS. Heat stress training should include:

  • Reviewing of heat-related disorders and their risk factors.
  • Recognizing the signs and symptoms of heat-related disorders and the importance of monitoring them.
  • Identifying preventive measures that the supervisor and employee will use.
  • Identifying fluid replacement options and expectations.
  • Understanding the importance of acclimatization.
  • Understanding how to contact emergency medical services.
Employee's Responsibility

Employees who work outdoors or indoors with excessive heat are responsible for:

  • Participating in your work unit’s heat stress training.
  • Learning the signs and symptoms of heat stress and risk factors.
  • Taking extra care if you are at increased risk. You may be at increased risk if you:
    • are older,
    • are overweight,
    • overexert,
    • have a chronic medical condition, including diabetes, heart or lung disease, thyroid disease, or high blood pressure.
    • take medications. Check with your doctor to see if you are at increased risk because of the effects of these medications. Heat tolerance can be affected by medications taken for colds, allergies, congestion, muscle spasms, blood pressure, urine production (diuretics), high blood pressure, diarrhea, dizziness/vertigo, psychosis, and depression.
  • Following the preventive measures listed in your work unit’s HMP Heat Stress Plan.
  • Taking time to adapt to excessive heat.
    • A heat wave is stressful for your body. You will have a greater tolerance for heat if you limit physical activity until you become accustomed to it.
  • Drinking small amounts of cool water frequently to relieve thirst and maintain adequate urine output (i.e., 1 quart each hour at the beginning of the shift; 12 ounces every 20 minutes during the heat of the day).
  • Wearing appropriate clothing.
    • Choose lightweight, light-colored, loose-fitting clothing that allows air ventilation to the body.
  • Protecting yourself from the sun by wearing a wide-brimmed hat. Sunglasses and sunscreen (SPF 15 or higher) are also recommended.
  • Pacing yourself. Start slowly and pick up the pace gradually.
  • Taking time to cool down and frequently resting in shady areas. 
  • Monitoring yourself and your coworkers for the signs and symptoms of heat-related illness described above.
  • Telling your supervisor about any known or suspected unsafe conditions or procedures.
EHS's Responsibility

Any Supervisor needing assistance with addressing heat stress in the workplace may request EHS to:

  • Evaluate the workplace for heat stress risks,
  • Evaluate temperature exposure,
  • Evaluate demands of employee work,
  • Evaluate protective equipment,
  • Recommend ways to manage exposure to heat,
  • Recommend additional controls, and
  • Recommend safe exposure times.

EHS is responsible for responding to Supervisor requests for assistance within five working days. EHS will provide a written report of the evaluation and recommendations.

University Responsibility

EHS or the University’s Office of Emergency Management and Planning will issue heat alerts when the National Weather Service or local news station issues the following heat-related alerts:

NWS Alert

Expected Condition

Communication Method

Responsible Party

Heat Advisory

Maximum heat index temperature is expected to be 100F or higher for at least two days, and nighttime air temperatures will not drop below 75F.

  • EHS social media post
  • EHS email to affected departments


Heat Wave

Daily maximum temperature exceeds 95◦F or when the daily maximum temperature exceeds 90◦F and is 9◦F or more above the maximum reached on the preceding days.

  • EHS social media post
  • EHS email to affected departments


Excessive Heat Warning

Maximum heat index temperature is expected to be 105◦F or higher for at least two days, and nighttime air temperatures will not drop below 75◦F.

  • Alert Carolina campus-wide message

Emergency Management and Planning

When the University issues a heat alert, departments and work units must:

  • Alert at-risk employees;
  • Implement their preventive measures for working in heat; and
  • Remind employees of:
    • Signs and symptoms of heat illness,
    • How to control exposure, and
    • Preventive work strategies employees must follow.


  • Acclimatization: allowing a person to adapt to excessive heat, which increases the body’s heat stress tolerance.
  • Control: A mechanism used to minimize or eliminate exposure to a hazard.
  • Excessive Heat: Heat index is 80F or higher. Occupational heat-related disorders become more frequent at this heat index.
  • Heat Index: A measure of how hot it feels when relative humidity is factored in with the air temperature.
  • Heat Stress: The total heat load a worker is exposed to from the combined contributions of physical exertion, environmental conditions, and clothing or PPE.
  • Signs: objective indicators viewable by a third party.
  • Symptoms: subjective experiences by the patient.

Related Requirements

External Regulations and Resources

University Policies, Standards, and Procedures

Contact Information

Policy Contacts

University Employee Occupational Health Clinic
Phone: 919-966-9119
Fax: 919-966-6337
UEOHC Website

Catherine Brennan, Executive Director
Department of Environment, Health & Safety
Phone: 919-843-5331

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Article ID: 131995
Thu 4/8/21 9:21 PM
Tue 5/21/24 10:58 AM
Responsible Unit
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Environment, Health and Safety
Issuing Officer
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Executive Director
Next Review
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03/01/2027 12:00 AM
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02/01/2019 7:55 AM
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05/01/2014 12:00 AM