Heat Illness Prevention

August 2, 2018

Beating the heat on a job site is much more difficult than staying cool at the neighborhood BBQ. Long shifts, strenuous work, ill-equipped employees, and insufficiently trained personnel all can contribute to heat related illnesses. Employers are often unaware of the recommended precautions, and in some states like California that means they may be violating state OSHA regulations. It is vital to crew safety that employees can find shade, drink lots of water, wear loose and light clothing, or take regular breaks.

Occupational safety and health (OSH) professionals know that exposure to high heat presents a real threat to workers. According to the most recent U.S. Heat Fatalities Map from the Occupational Safety and Health Administration (OSHA), 109 heat-related occupational fatalities occurred between 2008 and 2014. Agriculture and construction workers typically present the highest risk for heat-related emergencies. Construction workers in particular face significant risk as project schedules often require fast paced work in unavoidably hot conditions.

Heat Stress

Heat Stress is the perceived discomfort and physiological strain associated with exposure to a hot environment, especially during physical work. Heat stress can take several forms ranging from mild discomfort to life threatening conditions like “Hyperthermia,” and “Multi-Organ Disfunction Syndrome.”

  • Heat exhaustion – Mild-to-moderate illness due to water or salt depletion that results from exposure to high environmental heat or strenuous physical exercise; signs and symptoms include intense thirst, weakness, discomfort, anxiety, dizziness, fainting, and headache; core temperature may be normal, below normal, slightly elevated (>98.6F but <104F)
  • Heat stroke – Severe illness characterized by a core temperature >104F and central nervous system abnormalities such as delirium, convulsions, or coma resulting from exposure to environmental heat (classic heat stroke) or strenuous physical exercise (exertional heat stroke)
  • Hyperthermia – A rise in body temperature above the hypothalamic set point when heat dissipating mechanisms are impaired (by drugs or disease) or overwhelmed by external (environmental or induced) or internal (metabolic) heat
  • Multi-organ dysfunction syndrome – Continuum of changes that occur in more than one organ system after an incidents such as trauma sepsis, or heat stroke

All of these types of issues can create safety hazards for both the worker and their co-workers. According to OSHAs General Duty Clause, it is the responsibility of the employer to provide a safe and healthy work environment, which includes precautions for high heat work environments.

Risk Factors

Risk factors for heat stress include both “environmental” and “personal risk factors.” Heat Illness is a medical condition that results from the body’s inability to cope with heat and cool itself. Environmental risk factors for heat illness can be air temperature, relative humidity, radiant heat from the sun and other sources, conductive heat sources such as ground, air movement, work load severity and duration, protective clothing and personal protective equipment worn by employees. Personal risk factors for heat illness can be an individual’s age, degree of acclimatization, health, water consumption, alcohol consumption caffeine consumption, and use of prescription medications that affect the body’s water retention or other physiological responses to heat. Heat Illness can progress to heat stroke and be fatal, especially when emergency treatment is delayed. Some medicines reduce heat tolerance. Antibiotics, chemotherapy drugs and some pain medications recommend limiting exposure to direct sunlight and high heat. Your doctor should know about the heat exposure of your job before prescribing medicines.

First Signs

The first stage of a heat related illness is referred to as “Heat Cramps” and early warning signs include:

  • Headache
  • Muscle cramps
  • Unusual fatigue

Heat Cramps can quickly lead to Heat Exhaustion which can include the following symptoms:

  • Heavy sweating
  • Cramps
  • Rapid pulse
  • Headache
  • Nausea
  • Vomiting

If not treated Heat Exhaustion can lead to Heat Stroke, which is a potentially fatal condition characterized by the following:

  • Dry
  • Red skin color
  • Hot skin
  • High body temperature
  • Disoriented
  • Confused

If any employee suspects a co-worker has progressed into Heat Stroke, 911 or other emergency services should be contacted immediately.


Monitor the weather. If the prediction on the previous day is for the temperature-high to exceed 80 degrees F, precautions like the provision of shade must be provided as of the beginning of the shift and present throughout. Workers may want to check NOAA’s Heat Index to provide a relative temperature when presented with conditions of both high heat and high humidity. The perceived temperature may be significantly higher when humidity is factored. The table below shows the relationship between high heat and high humidity on perceived temperature.

Training is also an important aspect in reducing the risk of work during high heat. Topics which should be addressed include:

  • The importance of immediately reporting signs or symptoms of heat illness to supervision.
  • Procedures for responding to possible heat illness.
  • Procedures to follow when contacting emergency medical services and if necessary transporting employees
  • Employers procedures that ensure clear and precise directions to the work site will be provided to emergency medical services
  • Procedures to follow when an employee exhibits symptoms consistent with heat illness, including emergency response

Methods for Prevention

Access to sufficient amounts of fresh, pure and sufficiently cool drinking water shall be available at all times, w/at least one quart (4 cups) per employee per hour for the entire shift. Water must be provided at no cost to the employees. Supervisors must arrive with sufficient fresh, pure, and sufficiently cool, drinking water to supply all employees on site for the duration of the work day. Supervisors must have arranged before the start of the work day to provide replenishment during the work day if it is not feasible to begin the day with a sufficient quantity. Provision of water must be reliable! It is not reliable if you wait until employees request it. Water must be as close to the employee as is practical (unless employers can demonstrate that it is infeasible.) Below are important points to consider while working in high heat.

  • Designate a person(s) to periodically check the level of the water containers.
  • Check the temperature of the water to see if it is cool.
  • Encourage the Frequent Drinking of WATER
  • Shorten the distance between water and workers.
  • To augment, provide individual beverage containers.
  • Keep water cool & in very hot weather, have ice on hand.
  • Increase the number of water breaks, particularly during a heat wave.
  • Use daily reminders… JSA
  • Drink Water Frequently!
  • Don’t wait until your thirsty!
  • If you find you are excessively thirsty you may already be dehydrated.

Access to shade and recovery time for employees who co-workers suspect are in the beginning stages of a heat related illness are vital to employee safety. A “Preventative Cool Down Rest” should be provided to an employee suffering from heat illness or believing that a rest break is needed to recover from the heat. Employees must have access to an area with shade that is either open to the air or provided with ventilation or cooling for a period of no less than 5 minutes. During this period, the employees should be monitored for signs and symptoms of a heat related illness, encouraged to stay in the shade, and not ordered back to work until the symptoms are gone. Employees with symptoms of a heat related illness must be provided appropriate first aid or emergency response.

Some states like California have Heat Illness Prevention regulations which require provision of shaded rest areas, water, and training.

Allowing for employee acclimatization may be the most important and often overlooked aspects of Heat Illness prevention, and the company must allow for acclimatization.

Employee acclimatization procedures should be followed for the following employees:

  • Employees returning to work after a prolonged absence or recent illness
  • Employees recently moving from a cool to a hot climate
  • Employees working during the beginning stages of a heat wave
  • Adjust the strenuous work load so that it is during the cooler portion of the day; in the mornings
  • Progressively increase work time during the heat
  • Monitor employees closely for signs and symptoms of heat illness
  • Have employees take regular breaks in the shade
  • Have employees drink water regularly
  • Replace Salt Loss Due to Sweating


Employers must reduce risk to employees by engaging in adequate Heat Illness Prevention measures. Several states have introduced Heat Illness Prevention regulations, and by many accounts this will become a national standard in the coming years. Employers have the responsibility to provide a safe and healthy workplace, but from an organizational standpoint an employer can mitigate risk to the organization and increase productivity of employees by ensuring their employees are safe and healthy.

Pacific Safety

Pacific Safety Solutions provides innovative environmental, health and safety services delivered through a clear process, refined training and practical evaluation. They strive to provide these quality services with the highest integrity to all their clients. Learn More

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