Heat Stress Hazards and Safety Best Practices at Work

Working in hot environments can lead to heat illnesses. There are many employees who suffer heat-related illnesses each year due to not following the proper precautions. This post will discuss what heat illness is, OSHA requirements, heat illness statistics, warning signs, common heat illnesses, medical treatment, and best practices to mitigate heat hazards.

heat stress best practices

What is Heat Illness?

Heat-related illness is also referred to as hyperthermia. It is a condition resulting from exposure to heat where the body cannot properly cool. This leads to a rapid rise in body temperature.

High humidity can contribute to heat illness. The evaporation of sweat is a natural way to remove heat from the body, but when humidity is high, sweat cannot evaporate as quickly. This contributes to the body not being able to cool properly.

Common heat illnesses include heat cramps, heat exhaustion, and heat stroke. Employees who work in hot environments are at risk of experiencing a heat illness.

Risk Factors for Heat Illness

People younger than four years old and those older than 65 years old are at higher risk for heat illnesses or death. Existing medical conditions can also contribute to an individual experiencing a heat illness. Drinking alcohol or taking medication can also put an individual more at risk of experiencing a heat illness.

heat illness risk factors

Heat-Related Illness Statistics

Heat can be a killer on the job. According to a report published by the CDC, during 2004–2018, an average of 702 heat-related deaths (415 with heat as the underlying cause and 287 as a contributing cause) occurred in the United States annually.

Heat stress can be a contributing factor to other types of injuries or incidents to occur. Working in hot environments can lead employees to become fatigued or contribute to an inability to properly focus on work tasks. This negative impact on performance can lead to sprains, strains, struck-by incidents, slips, trips, falls, etc.

heat illness stats

The true impact that heat stress has on workplace safety is difficult to measure.

Heat-Related Illness Symptoms

There are many possible symptoms of heat-related illnesses. It is vital to know what they are and what to do in the event someone is experiencing symptoms.

For less severe heat illnesses, some of the common symptoms include:

  • Muscle cramping
  • Fatigue
  • Headache
  • Nausea or vomiting
  • Dizziness or fainting
  • Fast and weak pulse rate
  • Rapid and shallow breathing

Heat stroke, the most severe heat illness, may have some of the same symptoms as above. There are other key symptoms to consider, such as:

  • A body temperature greater than 103 degrees Fahrenheit (39.4 degrees Celsius)
  • Red, hot, and dry skin with an absence of sweat
  • Rapid, strong pulse
  • Throbbing headache
  • Dizziness
  • Confusion
  • Unconsciousness

It is vital to take these symptoms seriously and get the affected employee medical care immediately to prevent severe outcomes.

Does OSHA Have a Heat Stress Standard?

OSHA does not have a specific heat stress standard or heat prevention plan implemented at the federal level. Employers can, however, be cited for heat stress hazards under the General Duty Clause.

does osha have a heat stress standard

The General Duty Clause is found under Section 5(a)(1) of the Occupational Safety and Health Act of 1970. It states, “employers are required to provide their employees with a place of employment that is free from recognized hazards that are causing or likely to cause death or serious harm to employees.”

Certain states have their own OSHA-approved State plans and may have more stringent requirements when it comes to heat stress. For example:

  • California’s Heat Illness Prevention Standard requires employers to provide training, water, shade, and planning. A temperature of 80°F triggers the requirements. See CalOSHA’s website. See the full text of the California heat standard.
  • Minnesota. The standard applies to indoor places of employment. See the full text of the regulation.
  • Washington. See Washington State’s Outdoor Heat Exposure Rule. See the full text of the regulation.

OSHA often refers to NIOSH’s Recommended Heat Standard when providing guidance on how to mitigate heat stress. This standard can be found by clicking here. 

Common Heat Illnesses and Medical Treatment

As stated above, there are different types of heat illnesses. The most common are heat cramps, heat exhaustion, and heat stroke. There are descriptions below, as well as medical responses for each one.

Heat Cramps

Heat cramps are painful, brief muscle cramps. Muscles may spasm or jerk involuntarily. Heat cramps can occur during exercise or work in a hot environment or begin a few hours later.

heat cramp safety

Usually, heat cramps occur when someone first starts working in a hot environment. An employee may not experience any longer once they are acclimated to working in a hot environment and if they maintain adequate fluid replacement.

Medical Response for Heat Cramps

Heat cramps will normally go away on their own once work ceases in the hot environment. Resting in a cool place, drinking water, or drinking a sports drink with electrolytes can help treat heat cramps.

Heat Exhaustion

There are two types of heat exhaustion.

  1. Water depletion- Signs include excessive thirst, weakness, headache, and loss of consciousness.
  2. Salt depletion- Signs include nausea and vomiting, muscle cramps, and dizziness.

Heat exhaustion can lead to heat stroke if the appropriate care is not provided.

Medical Response for Heat Exhaustion

For people displaying symptoms of heat exhaustion, have them stop work and get to a shaded area. The affected person needs to consume water or electrolyte replacing sports drinks. The person should not return to work the rest of the day.

heat exhaustion medical care

Heat Stroke

Heat stroke is the most serious heat-related illness. Heat stroke can kill or cause damage to the brain and other internal organs. Heat stroke results from prolonged exposure to high temperatures — usually in combination with dehydration — which leads to failure of the body’s temperature control system.

Medical Response for Heat Stroke

For anyone who is displaying symptoms of a heat stroke, immediate medical attention is needed. Delaying calling 911 could result in irreversible injuries or death.

Symptoms of heat stroke include fainting, throbbing headache, dizziness, lack of sweating, vomiting, or behavioral changes such as confusion.

heat stroke medical care

The person should be cooled down immediately in a shaded area or indoors. DO NOT put ice-cold water on the victim as this can cause shock. Use cool water to lower the body temperature of the victim. Remove any unnecessary clothing and fan the victim until medics arrive.

Best Practices to Mitigate Heat Stress

There are simple best practices that should be followed to prevent heat illnesses. The list below does not encompass every possible mitigation action or best practice.


It is vital to provide safety training to employees who will be working in hot environments prior to beginning work. Employees should understand what heat stress is, the different types of heat illnesses, symptoms of heat illness, necessary medical treatment, and best practices to mitigate heat stress hazards.

Plan Work Around Weather

Proper pre-planning for all job tasks is critical to ensure safety and efficiency. Planning work in hot environments is especially important. Whenever possible, strenuous work tasks should occur in cooler weather or during cooler parts of the day.

Less strenuous work, or work indoors in controlled conditions, should take place during the hottest parts of the day.

job task preplanning

Acclimatization to Hot Environments

Allowing a person to acclimate to a hot environment is key to preventing injury and illness. There is no set time or number of days a person may properly acclimate to a hot environment. NIOSH states that employees should gradually increase their time spent in hot conditions over a period of 7 to 14 days.

It is also important to note that acclimatization can be lost after one week of being away from working in hot environments.

Drink Water

Drinking water, as well as electrolyte replenishing drinks, is vital when working in hot conditions. The body loses a lot of water and minerals through sweating when working in these conditions.

Employees should not wait until they are thirsty to drink fluids. Alcoholic beverages, sugary drinks, and caffeinated drinks should be avoided.

drink water when working in hot weather

Provide Breaks

Employees should be provided with a shaded, or preferably, cooled area to take breaks in. The hotter the environment or, the more strenuous the work, the more frequent breaks should be. Employees should be mandated to take breaks while working in hot environments, even if they do not feel like they need one.

Protective Clothing

The clothing worn by employees should be light and breathable whenever possible. Covering the skin is a best practice to protect the skin from harmful sun rays, but the clothing should not be heavy. Heavy clothing such as hoodies can contribute to a heat-related illness.


Heat stress needs to be taken seriously by those working in hot environments. Heat illnesses such as heat stroke can have life-long health impacts or lead to death if not prevented. Follow the best practices mentioned here as well as from other reputable sources such as the CDC or OSHA to mitigate the hazards of heat stress.

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