Workers and Heat Stress: What You Need to Know
Workers should avoid exposure to extreme heat, sun exposure, and high humidity whenever possible.
Workers who are exposed to extreme heat or work in hot environments may be at risk of heat stress. Exposure to extreme heat can result in illnesses and injuries. Prevention of heat stress in workers is important. Employers should provide training to workers so they understand what heat stress is, how it affects their health and safety, and how it can be prevented.
Heat Stress Risks
Heat stress can result in heat stroke, heat exhaustion, heat cramps, or heat rashes. Heat can also increase the risk of injuries in workers as it may result in sweaty palms, fogged-up safety glasses and dizziness. On top of that, burns may also occur as a result of accidental contact with hot surfaces or steam.
Workers at risk of heat stress include outdoor workers and workers in hot environments such as firefighters, bakery workers, farmers, construction workers, miners, boiler room workers, factory workers, and others. Workers at greater risk of heat stress include those who are 65 years of age or older, are overweight, have heart disease or high blood pressure, or take medications that may be affected by extreme heat (for more tips, also check out Beating the Heat).
Types of Heat Stress: Heat Stroke
Heat stroke is the most serious heat-related disorder. It occurs when the body becomes unable to control its temperature: the body's temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down. When heat stroke occurs, the body temperature can rise to 106 degrees Fahrenheit or higher within 10 to 15 minutes. Heat stroke can cause death or permanent disability if emergency treatment is not given (for related reading, see What should I provide for outdoor workers who are at risk of heat stress?).
Symptoms of Heat Stroke
Symptons of heat stroke include:
- Hot, dry skin or profuse sweating
- Throbbing headache
- High body temperature
- Slurred speech
First Aid for Heat Stroke
Take the following steps to treat a worker with heat stroke:
- Call 911 and notify their supervisor
- Move the sick worker to a cool shaded area
Cool the worker using methods such as:
- Soaking their clothes with water
- Spraying, sponging, or showering them with water
- Fanning their body
Identifying and Treating Heat Exhaustion
Heat exhaustion is the body's response to an excessive loss of the water and salt, usually through excessive sweating. Workers most prone to heat exhaustion are those that are elderly, have high blood pressure, and those working in a hot environment.
Symptoms of Heat Exhaustion
Symptoms of heat exhaustion include:
- Heavy sweating
- Extreme weakness or fatigue
- Dizziness, confusion
- Clammy, moist skin
- Pale or flushed complexion
- Muscle cramps
- Slightly elevated body temperature
- Fast and shallow breathing
First Aid for Heat Exhaustion
Treat a worker suffering from heat exhaustion with the following:
- Have them rest in a cool, shaded or air-conditioned area
- Have them drink plenty of water or other cool, nonalcoholic beverages
- Have them take a cool shower, bath, or sponge bath
Identifying and Treating Heat Syncope
Heat syncope is a fainting (syncope) episode or dizziness that usually occurs with prolonged standing or sudden rising from a sitting or lying position. Factors that may contribute to heat syncope include dehydration and lack of acclimatization.
Symptoms of Heat Syncope
Symptoms of heat syncope include:
First Aid for Heat Syncope
Workers with heat syncope should:
- Sit or lie down in a cool place when they begin to feel symptoms
- Slowly drink water, clear juice, or a sports beverage
Identifying and Treating Heat Cramps
Heat cramps usually affect workers who sweat a lot during strenuous activity. This sweating depletes the body's salt and moisture levels. Low salt levels in muscles causes painful cramps. Heat cramps may also be a symptom of heat exhaustion.
Symptoms of Heat Cramps
Muscle pain or spasms usually in the abdomen, arms, or legs.
First Aid for Heat Cramps
Workers with heat cramps should:
- Stop all activity, and sit in a cool place
- Drink clear juice or a sports beverage
- Do not return to strenuous work for a few hours after the cramps subside because further exertion may lead to heat exhaustion or heat stroke
- Seek medical attention if any of the following apply:
- The worker has heart problems
- The worker is on a low-sodium diet
- The cramps do not subside within one hour
Identifying and Treating Heat Rash
Heat rash is a skin irritation caused by excessive sweating during hot, humid weather
Symptoms of Heat Rash
Symptoms of heat rash include:
- Heat rash looks like a red cluster of pimples or small blisters
- It is more likely to occur on the neck and upper chest, in the groin, under the breasts, and in elbow creases
First Aid for Heat Rash
Workers experiencing heat rash should:
- Try to work in a cooler, less humid environment when possible
- Keep the affected area dry. Dusting powder may be used to increase comfort
Recommendations for Employers
Employers should take the following steps to protect workers from heat stress:
- Schedule maintenance and repair jobs in hot areas for cooler months
- Schedule hot jobs for the cooler part of the day
- Acclimatize workers by exposing them for progressively longer periods to hot work environments
- Reduce the physical demands of workers
- Use relief workers or assign extra workers for physically demanding jobs
- Provide cool water or liquids to workers
- Avoid alcohol, and drinks with large amounts of caffeine or sugar
- Provide rest periods with water breaks
- Provide cool areas for use during break periods
- Monitor workers who are at risk of heat stress
- Provide heat stress training that includes information about:
- Worker risk
- The importance of monitoring yourself and coworkers for symptoms
- Personal protective equipment
|Free Download: Hot Weather Survival Guide|
Recommendations for Workers
Workers should avoid exposure to extreme heat, sun exposure, and high humidity when possible. When these exposures cannot be avoided, workers should take the following steps to prevent heat stress:
- Wear light-colored, loose-fitting, breathable clothing such as cotton
- Avoid non-breathing synthetic clothing
- Gradually build up to heavy work
- Schedule heavy work during the coolest parts of day
- Take more breaks in extreme heat and humidity
- Take breaks in the shade or a cool area when possible
- Drink water frequently
- Drink enough water that you never become thirsty. Approximately 1 cup every 15-20 minutes
- Avoid alcohol, and drinks with large amounts of caffeine or sugar
- Be aware that protective clothing or personal protective equipment may increase the risk of heat stress
- Monitor your physical condition and that of your coworkers
NIOSH is revising the 1986 version of this criteria document. The draft document is available on the docket website. A public meeting for comment on the draft criteria document was held February 13, 2014.
CDC: Extreme Heat - Additional information on heat stress illnesses and prevention.
This document presents the criteria, techniques, and procedures for the assessment, evaluation, and control of occupational heat stress by engineering and preventive work practices. Included are ways of predicting health risks, procedures for control of heat stress, and techniques for prevention and treatment of heat-related illnesses.
Health Hazard Evaluations
- Health Hazard Evaluation Report, HETA 2006-0307-3139 [PDF - 3.67MB], Heat Stress and Strain Evaluation Among Aluminum Potroom Employees - Texas
- Health Hazard Evaluation Report, HETA 2005-0215-3099 [PDF - 3.89MB], Evaluation of Heat and Carbon Monoxide Exposures to Border Protection Officers at Ports of Entry
- Health Hazard Evaluation Report, HETA 2004-0334-3017, Transportation Security Administration, Palm Beach International Airport, West Palm Beach, Florida
- Health Hazard Evaluation Report, HETA 2003-0311-3052 , Evaluation of Heat Stress at a Glass Bottle Manufacturer, Lapel, Indiana
- Health Hazard Evaluation Report, HETA 2000-0061-2885, United States Air Force, Seymour Johnson air Force Base, Goldsboro, North Carolina
Fatality Assessment and Control Evaluation (FACE) Program
Additional reports can be found by searching for heat stress on FACE
More from AD Safety Network
- When should you consider using custom molded earplugs?
- At what height do falls become deadly?
- Who should be responsible for rescuing fallen workers?
- What kind of training do loading dock workers need?
- How often should I inspect a loading dock?
- How is wind chill calculated?
- What is the difference between occupational safety and process safety?
- Why should rubber insulating gloves be tested?
- What happens if I tie off at the foot level with a personal SRL?
- Why is testing with a NAIL4PET accredited lab important?
- What kind of face protection do I need when using a chainsaw?
- What is the permissible exposure limit (PEL) for silica?
- What is silica and why is it hazardous?
- Video Q&A - What is a safety policy?
- What kind of fire extinguisher is best for your work site?
- How do I choose the right respirator and mask for working with silica?
- Can I wear fall protection equipment over my rainwear or winter gear?
- When do I need a cage ladder?
- What types of gloves protect your hands from hazardous chemicals?
- How come I still got hurt while wearing flame-resistant clothing?
- How do I win over my most reluctant employees?
- What kinds of jobs should use disposable safety gloves?
- Is it true that safety shouldn't be a top priority?
- When are employers allowed to conduct drug and alcohol tests on their employees?
- How can I get employees more involved in the risk assessment plan?
- What are some of the indirect costs of workplace accidents?
- How often do fire extinguishers need to be inspected?
- What is the best way to store rubber safety gloves?
- How much voltage protection is needed for safety gloves used in electrical work?
- What is the difference between a safety valve and a release valve?
- When do workers have the right to refuse to work?
- What is the most overlooked item when designing Lockout/Tagout (LOTO) procedures?
- What are some of the misconceptions about heat stress and what should we do to address them?
- What tools should I tether when working at heights?
- What types of gas should I watch out for when working in a confined space?
- How do you create a culture of safety in your workplace?
- What is the difference between industrial safety and industrial hygiene?
- Is it important to get PPE assessments by trained professionals?
- What is a fault tree analysis?
- What kind of respirator cartridge should I use?
- What are the safety benefits of a whistleblower program?
- What type of safety record-keeping and recording should we be doing?
- What makes a hi-vis safety vest ANSI compliant?
- Why is it important to have air sampling done to determine my PELs?
- What is the life expectancy of fall protection equipment?
- What are some basic fall protection rules that each of my workers need to understand?
- How much clearance do I need to safely use a Leading Edge SRL?
- What is the difference between an acute hazard and a chronic hazard?
- What’s the difference between a bump test, a calibration check, and a full calibration?
- Is there any legislation regulating lone worker safety I should know about before hiring?
- What kind of fire extinguisher and accessories should be kept on hand on a factory floor?
- What can companies do to reduce their lost time injury frequency rates?
- Video Q&A - What's your safety network like?
- Video Q&A - What are the 3 levels of safety?
- Video Q&A - How do you treat a near miss?
- Does body weight affect falls differently?
- What ages are most affected by falls?
- Why do workers take risks?
- What Is the Difference Between OHSAS 18001 and 18002?
- What is the difference between lost time injury and medical treatment case?
- What is the difference between occupational health and safety and workplace health and safety?
- What is the difference between occupational health and occupational safety?
- What is the difference between a lost time injury and a disabling injury?