OSHA•NIOSH INFOSHEET

Protecting Workers from Heat Illness

At times, workers may be required to work in hot

environments for long periods. When the human body

is unable to maintain a normal temperature, heat-related

illnesses can occur and may result in death.This fact

sheet provides information to employers on measures

they should take to prevent heat-related illnesses and

death.

• Make sure that someone stays with the worker

until help arrives.

• Move the worker to a shaded, cool area and

remove outer clothing.

• Wet the worker with cool water and circulate the

air to speed cooling.

• Place cold wet cloths or ice all over the body or

soak the worker’s clothing with cold water.

Heat Exhaustion is the next most serious heatrelated health problem.

Symptoms of heat exhaustion:

• Headache

• Nausea

• Dizziness

• Weakness

• Irritability

• Thirst

• Heavy sweating

• Elevated body temperature

• Decreased urine output

If a worker shows signs of possible heat exhaustion:

• Workers with signs or symptoms of heat

exhaustion should be taken to a clinic or

emergency room for medical evaluation and

treatment.

• If medical care is not available, call 911

immediately.

• Make sure that someone stays with the worker

until help arrives.

• Workers should be removed from the hot area

and given liquids to drink.

• Remove unnecessary clothing including shoes

and socks.

• Cool the worker with cold compresses to the

head, neck, and face or have the worker wash

his or her head, face and neck with cold water.

FactorsThat Increase Risk to Workers

• High temperature and humidity

• Direct sun exposure (with no shade)

• Indoor exposure to other sources of radiant

heat (ovens, furnaces)

• Limited air movement (no breeze)

• Low fluid consumption

• Physical exertion

• Heavy personal protective clothing and

equipment

• Poor physical condition or health problems

• Some medications, for example, different

kinds of blood pressure pills or antihistamines

• Pregnancy

• Lack of recent exposure to hot working

conditions

• Previous heat-related illness

• Advanced age (65+)

Health Problems Caused by

Hot Environments

Heat Stroke is the most serious heat-related health

problem. Heat stroke occurs when the body’s

temperature regulating system fails and body

temperature rises to critical levels. Heat stroke is

a medical emergency that may rapidly result in

death!

Symptoms of heat stroke include:

• Confusion

• Loss of consciousness

• Seizures

• Very high body temperature

• Hot, dry skin or profuse sweating

If a worker shows signs of possible heat stroke:

• Heat stroke is a life-threatening emergency!

While first aid measures are being implemented,

call 911 and get emergency medical help.
• Encourage frequent sips of cool water. If the

worker is unable to drink, get emergency

medical help immediately.

Heat Cramps are muscle pains usually caused by

physical labor in a hot work environment. Heat

cramps are caused by the loss of body salts and

fluid during sweating.

If a worker shows signs of possible heat cramps:

• Workers should replace fluid loss by drinking

water and having a snack, and/or carbohydrateelectrolyte replacement liquids (e.g., sports

drinks) every 15 to 20 minutes.

• Workers should avoid salt tablets.

• Get medical help if the worker has heart

problems, is on a low sodium diet, or if cramps

do not subside within one hour.

Heat Rash is the most common problem in hot

work environments. Heat rash is caused by

sweating and looks like a red cluster of pimples or

small blisters. Heat rash usually appears on the

neck, upper chest, in the groin, under the breasts

and in elbow creases.

If a worker shows signs of possible heat rash:

• The best treatment for heat rash is to provide a

cooler, less humid work environment.

• The rash area should be kept dry.

• Powder may be applied to increase comfort.

• Ointments and creams should not be used on a

heat rash. Anything that makes the skin warm or

moist may make the rash worse.

Preventing Heat Illness

The best way to prevent heat illness is to make the

work environment cooler.

Recommendations for All Work Environments

(Indoors and Outdoors):

• Train workers and supervisors about the hazards

leading to heat illness and ways to prevent them.

• Train workers to recognize symptoms in themselves and others.

• Train and encourage workers to immediately

report symptoms in themselves and others.

• If you have someone who is new to the job or

who has been away for more than a week,

gradually increase the workload or allow more

frequent breaks the first week.

• Provide workers with plenty of cool water in

convenient, visible locations close to the work

area. Water should have a palatable (pleasant

and odor-free) taste and water temperature

should be 50-60oF if possible.

• Remind workers to frequently drink small

amounts of water before they become thirsty to

maintain good hydration. Simply telling them to

drink plenty of fluids is not sufficient. During

moderate activity, in moderately hot conditions,

workers should drink about 1 cup every 15 to 20

minutes. Instruct workers that urine should be

clear or lightly colored.

• Workers should eat regular meals and snacks

as they provide enough salt and electrolytes to

replace those lost through sweating as long as

enough water is consumed. Electrolyte drinks

(e.g. Gatorade®) are usually not necessary.

• Set up a buddy system if possible; if not, check

routinely (several times an hour) to make sure

workers are making use of water and shade and

not experiencing heat-related symptoms.

• Make workers aware that it is harmful to drink

extreme amounts of water. Workers should

generally not drink more than 12 quarts (48 cups)

in a 24 hour period. If higher amounts of fluid

replacement are needed due to prolonged work

in high heat conditions, a more comprehensive

heat illness prevention program may be

warranted.

• Reduce the physical demands of the job. If heavy

job tasks cannot be avoided, change work/rest

cycles to increase the amount of rest time.

• Schedule frequent rest periods with water breaks

in shaded or air-conditioned recovery areas.

Note that air conditioning will NOT result in loss

of heat tolerance and is recommended for rest

breaks.

Additional Recommendations for Outdoor Work

Environments

• Monitor weather reports daily and reschedule

jobs with high heat exposure to cooler times of

the day. Be extra vigilant during heat waves

when air temperatures rise above normal.

When possible, routine maintenance and repair

projects should be scheduled for the cooler

seasons of the year.

Additional Recommendations for Indoor Work

Environments

• Indoor workplaces may be cooled by using air

conditioning or increased ventilation, if cooler air

is available from the outside.

• Other methods to reduce indoor temperature

include providing reflective shields to redirect

radiant heat, insulating hot surfaces, and

decreasing water vapor pressure, e.g., by sealing

steam leaks and keeping floors dry.

• The use of fans to increase the air speed over the

worker will improve heat exchange between the
www.osha.gov

(800) 321-OSHA

www.cdc.gov/niosh

(800) 232-4636

For more complete information:

This InfoSheet is advisory in nature and informational in content. It is not a standard or regulation, and it neither

creates new legal obligations nor alters existing obligations created by OSHA standards or the Occupational Safety

and HealthAct. Pursuant to the OSHAct, employers must comply with safety and health standards and regulations

issued and enforced either by OSHA or by an OSHA-approved State Plan. In addition, theAct’s General Duty Clause,

Section 5(a)(1), requires employers to provide their employees with a workplace free from recognized hazards likely

to cause death or serious physical harm.The mention of any nongovernmental organization or link to its web site in

this guidance does not constitute an endorsement by NIOSH or OSHA of that organization or its products, services,

web site.

OSHA 3438-5-11 DHHS (NIOSH) 2011-174

skin surface and the air, unless the air temperature

is higher than the skin temperature.

• Reflective clothing, such as safety vests, worn as

loosely as possible, can minimize heat illness.

Water-dampened cotton whole-body suits are

an inexpensive and effective personal cooling

technique. Cooling vests with pockets that hold

cold packs are comfortable and effective.

• More complex and expensive water-cooled suits

are also available; however, these may require a

battery-driven circulating pump and liquid

coolant.

• In worksites where high ambient temperatures

typically occur (e.g., foundries, steel mills),

professional consultation should be sought to

evaluate the extent of the heat exposure and to

make recommendations on how to prevent

heat-related illnesses.

Resources

For more information about protecting workers from

heat-related illnesses visit:

• OSHA online at:

www.osha.gov/SLTC/heatstress/index.html

and www.osha.gov/dts/osta/otm/otm_iii/otm_iii_4.html

• NIOSH online at:

http://www.cdc.gov/niosh/topics/heatstress/

• Cal/OSHA’s Heat Safety program at:

www.99calor.org/english.html

OSHA Publications

OSHA has an extensive publications program.

For a listing of free items, visit OSHA’s web site at

www.osha.gov/publications or contact the OSHA

Publications Office, U.S. Department of Labor, 200

Constitution Avenue, N.W., N-3101, Washington, DC

20210. Telephone (202) 693-1888 or fax to (202)

693-2498.

Contacting OSHA

To report an emergency, file a complaint or seek

OSHA advice, assistance or products, call (800) 321-

OSHA (6742) or contact your nearest OSHA regional,

area, or State Plan office; TTY: 1-877-889-5627.

Contacting NIOSH

To receive documents or more information about

occupational safety and health topics, please

contact NIOSH: 1-800-CDC-INFO (1-800-232-4636);

TYY: 1-888-232-6348; e-mail: cdcinfo@cdc.gov or visit

the NIOSH web site at www.cdc.gov/niosh.