Outdoor Heat Exposure

Updated June 28, 2022

Excessive exposure to heat can cause a range of heat-related illnesses, from less serious heat rash and heat cramps to more serious heat exhaustion and heat stroke. Heat stroke requires immediate medical attention because it can result in serious health effects or death, so take precautions while working in the summer heat.

For people working in hot environments, both air temperature and humidity affect how hot you feel. The higher the heat and humidity, the hotter the weather feels, because sweat is unable to readily evaporate. If the sweat your body produces cannot evaporate, your body cannot easily cool down, and you may be at risk for a heat illness. Certain factors, including personal health conditions, activities being conducted, and weather can increase the risk of a heat-related illness.

Heat exhaustion can also make workers more susceptible to falls, equipment-related injuries, and other on-the-job safety hazards.

University units with personnel who work outdoors must plan, prepare, and train for heat-related illness.

Applicability

Washington state outdoor heat exposure rules in WAC 296-62-095 apply to UW departments with personnel performing work in an outdoor environment from May 1 through September 30, annually, only when personnel are exposed to outdoor heat at or above an applicable temperature listed in Table 1 below.

In addition to requirements in the permanent rule, as of June 15, 2022 through September 29, 2022, additional temporary requirements go into effect for cool water, shade, cool-down rest periods, and observing and communicating with workers about signs and symptoms of heat illness.

Table 1: Outdoor temperature action levels

TYPE OF CLOTHING WORN	ACTION REQUIRED AT OR ABOVE THIS TEMPERATURE
Non-breathable clothes, including vapor barrier clothing or PPE such as chemical resistant suits	52 degrees F
Double-layer woven clothes including coveralls, jackets, and sweatshirts	77 degrees F
All other clothing	89 degrees F

Exception: The rules do not apply if incidental exposure occurs when personnel are not required to perform a work activity outdoors for more than 15 minutes in any 60-minute period. The exception may be applied every hour during the work shift.

Responsibilities

Follow the University and unit requirements for preventing heat related illness.
Complete the Outdoor Heat Exposure and Heat-Related Illness Safety Training course.
Recognize symptoms of heat-related illness.
Drink adequate amounts of suitably cool water (up to one quart/hour).
Request breaks when needed.
When temperatures are at or above 89° Fahrenheit take preventive cool-down rest breaks of at least ten minutes every two hours.
Monitor your personal factors for heat-related illness, which may include:
- Obesity
- Diabetes
- High blood pressure
- Heart disease
- Low physical fitness level Medications
- Alcohol use Drug use
- Dehydration Nicotine use
- Lack of acclimatization
- Chronic disease

Ensure compliance with WAC 296-62-095 Outdoor Heat Exposure.
Develop and implement an Outdoor Heat Exposure Prevention Plan.
Make drinking water available and encourage personnel to frequently consume water or other acceptable beverages to ensure hydration.
- Provide one quart of cool drinking water per person per hour and readily accessible at all times.
- Ensure personnel have the opportunity to drink at least one quart of drinking water per hour.
Encourage personnel to take a preventive cool-down rest (time must be paid unless taken during a meal period) as needed and to protect themselves from overheating using sufficient means to reduce body temperature, such as shade or equally or more effective means.
Units are encouraged to closely observe new personnel and those returning to work in hot conditions after a prolonged absence for signs and symptoms of heat related illness for 14 days by implementing one or more of the monitoring options under WAC 296-62-09555(3). Close observation of personnel is also encouraged during a sudden temperature increase relative to temperatures on previous days.
Individuals showing signs or symptoms of heat-related illness must be relieved from duty, provided sufficient means to reduce body temperature, and must be monitored to determine whether medical attention is necessary.
When outdoor temperatures meet or exceed 89° Fahrenheit:
- Ensure that personnel take mandatory cool-down rest periods of at least 10 minutes every two hours. The mandatory cool-down rest period may be provided concurrently with any meal or rest period required under WAC 296-126-092 and must be paid unless taken during a meal period.
- Ensure that effective communication by voice, observation, or electronic means is maintained so that personnel at the work site and their supervisor can contact each other when necessary. An electronic device, such as a cellular phone or text messaging device, may be used for this purpose only if reception in the area is reliable.
  - Effectively observe personnel for signs and symptoms of heat related illness by implementing one or more of the following:
    
    (a) Regular communication with personnel working alone such as by radio or cellular phone; or
    
    (b) A mandatory buddy system; or
    
    (c) Other effective means of observation.
- Provide and maintain one or more areas with shade at all times while personnel are present that are either open to the air or provided with ventilation (e.g., fans or open windows) or cooling (e.g., air conditioning), and not adjoining a radiant heat source such as machinery or a concrete structure. The shade must be located as close as practicable to the areas where employees are working. If no shade is available, other sufficient means to reduce body temperature must be implemented.
Complete the Outdoor Heat Exposure and Heat-Related Illness Safety Training course and ensure employees complete the training.

Heat-related illness and first aid

Heat stroke

WHAT TO LOOK FOR	WHAT TO DO
High body temperature (103°F or higher) Hot, red, dry, or damp skin Fast, strong pulse Headache Dizziness Nausea Confusion Losing consciousness (passing out)	Call 9-1-1 right away-heat stroke is a medical emergency Move the person to a cooler place Help lower the person’s temperature with cool cloths or a cool bath Do not give the person anything to drink

Heat exhaustion

WHAT TO LOOK FOR	WHAT TO DO
Heavy sweating Cold, pale, and clammy skin Fast, weak pulse Nausea or vomiting Muscle cramps Tiredness or weakness Dizziness Headache Fainting (passing out)	Move to a cool place Loosen your clothes Put cool, wet cloths on your body or take a cool bath Sip water Get medical help right away if: You are throwing up Your symptoms get worse Your symptoms last longer than 1 hour

Heat cramps

WHAT TO LOOK FOR	WHAT TO DO
Heavy sweating during intense exercise Muscle pain or spasms	Stop physical activity and move to a cool place Drink water or a sports drink Wait for cramps to go away before you do any more physical activity Get medical help right away if: Cramps last longer than 1 hour You’re on a low-sodium diet You have heart problems

Sunburn

WHAT TO LOOK FOR	WHAT TO DO
Painful, red, and warm skin Blisters on the skin	Stay out of the sun until your sunburn heals Put cool cloths on sunburned areas or take a cool bath Put moisturizing lotion on sunburned areas Do not break blisters

Heat rash

WHAT TO LOOK FOR	WHAT TO DO
Red clusters of small blisters that look like pimples on the skin (usually on the neck, chest, groin, or in elbow creases)	Stay in a cool, dry place Keep the rash dry Use powder (like baby powder) to soothe the rash

Training

Prior to outdoor work in temperatures exceeding those listed in Table 1, personnel and supervisors must complete the Outdoor Heat Exposure and Heat-Related Illness training course located on the EH&S Training webpage.

Services available

If you need assistance related to preventing heat related illness, contact EH&S at ehsdept@uw.edu or (206) 543-7388.

More information

Frequently asked questions

Visit the Washington State L&I website to read frequently asked questions.

Glossary

A system where individuals are paired or teamed up into work groups so each employee can be observed by at least one other member of the group to monitor and report signs and symptoms of heat-related illness.

The use of devices to reduce exposure and aid cooling (i.e., air conditioning)