Number: 700-23

Effective Date:





1 of 7

Staff Contact:

Nancy A. Carlson

Approved By:

Denis Law


This program was developed to protect employees from hazards posed by working in the outdoor environment. The City of Renton is committed to preventing heat related illnesses that can occur to employees working outdoors by identifying, evaluating and controlling potential exposure to extreme temperature, humidity, and other environmental factors; by providing drinking water; and by providing supervisor, lead and employee training.

Between May 1st and September 30th of each calendar year, the Outdoor Heat Exposure rule applies annually, only when employees are exposed to outdoor heat at or above an applicable temperature listed in Table 1 below.


All departments/divisions


WAC 296-62-095


This program applies when employees are exposed to outdoor heat at or above the following temperature and clothing action levels.

Table 1

Outdoor Temperature & Clothing Action Levels

Non-breathing clothes including vapor barrier clothing or personal protective equipment (PPE) such as chemical resistant suits

52° F

Double-layer woven clothes including coveralls, jackets and sweatshirts

77° F

All other clothing

89° F

Outdoor work includes any employee assigned to work in the outdoor environment on a regular basis.

This program does not apply to incidental exposure, which exists when an employee is not required to perform a work activity outdoors for more than fifteen minutes in any 60-minute period.

Note: It is possible outdoor heat related illness might occur at temperatures below the action levels when employees have not acclimatized to sudden and significant increases in temperature and humidity. Supervisors and employees should monitor for signs and symptoms of outdoor heat-related illness when there is a significant and sudden increase in temperature.

Application of Table 1 with respect to clothing or PPE types must be based on the temperature category that best fits the garment in use. For example, light weight mesh high visibility safety vests and similar clothing are not substantive enough to use the “double layer” temperature category; instead, use category 1 for regular clothing at 89 degrees. Commonly used extra attire such as rain gear or sweatshirts are considered “double layer”; however, do not apply the non-breathable clothing category; instead use category 2 at 77 degrees. When considering whether or not clothing is “double layer,” do not count underwear as a layer. The term “action level” in the grid above refers to when to apply the heat exposure rule and supply drinking water. When the clothing and temperature level fit in the grid above, the outdoor heat exposure rule applies. For example: it is 52 degrees outside and staff are wearing non-breathing clothes, including vapor barrier clothing or personal protective equipment (PPE) such as chemical resistant suits. The City must apply the heat exposure rules and follow City policy.


Acclimatization means the body's temporary adaptation to work in heat that occurs as a person is exposed to it over time.

Double-layer woven clothing means clothing worn in two layers, allowing air to reach the skin. For example, coveralls worn on top of regular work clothes.

Drinking water means potable water that is suitable to drink. Drinking water packaged as a consumer product and electrolyte-replenishing beverages (i.e., sports drinks) that do not contain caffeine are acceptable.

Engineering controls means the use of devices to reduce exposure and aid cooling (i.e., air conditioning).

Environmental factors for heat-related illness means working conditions that increase susceptibility for heat-related illness such as air temperature, relative humidity, radiant heat from the sun and other sources, conductive heat sources such as the ground, air movement, workload (i.e., heavy, medium, or low) and duration, and personal protective equipment worn by employees.

Heat-related illness means a medical condition resulting from the body's inability to cope with a particular heat load, and includes, but is not limited to, heat cramps, heat rash, heat exhaustion, fainting, and heat stroke.

Outdoor environment means an environment where work activities are conducted outside. Work environments such as inside vehicle cabs, sheds, and tents or other structures may be considered an outdoor environment if the environmental factors affecting temperature are not managed by engineering controls. Construction activity is considered to be work in an indoor environment when performed inside a structure after the outside walls and roof are erected.

Vapor barrier clothing means clothing that significantly inhibits or completely prevents sweat produced by the body from evaporating into the outside air. Such clothing includes encapsulating suits, various forms of chemical resistant suits used for PPE, and other forms of non-breathing clothing.


City departments that have staff who perform work outdoors are responsible for implementing this program as part of the City Accident Prevention Program. Supervisors are responsible for encouraging employees to frequently consume water or other acceptable beverages to ensure hydration. Employees are responsible for monitoring their own personal factors for heat related illness including consumption of water or other acceptable beverages to ensure hydration.

6.1    Evaluating and Controlling Outdoor Heat Stress Factors

6.1.1    In addition to outdoor temperature, supervisors should evaluate other potential heat stress factors. These factors include:

1.    Radiant Heat (Example: Reflection of heat from asphalt, rocks, or composite roofing material, or work in direct sunlight)

2.    Air Movement (Example: Wind blowing and temperature above 95° F)

3.    Conductive Heat (Example: Operating orchard tractor for mowing)

4.    Workload Activity and Duration (Examples: Hand sawing, digging with a shovel)

5.    Personal Protective Equipment (Examples: Wearing a respirator, chemical resistant suit and gloves for pesticide application, or leathers and gloves for welding)

6.1.2    Supervisors should attempt to control outdoor heat stress factors when feasible. Controls to consider include:

1.    Taking breaks in a shaded area (building, canopy and under trees)

2.    Starting the work shift early (when daylight begins) and ending the shift early and/or not working outside during the hottest part of the day.

3.    Removing personal protective equipment such as respirators, chemical resistant clothing and gloves, and welding leathers during breaks

4.    Using cooling vests or headbands

6.1.3    Employees have an obligation to monitor their own personal factors and need to consume sufficient liquids to stay hydrated. Employees and supervisors must understand and be aware of this requirement.

6.2    Drinking Water

Keeping workers hydrated in a hot outdoor environment requires that more water be provided than at other times of the year. Sufficient quantity of drinking water will be provided and made accessible to employees. The City will supply at least one quart of drinking water per employee per hour. When employee exposure is at or above an applicable temperature listed in the table in Section 4.0, the City must ensure that a sufficient quantity of drinking water is readily accessible to employees at all times; and that all employees have the opportunity to drink at least one quart of drinking water per hour.

The City may begin the shift with smaller quantities of drinking water if effective procedures are established for replenishment during the shift. Ready access to drinking water generally means that employees can drink when thirsty and without undue delay (within a few minutes). However, in certain circumstances (e.g. performing work in restricted areas) an employee may not be able to stop working on particular tasks in order to drink. In these circumstances, the City will have provisions in place to ensure that employees are adequately hydrated. This may include providing the opportunity for employees to drink water prior to beginning the assignment and/or limiting work time.

Employees may voluntarily bring their own drinking water or other appropriate beverages to work; however, the employer is still responsible for ensuring that a sufficient quantity of drinking water is available at the worksite so that each employee has the opportunity to drink at least one quart per hour.

6.3    Procedures for Responding to a Heat-Related Illness

Supervisors will respond to heat-related illness in a quick and safe manner. The table below outlines the potential types of heat-related illnesses, signs and symptoms and specific first aid and emergency procedures. The information should be present at all work sites where outdoor work activities are conducted.

Employees experiencing signs and symptoms of a heat-related illness are to cease work and report their condition to their supervisor. Employees showing signs or demonstrating symptoms of heat-related illness are to be relieved from duty and provided sufficient means to reduce body temperature. Employees experiencing sunburn, heat rash or heat cramps will be monitored to determine whether medical attention is necessary. Emergency medical services will be called (911) when employees experience signs and symptoms of heat exhaustion or heat stroke.

Heat-Related Illness First Aid and Emergency Response Procedures

Heat-Related Illness:

Signs and Symptoms:

First Aid and Emergency Response Procedures:


Red, hot skin; possibly blisters

1.    Move to shade, loosen clothes

2.    Apply cool compress or water to burn

3.    Get medical evaluation if severe

Heat Rash

1.    Red, itchy skin

2.    Bumpy skin

3.    Skin infection

1.    Apply cool water or cool compress to rash to cool it down

2.    Keep affected area dry after it is cooled down

Heat Cramps

1.    Muscle cramps or spasms

2.    Grasping the affected area

3.    Abnormal body posture

1.    Drink water to hydrate body

2.    Rest in a cool, shaded area

3.    Massage affected muscles

4.    Get medical attention if cramps persist

Heat Exhaustion

1.    High pulse rate

2.    Extreme sweating

3.    Pale face

4.    Insecure gait

5.    Headache

6.    Clammy and moist skin

7.    Weakness

8.    Fatigue

9.    Dizziness

1.    CALL 911*

2.    Provide EMS with directions to worksite

3.    Move to shade and loosen clothing

4.    Start rapid cooling with fan, water mister or ice packs

5.    Lay flat and elevate feet

6.    Drink small amounts of water to hydrate and cool body

Heat Stroke

1.    Any of the above, but more severe

2.    Hot, dry skin (25-50% of cases)

3.    Altered mental status with confusion and agitation

4.    Can progress to loss of consciousness and seizures

1.    CALL 911*

2.    Provide EMS with directions to worksite

3.    Immediately remove from work area
Start rapid cooling with fan, water mister or ice packs

4.    Lay flat and elevate feet

5.    If conscious give sips of water

6.    Monitor airway and breathing, administer CPR if needed

*In remote areas specific procedures might be required to move or transport employees to a place where they can be reached by emergency medical services.

6.4    Training

6.4.1    Supervisor Training

Prior to supervising employees working in outdoor environments with heat exposure at or above the action levels, supervisors will receive training in the following topics:

1.    The content and procedures contained in this program.

2.    Procedures (listed in this program) the supervisor will follow if an employee shows signs and symptoms consistent with possible heat-related illness.

3.    Specific procedures, if necessary, describing how to move or transport employees to a place where they can be reached by emergency medical services.

4.    Information provided to employees.

6.4.2    Employee Training

Employees who may be exposed to outdoor heat at or above the action levels are to be trained on the following topics:

1.    Environmental factors that might contribute to the risk of heat-related illness (temperature, humidity, radiant heat, air movement, conductive heat sources, workload activity and duration, and personal protective equipment)

2.    Personal factors that may increase susceptibility to heat-related illness (age, degree acclimatization, medical conditions, drinking water, consuming alcohol, caffeine use, nicotine use and use of medications that affect the body’s response to heat).

3.    The importance of removing heat retaining personal protective equipment, such as non-breathable chemical resistant clothing, during breaks.

4.    The importance of frequent drinking of small quantities of water.

5.    The importance of acclimatization.

6.    The different types and common signs and symptoms of heat-related illnesses.

7.    The procedure for immediately reporting signs and symptoms of heat-related illness in themselves or co-workers to their supervisor or person in charge.

6.4.3    Refresher Training

Supervisors and employees covered by this program are to receive annual refresher training prior to May 1st every year.