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WA DOSH

Outdoor Heat Exposure - Washington (DOSH)

This talk follows Washington (WAC) rules · See the federal OSHA version →

Updated 2026-09-30

In this bundle Health & Environmental Exposure

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Washington's outdoor heat exposure rules apply all year, whenever workers are exposed to outdoor heat, and the trigger depends on what the crew is wearing: 80°F in ordinary clothing, but only 52°F for anyone in nonbreathable clothing or vapor barrier PPE. At 90°F, cool-down breaks stop being optional. This Washington Outdoor Heat Exposure Toolbox Talk covers the triggers, the high heat procedures, and who does what.

Where the boundary of this talk sits#

This talk covers the Washington outdoor heat rules in WAC 296-62-095 through 296-62-09560. How the body overheats, sun protection, and general hydration belong to their own talks. Wildfire smoke has its own Washington rule and its own talk.

The anchor#

Here is the distinction that carries this whole talk: in Washington the heat rule starts at a temperature set by what you are wearing, not by the season — at or above 80°F in all other clothing, or 52°F in nonbreathable clothing including vapor barrier clothing or chemical resistant suits, the employer must provide shade, a quart of water per hour, a written heat program, and 14 days of close observation for new and returning workers — and at 90°F and 100°F the rule adds cool-down rest periods that are mandatory and paid, so a crew in chemical suits can be under the heat rule on a 55°F morning, and a crew in T-shirts must stop for 10 minutes every two hours once the thermometer reads 90°F.

Who is covered#

WAC 296-62-09510 applies to all employers with employees working in an outdoor environment when they are exposed to outdoor heat. It does not apply to incidental exposure, meaning the employee is not required to work outdoors for more than 15 minutes in any 60-minute period, and that exception is judged hour by hour. Firefighting and agriculture have separate standards.

The definition in WAC 296-62-09520 says 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. An equipment cab without working air-conditioning can count.

L&I's publication on the 2023 changes says the requirements are year-round, in effect whenever workers are exposed to outdoor heat.

Table 1: the trigger depends on the clothing#

WAC 296-62-09530 Table 1 sets the temperature at which the rule applies:

  • Nonbreathable clothes, including vapor barrier clothing or PPE such as chemical resistant suits: 52°F
  • All other clothing: 80°F

The rule says no temperature records are required.

The written program#

At or above Table 1, the employer must address the outdoor heat program in its written accident prevention program, in a language employees understand. At a minimum, it must cover procedures for cool drinking water; shade or other cooling, including where it is and how to get there; emergency response for heat-related illness; acclimatization; high heat procedures; and the specific method used to closely observe workers. A copy must be available to employees and their authorized representatives.

The employer must also encourage frequent drinking, and encourage and allow a preventative cool-down rest whenever an employee feels the need to protect themselves from overheating. That rest must be paid unless taken during an unpaid meal period.

Shade#

WAC 296-62-09535 requires one or more shaded areas at all times while employees are present. The shade must be open to the air or provided with ventilation or cooling, and not next to a radiant heat source such as machinery or a concrete structure. It must be large enough for the employees on a meal or rest period to sit in a normal posture fully in the shade. Other cooling, such as misting stations, cooling vests, or air-conditioned areas, is allowed only if the employer can show it is equally or more effective.

Drinking water#

WAC 296-62-09540 requires a sufficient quantity of suitably cool drinking water readily accessible at all times, and the opportunity for every employee to drink at least one quart per hour. Water can be refilled during the shift instead of all brought at the start.

Acclimatization: 14 days of close observation#

WAC 296-62-09545 requires the employer to closely observe employees for 14 days when they are newly assigned to work at or above Table 1, or when they return after an absence of seven days or more. It also requires close observation during a heat wave, defined as any day when the predicted high is at least the Table 1 temperature and at least 10°F higher than the average daily high of the preceding five days.

High heat: 90°F and 100°F#

WAC 296-62-09547 applies at or above 90°F unless engineering or administrative controls, such as air-conditioning or scheduling work at cooler times, bring exposure below 90°F. Employees must take at least these mandatory cool-down rest periods in the shade or other equally effective cooling:

  • At or above 90°F: 10 minutes every 2 hours
  • At or above 100°F: 15 minutes every hour

The cool-down can run at the same time as a required meal or rest break and must be paid unless taken during an unpaid meal period. The employer must also closely observe employees through regular radio or phone contact with anyone working alone, a mandatory buddy system, or other effective means.

When someone shows signs#

WAC 296-62-09550 requires effective communication by voice, observation, or electronic means so employees and their supervisor can report symptoms and get medical help. A cell phone counts only if reception in the area is reliable. An employee showing signs or symptoms must be relieved from duty, given a means to cool down, and monitored to decide whether medical attention is needed.

Training#

WAC 296-62-09560 requires training for all employees and supervisors before outdoor work where heat exposure might occur, and at least annually after that, in a language and manner they understand. Supervisors are also trained on their procedures, on controls, and on getting a sick worker to where emergency medical services can reach them.

Washington versus federal#

As of this writing, federal OSHA has no final heat standard. Its proposed rule, published August 30, 2024, completed its public hearing on July 2, 2025, and was still pending. Washington's rule is in force now.

Where the duty sits#

WAC 296-62-09510 sets scope and the 15-minute incidental exception. WAC 296-62-09520 defines outdoor environment. WAC 296-62-09530 sets Table 1, the written program, and paid preventative cool-downs. WAC 296-62-09535 sets shade, WAC 296-62-09540 water, WAC 296-62-09545 acclimatization and heat waves, WAC 296-62-09547 high heat, WAC 296-62-09550 response, and WAC 296-62-09560 training.

What can go wrong?#

  • An abatement crew in chemical suits works at 60°F and nobody thinks the heat rule applies.
  • The only shade is next to the running generator.
  • A worker returns from two weeks off and goes straight to full duty with no one watching.

How do we manage this properly?#

  • Check the clothing — 52°F in nonbreathable PPE, 80°F otherwise.
  • Set up shade first — away from radiant heat, big enough for everyone on break.
  • Water: one quart per hour — cool, close, and refilled.
  • Watch new and returning workers — 14 days of close observation.
  • At 90°F, take the breaks — 10 minutes every 2 hours; at 100°F, 15 minutes every hour, paid.
  • Report symptoms immediately — in yourself or a coworker.

Before you start#

Check today's forecast and what the crew is wearing. Confirm where the shade and water are, who is new or returning, and how anyone working alone will be checked on.

Talk it over#

  • Which trigger applies to us today, 52°F or 80°F?
  • Where is the shade, and is it next to anything hot?
  • Who on this crew is in their first 14 days?

The bottom line#

Washington's outdoor heat rules apply year-round, starting at 80°F in ordinary clothing and 52°F in nonbreathable clothing. At those temperatures the employer must provide shade, at least a quart of cool water per hour, a written program, and 14 days of close observation for new and returning workers. At 90°F, cool-downs of 10 minutes every two hours become mandatory; at 100°F, 15 minutes every hour. They are paid.

Frequently asked questions about the Washington outdoor heat rule#

When do mandatory cool-down breaks start in Washington?

At or above 90°F, under WAC 296-62-09547, unless controls bring exposure below 90°F. At 90°F, employees take at least 10 minutes every two hours; at 100°F, at least 15 minutes every hour. The breaks are paid unless taken during an unpaid meal period.

Download the Washington outdoor heat exposure toolbox talk PDF#

Download this Washington Outdoor Heat Exposure Toolbox Talk as a printable PDF in English and Spanish, and review it with the crew before the next hot shift.

Related toolbox talks#

Sources#

Written by FieldSafetyTalk's safety professional — a CSP, ASP, CHST and OSHA Authorized Outreach Trainer with 14+ years of international construction safety experience across federal, heavy civil, and industrial projects.

Hazards covered

heat
By Mustafa Tok, CSP, ASP, CHST

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