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Toolbox Talk: Permanent Changes to Outdoor Heat Exposure Rules

By August 1, 2023 August 11th, 2023 No Comments

Permanent Changes to Outdoor Heat Exposure Rules

Working in heat increases the risk for heat-related illness, including heat exhaustion, and life-threatening heat stroke in addition to acute kidney damage. Heat exposure can also make workers more susceptible to falls, equipment-related injuries, and other on-the-job safety hazards.

On June 27, 2023, the Washington State Department of Labor & Industries (L&I) adopted updates to Outdoor Heat Exposure rules to prevent heat-related illness and reduce traumatic injuries associated with heat exposure. The adopted rules include requirements for shade, rest, and acclimatization, and lowers the temperatures at which some preventive actions must be taken.

Under the adopted rules:

  • Requirements are year-round, in effect whenever workers are exposed to outdoor heat.
  • Scope no longer includes workers that fall under Chapter 296-305 WAC, Safety Standards for Firefighters.
  • Outdoor temperature action levels are:
    • Non-breathable clothing: 52°F
    • All other clothing: 80°
  • Employers must include certain specific elements in their written outdoor heat exposure safety programs in a language employees understand.
  • Training requirements are updated to incorporate the changes in the adopted rule.
  • Employers must encourage and allow employees to take preventative cool-down rest periods at or above outdoor temperature action levels.
  • Shade, or other sufficient means for cooling down, must be provided any time employees are exposed to heat at or above action levels.
    • There must be enough shade for all employees on a meal or rest period to sit fully in the shade, and it must be located close to where employees are working.

Having shade available to block direct heat from the sun helps workers cool down during meal or rest periods.

  • Drinking water must be suitably cool in temperature. Current rules require sufficient quantities for each worker to drink at least a quart per hour at the applicable action level.
  • Close observation for 14 consecutive days is required for employees not acclimatized to the heat, including new employees, those returning from absences, and all workers during a heat wave.
    • Heat waves are days when heat will be at or above the action levels and at least 10°F higher than the five-day average highs.
    • Close observation is defined as regular communication with employees working alone, such as by radio or cellular phone; a mandatory buddy system; or other effective means of observation.

Workers are at higher risk of heat-related illness if they are not acclimatized or used to the heat. Acclimatization takes 7–14 days to develop and can be lost after seven days away from working in the heat. A sudden increase in temperature does not allow time for any workers to acclimatize.

  • At or above 90°F, a 10-minute cool-down rest period every two hours and close observation to help identify employees showing signs and symptoms of heat-related illness is mandatory. At or above 100°F, the cool-down rest periods must be 15 minutes every hour. These can be taken at the same time with any meal or rest period under wage and hour laws and must be paid unless taken during a meal period. In order to ensure public safety in crisis or disaster situations, an exemption was added excluding emergency response operations from mandatory cool-down rest periods when restoring or maintaining critical infrastructure at risk.

Allowing the body to rest is a critical prevention measure in high heat. When temperatures reach 100°F in Washington state, it is usually in the afternoon. We’ve heard some employers move the start of a shift earlier to reduce work time at or above 100°F, a practice some agriculture employers already follow.

For more information, links to FAQs, and more, visit L&I’s Outdoor Heat Exposure Rule Page at

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