May 11, 2023

As outdoor temperatures warm up, University units and personnel are reminded to start preparing for ways to work safely outdoors and prevent heat-related illness. The Washington State Department of Labor and Industries (L&I) safety requirements for outdoor workers are summarized on the EH&S Outdoor Heat Exposure webpage, including Outdoor Heat Exposure safety training and an Outdoor Heat Exposure Prevention Plan, among other requirements. Please note the L&I regulations are expected to be updated in June. 

For people working in hot environments, both temperature and humidity affect how hot you may feel. The higher the air temperature and percent humidity, the hotter the weather feels; your sweat is unable to readily evaporate and can’t aid in cooling your body down. 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. Fortunately, there are measures you and your unit can take to prevent these heat-related illnesses, some of which are required by regulations protecting employee health.

University units and departments with personnel working outdoors take the following measures to prevent heat-related illness:

  • Enough cool water available so that each worker is able to drink at least a quart (about one liter) every hour; and
  • Enough shade available to fully cover workers during a break, or employers can use alternatives to shade like an air-conditioned break area; and
  • Workers are encouraged and allowed to take paid cool-down breaks when they start to feel overheated and paid mandatory 10-minute breaks every 2 hours to cool down; and
  • Supervisors have worker observation and communication methods in place to detect and respond to signs or symptoms of heat illness.

Contact the EH&S Air Quality team at or 206.543.7388 with questions.