A study on outdoor workers and heat illness found that the number of days workers were at or above heat thresholds varied by both regional location and the time of year.
Researchers sought to find the relationship between time and location in regard to exposure to extreme heat for those who work outdoors, such as agriculture and construction workers.
The study, which was conducted by the University of Washington, Washington State Department of Labor & Industries and the National Institute for Occupational Safety and Health (NIOSH), examined spatiotemporal patterns of days and heat levels experienced by outdoor workers in Washington State.
County-level daily heat patterns studied
Researchers examined the county-level patterns of days from 2011 to 2020 that were at or above maximum daily temperature thresholds of:
- 80 degrees Fahrenheit
- 85 degrees
- 89 degrees
- 90 degrees, and
- 95 degrees.
They also looked at the distribution of heat-wave days. Heat-wave days are defined as a day that has a temperature of 80 degrees or above and is 10 or more degrees hotter than the average high temperature of the preceding five days.
The number of days at or above heat thresholds varied by both location and time of year, according to the study.
Workers in Central, Coastal Washington more at risk
Overall, researchers found that Central Washington, which has a large number of agriculture workers, had the highest number of days at or above heat thresholds of 90 and 95 degrees. This timing of when heat thresholds were exceeded overlapped with summer peaks in outdoor employment.
Heat-wave days were found to be pretty uniformly distributed across the state, with the longest duration of successive heat-wave days occurring in Central Washington.
Workers’ days at risk for exceeding heat thresholds followed exceedance and employment patterns with the highest in:
- Central Washington among agriculture workers, and
- Coastal Washington among construction workers.
Results can inform best practices to protect outdoor workers
According to NIOSH, these results:
- demonstrate the importance of understanding occupational heat exposure in different geographical areas over time, and
- can help inform policies and best practices to protect outdoor workers who are subjected to high temperatures.