Cooler Laws, Safer Workers: Evaluating California’s Heat Standard and Injury Reduction

A growing body of research shows that excessive heat increases the frequency of heat-related injuries at work. While interest in mitigating occupational risks from excessive heat is high, there is little evidence on whether legislation targeting heat exposure can reduce such injuries. Using a triple-differences approach and administrative data from workers’ compensation systems, we evaluate California’s heat standard – adopted in 2005 - and find that the standard substantially reduces the frequency of work injuries in the construction, agriculture, and transportation industries. The effects increase with outside temperatures and are larger among younger workers. Our findings have clear implications for workplace safety and contribute to ongoing policy debates.