An early-season heat wave is impacting California this week, bringing unusually high, summer-like temperatures well above typical March averages. In response, Cal/OSHA is urging employers to take proactive steps to protect workers during early-season heat wave, emphasizing that many may not yet be acclimated and are therefore at increased risk of heat-related illness.
“Acclimatization” refers to the process by which the human body gradually adapts to heat stress and becomes more tolerant of elevated temperatures. Workers who are new to hot environments, or returning after time away, are often not yet acclimatized, meaning their bodies need time to adjust to these conditions. OSHA highlights the importance of a gradual acclimatization schedule, recommending a structured approach to increasing heat exposure. For new workers, this typically involves starting at 20% of usual heat exposure on Day 1 and increasing incrementally to 100% by Day 5. For experienced workers, a shorter schedule is recommended, beginning at 50% on Day 1 and reaching full exposure by Day 4.
To further reduce risk, OSHA Heat Illness Prevention Campaign outlines key protective measures employers must implement. These include providing adequate drinking water, access to shade or cool-down areas, regular rest breaks, employee training, and written heat illness prevention plans. Specific requirements are triggered at defined temperature thresholds for both indoor and outdoor work environments. OSHA stresses that heat illness can be severe, making vigilance essential during periods of elevated temperatures.
This early-season heat wave highlights how quickly hazardous conditions can arise before workers have had the opportunity to acclimate. When gradual acclimatization is not feasible, it is especially important for employers to strengthen other protective measures. Increasing the frequency of rest breaks, ensuring continuous access to water and shade, closely monitoring workers for signs of heat stress, and adjusting workloads or schedules can significantly reduce risk. Taking these proactive steps is critical to safeguarding workers and preventing heat-related illnesses during sudden and extreme heat events.
Contact RHP Risk Management to Reduce the Risk of Heat Stress in Your Workplace
To learn more about RHP’s expertise in heat stress, explore insights from Rod Harvey, P.E., CIH, CSP, CHMM. He shares warning signs, training, and practical solutions on the Missouri Employers Mutual podcast, and covers OSHA’s National Emphasis Program on heat hazards, along with prevention strategies, controls, training, and related litigation on the Greenberg Traurig podcast.
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