Acclimatization is a process by which the body adjusts to increased hot exposure. The body needs to adapt when working in hotter environments.

According to Cal/OSHA guidance, employees are more likely to develop heat illness if they don't take it easy when a heat wave strikes or when starting a job that newly exposes them to heat. Most people are usually acclimated within four to 14 days of regular work involving at least two hours per day in the heat.

Under the prior standard, acclimatization procedures were part of the high heat standard applying to specified industries.

The revised standard, however, sets new acclimatization procedures that apply to all outdoor places of employment.1

All employees must be closely observed by a supervisor during a “heat wave” — defined as any day in which the “predicted” high temperature will be at least 80 degrees and at least ten degrees higher than the average high daily temperature in the preceding five days.

Employers are also required to be extra vigilant with new employees — close observation by a supervisor or designee is required for the first 14 days of employment.

Cal/OSHA guidance indicates that best practices include finding ways to lessen the intensity of work during heat waves and during the first two weeks of employment.​

Legal References

1. 8 CCR sec. 3395(g)