Acclimatization is the process of adjusting to a change in environment over time. This is especially important when thinking about work environments in which workers are exposed to high temperatures, as the risk of heat illness decreases after the person has had the chance to acclimatize. In a BLR webinar titled "Heat Illness: How to Prevent—and Treat—Dangerously Overheated Workers," Don Dressler, Gil Molina, and Sheilaja Mittal offered some information on acclimatization.
Heat illness tends to occur more frequently on the first days on the job (or on the sports field). These days are the highest danger! Almost 50 percent of reported heat illnesses occur on the first day of work, and 80 percent of illnesses occur within the first four days of work.
Anyone working for the first time under heat stress will develop signs of strain such as a high body temperature or a pounding heart. On each succeeding day, their work ability increases. Our body adjusts physiologically:
- Increased, more dilute sweat provides more evaporation
- Increased core-skin temp gradient means more convection
- Increased maximal cardiac output means less heat generation
- Decreased peak heart rate also means less heat generation
Other first day factors can be psychological:
- Being new – want to show that I am a good worker
- Don’t stop to drink water or take breaks
- Don’t know how to dress appropriately for evaporative cooling
Besides all of these factors, even more factors can be at play, such as dehydration due to caffeine or alcohol.
Don Dressler of Don Dressler Consulting of Irvine, California, (www.dondressler.com), has been working with heat illness safety for over 15 years.
Gil Molina is CEO of the California Association of Agricultural Labor. (www.caalag.org) Molina is a former U.S. Department of Labor Wage and Hour Investigator.
Sheilaja Mittal, MD, QME, MRO, is the Medical Director for WorkWell Medical Group. (www.workwellmedical.org) She has an extensive medical perspective for identifying signs of heat illness and how to respond when the first signs of heat stress begin.
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