Acclimatization and Other Tips to Avoid Heat Illness

By Rich Gaul, Safety Technical Advisor

With summer just around the corner, now is the time to learn about heat illness so you can take the proper precautions. Almost 50% of heat-related deaths occur on a worker’s first day on the job and over 70% occur during a worker’s first week.* High school and college students starting new summer jobs, like landscaping, are at high risk because they may work 8-12 hours per day in the heat.

In an earlier blog, we discussed the signs and symptoms of heat illness. Now we’ll talk about preparing for the heat. Prior to beginning any strenuous physical work or recreational activity, it is important to prepare your body by warming up slowly. Preparing for strenuous activities in the hot summer months is no different.

One of the most important and often overlooked heat illness prevention strategies is called acclimatization. This involves slow and gradual increases to heat exposure over a period of 7 to 14 days. Physiological adaptations occur in the human body during that time period that increase tolerance of heat exposure. The National Institute for Occupational Safety and Health (NIOSH) recommends 20% exposure on day one, with 20% increase in exposure each additional day. Acclimatizing periods are particularly important for new employees and those returning from extended leaves of absence. Employers should have acclimatization plans in place now to help prepare their employees for heat exposure.

A NIOSH study of heat-related illnesses and death found that in most cases, the employers had no program to prevent heat illness, or their programs were deficient. Acclimatization was the program element most commonly missing and most directly associated with worker death.

We all look forward to enjoying the summer months, but it’s important to take the proper precautions. Whether you work in a hot environment or just enjoy summer recreational activities, slow and gradual exposure to heat over a period of several days or weeks will help your body acclimatize.

In addition to acclimatization, following the simple guidelines below will also help prevent heat-related illnesses. 

Other tips to avoid heat illness:

  • Take frequent breaks in shaded areas or air conditioning.
  • Drink plenty of water throughout the day (eight ounces every 15-20 minutes).
  • Avoid direct sunlight to minimize heat load and harmful UV rays.
  • Wear light-colored, light weight, loose clothing that provides natural ventilation.
  • Perform strenuous work in the morning or late afternoon when temperatures are cooler.
  • Know the early warning signs and symptoms of heat illness and seek help when needed.
  • Plan for and know what to do in an emergency.

Use the information in this two-part blog series to prevent heat illness so you can enjoy summer safely. For additional information about heat illness prevention, attend BWC’s virtual training class on Thermal Stress on June 9, 2021 or read BWC’s Heat Stress Safety Talk. The Occupational Safety and Health Administration’s (OSHA’s) website provides workers and employers with additional information and resources on heat illnesses and how to prevent it, including heat stress prevention QuickCards available in both English and Spanish. The National Institute for Occupational Safety and Health also has information on preventing heat-related illness at work in its May 7, 2021 blog.

*Source: OSHA, Heat: Prevention: Protecting New Workers


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