Why Your Workplace Needs a Heat Acclimatization Program

Farm Workers, Heat Stress, Heat Acclimatization
Agricultural workers often face hot temperatures at work. Photo: Wikimedia Commons/Holgerhubbs

Heat illnesses like heat stroke and heat exhaustion affect many workplaces during the summer, especially outdoor workplaces. Long hours spent in direct sun quickly lead to dehydration and rising body temperatures, particularly in new workers or those who have recently returned to work after an absence.

The Centers for Disease Control and Prevention (CDC) recently released a report that found a lack of heat acclimatization, which is allowing workers to slowly increase the amount of time they work in the heat, was the biggest factor that contributed to worker deaths related to heat illness in 2012 and 2013. The CDC evaluated the 20 heat-related inspections that OSHA did during that period and determined these illnesses and deaths were not only preventable, but many could have been avoided using similar safety measures.

According to a press release from OSHA, the CDC found nine of the 13 fatalities studied occurred during the first three days on the job. Four of those deaths even occurred during an employee’s first day at work. These facts, as well as an observed lack of adequate heat illness prevention programs, led the CDC to conclude that a formal heat acclimatization program paired with standard heat precautions like ample water and rest breaks is integral to keeping employees safe during hot weather.

What Is Heat Acclimatization?

Heat acclimatization is the process of slowly exposing the body to high temperatures so it can build up a tolerance. Even when workers are given time to get used to the heat, they often feel uncomfortable at first and experience heavy sweating and fatigue.

Acclimatization is a process and it allows the body to physiologically adapt to temperatures in the workplace. According to the CDC, these adaptions include developing sweating efficiency and a stabilization in circulation.

Healthy people typically acclimatize more quickly than those who are less physically fit or have health problems, explains Safe Work Manitoba, an organization dedicated to promoting workplace safety in Canada. The organization also reports that once an employee is acclimatized he or she will maintain that heat tolerance for about a week when away from work. After that, an employee will need to be re-acclimatized.

Tips for a Good Heat Acclimatization Program

heat stress, heat acclimatization
Proper hydration in conjunction with an acclimatization program can help prevent heat illnesses. Photo: OSHA

Acclimatizing employees to the heat should be done over the course of a week, and for some employees complete adjustment may take longer. The CDC advises having all new workers and workers returning from an absence (of a week or more) only work for 20 percent of the normal work period on their first day. This period can be increased by 20 percent each subsequent day. During a heat wave, all workers should work in the heat for a reduced period of time. Starting out at about 50 percent of normal work duration is generally a good idea.

Employers and managers should also consider the type of work being done at the job site. Moderate work such as walking and doing some pushing or lifting, for example, requires more recovery time than lighter work, but less time than heavy work like shoveling or heavy lifting.

In general, employees working in hot conditions need to be given regular rests breaks in shade or air conditioning. They also need to drink plenty of fluids throughout the workday. These measures should be used in conjunction with a heat acclimatization plan.

Heat illnesses often occur in outdoor workers such as those who work in agriculture or construction, but many other industries are at risk. The CDC study evaluated heat illness incidents involving postal workers, waste collectors, park workers and laundry workers. Therefore, everyone should know how to prepare for the heat. 

Heat Safety Supplementary Information

heat stress
OSHA’s Campaign to Prevent Heat Illness in Outdoor Workers focuses on hydration and rest breaks. Image: OSHA

For the past four years, OSHA has raised awareness about heat illnesses through its Campaign to Prevent Heat Illness in Outdoor Workers. The campaign’s slogan—Water. Rest. Shade.—emphasizes the need for regular rest and lots of hydration. OSHA also suggests workers wear a hat and light-colored clothing, learn the signs of heat illness and watch out for co-workers.

Supervisors at the job site can also use OSHA’s Heat Safety Tool, which is an app that calculates the heat index and suggests protective measures that should be used under the current conditions.

Many workplaces also use the wet bulb globe temperature (WBGT), a measurement that can provide an even more accurate assessment of the environmental conditions. The WBGT evaluates heat stress in direct sunlight and takes temperature, wind speed, sun angle, humidity and cloud cover into consideration in the calculation. If employees are working in direct sun, this number is often more accurate than the heat index, which is measured in the shade.

If your workplace is indoors but still hot (like a laundry, bakery or kitchen), consider posting signs with symptoms of heat stress employees should watch out for. These signs can also list what steps to take when working in the heat.

heat illness, heat acclimatization

While OSHA’s efforts to raise awareness about heat illness have helped many workers, the CDC’s report shows that many workplaces still lack appropriate safety programs for dealing with the heat. Employers should familiarize themselves with necessary safety precautions and make their enforcement a part of daily life. Oftentimes workers will continue working in the heat when they feel ill to demonstrate they are good workers, and this can lead to serious illnesses and even death.

For more information about identifying heat illnesses, read Heat Illness in the Workplace.

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