Take Time to Acclimatize Workers in Hot Environments

he typically hotter temperatures of July and August (and often into September),
which last for days or weeks with little or no relief, are still ahead of us.
Many workers will be outside laboring in the extreme heat. It is important for
employers to make the effort to protect their workers from heat-related
illnesses, such as heat exhaustion and the often fatal heat stroke.

Hot environments can be dangerous, but employers may be able to decrease the
risk of heat-related illness at their workplace by providing workers with the
opportunity to acclimatize, providing hydrating beverages such as water, and
encouraging hydration and rest breaks.

Providing workers with rest periods in shaded or cool areas, ensuring they have
access to water or other hydrating beverages, and training workers to recognize
symptoms of heat-related illness are all important. However, employers should
also take the opportunity to acclimatize workers who will be spending time in
the heat. Acclimatization is the beneficial, physiological adaptations that
occur during repeated exposure to a hot environment. These adaptations may
include increased sweating efficiency, stabilization of the circulation, and
the ability to perform work with lower core temperature and heart rate. If
workers are not acclimatized, then they may more quickly show signs of heat
stress and have difficulty replacing water lost in sweat.

As part of their heat illness prevention program, employers should implement an
acclimatization plan for new and returning workers. The level of
acclimatization and the time it takes to become acclimatized vary depending on
the fitness level and the total heat stress (i.e., metabolic and environmental)
experienced by the worker. To acclimatize workers, exposure to the hot
environment should gradually be increased over a 7 to 14 day period. For new
workers, the schedule should involve no more than 20% exposure on Day 1 and no
more than 20% increase on each additional day. For workers who have had
previous experience with the job, the schedule should be no more than 50%
exposure on Day 1, 60% on Day 2, 80% on Day 3, and 100% on Day 4.

Acclimatization can be maintained for a few days when the worker is not in the
hot environment, such as when they go home for the weekend. However if the
worker is away for a longer period (e.g., week-long vacation), then many of the
beneficial adaptations from acclimatization may be lost. It is also important
for employers to understand that extreme heat events or heat waves can result
in previously acclimatized workers no longer having the appropriate
physiological adaptations for the new higher temperatures of the environment.
During extreme heat events, adjusted work-rest schedules may be required to
allow workers the extra time needed to cool down. In addition, the workers
should be provided with hydrating beverages and encouraged by their supervisors
to take frequent hydration and rest breaks.

More information: - Source: Centre for Occupational Health and Safety