Preventing and Responding to Heat Illness
Elements of Your Written Program and Effective Work Practices
T8CCR 3395(b) Definitions states the following:
“Acclimatization” means temporary adaptation of the body to work in the heat
that occurs gradually when a person is exposed to it. Acclimatization peaks in
most people within four to fourteen days of regular work for at least two hours
per day in the heat.
T8CCR 3395(f) Training states the following:
(1) Employee training. Effective training in the following topics shall be
provided to each supervisory and non-supervisory employee before the employee
begins work that should reasonably be anticipated to result in exposure to the
risk of heat illness:
(D) The importance of Acclimatization
Cal/OSHA investigations (Study 1) showed that in 2005:
- 46% of the reported cases of heat illness occurred on the employee’s
first day on the job.
- 80% of the reported cases of heat illness occurred within the first four
days of employment.
In fully acclimatized individuals, sweating starts faster and the sweat
carries less salt and other minerals out of the body. As a result, by sweating
more efficiently the body cools down faster. Also there is less demand on the
heart and cardiovascular system. For the reasons given above, being fully
acclimatized can decrease the risk of heat illness and unsafe acts.
In general, physically fit individuals become acclimatized about 50% faster
than those individuals who are not physically fit. Overweight individuals may
retain more body heat and therefore may be more prone to developing heat
To minimize the risk of heat illness, encourage employees to report to their
supervisors if they have:
- Returned to work after an absence
- Recently been working in cool climate and are just now starting work in
a warm or hot climate
- Had a change in their work activities, locations or conditions
Any of the above mentioned circumstances may mean that employees are not
acclimatized to working in warm or hot environments, and are at greater risk for
Make Sure Employees Are Trained, Monitored and Watched Closely.
Remember that employees who are not acclimatized to working in the heat are
at greater risk for developing heat illness. Unacclimatized employees should not
work alone. It is important to:
- Train employees and supervisors on the importance of recognizing and
reporting heat illness symptoms
- Have supervisors and coworkers use a “buddy system” to watch each other
closely for discomfort or signs of heat illness
- Set-up a system to account for the whereabouts of your crew at
appropriate intervals throughout the work shift and at the end of the work
shift (e.g., keep a log of employees on your work crews including their
names, supervisors, work locations, and hours worked on a given day, etc.)
During high heat even previously acclimatized employees are at risk for heat
illness because the body has not had enough time to adjust to a sudden,
abnormally high temperature or other extreme conditions.
Options for Acclimatizing Employees to Work in Warm or Hot Environments include One or More of the Following:
Have Employees Pace Themselves
- If they are not accustomed to working in warm or hot environments, they should start work slowly and pick up the pace gradually.
Reduce Physical Demands
- Assign employees to less physically demanding tasks during their first 14 days of working in a warm or hot environment.
- Schedule and provide frequent breaks. Supply sufficient amounts of drinking water
Start an Acclimatization Program
The acclimatization schedule by NIOSH, as shown above, is only an
Depending on the environmental and personal risk factors present, you may need to extend the time employees spend in your acclimatization program. This means that for some employees it may take up to 14 days of working in the heat for them to become fully acclimatized. Throughout this time period you should gradually increase employee’s time working in the heat.
Consult with Your Physician Before Replacing Salts and Minerals
For un-acclimatized employees, or those on a restricted salt diet, additional
salting of food with the approval of their physician may be required to replace
the salt and minerals lost in sweating. Acclimatized employees generally loose
relatively little salt in their sweat, therefore salt and mineral supplements
are normally not required.