Most of the people who die from heatstroke at work were in their first few days on the job, or
were working during a heat wave. It takes time for the body to adapt to working in a new
temperature and conditions, even if he or she has done similar work in the past. Just one week
away from working in the heat can put workers at a higher risk upon the return of hotter and/or
more humid weather.

Heat waves are prolonged periods of hotter and/or more humid weather than average for a
location at that time of year. Direct sun exposure can increase the heat index by up to 15 degrees.
Even workers who are acclimatized to work in the heat, during a heat wave there is an additional
period of acclimatization where he or she is at a higher risk of heat-related illness similar to
someone new to the job.

What are the signs of heat-related illness?

Heat Exhaustion:
Dizziness; headache; sweaty skin; fast heartbeat; nausea/vomiting; weakness; cramps
Heat Stroke:
Red, hot, dry skin; high temperature; confusion; fainting; convulsions

How can heat-related illness be prevented?

Water.Rest.Shade. These will mean the difference between life and death. In addition, building
tolerance to working in the heat (acclimatization) is essential to prevent heat-related illnesses and
deaths especially for new workers or those who have been away for a week or more, but for all
workers during a heat wave. This means employers must provide time for workers to adjust to
the heat- gradually increasing the workload and providing appropriate water, rest and shade.

https://www.osha.gov/SLTC/heatillness/heat_enewsletter.html