Acclimatization Planning for New Workers

Talking points

1. About 80% of heat-related fatalities occur during the worker's first week on the job or after returning from a week or more away. The body needs time to adapt to working in heat.
2. For new workers, start at 20% of the normal workload on day one and increase by no more than 20% each day over five days. Full acclimatization takes 7-14 days.
3. Workers returning from an absence of a week or more have lost much of their acclimatization. They need a modified buildup schedule — starting at about 50% and increasing over 3-4 days.
4. Acclimatization is individual — age, fitness level, weight, medications, and prior heat exposure all affect how quickly someone adapts. Watch new and returning workers more closely.
5. OSHA's proposed heat rule will codify acclimatization requirements. Even before it takes effect, implementing an acclimatization plan now protects your workers and demonstrates good faith.

Ask the crew

Do we have any new workers or anyone returning from time off this week — and have we adjusted their workload for the heat?

Standards this talk is built on

• Proposed Rule 2026

A toolbox talk is a short safety briefing. It supports the training a standard requires; it does not replace it.

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