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Preventing and Responding to Heat Illness

Best Practises - Your Written Program

I. Effective Work Practices

3. Adjustments to Workload Severity and Duration

Work Severity

Smart Tips

In warm or hot weather, try to schedule slower paced, less physically demanding work during the hot parts of the day and the heaviest work activities during the cooler parts of the day (early-morning or evening).


Work Scheduling

Smart Tips

In warm or hot weather, avoid over time work and double shifts. You can choose to postpone non-essential work to be done until a later time when it is cooler. Also, you can rotate employees through less physically demanding jobs or add extra personnel to reduce exposure time for each employee. In spite of these measures be aware that heat illness can still develop.


During a heat wave it may be necessary to change work scheduling and assignments or stop work altogether (see 6. Extra measures during a heat wave).

In order to prevent heat illness it is important to allow the body to cool down. By stopping physical work activities and replacing them with rest the body cools down. Regular resting periods and Preventative Recovery Periods (PRPs) both allow the body to cool thus helping to prevent overheating.

Shaded area with water container


Encouraging Work-rest Cycles

A work-rest cycle is not the same as a Preventative Recovery Period (PRP). Cal/OSHA requires that employees be given a PRP if they are suffering from heat illness, or believe they need a PRP. Work-rest cycles help cool the body to eliminate the need for a PRP. They involve alternating normal work activities with regularly scheduled rest breaks. There are numerous ways to enhance cooling the body during rest breaks (see Provide Cooling from Shade and Provide Cooling Using Alternative Measures)

Smart Tips

Taking Breaks

The judgement and experience of supervisors or other designated person(s) who are at the worksite is vital when scheduling breaks. The timing, frequency, and length of breaks needs to be based on:

  • The temperatures and other risk factors present at the worksite at any given time throughout the workday
  • Careful observation of employees behavior and physical condition

Remember, healthy employees are far more productive throughout the work shift and are also much less likely to develop heat illness or become injured. Ensure that your employees take their regularly scheduled breaks (and frequently drink sufficient amounts of water). It is important to:

  • Train employees and supervisors to understand the importance of taking breaks
  • Use a "buddy system" to have supervisors and fellow employees watch each other closely at all times
  • Recognize employees who have reduced work capacities because of personal risk factors and may need more flexible or additional work-rest cycles
  • Provide more frequent breaks for employees performing tasks requiring constant attention (e.g., equipment operators) or wearing PPE
  • Use portable structures (or other portable alternative cooling measures) for mobile crews. These measures can provide cooling during breaks for mobile crews as they change their work locations
  • Provide areas for employees to take their breaks which are:
    • Readily accessible
    • Open to the air and ventilated or cooled, or in shaded areas
    • Near sufficient supplies of drinking water

Men sitting down and drinking water in shaded area  Man sitting down and drinking water in shaded area