Heat illness prevention plans

Where the duty comes from

Federal OSHA enforces heat through the General Duty Clause, Section 5(a)(1) of the Occupational Safety and Health Act of 1970, which requires employers to provide a place of employment “free from recognized hazards that are causing or are likely to cause death or serious physical harm to employees”. OSHA also runs a National Emphasis Program for outdoor and indoor heat-related hazards, which is what drives the inspections.

Several states operating their own plans have gone further and adopted heat standards of their own with specific temperature triggers, shade and water requirements. Those are state law and they differ — check your own state plan’s current rule rather than a national summary, because this is the fastest-moving area in construction safety regulation.

How OSHA measures a heat hazard

This is the technical detail most plans get wrong. OSHA states that its Technical Manual chapter on heat stress uses wet bulb globe temperature (WBGT) to determine whether a heat hazard was present. WBGT incorporates temperature, humidity, sunlight and air movement into a single measurement, and an on-site meter is described as the most accurate way to measure environmental heat impact on body temperature.

The NIOSH/OSHA Heat App is useful but is not the same instrument: OSHA notes plainly that the app provides only heat index, not WBGT, though it does give workload guidance. A plan whose triggers are written in heat-index degrees is measuring something different from what an inspector will measure.

Occupational risk factors OSHA names: heavy physical activity, warm or hot environmental conditions, lack of acclimatisation, and clothing that holds in body heat. That last one is why a plan has to talk to the PPE selection — impermeable coveralls change the arithmetic entirely.

Acclimatisation, the part that gets skipped

OSHA is direct about it: workers who have not spent time recently in warm or hot environments, and/or being physically active, need time to build tolerance to the heat. New hires, returning workers and everyone during the first heat wave of the season are the exposed group — not the crew that has been out there all summer.

Practical measures OSHA points to: slowing physical activity, reducing manual-handling speeds, scheduling work for the morning, and shorter shifts with frequent rest breaks in the shade or at least away from heat sources. Heat stress degrades fine motor performance — rebar tying is the example OSHA gives — even in acclimatised individuals, so the risk is not only medical. A dropped tool is a struck-by hazard.

What the written plan needs

1. A named person responsible for monitoring conditions and calling the schedule change.
2. How you measure, with the instrument named. If you use WBGT, say so; if you use heat index, record that you know the difference.
3. Water, rest and shade provision in quantities and locations, not adjectives. OSHA names water, rest and shade as prevention and treatment.
4. An acclimatisation schedule for new and returning workers, with the days written out.
5. Symptom recognition and response, including who calls emergency services and what happens while they come.
6. Training, which is where 1926.21(b)(2) bites — instruct each employee in the recognition and avoidance of unsafe conditions.

Attach the plan to the site-specific safety plan, and run the talk in the week before the first heat, not during it — the topic list is in toolbox talk topics.

One recordkeeping note: a heat illness that meets any criterion in 1904.7 — medical treatment beyond first aid, days away, restricted work, loss of consciousness — is a recordable case like any other.

Acclimatise