Heat stress prevention: a QEHS program guide

OSHA's National Emphasis Program on heat hazards targets over 70 high-risk industries. Inspections trigger when the heat index exceeds 80°F. A prevention program needs: environmental monitoring, acclimatisation protocols (20% exposure day 1, increasing 20% per day), work/rest schedules, access to water (1 quart/worker/hour), shaded rest areas, buddy systems, and emergency response for heat stroke.

Heat illness is 100% preventable. Every heat-related fatality is a system failure. See also the industrial hygiene, PPE management, and TLV glossary entries.

The National Emphasis Program is the enforcement lever, and it is the one that changes a heat program from a recommendation to an inspection risk. The OSHA NEP on heat hazards targets the industries with the highest heat exposures — construction, agriculture, landscaping, oil and gas well operations, and the indoor bakeries, kitchens, and laundries — and the inspection triggers when the heat index exceeds the threshold. A site in a targeted industry on a high-heat day is a site the NEP can inspect without a complaint, and the inspection that arrives reads the heat program for the controls the site said it had. A program that exists on the heat index chart and not in the work is the program the NEP finds absent.

The heat index and the WBGT are the two measures a program has to hold straight, and they are not the same. The heat index is the feels-like temperature from the air temperature and the humidity, and it is the number the NEP threshold uses. The wet-bulb globe temperature (WBGT) is the measure that accounts for the radiant heat, the air movement, and the workload, and it is the measure the industrial hygienist uses for the work-rest schedule. A program that measures the heat index and applies a WBGT-based schedule is a program that under-protects on a sunny, still day, and the program that measures the WBGT is the program that matches the control to the actual heat load.

Acclimatisation is the single most important control, and it is the one the program most often omits. A worker new to the heat — a new hire, a returning worker, a worker back from leave — needs a ramp-up of about 20 percent exposure on day one, increasing by 20 percent per day, to build the physiological tolerance over five to seven days. The worker who is thrown into a full shift on the first high-heat day is the worker at the highest risk of heat illness, and the acclimatisation that is skipped is the control whose absence the fatality investigation cites. The program that holds the acclimatisation schedule per worker is the program that does not lose the new hire to the first heat wave.

The work-rest schedule is the control that matches the workload to the heat load, and it is the one the WBGT drives. A heavy workload at a high WBGT requires more frequent rest breaks in a shaded or cooled area, and the schedule is a table of workload, WBGT, and break ratio, not a judgment call by the supervisor. The water is the other control — about a quart per worker per hour, with access that does not require the worker to leave the work area or to ask — and the water that is a walk away is the water the worker skips. The buddy system is the control that catches the early symptoms, because heat illness impairs the judgment of the person it is affecting, and the worker who is alone is the worker whose symptoms go unobserved.

• Monitoring — measure the heat index or the WBGT at the work, not at the weather station, and trigger the controls at the threshold the schedule sets.
• Acclimatisation — ramp the new and returning workers over five to seven days, and hold the schedule per worker, not per crew.
• Hydration — provide about a quart of water per worker per hour, accessible at the work, and do not rely on thirst as the trigger to drink.
• Work-rest — match the break ratio to the workload and the WBGT from the published table, and provide a shaded or cooled rest area.
• Buddy system — pair the workers so the early symptoms are observed, because heat illness impairs the judgment of the person it affects.
• Emergency response — train the supervisors to recognise heat stroke, start the cooling immediately, and call for emergency transport, and drill the response.

The recordability of a heat illness is the question the recordkeeper has to answer, and it is the one the work-relatedness standard governs. A heat illness that a worker develops on a high-heat workday is work-related by default under the recordkeeping standard, and the case enters the 300 log as a recordable if it involved medical treatment beyond first aid, days away, or restricted duty. The program that does not record the heat illness because the worker did not report it is the program whose TRIR understates the heat risk, and the audit that reads the 300 log against the weather data is the audit that finds the under-recorded heat cases. The heat program and the recordkeeping program are the same program on a high-heat day.

1. Load the targeted-industry list and the heat-index thresholds, and configure the platform to alert the supervisor when the threshold is crossed at the site.
2. Hold the acclimatisation schedule per worker — the start date, the ramp percentage, and the completion date — so the new hire is not on a full shift before the schedule is complete.
3. Configure the work-rest schedule as a table of WBGT and workload, so the supervisor reads the break ratio from the table and not from judgment.
4. Schedule the heat-stress training before the high-heat season, and the emergency-response drill, with the completion tracked per worker.
5. Record the heat illness at the point of entry against the recordkeeping standard, so the 300 log reflects the heat risk and the heat program is read against the record.

The heat program is the one that has to be ready before the heat wave and not built during it, and it is the one the NEP reads without warning. A program that is configured before the season — the thresholds, the schedules, the training, the drills — is a program that runs on the first high-heat day, and a program that is built during the heat wave is a program that loses the first week to the setup. For the related concepts, see the industrial hygiene, PPE management, and TLV glossary entries; for the recordkeeping of the heat illness, the OSHA 300 fastest-path post, and for the industrial hygiene program, the TLV guide.

The indoor heat is the half the program forgets, and it is the half the NEP names. The bakeries, the commercial kitchens, the laundries, the foundries, and the warehouses without ventilation are the indoor environments where the heat index can exceed the outdoor one, and the worker in a 95-degree kitchen is the worker the outdoor heat-index chart does not protect. The indoor heat program measures the WBGT at the workstation, not the heat index at the weather station, and the program that applies the outdoor chart to the indoor kitchen is the program that under-protects the cook.

The new hire is the worker at the highest risk, and the worker at the highest risk is the one the program has to hold by name. The fatality data the agency collects shows that the first days on the job are the days the heat deaths cluster, and the acclimatisation that is skipped on the first day is the control whose absence the data names. A program that holds the acclimatisation schedule per worker is a program that knows which worker is on day one and which is past the ramp, and the program that acclimatises by crew and not by worker is the program that loses the new hire to the first heat wave.

The climate trend is the one that makes the heat program a permanent fixture and not a seasonal one, and it is the one the board reads. The number of high-heat days per year is rising across most of the country, and the heat program that is built for the historical average is the program that is under-built for the present. A platform that holds the heat events against the weather data is a platform where the trend is visible in the records, and the trend that is visible is the trend that justifies the program to the board that funds it.