Heat Illness Prevention Plan: A Practical Template for EHS Managers

Most workplace heat illness programmes fail at the same point: they stop at prevention and have no credible emergency response. They cover water access, shade, and rest breaks. They do not answer the question that matters when a worker goes down: what do we do in the next 10 minutes? This guide builds a heat illness prevention plan that covers both layers — prevention and emergency response — in a format you can adapt to your site, industry, and workforce.

Layer 1 — Hazard assessment

Before writing any procedure, map the actual exposure. This means identifying which jobs, locations, and time windows carry meaningful heat risk, and quantifying them.

Outdoor worksites. Use the heat index (air temperature combined with relative humidity) as your baseline metric, supplemented by wet bulb globe temperature (WBGT) where possible. WBGT accounts for radiant heat from the sun and wind speed, making it a more accurate indicator of physiological load than heat index alone. NIOSH uses WBGT to set recommended exposure limits. For practical field use, the OSHA-NIOSH Heat Safety Tool app calculates real-time risk levels by location and can be used by supervisors before and during each shift.

Indoor worksites. Heat risk is not limited to outdoor work. Foundries, steel mills, commercial kitchens, bakeries, warehouses without climate control, and laundries can generate ambient temperatures and radiant heat loads that are more dangerous than a summer construction site. Map every indoor area where air temperature, radiant heat from equipment, or humidity creates sustained thermal load.

Individual risk factors to flag. Some workers carry elevated personal risk regardless of ambient conditions: those in the first 14 days on a job with heat exposure, workers returning from illness or extended leave, workers over 55 or under 25, pregnant workers, and those taking diuretics, antihistamines, antipsychotics, or beta-blockers. Flag these individuals for closer supervision during heat conditions — not to exclude them from work, but to ensure monitoring is in place.

Document all of this in writing. The hazard assessment is the foundation of your Heat Injury and Illness Prevention Plan (HIIPP) under the OSHA proposed standard, and it is the document that will be reviewed first in any enforcement inspection.

Layer 2 — Prevention controls

Engineering controls (highest priority). Reduce heat load at the source where feasible: shade structures over outdoor work areas, air conditioning or evaporative cooling in enclosed spaces, insulation on hot surfaces, and radiant heat shields near furnaces or ovens. These are permanent controls that work regardless of whether supervisors remember to enforce rest breaks.

Administrative controls. Shift the work schedule. Start outdoor work earlier — 5am or 6am — and reduce or suspend physical work between 11am and 3pm during high heat alerts. Rotate workers through high-exposure tasks to limit individual duration. This is particularly important for physically demanding roles in construction, landscaping, and agriculture.

Water, rest, and shade — the minimum standard. The OSHA proposed standard requires drinking water at no cost to employees, accessible within a short walk from every work area. The guideline is approximately 250ml (8oz) every 15-20 minutes during heat exposure — not on demand, but on a schedule, because workers in heat often underestimate their own dehydration. Rest areas must be shaded or cooled to below 35°C (95°F). Rest breaks must be a minimum of 15 minutes every two hours at the high heat trigger level (90°F/32°C heat index).

Acclimatisation protocol. This is the most consistently neglected element of heat illness prevention programmes, and the data is unambiguous on its importance. New workers and those returning after more than 14 days away should be exposed to heat conditions gradually:

Days 1-3: no more than 20% of shift at peak heat exposure
Days 4-5: 40% exposure
Days 6-7: 60% exposure
Days 8-9: 80% exposure
Day 10 onwards: full exposure permitted

This schedule applies to the physically demanding portions of the role, not necessarily to the full shift. Workers who fall ill during acclimatisation should restart the protocol from day one.

Layer 3 — Monitoring and supervision

A heat illness programme that relies on workers self-reporting symptoms is not a programme — it is a formality. Exertional heat stroke characteristically impairs judgment before it impairs consciousness. A worker who is confused, unsteady, or behaving unusually may not recognise it themselves or may actively resist stopping work.

The buddy system. Assign each worker a partner during high heat conditions. Their role is specifically to watch for behavioural changes — confusion, stumbling, slurred speech, unusual aggression or apathy — not just physical collapse. Train supervisors that a worker who "seems off" warrants immediate removal from the heat source and assessment, not reassurance.

Supervisory check-ins. At the high heat trigger level, supervisors must conduct in-person checks at least every two hours. Remote or phone-based check-ins are insufficient. The check should include a brief verbal exchange and direct observation of the worker's physical state.

Monitoring technology. Wearable heat stress monitors that track core temperature, heart rate, and sweat rate are increasingly available and cost-effective for high-risk roles. For workers in enclosed protective suits or heavy PPE — where heat load is amplified and visual signs are masked — wearable monitoring is the only reliable early warning system.

Layer 4 — Emergency response

This is where most heat illness plans stop writing and start hoping. It is also the layer that determines whether a heat stroke case is a fatality or a full recovery.

Recognise the difference between heat exhaustion and heat stroke. Heat exhaustion involves heavy sweating, weakness, cold or pale skin, fast but weak pulse, nausea, and possible fainting. The worker is still mentally coherent. Move them to a cool environment, hydrate, and monitor. This is not a 999/911 situation in most cases.

Heat stroke is different. The worker is confused, disoriented, has lost coordination, may have stopped sweating, and may be unresponsive. Core temperature is above 40°C. This is a life-threatening emergency. Every minute without effective cooling increases the probability of permanent organ damage.

The 5-step emergency protocol for suspected heat stroke:

Call EMS immediately. Communicate the location precisely — on remote or large industrial sites, GPS coordinates, not just an address.
Move the worker to shade. Do not transport to hospital before cooling has been initiated.
Begin cooling immediately. Cold water immersion is the gold standard, with a documented cooling rate of 0.35°C per minute — ten times faster than ice packs or wet towels. If immersion is available, use it.
Continue cooling until core temperature reaches 39°C or EMS arrives and takes over. Do not remove from cooling to transport.
Monitor airway and consciousness. Position lateral if unconscious.

The principle underpinning steps 3 and 4 is Cool First, Transport Second — the protocol validated by the ACSM, the IOC, and the Korey Stringer Institute. The 30-minute window to bring core temperature below 40°C is the single most important factor in heat stroke survival. On remote sites where EMS response times exceed 15-20 minutes, the gap between calling for help and the arrival of trained responders is where outcomes are decided.

Kollder is a portable emergency cooling tub designed for this gap. It deploys in under 30 seconds by one person on any surface — a car park, a factory floor, a construction site — and allows full patient access during immersion for monitoring and airway management. For EHS teams that want to close the space between prevention protocol and emergency capability, visit kollder.com/#contact.

Layer 5 — Documentation and review

A heat illness prevention plan is a living document. At a minimum, it requires:

An annual review before the heat season begins, incorporating any incident data from the previous year, updates to OSHA or NIOSH guidance, and changes to the workforce or site layout.

A post-incident review within 72 hours of any heat illness event, regardless of severity. Near-misses — workers who were symptomatic but recovered without EMS involvement — are the most valuable learning opportunities and the most commonly ignored.

Training records for every worker and supervisor, documenting content, date, and attendance. Under the OSHA proposed standard, training must occur before exposure and must be refreshed. Records are the first thing an enforcement inspector asks for.

A written emergency response procedure specific to each site, including EMS contact information, the location and inventory of cooling equipment, and the name of the designated first responder for heat emergencies. This document should be posted at every site where workers may be exposed to heat.