Working in extreme heat: employer duties and prevention under ISO 45001

A heatwave is not a passing discomfort. On a construction site, in a workshop or in a warehouse, it alters alertness, coordination and tolerance to effort. It turns normally controlled situations into hazardous ones, and the most frequent danger is not the one people expect: long before heat stroke, there is the accident caused by a second of inattention. This article sets out what the employer must assess, what must be put in place, and what must remain documented to be demonstrable in an audit.

What the Moroccan framework expects from the employer

In Morocco, the employer's occupational health and safety duty is set out in the Labour Code (law 65-99), whose title devoted to hygiene and safety states the principle: the employer preserves the health and safety of the people working for the organisation and takes the measures required to that end.

This duty is not met by applying a single threshold across an entire site. Two workstations exposed to the same outdoor temperature are not exposed in the same way: an operator working hard next to a furnace, wearing an impermeable coverall, faces a thermal strain in no way comparable to that of an office worker in the same building. It is the assessment, workstation by workstation, that determines the measures. To place this duty within a structured framework, our article on the occupational health and safety management system presents the overall architecture.

Heat is a hazard, not a discomfort

The body regulates its temperature through sweating and increased skin blood flow. When heat, humidity and physical effort combine, that regulation reaches its limits. Dehydration, cramps, fatigue, longer reaction times and reduced attention follow.

It is this last effect that causes the most accidents. A forklift driver whose alertness drops, a roofer whose coordination deteriorates, an operator who overlooks an instruction because all he can think about is the heat: the initial hazard is thermal, the feared event is an impact, a fall or a cut.

Several factors aggravate the strain and must be identified as such:

• the intensity of the physical effort and how long it lasts without recovery;
• protective equipment that prevents sweat from evaporating, particularly impermeable coveralls and chemical protective clothing;
• humidity, which reduces the effectiveness of sweating, and the absence of ventilation;
• heat sources inherent to the process, such as furnaces, engines and sun-exposed surfaces;
• lone working, which delays the alert when someone becomes unwell;
• the lack of acclimatisation, which primarily concerns new starters, temporary workers and employees returning from leave.

Assessing thermal strain within the risk assessment

The ISO 45001:2018 standard requires, in clause 6.1.2, that hazards be identified and risks assessed proactively, taking real working situations into account. Heat belongs there, on the same footing as other physical hazards.

A useful assessment is not based on the temperature announced by the weather forecast, but on the situation at the workstation. Four elements deserve to be characterised: the temperature and humidity actually experienced where the work takes place, the duration of exposure without recovery, the intensity of the effort, and the clothing worn. To these must be added the means available on site: access to water, to shade, to a cooled room, and a genuine opportunity to take a break.

The identification and rating method does not differ from the one applied to other hazards; it is detailed in our article on hazard identification and risk assessment. To check where you stand before an audit, the ISO 45001 audit readiness grid sets out, clause by clause, the requirements to be demonstrated, including those of 6.1.2.

Acting in the right order, not in a hurry

Clause 8.1.2 of ISO 45001 imposes a hierarchy of controls. It applies particularly well to heat, where the reflex is too often to hand out water bottles and consider the matter settled.

• Eliminate or substitute. Move the most exposing tasks to cooler hours, mechanise a manual handling operation, relocate an operation to a temperature-controlled room.
• Act on facilities and organisation. Shade work areas, ventilate, cool rest rooms, bring water points closer, adjust working hours, introduce rotations and recovery breaks counted as working time.
• Frame the work with instructions. Inform people about warning signs, prohibit lone working during the hottest hours, organise mutual supervision in pairs, adapt work rates, and plan a gradual acclimatisation over several days for anyone newly exposed.
• Protect individually last. Light, covering clothing, head protection, and above all a review of existing protective equipment: an item that is indispensable against a chemical risk may become the main source of thermal strain, which calls for adjusting wearing time rather than removing it.

Water remains necessary, but it is one measure among others, and the last item on the list never replaces the first ones.

Recognising heat stroke and responding

Warning signs often appear gradually: headache, nausea, dizziness, cramps, intense thirst, unusual fatigue. They must lead to stopping the activity immediately and moving the person to a cool place.

Heat stroke itself is a life-threatening emergency. It presents as confusion, incoherent speech, very hot skin, sometimes an absence of sweating, and can progress to loss of consciousness. It requires calling the emergency services without delay, placing the person in the shade in a ventilated area, cooling them down, and never leaving them alone.

This response cannot be improvised on the day it is needed. Clause 8.2 of ISO 45001 requires precisely that emergency situations be identified, that the response be planned and that it be tested. Our article on emergency preparedness and response details this requirement.

What must remain documented

A prevention arrangement that leaves no trace cannot be demonstrated, neither to an auditor, nor to an inspector, nor to a judge. Four items deserve to be kept:

• the updated risk assessment, with thermal strain explicitly addressed workstation by workstation;
• the action plan, stating what was decided, by whom and by when;
• evidence that teams were informed and trained, including temporary workers and contractors;
• incidents, and above all episodes of faintness with no lost time, which are the most useful weak signal and the least often recorded.

Two HEMC resources make it possible to act without starting from a blank page:

The ISO 45001 toolkit covers risk assessment, the action plan and emergency situations, procedures and forms included. For recording events, including episodes of faintness with no lost time, the OHS incident reporting and follow-up register is ready to use.

Going further with HEMC

Occupational risk assessment and the implementation of occupational health and safety management systems are among HEMC's areas of expertise. We work on diagnosis, documentation structuring, team training and preparation for the certification audit. To find out more, explore our QHSE expertise or talk to our consultants.

This article is provided for information purposes and constitutes neither legal nor medical advice. It does not replace the text of the Labour Code or of the ISO 45001:2018 standard, which prevail, nor the opinion of the occupational physician.