Working at 45 °C: dressing your teams for the Moroccan summer

Fabric weight, expressed in grams per square metre, measures mass — and therefore, very directly, what sits on the shoulders and how much heat is held in. An all-round work twill often sits around 240–260 g/m², an excellent compromise from October to May. Above 35 °C, it is a coat. Summer versions typically drop to 180–200 g/m², and the difference is felt within the first hour of the shift.

The debate is old and often badly framed. Cotton absorbs moisture and lets air through: it gives that cool feel appreciated early in the day. But once saturated with sweat it stays wet, clings to the skin and dries slowly. Polyester does the opposite: it absorbs little, wicks outwards and dries fast, at the price of a less pleasant feel against the skin and a tendency to hold odour.

The summer reflex is to cut things shorter: short sleeves, shorts, a t-shirt on its own. That is often a mistake, especially outdoors. A light, pale long sleeve shields against direct radiation, reduces skin heating and prevents the sunburn that, accumulated over a season, becomes a genuine health issue. Desert peoples do not dress short, and that is not an accident.

• Favour a loose cut that lets a layer of air move between fabric and skin.
• Look for ventilation: mesh panels under the arms, at the back, behind the knees.
• Prefer light shades outdoors: they reflect part of the radiation instead of absorbing it.
• Think about headwear compatible with the helmet, and neck protection on exposed roles.
• Add a technical wicking base layer: it transforms an outfit's comfort without changing a single seam.

This is the most uncomfortable situation, and the most common on sites and roadways. High-visibility clothing imposes minimum areas of fluorescent material and retroreflective banding, which limits how much can be opened up. The answer is not to remove the vest, but to move the visibility onto the lightest possible garment.

• Replace the full high-visibility set with a certified t-shirt or polo, worn on its own in hot weather.
• Choose segmented-band versions: they breathe more than continuous banding.
• Check the class the role requires before lightening: a class 3 is not replaced by a class 1 because it is hot.
• For summer night work, keep the highest class: cooler nights make the trade-off unnecessary.

The detail of classes and required areas is in our article on high visibility in construction, and the matching models are in the safety catalogue.

No fabric compensates for badly organised work. Clothing reduces heat strain, it does not remove it. The most effective levers remain shifting heavy tasks to early morning, accessible shade on outdoor stations, water within a few dozen metres, and attention to new starters, who are not yet acclimatised and pay the heaviest price in the first heat waves.