If you are working outdoors for prolonged periods:

Apply sunscreen before exposure
Reapply during the day
Hydrate consistently
Use shade during breaks where possible
Wear suitable hats, eyewear and clothing where practical
Watch for headaches, dizziness and fatigue
Look out for your crew as well as yourself

Heat exhaustion affects concentration and decision-making long before somebody becomes seriously unwell.

Sunburn should not be viewed as “part of the job”. It is a visible sign of skin damage caused by overexposure to UV radiation.

Signs crews should not ignore:

Dizziness
Headaches
Nausea
Cramps
Unusual fatigue
Excessive sweating
Loss of concentration
Confusion or feeling faint

If somebody is struggling, cool them down, hydrate early and move them into the shade.