[Summary of key findings and recommendations:

1. The wet-bulb globe temperature (WGBT) index is a reliable basis on which employers can adapt their mitigation processes;
2. Working hours of between 16.00 and 02.00 are optimum for decreasing risk of heat stress and insufficient sleep;
3. There is no relationship between workers' ethnicity and susceptibility to heat stress; all workers should undergo proactive health checks to identify heat stress symptoms;
4. 1 in 3 workers performed up to 5% of their job while hyperthermic. Heat mitigation plans supported by hydration strategies can reduce incidence of hyperthermia;
5. Workers must be empowered to take breaks, and self-pace themselves to work at low intensity;
6. Those working continuously in the shade outdoors can work safely provided their day is punctuated with regular breaks;
7. Appropriate clothing and hydration were effective strategies for reducing heat stress;
8. Providing workers with 750ml water on an hourly basis most effectively reduced dehydration, hyperthermia and labour effort; and
9. When extensive heat mitigation strategies are in place, workers perceive their working conditions to be safer.]