Heat exposure presents a serious health risk to anyone that is physically active, especially if working in outdoor environments, or indoor environments where temperatures are not adequately controlled. This is an important concern, as the 5th IPCC Assessment Report predicts with 90% certainty that heat waves will be more frequent and longer-lasting1. In Da Nang, Vietnam, the past decade has already seen increases in maximum daily temperature and in the frequency of extreme heat events. Evidence from the study on the adaptive capacity of outdoor workers2 presented in this briefing suggests that the knowledge of outdoor workers regarding the risks of heat stress, and their ability to adapt to high temperatures, is extremely limited. This has an effect on worker health and productivity. This briefing highlights recommendations to limit these impacts.