Occupational heat stress management: Does one size fit all?

Heat stress is a deadly occupational hazard that is projected to increase in severity with global warming. While upper limits for heat stress designed to protect all workers have been recommended by occupational safety institutes for some time, heat stress continues to compromise health and productivity. In our view, this is largely explained by the inability of existing guidelines to consider the inter-individual (age, sex, disease, others) and intra-individual (medication use, fitness, hydration, others) factors that cause extensive variability in physiological tolerance to a given heat stress. In conditions that do not exceed the recommended limits, this 'one size fits all' approach to heat stress management can lead to reductions in productivity in more heat-tolerant workers, while compromising safety in less heat-tolerant workers who may develop heat-related illness, even in temperate conditions. Herein, we discuss future directions in occupational heat stress management that consider this individual variability.