Background/Objectives

Over a billion outdoor workers live in the tropics, where high temperatures and humidity are often a feature of daily life. Future global climate change and local land use changes could magnify impacts of humid heat on these workers. To date, reviews have focused on summarizing historical and future heat impacts, such as impacts on worker health, well being, and productivity. Few syntheses have focused on solutions - that is, modifiable factors that can reduce worker vulnerability and increase resilience to heat. 

Approach/Activities

We first highlight where humid heat exposure is already likely impacting outdoor workers, as well as where global climate change and local land use change will magnify outdoor heat exposure. We then reorient the discussion of worker heat exposure to focus on specific actions by governments, employers, communities, households, and individuals, as well as the many uncertainties that exist around how to mitigate and adapt to humid heat. 

Results/Lessons Learned

We estimate that in the last 20 years, ~1% of the population (0.06% - 2.35%) in the tropics resided in locations where labor recommendations suggest heavy work should be restricted for over half of the year’s hours. Under an additional 1°C of global warming, ~13% of the population in the tropics (8.4%-21.2%) will be located in places where heavy work should be restricted for over half of the year's hours. To bolster efforts to improve worker resilience and well being, our review provides foundational insights into actions that can be taken now and in preparation for future impacts, as well as critical future research that is urgently needed. Action types range from reducing fossil fuel emissions, to adopting heat-mitigating land uses, to employer-specific actions such as providing access to cooling centers, to worker-specific actions like adopting new livelihoods with less heat exposure. To increase resilience, it is important to consider the full range of heat exposure modifying factors and how they align. Our framework allows for a broad assessment of the limitations and challenges for facilitating reasonable adaptations to heat stress and can also be used to explore potential tradeoffs that may influence resilience at various temporal and spatial scales. For example, labor regulations could increase safety protections across entire sectors in the formal economy, but in emerging economies these regulations may lead to non-trivial feasibility concerns for informal sector employers and workers.