Global Warming Making Outdoor Labor More Dangerous

“No amount of labor can be safely sustained”

The increased summer heat brought by climate change is naturally accompanied by greater humidity, making peak summer months more dangerous for outdoor laborers like construction workers and farmers. Under very hot and humid conditions, the human body cannot give off heat as fast as it creates it—a hyperthermic condition that can lead to low blood pressure, organ failure, and death.

Based on existing guidelines regarding heat stress, the authors measure labor capacity as wet-bulb temperature thresholds at which an individual’s ability to perform heavy, moderate, or light labor is reduced. Under most conditions, productivity could be maintained by adding workers, but with 77°F (25°C) as the limit for 100% heavy labor, the authors estimate that beyond 91.4°F (33°C), “no amount of labor can be safely sustained over the typical eight-hour work period.”