Many laborers are confronted with occupational heat stress from physically demanding work in high environmental temperatures with inadequate protections. Heat stress has multiple well-established adverse health outcomes, including increased accidents, heart attacks, heat illness, stroke, and organ damage including kidney diseases. All are potentially fatal and associated with decreased productivity. Heat stress and its health effects harm workers, communities, employers, and health systems. Active intervention in a warming world is required. Chronic Kidney Disease of undetermined causes (CKDnT) is a fatal progressive loss of kidney function that has killed more than 40,000 people in Mesoamerica and Sri Lanka alone in the last 10 years. Treatment is out of reach for most ensuring an early death for those affected.