Reconstructing the environmental and temporal contexts of heat-related deaths on the Arizona Borderscape through a multivariate typology of heat exposure

Of those known, heat exposure is a leading cause of death among undocumented border crossers in southern Arizona. To date, studies have examined the effects of climate and policy on border-crossing deaths but have relied heavily on temporally-fixed indices. This study asks whether heat-related deaths correspond to recurring combinations of environmental and physiological conditions across space and time. I analyzed heat-related deaths recorded from 2000 to 2025 by the Pima County Office of the Medical Examiner. Post-mortem interval estimates were used to identify possible death months rather than relying only on when remains were recovered. I combined monthly meteorological data, modeled radiant heat, and terrain-derived exertional variables to classify Thermal Exposure Regimes, using Body Heat Storage modeling to describe the resulting classes: recurring spatiotemporal typologies of environmental heat exposure, terrain-associated exertional demand, and modeled physiological burden. Results show that recovered remains did not occur simply in "hot" or "demanding" areas, but across seven typologies that varied in heat, humidity, wind, radiant exposure, exertion, and heat storage. Recovery locations were concentrated in two intermediate regimes relative to mapped area, although the differences attenuated against other recovery locations. These findings deliver a reproducible framework for linking incomplete mortality records with environmental and physiological conditions when the timing of death is uncertain.