Heat-related mortality in Mexico: A multi-scale spatial analysis of extreme heat effects and municipality-level vulnerability

Lara Schwarz; Chen Chen; Javier Emmanuel Castillo Quiñones; L C Aguilar-Dodier; Kristen Hansen; Jaime Reyes Sanchez; David J X González; Gordon McCord; Tarik Benmarhnia

doi:10.1016/j.envint.2024.109231

Heat-related mortality in Mexico: A multi-scale spatial analysis of extreme heat effects and municipality-level vulnerability

Environ Int. 2024 Dec 20:195:109231. doi: 10.1016/j.envint.2024.109231. Online ahead of print.

Authors

Lara Schwarz¹, Chen Chen², Javier Emmanuel Castillo Quiñones³, L C Aguilar-Dodier³, Kristen Hansen⁴, Jaime Reyes Sanchez⁵, David J X González⁶, Gordon McCord⁷, Tarik Benmarhnia⁸

Affiliations

¹ School of Public Health, San Diego State University, San Diego, CA, USA; Herbert Wertheim School of Public Health and Longevity Science, University of California San Diego, La Jolla, CA, USA; Division of Environmental Health Sciences, School of Public Health, University of California Berkeley, Berkeley, CA, USA. Electronic address: [email protected].
² Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA.
³ Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Tijuana, México.
⁴ Axle Research and Technology, Rockville, MD, USA.
⁵ Department of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, CA, USA.
⁶ Division of Environmental Health Sciences, School of Public Health, University of California Berkeley, Berkeley, CA, USA.
⁷ School of Global Policy and Strategy, University of California, San Diego, La Jolla, CA, USA.
⁸ Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA; Irset Institut de Recherche en Santé, Environnement et Travail, UMR-S 1085, Inserm, University of Rennes, EHESP, Rennes, France.

PMID: 39719756
DOI: 10.1016/j.envint.2024.109231

Abstract

Understanding effects of extreme heat across diverse settings is critical as social determinants play an important role in modifying heat-related risks. We apply a multi-scale analysis to understand spatial variation in the effects of heat across Mexico and explore factors that are explaining heterogeneity. Daily all-cause mortality was collected from the Mexican Secretary of Health and municipality-specific extreme heat events were estimated using population-weighted temperatures from 1998 to 2019 using Daymet and WorldPop datasets. We analyzed the association between single-day extreme heat events defined at the 99th percentile of the same-day maximum temperature and mortality, and seven heat threshold metrics based on relative and absolute scales were considered as sensitivity analyses. A time-stratified case-crossover was applied to evaluate heat impacts across 32 states in Mexico. A within-community matched design with Bayesian Hierarchical model explored effects across 2456 municipalities. A random-effects meta-regression was applied to understand which municipality-level socio-demographic characteristics such as education, age and housing predicted observed spatial heterogeneity. Extreme heat increased the odds of mortality overall, and this was consistent across extreme heat thresholds. At the state level, extreme heat events showed highest impact on mortality in Tabasco [OR: 1.23, 95% CI: 1.17, 1.30]. The municipality-level spatial analysis showed substantial differences across regions with highest effects observed along the eastern, southwestern and Sonora coasts. Municipalities with older populations, higher marginalization, lower education, and poorer housing conditions were more vulnerable to heat effects. Understanding the differential risks of extreme heat events at varying scales is important to prioritize at-risk populations in action plans and policies to reduce their burden.

Keywords: Extreme heat; Mexico; Social vulnerability; Spatial analysis.