Extreme heat represents a growing threat to public health as climate change intensifies. While its mortality impacts are well recognised, the interplay between heat, air pollution, and socioeconomic vulnerability remains insufficiently understood. We quantified the associations of extreme maximum temperatures and heatwaves with daily mortality in Catalonia (2012-2022) and evaluated how air pollutants-particularly ozone, nitrogen dioxide and particulate matter-and socioeconomic factors confound or modify this relationship. We conducted a time-series ecological analysis across 379 Basic Health Areas during summer months, linking mortality with meteorological, air pollution and socioeconomic indicators. Hierarchical Bayesian zero-inflated negative binomial models were fitted with nested spatiotemporal random effects (Matérn SPDE field evolving over years; month nested within year; unstructured ABS frailty). Among 210.860 summer deaths in the complete environmental sample, extreme heat and heatwaves were associated with higher mortality after multi-pollutant and socioeconomic adjustment (e.g., extreme heat at lag 2: RR $1.105$, 95% CrI $1.086$-$1.125$; heatwave at lag 3: RR $1.142$, 95% CrI $1.116$-$1.167$; posterior Prob $\approx 1$). Ozone concentrations $\geq 100\,μ$g/m$^3$ were positively associated with mortality, and extreme heat$\times$high ozone interactions further elevated risk. Areas with higher income inequality and older population structures also showed elevated mortality. These findings indicate that heat indicators raise summer mortality in Catalonia even after environmental and socioeconomic adjustment, while compound ozone exposure and contextual vulnerability further shape risk. Adaptation strategies should therefore combine heat-health warnings with air quality management and equity-oriented interventions.

翻译：暂无翻译