Widowhood disparities in nonaccidental mortality attributable to heat waves and ozone.

Emerging evidence suggests that heat waves and ozone (O) contribute to increased mortality risks. Since widowhood is a common event that can increase individuals' susceptibility to the environment, it is of great importance and interest to elucidate the widowhood disparity in mortality attributable to heat waves and O. We therefore conducted a case-crossover study of 1,214,763 nonaccidental deaths in Jiangsu Province, China, during 2015-2021 to investigate the independent and interactive associations of exposure to heat waves and O with mortality by widowhood status. Grid-level heat waves were defined by multiple combinations of apparent temperature thresholds and durations. Residential heat waves and O exposures were assessed using validated grid datasets. Conditional logistic regression models were applied for exposure-response analyses and evaluations of additive interactions. Exposure to heat waves and O was significantly associated with increased odds of mortality in both widowed (odds ratio for heat waves, 1.25; O, 1.06 per interquartile range increase) and married subjects (1.08; 1.03), and these associations were higher in widowed subjects. A significant synergistic interaction was observed between heat waves and O, which was stronger in widowed subjects (relative excess odds due to interaction, 0.14 vs. 0.03). Up to 6.43% and 3.56% of deaths were attributable to heat waves, O pollution, and their compound events in widowed and married subjects, respectively. Our findings suggest that widowed individuals are more susceptible to heat waves and O and highlight the need to consider differences associated with widowhood disparities in preventing premature deaths due to heat waves and O exposures.