Impacts of drought on respiratory mortality in the upper midwest United States: a population subgroup assessment

Abstract Drought is a complex climate phenomenon that varies regionally and temporally across the globe. Its frequency and intensity are expected to increase due to climate change, posing significant threats to human health. Despite these risks, there remains a notable gap in research on the health impacts of drought, particularly at the regional level within the United States. This study aims at assessing the risk of severe drought exposure to respiratory mortality in the Upper Midwest of the United States among the general population and at-risk subgroups from 2000 to 2018. Respiratory mortality was obtained for each county and month during study period based on the 10th International Classification of Disease codes. We used the Evaporative Demand Drought Index categorized into three levels and analyzed it at two timescales: 6 months and 12 months. A Bayesian two-stage time-series modeling approach was applied to estimate the county-level and overall risk along with the 95% Credible Intervals (Cr). Stratification analyses were conducted by age group, gender, race, urbanicity, and state within the region. Statistically significant associations were identified between respiratory mortality and the severe droughts. The estimated risks were 1.151 (95% Cr: 1.126–1.178) and 1.092 (95% Cr: 1.063–1.120) for the 6 and 12 month severe droughts. Our study suggests that the risks differs by subgroups: elevated risks in elderly (higher 14.4% and 9.8% for 6 and 12 month), White (15.1% and 9.0% higher for 6 and 12 month), males (12.7% and 5.1% higher for 6 and 12 month), females (15.8% and 11.1% higher for 6 and 12 month), urban 15.8% and 8.8% higher for 6 and 12 month), and rural (13.6% and 9.9% higher for 6 and 12 month) communities. Iowa showed the greatest increase (23.1%) in the 6 month severe drought, while Minnesota had the highest 20.3% in the 12 month severe drought. Our findings suggested that the elderly, both males and females, both rural and urban areas were the most affected subgroups. These findings demonstrate the need for policymakers and communities to adopt more effective drought mitigation strategies in this region.