Independent associations of air pollution and weather with hospital admissions for circulatory and respiratory diseases in the Lyon metropolitan area, France (2012–2019): a distributed lag nonlinear analysis

The impact of air pollution on respiratory and circulatory diseases is a major public health topic. The present study examines the impact of air pollution and weather on hospital admissions for circulatory and respiratory diseases in adults in the Lyon metropolitan area, France. A quasi-Poisson generalized linear model, along with a distributed lag nonlinear model (DLNM), was used to investigate the nonlinear exposure-response relationships of air pollutants and weather variables on daily adult hospital admissions from 2012 to 2019. Subgroup analyses by age, French deprivation index (FDep), and Charlson comorbidity index (CCI) were performed. Based on cumulative effects over the entire lag range, results showed that for respiratory admissions, CO at the 99th percentile was positively associated with overall admissions, and admissions of patients aged $$\ge $$ 65 years, FDep>1, and CCI $$=\{0,1\}$$ . PM10 >75th percentile was negatively associated with overall admissions and admissions of patients aged $$\ge $$ 65, FDep=1 or >1, and CCI $$=\{0,1\}$$ . Ox below the median was positively associated with admissions in patients aged $$\ge $$ 65, and negatively associated at the 75th percentile. Temperature at the 99th percentile was negatively associated with overall admissions, and admissions in patients categorized as FDep=1 and CCI>1. Rainfall at the 99th percentile was negatively associated with admissions in patients categorized as CCI $$=\{0,1\}$$ . For circulatory admissions, only wind speed above the median was positively associated with overall admissions and admissions of patients categorized as FDep=1. Lag-specific associations revealed heterogeneous temporal patterns across exposures and subgroups.