Urban indoor airborne antibiotic resistance genes: Role of antibiotic use and outdoor air pollution

= 0.18, P = 0.03), but no consistent temporal shift over the 10-year period. Macrolide, tetracycline, and aminoglycoside resistance genes were among the most abundant and persistent classes. A previously undetected macrolide resistance sequence was identified across all cities in 2022. Although national antibiotic consumption declined, cross-sectional correlations between national antibiotic consumption and ARG abundance strengthened from 2012 (Spearman's ρ = 0.25) to 2022 (ρ = 0.37), suggesting sustained ARG presence despite reduced antibiotic consumption. Several ARG classes showed associations with outdoor particulate matter, and these relationships were influenced by local meteorological conditions. For example, higher absolute humidity was associated with a weaker relationship between PM and polymyxin resistance genes, whereas stronger wind speeds were associated with stronger relationships between PM and Sulfonamide resistance genes. These findings highlight the complex environmental interplay between antibiotic consumption, air pollution, meteorological factors, and ARG dynamics in indoor air, emphasizing the need for integrated environmental and AMR surveillance, especially in the context of climate change.