Correlation of air quality with population aging, industrial structure upgrading, and research and development in China based on empirical analysis

China's population has been aging quickly in recent years, putting pressure on the environment. Population aging has also amplified the role of industrial upgrading and research and development (R&D) on environmental quality. Against this backdrop, we investigated the long-run and short-run relationships among population aging, industrial structure upgrading, R&D, and air quality in 30 Chinese provinces from 2006 to 2020. The panel autoregressive distributed lag (ARDL) model was first applied in this study. The results revealed that population aging temporarily harmed air quality but improved it over time. The favorable impact of industrial upgrading on air quality was enhanced by population aging, but the positive impact of R&D investment on air quality was reduced. Furthermore, Dumitrescu and Hurlin (D-H) Granger causality tests were adopted to confirm that population aging had a single-way causal link with air quality, whereas industrial upgrading and R&D had dual-way causal associations with air quality.