Fig. 3: LISA cluster of the PM2.5 concentrations in 2010, 2013, 2017 and 2021.

The figure shows the local spatial autocorrelation characteristics of PM2.5 concentrations across 285 cities during four time periods: a 2010, b 2013, c 2017, and d 2021.
The figure shows the local spatial autocorrelation characteristics of PM2.5 concentrations across 285 cities during four time periods: a 2010, b 2013, c 2017, and d 2021.