Fig. 4: National population-weighted AQI changes.
From: Improving air quality assessment using physics-inspired deep graph learning

a Monthly trend for total AQI and each air pollutant AQI with the shade of 95% confidence intervals. b, c Total air quality index (AQI) changes in winter between 2015 and 2018 (b), and in summer between 2015 and 2018 (c) in mainland China (mean AQI change by latitude, below in b, c; mean AOI change by longitude on the right in b, c).