Surface Ozone in the Yangtze River Delta, China: A Synthesis of Basic Features, Meteorological Driving Factors, and Health Impacts

Ozone (O-3) is of great importance to air quality in the Yangtze River Delta (YRD) region, China. Focusing on surface O-3 in the YRD, its spatiotemporal characteristics, meteorological driving factors, and health impacts are investigated based on surface O-3 observations in this study. We find that from 2015 to 2019, most cities failed to meet the national standards and O-3 pollution mainly occurred in warm seasons (April-September). Surface O-3 in the YRD increased in the recent years, so did tropospheric column O-3. Spatially, surface shows a significant positive autocorrelation over the YRD except for 2019, and high O-3 values mainly gather in the central of the YRD. The first two empirical orthogonal functions (EOFs) of O-3 accounted for 37.4% and 20.0% of the total variance in O-3, respectively, with their spatial patterns characterized by the same phase and west and east contrast, respectively. The EOF1 is related to the change in radiation and the EOF2 is attributed to regional transport by prevailing westerly wind. Downward UV radiation, temperature and u wind are crucial factors. The premature mortality caused by O-3 for respiratory disease in the YRD is estimated to be 5,889 cases per year. Furthermore, we find that premature mortality is more sensitive to O-3 concentration than population, suggesting that controlling peak O-3 concentration can bring great health benefits.