Influence of transboundary air pollution and meteorology on air quality in three major cities of Anhui Province, China

Abstract The variations of criteria air pollutants (CAPs), the influence of transboundary air pollution, and the meteorological effects on air quality in Hefei, Fuyang, and Suzhou were investigated during 2015–2019. In Hefei, continuous decreases in the concentrations of PM2.5 (5.5 μg/m3 yr−1) and PM10 (6.7 μg/m3 yr−1) were observed over time. PM2.5 and PM10 concentrations also exhibited substantial downward trends in Fuyang (PM2.5: 9.4 μg/m3 yr−1; PM10: 13.5 μg/m3 yr−1) and Suzhou (PM2.5: 10.9 μg/m3 yr−1; PM10: 9.1 μg/m3 yr−1) during 2017–2019. However, they increased during 2015–2017. NO2 decreased in Suzhou (9.3 μg/m3 yr−1) and Hefei (5.2 μg/m3 yr−1) during 2017–2019, and in Fuyang (5.2 μg/m3 yr−1) over 2016–2018. Alternatively, O3 increased by 8.3, 8.2, and 5.2 μg/m3 yr−1 in Fuyang, Suzhou, and Hefei, respectively. Despite the reductions, PM2.5 and PM10 still substantially exceeded the annual Grade I and Grade II CAAQS. The relationships between the pollutants and meteorological variables were relatively similar with the correlations varying by season. High primary pollutants concentrations were attributed to poorer dispersion, while elevated temperatures and greater solar radiation were related to higher O3 concentrations. The results of 120-h backward trajectories showed that the study areas were dominantly influenced by the northwesterly and northerly winds. Thus, elevated concentrations of most air pollutants observed in the study areas were associated with transboundary regional transport of air pollution from neighboring cities and provinces. This study shows that effective emissions control strategies that would simultaneously reduce PM2.5 and O3 across the cities in Anhui Province and the surrounding provinces are urgently needed.