Impacts of emissions along the lower Yangtze River on air quality and public health in the Yangtze River delta, China

The area along (and on) the lower Yangtze River is a hotspot in the Yangtze River Delta (YRD) due to intense anthropogenic emissions to both the water and the atmosphere. However, air emissions in the vicinity of the river have received less attention. In this study, the Community Multi-scale Air Quality (CMAQ) model and the Environmental Benefits Mapping and Analysis Program-Community Edition (BenMAP-CE) were applied to quantify the impacts of air emissions in the area within 4 km of the Yangtze River (referred to as the 4 YR area) on the air quality and public health in the YRD in 2017. The 4 YR area had air pollutant emission intensities 1.6–9.6 times higher than the domain-wide averages, and contributed ∼7.5% of the annual PM2.5 concentration across the YRD. Moreover, the emissions led to widespread enhancement of the daily maximum 8-h average (MDA8) O3 concentration in the downwind areas in summer, with an average contribution of 1.5%, while titration of O3 occurred in other seasons. As a result, the emissions increased population-weighted concentration (PWC) of PM2.5 by up to 11.5 μg m−3 near the river, leading to premature mortality of ∼17,000 in the YRD. Additionally, the mortality in terms of O3 exposure was less substantial, due to the lower PWC of O3 at distances of less than 40 km from the river. The emissions were responsible for mortality of ∼6000 due to higher exposure to NO2. The results suggest that it is beneficial to public health to reduce emissions in the 4 YR area.