Contrasting effects of emission control on air pollution in Central China during the 2019 Military World Games based on satellite and ground observations

Abstract

To ensure a good air quality during the 7th Military World Games (MWG) held in the megacity, Wuhan of central China, an unprecedented substantial emission reduction has been conducted during October 13–27, 2019. Here we present an observational overview on the effects of emission control measures as well as their implications by integrated satellite observations and surface measurements. Compared with air quality before control, there is a remarkable overall decline (~15–30%) in PM10 and SO2 concentration in control period. By contrast, NOx and O3 remain at high levels under persistent stagnant weather conditions since vehicle emission is not restricted. Despite high NOx (~100 μg/m3) in ground measurements, satellite column NO2 exhibits a considerable decline (~30–50%) over Wuhan, indicating that the large reduction of industrial emission from elevated chimneys has limited effects on changes of NOx near surface. The NO3− and NH4+ in PM2.5 reach peak values at the beginning of emergency control period, and then decrease steadily with a rising temperature. Meanwhile, OC and EC in PM2.5 have a continuous accumulation process on the premise of enhanced emission control, which can be caused by vehicle emissions. Generally, the stringent emission reduction focusing on industrial sources obviously mitigates particle pollution in Wuhan. Considering complicated relationship between atmospheric pollutants and their precursors, synchronized emission reduction measures based on their accurate roles are necessary in improving air quality effectively.