Enhanced secondary haze by emission reduction during COVID-19 lockdown in China

The research, led by Nanjing University and Tsinghua University, investigated China’s emission change due to the sharp drop of anthropogenic activities. Using comprehensive measurements and modeling, the authors show that the haze during the COVID lockdown were driven by enhancements of secondary pollution. These findings indicate that haze mitigation depends upon a coordinated and balanced strategy for controlling multiple pollutants.