Ozone pollution in the North China Plain spreading into the late-winter haze season
Ke Li, Daniel J. Jacob, Hong Liao, Yulu Qiu, Lu Shen, Shixian Zhai, Kelvin H. Bates, Melissa P. Sulprizio, Shaojie Song, Xiao Lu, Qiang Zhang, Bo Zheng, Yuli Zhang, Jinqiang Zhang, Hyun Chul Lee, Su Keun Kuk
Abstract
Significance The North China Plain experiences severe summer ozone pollution, but ozone during winter haze (particulate) pollution events has been very low. Here, we show that the abrupt decrease in nitrogen oxide (NO x ) emissions following the COVID-19 lockdown in January 2020 drove fast ozone production during winter haze events to levels approaching the air quality standard. This fast ozone production was driven by formaldehyde originating from high emissions of volatile organic compounds (VOCs). The COVID-19 experience highlights a general 2013 to 2019 trend of rapidly increasing ozone pollution in winter–spring in China as NO x emissions have decreased. VOC emission controls would mitigate the spreading of ozone pollution into winter–spring with benefits for public health, crop production, and particulate pollution.