“…The Chinese New Year (CNY) holiday has been widely used as a naturally controlled experiment to investigate the response of gaseous and particulate matter (PM) species to the changes in anthropogenic emissions ( Jiang et al, 2015 ; Wang et al, 2017 ; Wang et al, 2021 ), and also the period of coronavirus disease (COVID-19) outbreak when the cities implemented lockdown measures ( Dai et al, 2021 ; Javed et al, 2021 ; Sun et al, 2020 ). Previous studies have found ubiquitous reductions in aerosol and gaseous species from primary emissions during the CNY while secondary aerosol species showed less reductions and even increases due to enhanced secondary production.…”