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Markedly Enhanced Levels of Peroxyacetyl Nitrate (PAN) During COVID‐19 in Beijing
Author(s) -
Qiu Yulu,
Ma Zhiqiang,
Li Ke,
Lin Weili,
Tang Yingxiao,
Dong Fan,
Liao Hong
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl089623
Subject(s) - peroxyacetyl nitrate , beijing , ozone , context (archaeology) , environmental science , pollutant , environmental chemistry , atmospheric sciences , photochemistry , meteorology , chemistry , china , geography , physics , nox , organic chemistry , archaeology , combustion
High levels of secondary air pollutants during COVID‐19 in China have aroused great concern. In Beijing, measured daily mean peroxyacetyl nitrate (PAN) concentrations reached 4 ppb over the lockdown period (24 January to 15 February), whose averages were 2–3 times that before lockdown (1–23 January). The lockdown PAN levels also reached a high historical record based on our long‐term measurements (2016–2019). Unlike ozone and PM 2.5 , PAN formation depends on less complex photochemistry between NO x and volatile organic compounds (VOCs), providing a novel approach to investigate the wintertime photochemistry during COVID‐19. The GEOS‐Chem simulations suggest a markedly enhanced photochemistry by a factor of 2 during the lockdown. Change of meteorology featuring with anomalous wind convergence under higher temperatures is the main reason for enhanced photochemical formation of PAN, while chemically nonlinear feedbacks also play a role. Our results suggest implementing targeted VOC emission controls in the context of increasing photochemical pollution over this complex polluted region.