TY - JOUR
T1 - Opposite impact of emission reduction during the COVID-19 lockdown period on the surface concentrations of PM2.5 and O3 in Wuhan, China
AU - Yin, Hao
AU - Liu, Cheng
AU - Hu, Qihou
AU - Liu, Ting
AU - Wang, Shuntian
AU - Gao, Meng
AU - Xu, Shiqi
AU - Zhang, Chengxin
AU - Su, Wenjing
N1 - Funding Information:
This work was supported by the National Key Research and Development Program of China (No. 2017YFC0210002 , No. 2018YFC0213104 , No. 2016YFC0203302 , No. 2017YFC0212800 and No. 2019YFC0214802 ), the Chinese Academy of Engineering Grant ( 2020-ZD-15 ), the National Natural Science Foundation of China (No. 41722501 , No. 51778596 , No. 41977184 and No. 41941011 ), Anhui Science and Technology Major Project (No. 18030801111 ), the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA23020301 ), the National Key Project for Causes and Control of Heavy Air Pollution (No. DQGG0102 and No. DQGG0205 ), the Major Projects of High Resolution Earth Observation Systems of National Science and Technology ( 05- Y30B01-9001-19/20-3 ).
Publisher Copyright:
© 2021
PY - 2021/11/15
Y1 - 2021/11/15
N2 - To prevent the spread of the COVID-19 epidemic, the Chinese megacity Wuhan has taken emergent lockdown measures starting on January 23, 2020. This provided a natural experiment to investigate the response of air quality to such emission reductions. Here, we decoupled the influence of meteorological and non-meteorological factors on main air pollutants using generalized additive models (GAMs), driven by data from the China National Environmental Monitoring Center (CNEMC) network. During the lockdown period (Jan. 23 – Apr. 8, 2020), PM2.5, PM10, NO2, SO2, and CO concentrations decreased significantly by 45 %, 49 %, 56 %, 39 %, and 18 % compared with the corresponding period in 2015–2019, with contributions by S(meteos) of 15 %, 17 %, 13 %, 10 %, and 6 %. This indicates an emission reduction of NOx at least 43 %. However, O3 increased by 43 % with a contribution by S(meteos) of 6 %. In spite of the reduced volatile organic compound (VOC) emissions by 30 % during the strict lockdown period (Jan. 23 – Feb. 14, 2020), which likely reduced the production of O3, O3 concentrations increased due to a weakening of the titration effect of NO. Our results suggest that conventional emission reduction (NOx reduction only) measures may not be sufficient to reduce (or even lead to an increase of) surface O3 concentrations, even if reaching the limit, and VOC-specific measures should also be taken.
AB - To prevent the spread of the COVID-19 epidemic, the Chinese megacity Wuhan has taken emergent lockdown measures starting on January 23, 2020. This provided a natural experiment to investigate the response of air quality to such emission reductions. Here, we decoupled the influence of meteorological and non-meteorological factors on main air pollutants using generalized additive models (GAMs), driven by data from the China National Environmental Monitoring Center (CNEMC) network. During the lockdown period (Jan. 23 – Apr. 8, 2020), PM2.5, PM10, NO2, SO2, and CO concentrations decreased significantly by 45 %, 49 %, 56 %, 39 %, and 18 % compared with the corresponding period in 2015–2019, with contributions by S(meteos) of 15 %, 17 %, 13 %, 10 %, and 6 %. This indicates an emission reduction of NOx at least 43 %. However, O3 increased by 43 % with a contribution by S(meteos) of 6 %. In spite of the reduced volatile organic compound (VOC) emissions by 30 % during the strict lockdown period (Jan. 23 – Feb. 14, 2020), which likely reduced the production of O3, O3 concentrations increased due to a weakening of the titration effect of NO. Our results suggest that conventional emission reduction (NOx reduction only) measures may not be sufficient to reduce (or even lead to an increase of) surface O3 concentrations, even if reaching the limit, and VOC-specific measures should also be taken.
KW - Atmospheric pollution
KW - Generalized additive models
KW - Meteorological factors influence
KW - Titration effect
KW - VOC reduction
UR - http://www.scopus.com/inward/record.url?scp=85111707430&partnerID=8YFLogxK
U2 - 10.1016/j.envpol.2021.117899
DO - 10.1016/j.envpol.2021.117899
M3 - Journal article
C2 - 34358865
AN - SCOPUS:85111707430
SN - 0269-7491
VL - 289
JO - Environmental Pollution
JF - Environmental Pollution
M1 - 117899
ER -