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Unexpected rise of ozone in urban and rural areas, and sulfur dioxide in rural areas during the coronavirus city lockdown in Hangzhou, China: implications for air quality.
Environ Chem Lett. 2020 Jun 12 [Online ahead of print]EC

Abstract

The outbreak of coronavirus named COVID-19, initially identified in Wuhan, China in December 2019, has spread rapidly at the global scale. Most countries have rapidly stopped almost all activities including industry, services and transportation of goods and people, thus decreasing air pollution in an unprecedented way, and providing a unique opportunity to study air pollutants. While satellite data have provided visual evidence for the global reduction in air pollution such as nitrogen dioxide (NO2) worldwide, precise and quantitative information is missing at the local scale. Here we studied changes in particulate matter (PM2.5, PM10), carbon monoxide (CO), NO2, sulfur dioxide (SO2) and ozone (O3) at 10 urban sites in Hangzhou, a city of 7.03 million inhabitants, and at 1 rural site, before city lockdown, January 1-23, during city lockdown, January 24-February 15, and during resumption, February 16-28, in 2020. Results show that city lockdown induced a sharp decrease in PM2.5, PM10, CO, and NO2 concentrations at both urban and rural sites. The NO2 decrease is explained by reduction in traffic emissions in the urban areas, and by lower regional transport in rural areas during lockdown, as expected. SO2 concentrations decreased from 6.3 to 5.3 μg m-3 in the city, but increased surprisingly from 4.7 to 5.8 μg m-3 at the rural site: this increase is attributed both to higher coal consumption for heating and emissions from traditional fireworks of the Spring Eve and Lantern Festivals during lockdown. Unexpectedly, O3 concentrations increased by 145% from 24.6 to 60.6 μg m-3 in the urban area, and from 42.0 to 62.9 μg m-3 in the rural area during the lockdown. This finding is explained by the weakening of chemical titration of O3 by NO due to reductions of NOx fresh emissions during the non-photochemical reaction period from 20:00 PM to 9:00 AM (local time). During the lockdown, compared to the same period in 2019, the daily average concentrations in the city decreased by 42.7% for PM2.5, 47.9% for PM10, 28.6% for SO2, 22.3% for CO and 58.4% for NO2, which is obviously explained by the absence of city activities. Overall, we observed not only the expected reduction in some atmospheric pollutants (PM, SO2, CO, NO2), but also unexpected increases in SO2 in the rural areas and of ozone (O3) in both urban and rural areas, the latter being paradoxically due to the reduction in nitrogen oxide levels. In other words, the city lockdown has improved air quality by reducing PM2.5, PM10, CO, and NO2, but has also decreased air quality by augmenting O3 and SO2.

Authors+Show Affiliations

Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Education; Research Center for Air Pollution and Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 Zhejiang People's Republic of China.Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Education; Research Center for Air Pollution and Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 Zhejiang People's Republic of China.Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Education; Research Center for Air Pollution and Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 Zhejiang People's Republic of China. Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 USA.Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Education; Research Center for Air Pollution and Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 Zhejiang People's Republic of China.Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Education; Research Center for Air Pollution and Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 Zhejiang People's Republic of China.Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Education; Research Center for Air Pollution and Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 Zhejiang People's Republic of China.Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Education; Research Center for Air Pollution and Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 Zhejiang People's Republic of China.Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Education; Research Center for Air Pollution and Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 Zhejiang People's Republic of China.Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Education; Research Center for Air Pollution and Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 Zhejiang People's Republic of China.Key Laboratory of Environmental Remediation and Ecological Health, Ministry of Education; Research Center for Air Pollution and Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058 Zhejiang People's Republic of China.College of Science and Technology, Hebei Agricultural University, Baoding, 071000 Hebei People's Republic of China.Aix-Marseille Univ, CNRS, Coll France, CNRS, INRA, IRD, CEREGE, Avenue Louis Philibert, 13100 Aix En Provence, France. State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, 710049 Shaanxi People's Republic of China.Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 USA.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

32837481

Citation

Wang, Liqiang, et al. "Unexpected Rise of Ozone in Urban and Rural Areas, and Sulfur Dioxide in Rural Areas During the Coronavirus City Lockdown in Hangzhou, China: Implications for Air Quality." Environmental Chemistry Letters, 2020, pp. 1-11.
Wang L, Li M, Yu S, et al. Unexpected rise of ozone in urban and rural areas, and sulfur dioxide in rural areas during the coronavirus city lockdown in Hangzhou, China: implications for air quality. Environ Chem Lett. 2020.
Wang, L., Li, M., Yu, S., Chen, X., Li, Z., Zhang, Y., Jiang, L., Xia, Y., Li, J., Liu, W., Li, P., Lichtfouse, E., Rosenfeld, D., & Seinfeld, J. H. (2020). Unexpected rise of ozone in urban and rural areas, and sulfur dioxide in rural areas during the coronavirus city lockdown in Hangzhou, China: implications for air quality. Environmental Chemistry Letters, 1-11. https://doi.org/10.1007/s10311-020-01028-3
Wang L, et al. Unexpected Rise of Ozone in Urban and Rural Areas, and Sulfur Dioxide in Rural Areas During the Coronavirus City Lockdown in Hangzhou, China: Implications for Air Quality. Environ Chem Lett. 2020 Jun 12;1-11. PubMed PMID: 32837481.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Unexpected rise of ozone in urban and rural areas, and sulfur dioxide in rural areas during the coronavirus city lockdown in Hangzhou, China: implications for air quality. AU - Wang,Liqiang, AU - Li,Mengying, AU - Yu,Shaocai, AU - Chen,Xue, AU - Li,Zhen, AU - Zhang,Yibo, AU - Jiang,Linhui, AU - Xia,Yan, AU - Li,Jiali, AU - Liu,Weiping, AU - Li,Pengfei, AU - Lichtfouse,Eric, AU - Rosenfeld,Daniel, AU - Seinfeld,John H, Y1 - 2020/06/12/ PY - 2020/05/13/received PY - 2020/06/01/accepted PY - 2020/8/25/entrez PY - 2020/8/25/pubmed PY - 2020/8/25/medline KW - Air quality KW - CO KW - COVID-19 KW - Coronavirus KW - Emission reductions KW - Hangzhou KW - Lockdown KW - NO2 KW - O3 KW - PM10 KW - PM2.5 KW - SO2 SP - 1 EP - 11 JF - Environmental chemistry letters JO - Environ Chem Lett N2 - The outbreak of coronavirus named COVID-19, initially identified in Wuhan, China in December 2019, has spread rapidly at the global scale. Most countries have rapidly stopped almost all activities including industry, services and transportation of goods and people, thus decreasing air pollution in an unprecedented way, and providing a unique opportunity to study air pollutants. While satellite data have provided visual evidence for the global reduction in air pollution such as nitrogen dioxide (NO2) worldwide, precise and quantitative information is missing at the local scale. Here we studied changes in particulate matter (PM2.5, PM10), carbon monoxide (CO), NO2, sulfur dioxide (SO2) and ozone (O3) at 10 urban sites in Hangzhou, a city of 7.03 million inhabitants, and at 1 rural site, before city lockdown, January 1-23, during city lockdown, January 24-February 15, and during resumption, February 16-28, in 2020. Results show that city lockdown induced a sharp decrease in PM2.5, PM10, CO, and NO2 concentrations at both urban and rural sites. The NO2 decrease is explained by reduction in traffic emissions in the urban areas, and by lower regional transport in rural areas during lockdown, as expected. SO2 concentrations decreased from 6.3 to 5.3 μg m-3 in the city, but increased surprisingly from 4.7 to 5.8 μg m-3 at the rural site: this increase is attributed both to higher coal consumption for heating and emissions from traditional fireworks of the Spring Eve and Lantern Festivals during lockdown. Unexpectedly, O3 concentrations increased by 145% from 24.6 to 60.6 μg m-3 in the urban area, and from 42.0 to 62.9 μg m-3 in the rural area during the lockdown. This finding is explained by the weakening of chemical titration of O3 by NO due to reductions of NOx fresh emissions during the non-photochemical reaction period from 20:00 PM to 9:00 AM (local time). During the lockdown, compared to the same period in 2019, the daily average concentrations in the city decreased by 42.7% for PM2.5, 47.9% for PM10, 28.6% for SO2, 22.3% for CO and 58.4% for NO2, which is obviously explained by the absence of city activities. Overall, we observed not only the expected reduction in some atmospheric pollutants (PM, SO2, CO, NO2), but also unexpected increases in SO2 in the rural areas and of ozone (O3) in both urban and rural areas, the latter being paradoxically due to the reduction in nitrogen oxide levels. In other words, the city lockdown has improved air quality by reducing PM2.5, PM10, CO, and NO2, but has also decreased air quality by augmenting O3 and SO2. SN - 1610-3653 UR - https://www.unboundmedicine.com/medline/citation/32837481/Unexpected_rise_of_ozone_in_urban_and_rural_areas_and_sulfur_dioxide_in_rural_areas_during_the_coronavirus_city_lockdown_in_Hangzhou_China:_implications_for_air_quality_ L2 - https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/32837481/ DB - PRIME DP - Unbound Medicine ER -
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