Articles | Volume 25, issue 20
https://doi.org/10.5194/acp-25-13585-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-25-13585-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
23 Oct 2025
Research article |
| 23 Oct 2025
| 23 Oct 2025
Rethinking machine learning weather normalisation: a refined strategy for short-term air pollution policies
Yuqing Dai
School of Geography, Earth and Environmental Science, University of Birmingham, Birmingham, B15 2TT, UK
Bowen Liu
Department of Management, Business School, University of Birmingham, Birmingham, B15 2TT, UK
Chengxu Tong
School of Geography, Earth and Environmental Science, University of Birmingham, Birmingham, B15 2TT, UK
David C. Carslaw
Wolfson Atmospheric Chemistry Laboratories, University of York, York, YO10 5DD, UK
A. Robert MacKenzie
CORRESPONDING AUTHOR
School of Geography, Earth and Environmental Science, University of Birmingham, Birmingham, B15 2TT, UK
School of Geography, Earth and Environmental Science, University of Birmingham, Birmingham, B15 2TT, UK
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Guohua Zhang, Xiaodong Hu, Wei Sun, Yuxiang Yang, Ziyong Guo, Yuzhen Fu, Haichao Wang, Shengzhen Zhou, Lei Li, Mingjin Tang, Zongbo Shi, Duohong Chen, Xinhui Bi, and Xinming Wang
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Shipra Jain, Ruth M. Doherty, David Sexton, Steven Turnock, Chaofan Li, Zixuan Jia, Zongbo Shi, and Lin Pei
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Aileen B. Baird, Edward J. Bannister, A. Robert MacKenzie, and Francis D. Pope
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Clarissa Baldo, Akinori Ito, Michael D. Krom, Weijun Li, Tim Jones, Nick Drake, Konstantin Ignatyev, Nicholas Davidson, and Zongbo Shi
Atmos. Chem. Phys., 22, 6045–6066, https://doi.org/10.5194/acp-22-6045-2022, https://doi.org/10.5194/acp-22-6045-2022, 2022
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Ülkü Alver Şahin, Roy M. Harrison, Mohammed S. Alam, David C. S. Beddows, Dimitrios Bousiotis, Zongbo Shi, Leigh R. Crilley, William Bloss, James Brean, Isha Khanna, and Rulan Verma
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Yanhong Zhu, Weijun Li, Yue Wang, Jian Zhang, Lei Liu, Liang Xu, Jingsha Xu, Jinhui Shi, Longyi Shao, Pingqing Fu, Daizhou Zhang, and Zongbo Shi
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Yingze Tian, Xiaoning Wang, Peng Zhao, Zongbo Shi, and Roy M. Harrison
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2021-1007, https://doi.org/10.5194/acp-2021-1007, 2022
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Deepchandra Srivastava, Jingsha Xu, Tuan V. Vu, Di Liu, Linjie Li, Pingqing Fu, Siqi Hou, Natalia Moreno Palmerola, Zongbo Shi, and Roy M. Harrison
Atmos. Chem. Phys., 21, 14703–14724, https://doi.org/10.5194/acp-21-14703-2021, https://doi.org/10.5194/acp-21-14703-2021, 2021
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This study presents the source apportionment of PM2.5 performed by positive matrix factorization (PMF) at urban and rural sites in Beijing. These factors are interpreted as traffic emissions, biomass burning, road and soil dust, coal and oil combustion, and secondary inorganics. PMF failed to resolve some sources identified by CMB and AMS and appears to overestimate the dust sources. Comparison with earlier PMF studies from the Beijing area highlights inconsistent findings using this method.
Rebecca L. Wagner, Naomi J. Farren, Jack Davison, Stuart Young, James R. Hopkins, Alastair C. Lewis, David C. Carslaw, and Marvin D. Shaw
Atmos. Meas. Tech., 14, 6083–6100, https://doi.org/10.5194/amt-14-6083-2021, https://doi.org/10.5194/amt-14-6083-2021, 2021
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We describe the use of a selected-ion flow-tube mass spectrometer (SIFT-MS) in a mobile laboratory to provide on-road, high spatial and temporal measurements of CO2, CH4, multiple volatile organic compounds (VOCs) and other trace gases. Results are presented that highlight the potential of this platform for developing characterisation methods of different emissions sources in complex urban areas.
Gongda Lu, Eloise A. Marais, Tuan V. Vu, Jingsha Xu, Zongbo Shi, James D. Lee, Qiang Zhang, Lu Shen, Gan Luo, and Fangqun Yu
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2021-428, https://doi.org/10.5194/acp-2021-428, 2021
Revised manuscript not accepted
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Emission controls were imposed in Beijing-Tianjin-Hebei in northern China in autumn-winter 2017. We find that regional PM2.5 targets (15 % decrease relative to previous year) were exceeded. Our analysis shows that decline in precursor emissions only leads to less than half (43 %) the improved air quality. Most of the change (57 %) is due to interannual variability in meteorology. Stricter emission controls may be necessary in years with unfavourable meteorology.
Congbo Song, Manuel Dall'Osto, Angelo Lupi, Mauro Mazzola, Rita Traversi, Silvia Becagli, Stefania Gilardoni, Stergios Vratolis, Karl Espen Yttri, David C. S. Beddows, Julia Schmale, James Brean, Agung Ghani Kramawijaya, Roy M. Harrison, and Zongbo Shi
Atmos. Chem. Phys., 21, 11317–11335, https://doi.org/10.5194/acp-21-11317-2021, https://doi.org/10.5194/acp-21-11317-2021, 2021
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We present a cluster analysis of relatively long-term (2015–2019) aerosol aerodynamic volume size distributions up to 20 μm in the Arctic for the first time. The study found that anthropogenic and natural aerosols comprised 27 % and 73 % of the occurrence of the coarse-mode aerosols, respectively. Our study shows that about two-thirds of the coarse-mode aerosols are related to two sea-spray-related aerosol clusters, indicating that sea spray aerosol may more complex in the Arctic environment.
Siqi Hou, Di Liu, Jingsha Xu, Tuan V. Vu, Xuefang Wu, Deepchandra Srivastava, Pingqing Fu, Linjie Li, Yele Sun, Athanasia Vlachou, Vaios Moschos, Gary Salazar, Sönke Szidat, André S. H. Prévôt, Roy M. Harrison, and Zongbo Shi
Atmos. Chem. Phys., 21, 8273–8292, https://doi.org/10.5194/acp-21-8273-2021, https://doi.org/10.5194/acp-21-8273-2021, 2021
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This study provides a newly developed method which combines radiocarbon (14C) with organic tracers to enable source apportionment of primary and secondary fossil vs. non-fossil sources of carbonaceous aerosols at an urban and a rural site of Beijing. The source apportionment results were compared with those by chemical mass balance and AMS/ACSM-PMF methods. Correlations of WINSOC and WSOC with different sources of OC were also performed to elucidate the formation mechanisms of SOC.
Jingsha Xu, Di Liu, Xuefang Wu, Tuan V. Vu, Yanli Zhang, Pingqing Fu, Yele Sun, Weiqi Xu, Bo Zheng, Roy M. Harrison, and Zongbo Shi
Atmos. Chem. Phys., 21, 7321–7341, https://doi.org/10.5194/acp-21-7321-2021, https://doi.org/10.5194/acp-21-7321-2021, 2021
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Source apportionment of fine aerosols in an urban site of Beijing used a chemical mass balance (CMB) model. Seven primary sources (industrial/residential coal burning, biomass burning, gasoline/diesel vehicles, cooking and vegetative detritus) explained an average of 75.7 % and 56.1 % of fine OC in winter and summer, respectively. CMB was found to resolve more primary OA sources than AMS-PMF, but the latter apportioned more secondary OA sources.
Steven J. Campbell, Kate Wolfer, Battist Utinger, Joe Westwood, Zhi-Hui Zhang, Nicolas Bukowiecki, Sarah S. Steimer, Tuan V. Vu, Jingsha Xu, Nicholas Straw, Steven Thomson, Atallah Elzein, Yele Sun, Di Liu, Linjie Li, Pingqing Fu, Alastair C. Lewis, Roy M. Harrison, William J. Bloss, Miranda Loh, Mark R. Miller, Zongbo Shi, and Markus Kalberer
Atmos. Chem. Phys., 21, 5549–5573, https://doi.org/10.5194/acp-21-5549-2021, https://doi.org/10.5194/acp-21-5549-2021, 2021
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In this study, we quantify PM2.5 oxidative potential (OP), a metric widely suggested as a potential measure of particle toxicity, in Beijing in summer and winter using four acellular assays. We correlate PM2.5 OP with a comprehensive range of atmospheric and particle composition measurements, demonstrating inter-assay differences and seasonal variation of PM2.5 OP. Using multivariate statistical analysis, we highlight specific particle chemical components and sources that influence OP.
Wenhua Wang, Longyi Shao, Claudio Mazzoleni, Yaowei Li, Simone Kotthaus, Sue Grimmond, Janarjan Bhandari, Jiaoping Xing, Xiaolei Feng, Mengyuan Zhang, and Zongbo Shi
Atmos. Chem. Phys., 21, 5301–5314, https://doi.org/10.5194/acp-21-5301-2021, https://doi.org/10.5194/acp-21-5301-2021, 2021
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We compared the characteristics of individual particles at ground level and above the mixed-layer height. We found that the particles above the mixed-layer height during haze periods are more aged compared to ground level. More coal-combustion-related primary organic particles were found above the mixed-layer height. We suggest that the particles above the mixed-layer height are affected by the surrounding areas, and once mixed down to the ground, they might contribute to ground air pollution.
Stuart K. Grange, James D. Lee, Will S. Drysdale, Alastair C. Lewis, Christoph Hueglin, Lukas Emmenegger, and David C. Carslaw
Atmos. Chem. Phys., 21, 4169–4185, https://doi.org/10.5194/acp-21-4169-2021, https://doi.org/10.5194/acp-21-4169-2021, 2021
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The changes in mobility across Europe due to the COVID-19 lockdowns had consequences for air quality. We compare what was experienced to estimates of "what would have been" without the lockdowns. Nitrogen dioxide (NO2), an important vehicle-sourced pollutant, decreased by a third. However, ozone (O3) increased in response to lower NO2. Because NO2 is decreasing over time, increases in O3 can be expected in European urban areas and will require management to avoid future negative outcomes.
Lei Liu, Jian Zhang, Yinxiao Zhang, Yuanyuan Wang, Liang Xu, Qi Yuan, Dantong Liu, Yele Sun, Pingqing Fu, Zongbo Shi, and Weijun Li
Atmos. Chem. Phys., 21, 2251–2265, https://doi.org/10.5194/acp-21-2251-2021, https://doi.org/10.5194/acp-21-2251-2021, 2021
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We found that large numbers of light-absorbing primary organic particles with high viscosity, especially tarballs, from domestic coal and biomass burning occurred in rural and even urban hazes in the winter of North China. For the first time, we characterized the atmospheric aging process of these burning-related primary organic particles by microscopic analysis and further evaluated their light absorption enhancement resulting from the “lensing effect” of secondary inorganic coatings.
Jingsha Xu, Shaojie Song, Roy M. Harrison, Congbo Song, Lianfang Wei, Qiang Zhang, Yele Sun, Lu Lei, Chao Zhang, Xiaohong Yao, Dihui Chen, Weijun Li, Miaomiao Wu, Hezhong Tian, Lining Luo, Shengrui Tong, Weiran Li, Junling Wang, Guoliang Shi, Yanqi Huangfu, Yingze Tian, Baozhu Ge, Shaoli Su, Chao Peng, Yang Chen, Fumo Yang, Aleksandra Mihajlidi-Zelić, Dragana Đorđević, Stefan J. Swift, Imogen Andrews, Jacqueline F. Hamilton, Ye Sun, Agung Kramawijaya, Jinxiu Han, Supattarachai Saksakulkrai, Clarissa Baldo, Siqi Hou, Feixue Zheng, Kaspar R. Daellenbach, Chao Yan, Yongchun Liu, Markku Kulmala, Pingqing Fu, and Zongbo Shi
Atmos. Meas. Tech., 13, 6325–6341, https://doi.org/10.5194/amt-13-6325-2020, https://doi.org/10.5194/amt-13-6325-2020, 2020
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An interlaboratory comparison was conducted for the first time to examine differences in water-soluble inorganic ions (WSIIs) measured by 10 labs using ion chromatography (IC) and by two online aerosol chemical speciation monitor (ACSM) methods. Major ions including SO42−, NO3− and NH4+ agreed well in 10 IC labs and correlated well with ACSM data. WSII interlab variability strongly affected aerosol acidity results based on ion balance, but aerosol pH computed by ISORROPIA II was very similar.
Liang Xu, Satoshi Fukushima, Sophie Sobanska, Kotaro Murata, Ayumi Naganuma, Lei Liu, Yuanyuan Wang, Hongya Niu, Zongbo Shi, Tomoko Kojima, Daizhou Zhang, and Weijun Li
Atmos. Chem. Phys., 20, 14321–14332, https://doi.org/10.5194/acp-20-14321-2020, https://doi.org/10.5194/acp-20-14321-2020, 2020
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We quantified the mixing structures of soot particles and found that the dominant mixing structure changed from fresh to partially embedded to fully embedded along the pathway of an Asian dust storm from eastern China to Japan. Soot particles became more compact following transport. Our findings not only provide direct evidence for soot aging during regional transport but also help us understand how their morphology changes in different air environments.
Clarissa Baldo, Paola Formenti, Sophie Nowak, Servanne Chevaillier, Mathieu Cazaunau, Edouard Pangui, Claudia Di Biagio, Jean-Francois Doussin, Konstantin Ignatyev, Pavla Dagsson-Waldhauserova, Olafur Arnalds, A. Robert MacKenzie, and Zongbo Shi
Atmos. Chem. Phys., 20, 13521–13539, https://doi.org/10.5194/acp-20-13521-2020, https://doi.org/10.5194/acp-20-13521-2020, 2020
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We showed that Icelandic dust has a fundamentally different chemical and mineralogical composition from low-latitude dust. In particular, magnetite is as high as 1 %–2 % of the total dust mass. Our results suggest that Icelandic dust may have an important impact on the radiation balance in the subpolar and polar regions.
Sarah S. Steimer, Daniel J. Patton, Tuan V. Vu, Marios Panagi, Paul S. Monks, Roy M. Harrison, Zoë L. Fleming, Zongbo Shi, and Markus Kalberer
Atmos. Chem. Phys., 20, 13303–13318, https://doi.org/10.5194/acp-20-13303-2020, https://doi.org/10.5194/acp-20-13303-2020, 2020
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Air pollution is of growing concern due to its negative effect on public health, especially in low- and middle-income countries. This study investigates how the chemical composition of particles in Beijing changes under different measurement conditions (pollution levels, season) to get a better understanding of the sources of this form of air pollution.
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Short summary
Air pollution causes millions of deaths annually, driving policies to improve air quality. However, assessing these policies is challenging because weather changes can hide their true impact. We created a logical evaluation framework and found that a widely applied machine learning approach that adjusts for weather effects could underestimate the effectiveness of short-term policies, like emergency traffic controls. We proposed a refined approach that could largely reduce such underestimation.
Air pollution causes millions of deaths annually, driving policies to improve air quality....
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