Exploring the Holiday Effect on Elevated Traffic-Related Air Pollution with Hyperlocal Measurements in Chengdu, China

Traffic-related air pollutants (TRAPs) pose significant health risks in megacities, yet fixed monitoring sites often fail to capture their complexity. To characterize the TRAP concentrations which fixed sites cannot address, we employed a mobile platform to effectively capture real-time hyperlocal-s...

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Main Authors: Sheng Xiang, Jiaojiao Yu, Yu Ting Yu, Pengbo Zhao, Tie Zheng, Jingsong Yue, Yuanyuan Yang, Haobing Liu
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Atmosphere
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Online Access:https://www.mdpi.com/2073-4433/16/2/171
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author Sheng Xiang
Jiaojiao Yu
Yu Ting Yu
Pengbo Zhao
Tie Zheng
Jingsong Yue
Yuanyuan Yang
Haobing Liu
author_facet Sheng Xiang
Jiaojiao Yu
Yu Ting Yu
Pengbo Zhao
Tie Zheng
Jingsong Yue
Yuanyuan Yang
Haobing Liu
author_sort Sheng Xiang
collection DOAJ
description Traffic-related air pollutants (TRAPs) pose significant health risks in megacities, yet fixed monitoring sites often fail to capture their complexity. To characterize the TRAP concentrations which fixed sites cannot address, we employed a mobile platform to effectively capture real-time hyperlocal-scale TRAP variations in Chengdu, China. A 17-day sampling campaign was conducted covering the National Holiday of China and collected ~1.2 × 10<sup>5</sup> 1 Hz paired data. We measured particle number concentration (PNC), black carbon (BC), and nitrogen oxides (NO<sub>x</sub>) across urban and rural freeway environments to assess the impact of reduced heavy-duty diesel vehicles (HDDVs) during the holiday (i.e., holiday effect). No clear impact of wind direction on TRAP concentrations was found in this study. However, substantial differences (two times) were observed when comparing non-holiday to holiday campaigns. Spearman correlations (0.21–0.56) between TRAPs persistently exceeded Pearson correlations (0.14–0.41), indicating non-linear relationships and suggesting the necessity for data transformations (e.g., logarithms) in TRAP analysis. The comparison of the background subtracted TRAPs concentrations between non-holiday and holidays, revealing approximately a 50% reduction in TRAPs across microenvironments. Among the TRAPs, NO<sub>x</sub> emerged as a reliable indicator of HDDV emissions. The study provides insights into vehicle fleet composition impacts, paving the way for enhanced exposure assessment strategies.
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spelling doaj-art-c689d0ad2a6b480da2cd03d3e9bcf7852025-08-20T02:44:36ZengMDPI AGAtmosphere2073-44332025-02-0116217110.3390/atmos16020171Exploring the Holiday Effect on Elevated Traffic-Related Air Pollution with Hyperlocal Measurements in Chengdu, ChinaSheng Xiang0Jiaojiao Yu1Yu Ting Yu2Pengbo Zhao3Tie Zheng4Jingsong Yue5Yuanyuan Yang6Haobing Liu7State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, ChinaSchool of Customs and Public Administration, Shanghai Customs College, Shanghai 201204, ChinaSchool of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, ChinaCollege of Environmental Science and Engineering, Tongji University, Shanghai 200092, ChinaSchool of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, ChinaShanghai Urban Investment Ring Expressway Construction and Development Co., Ltd., No. 3066, Huaxu Highway, Qingpu District, Shanghai 201804, ChinaShanghai Urban Investment Ring Expressway Construction and Development Co., Ltd., No. 3066, Huaxu Highway, Qingpu District, Shanghai 201804, ChinaThe Key Laboratory of Road and Traffic Engineering, Ministry of Education, Tongji University, 4800 Caoan Road, Shanghai 201804, ChinaTraffic-related air pollutants (TRAPs) pose significant health risks in megacities, yet fixed monitoring sites often fail to capture their complexity. To characterize the TRAP concentrations which fixed sites cannot address, we employed a mobile platform to effectively capture real-time hyperlocal-scale TRAP variations in Chengdu, China. A 17-day sampling campaign was conducted covering the National Holiday of China and collected ~1.2 × 10<sup>5</sup> 1 Hz paired data. We measured particle number concentration (PNC), black carbon (BC), and nitrogen oxides (NO<sub>x</sub>) across urban and rural freeway environments to assess the impact of reduced heavy-duty diesel vehicles (HDDVs) during the holiday (i.e., holiday effect). No clear impact of wind direction on TRAP concentrations was found in this study. However, substantial differences (two times) were observed when comparing non-holiday to holiday campaigns. Spearman correlations (0.21–0.56) between TRAPs persistently exceeded Pearson correlations (0.14–0.41), indicating non-linear relationships and suggesting the necessity for data transformations (e.g., logarithms) in TRAP analysis. The comparison of the background subtracted TRAPs concentrations between non-holiday and holidays, revealing approximately a 50% reduction in TRAPs across microenvironments. Among the TRAPs, NO<sub>x</sub> emerged as a reliable indicator of HDDV emissions. The study provides insights into vehicle fleet composition impacts, paving the way for enhanced exposure assessment strategies.https://www.mdpi.com/2073-4433/16/2/171mobile monitoringparticulate matternitrogen oxidesvehicle emissionsurban environment
spellingShingle Sheng Xiang
Jiaojiao Yu
Yu Ting Yu
Pengbo Zhao
Tie Zheng
Jingsong Yue
Yuanyuan Yang
Haobing Liu
Exploring the Holiday Effect on Elevated Traffic-Related Air Pollution with Hyperlocal Measurements in Chengdu, China
Atmosphere
mobile monitoring
particulate matter
nitrogen oxides
vehicle emissions
urban environment
title Exploring the Holiday Effect on Elevated Traffic-Related Air Pollution with Hyperlocal Measurements in Chengdu, China
title_full Exploring the Holiday Effect on Elevated Traffic-Related Air Pollution with Hyperlocal Measurements in Chengdu, China
title_fullStr Exploring the Holiday Effect on Elevated Traffic-Related Air Pollution with Hyperlocal Measurements in Chengdu, China
title_full_unstemmed Exploring the Holiday Effect on Elevated Traffic-Related Air Pollution with Hyperlocal Measurements in Chengdu, China
title_short Exploring the Holiday Effect on Elevated Traffic-Related Air Pollution with Hyperlocal Measurements in Chengdu, China
title_sort exploring the holiday effect on elevated traffic related air pollution with hyperlocal measurements in chengdu china
topic mobile monitoring
particulate matter
nitrogen oxides
vehicle emissions
urban environment
url https://www.mdpi.com/2073-4433/16/2/171
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