ABSTRACT
Shanghai, one of China's most important economic centres, imposed a citywide lockdown in April and May 2022 to contain a resurgence in cases of the coronavirus disease in 2019. Compared with the 2020 lockdown, the 2022 lockdown occurred in a warm season and lasted much longer, thereby serving as a relevant real-world test of the response of ambient ozone (O3) concentrations to emission reductions in a high-O3 season. In this study, we analysed surface observations of O3 and nitrogen dioxide (NO2) concentrations and satellite-retrieved tropospheric NO2 and formaldehyde (HCHO) column concentrations in the first 5 months of 2022 with comparisons to the year 2021. During the 2-month 2022 lockdown, the maximum daily 8 h average (MDA8) O3 concentrations at 1 or more of the city's 19 sites exceeded China's air quality standard of 160 µgm-3 21 times, with the highest value being 200 µgm-3. The city-average MDA8 O3 concentration increased by 13 % in April–May 2022 year-on-year, despite sharp declines in NO2 surface and column concentrations (both by 49 %) and a 19 % decrease in the HCHO column concentration. These results show that the reductions in O3 precursors and other pollutants during the 2022 lockdown did not prevent ground-level O3 pollution. An analysis of meteorological data indicates that there were only small changes in the meteorological conditions, and there was little transport of O3 from the high-O3 inland regions during the 2022 lockdown, neither of which can account for the increased and high concentrations of O3 that were observed during this period. The mean HCHO/NO2 ratio in April–May increased from 1.11 in 2021 to 1.68 in 2022, and the correlation between surface O3 and NO2 concentrations changed from negative in 2021 to positive in 2022. These results indicate that the high O3 concentrations in 2022 were mainly due to large reductions in the emissions of NOx and that the decrease in the concentrations of volatile organic compounds (VOCs) could not overcome the NO titration effect. During the 2022 lockdown, Shanghai's urban centre remained VOC-sensitive despite drastic reductions in road transportation (73 %–85 %) and industrial activities (∼60 %), whereas its semi-rural areas transitioned from VOC-limited to VOC–NOx-co-limited regimes. Our findings suggest that future emission reductions similar to those that occurred during the lockdown, such as those that will result from electrifying transportation, will not be sufficient to eliminate O3 pollution in urban areas of Shanghai and possibly other VOC-limited metropoles without the imposition of additional VOC controls or more substantial decreases in NOx emissions.
ABSTRACT
Atmospheric particulate matter (PM10) is one of the most important pollutants for human health, and road transport could be a major anthropogenic source of it. Several research studies have shown the impact of roads on the air quality in urban areas, but the relationship between road and rail networks and ambient PM10 concentrations has not been well studied, especially in suburban and rural landscapes. In this study, we examined the link between the spatial characteristics of each road type (motorway, primary road, secondary road, and railway) and the annual average PM10 concentration. We used the European 2931 air quality (AQ) station dataset, which is classified into urban, suburban, and rural landscapes. Our results show that in urban and rural landscapes, the spatial characteristics (the density of the road network and its distance from the AQ monitoring points) have a significant statistical relationship with PM10 concentrations. According to our findings from AQ monitoring sites within the urban landscape, there is a significant negative relationship between the annual average PM10 concentration and the density of the railway network. This result can be explained by the driving wind generated by railway trains (mainly electric trains). Among the road network types, all road types in the urban landscape, only motorways in the suburban landscape, and only residential roads in the rural landscape have a significant positive statistical relationship with the PM10 values at the AQ monitoring points. Our results show that in the suburban zones, which represent the rural–urban fringe, motorways have a strong influence on PM-related air pollution. In the suburban areas, the speed of vehicles changes frequently near motorways and intersections, so higher traffic-related PM10 emission levels can be expected in these areas. The findings of this study can be used to decrease transportation-related environmental conflicts related to the air quality in urban, urban–rural fringe, and rural (agricultural) landscapes.
ABSTRACT
Complete Streets Council Consultants Council Connected and Automated Vehicles Standing Committee Education Council Mobility as a Service (MaaS) / Mobility on Demand (MOD) Steering Committee Parking Standing Committee Pedestrian and Bicycle Standing Committee Smart Communities Standing Committee Sustainability Standing Committee Urban Goods Movement Standing Committee Traffic Engineering Council Transit Standing Committee Transportation Planning Council Vision Zero Standing Committee The Developing Trends Report aims to give insight into the transportation complexities that can guide the profession's discussions on implementing new solutions and re-evaluating traditional approaches. Safety * Enhancing Safety on Rural Roads through Signing and Pavement Markings * Passive Pedestrian Detection at Signalized Intersections * Safety: A Pillar in Assessing Site Generated Impacts in Transportation Impact Studies * Making the Invisible Visible - Conflict Data Analytics for Vision Zero COVID-19 Responses * Transit Ridership Impacts and Agency Response to COVID-19 * Short- and Long-Term Impacts of COVID-19 on Transportation Education * Post COVID-19 Trends in Active Transportation * Impacts of the COVID-19 Pandemic on Parking Demand Technology * Unmanned Aircraft Systems: Bringing the Third Dimension into Surface Transportation * Connected and Automated Vehicle (CAV) Deployment Lessons Learned * Cybersecurity for Surface Transportation Mobility * Netflix of Transport: The Mainstreaming of Mobility-as-a-Service * 15-Minute City: Prioritizing Access over Mobility Design * Curbside Management and the Repurposing of On-Street Parking * Curbside Management Regulations and Technologies are Increasing Person Access and Throughput Planning * EVs, Electrification, and Emission Reduction Planning * Scenario Planning: Forecasting for an Uncertain Future The Developing Trends Report is designed to inspire creativity and motivate agents of change within ITE and across the full spectrum of the transportation industry. If reading this document inspires you, please reach out to one of our Council and Committee Chairs by visiting our website at www.ite.org/technical-resources/councils. itej Acknowledgments ITE would like to thank all the individuals who contributed to the content of this report and its production.