Emergency responses to the COVID-19 pandemic led to major changes in travel behaviours and economic activities in 2020. Machine learning provides a reliable approach for assessing the contribution of these changes to air quality. This study investigates impacts of health protection measures upon air pollution and traffic emissions and estimates health and economic impacts arising from these changes during two national 'lockdown' periods in Oxford, UK. Air quality improvements were most marked during the first lockdown with reductions in observed NO2 concentrations of 38% (SD ± 24.0%) at roadside and 17% (SD ± 5.4%) at urban background locations. Observed changes in PM2.5, PM10 and O3 concentrations were not significant during first or second lockdown. Deweathering and detrending analyses revealed a 22% (SD ± 4.4%) reduction in roadside NO2 and 2% (SD ± 7.1%) at urban background with no significant changes in the second lockdown. Deweathered-detrended PM2.5 and O3 concentration changes were not significant, but PM10 increased in the second lockdown only. City centre traffic volume reduced by 69% and 38% in the first and second lockdown periods. Buses and passenger cars were the major contributors to NO2 emissions, with relative reductions of 56% and 77% respectively during the first lockdown, and less pronounced changes in the second lockdown. While car and bus NO2 emissions decreased during both lockdown periods, the overall contribution from buses increased relative to cars in the second lockdown. Sustained NO2 emissions reduction consistent with the first lockdown could prevent 48 lost life-years among the city population, with economic benefits of up to £2.5 million. Our findings highlight the critical importance of decoupling emissions changes from meteorological influences to avoid overestimation of lockdown impacts and indicate targeted emissions control measures will be the most effective strategy for achieving air quality and public health benefits in this setting.
Bibliographical noteFunding Information:
The work was supported by the Natural Environment Research Council grant ‘Assessing environmental impacts of COVID-19 emergency public health measures in Oxford City’ (NE/V010360/1) and the National Institute for Health Research Public Health Research (NIHR PHR) Programme ( NIHR130095 ). The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care. We also acknowledge the support from the University of Birmingham Institute for Global Innovation Clean Air Theme.
We are most grateful to key members of the OxAria Study Team for supporting this study: Pedro Abreu (Oxford City Council) for his assistance in data validation, interpretation and manuscript preparation; Stuart Cole (Oxfordshire County Council) and Tony Bush (University of Oxford) for their expert advice and assistance with manuscript preparation. We thank Phil Southall (Managing Director at Oxford Bus Company, Thames Travel, Carousel Buses and City Sightseeing Oxford) and Stagecoach staff for provision of bus fleet information and George Economides (Oxfordshire County Council) for provision of vehicle activity data for this study. We are grateful to David Carslaw (Ricardo Energy & Environment, University of York) and Guy Hitchcock (Ricardo Energy & Environment) for their expert advice and Tianjiao Guo (University of Birmingham), Kayla Schulte (University of Oxford) for their assistance. We also thank the OxAria Study Advisory Committee (notably Chair Neil Harris and former Chair the late Martin Williams) for their expert advice and support for undertaking all project activities.
© 2021 The Authors
- Air quality
- Vehicle emissions
- Oxford city
ASJC Scopus subject areas
- Health, Toxicology and Mutagenesis