Air quality impacts of new public transport provision: A causal analysis of the Jubilee Line Extension in London
File(s)
Accepted version
Author(s)
Ma, Liang
Graham, Daniel J
Stettler, Marc EJ
Type
Journal Article
Abstract
Public transport is commonly associated with benefits such as reducing road traffic congestion and improving air quality. This paper focuses on evaluating the causal impact of a new public transport provision in London, the Jubilee Line Extension (JLE) in 1999, on air quality. Using meteorological normalisation and a regression discontinuity design with time as the forcing variable, we show that the JLE led to only small changes in air pollution at some specific locations; detectable changes in NOx, NO2, and O3 concentrations were found at 63%, 43% and 29% of air pollution monitoring sites, respectively. For those sites where a change in pollution was detected, the responses ranged from −2% to +1% for NO2 and -1% to 0% for O3. We calculate that the long-run effects are greater, ranging from −11% to +3% for NO2 and from −2% to +2% for O3 at sites that showed a response to the JLE. Aggregating across all sites in London for a city-wide effect, both short and long-run effects were less than 1% or insignificant. We find statistically significant increases in NO2 and O3 concentrations at some background sites, but the magnitude of effect is within +1% in the short-run and +3% in the long-run. Our analysis shows that the effect of the JLE on air pollution in some areas was greater than others, however across London the effect was small and this indicates that public transport provision on its own is not an effective strategy to improve air quality.
Date Issued
2021-01
Date Acceptance
2020-10-19
Citation
Atmospheric Environment, 2021, 245, pp.118025-118025
ISSN
1352-2310
Publisher
Elsevier BV
Start Page
118025
End Page
118025
Journal / Book Title
Atmospheric Environment
Volume
245
Copyright Statement
© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor
Commission of the European Communities
Identifier
https://www.sciencedirect.com/science/article/pii/S1352231020307585?via%3Dihub
Grant Number
730459
Subjects
0104 Statistics
0401 Atmospheric Sciences
0907 Environmental Engineering
Meteorology & Atmospheric Sciences
Publication Status
Published online
Article Number
118025
Date Publish Online
2020-10-20