Impacts of COVID-19 Lockdown on Traffic Flow, Active Travel and Gaseous Pollutant Concentrations; Implications for Future Emissions Control Measures in Oxford, UK

The COVID-19 lockdown provided a unique opportunity to test the impacts of changes in travel patterns on air quality and environment. Therefore, this study provides insights into emergency public health “lockdown” measures upon traffic flow, active gaseous pollutant concentrations (NO, NO2 O3) Oxford city centre during 2020 using time-series analysis linear regression methods. Comparisons counts indicated pronounced volume associated with national periods. Car reduced by 77.5% (statistically significant) first lockdown, lesser goods vehicles transport (bus) activity second lockdown. Cycle flow substantively only. These resulted reduction nitric oxide (NO) nitrogen dioxide (NO2) 75.1% 47.4%, respectively, at roadside, 71.8% 34.1% urban background period. In contrast ozone (O3) increased site 22.3% period, no significant either roadside or location. diurnal pattern peak mean NO magnitude was shifted approximately 2 h earlier morning later evening (roadside) 3 (urban background). Our findings provide an example how environments could respond future restrictions, suggesting benefits from reductions daily exposures may be offset harms arising increases ground level O3 summer months.