Isolating the impact of COVID-19 lockdown measures on urban air quality in Canada.

ABSTRACT: We have investigated the impact of reduced emissions due to COVID-19 lockdown measures in spring 2020 on air quality in Canada's four largest cities: Toronto, Montreal, Vancouver, and Calgary. Observed daily concentrations of NO₂, PM_2.5, and O₃ during a "pre-lockdown" period (15 February-14 March 2020) and a "lockdown" period (22 March-2 May 2020), when lockdown measures were in full force everywhere in Canada, were compared to the same periods in the previous decade (2010-2019). Higher-than-usual seasonal declines in mean daily NO₂ were observed for the pre-lockdown to lockdown periods in 2020. For PM_2.5, Montreal was the only city with a higher-than-usual seasonal decline, whereas for O₃ all four cities remained within the

SUBMITTER: Mashayekhi R 

PROVIDER: S-EPMC8130219 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature