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, PM2.5, 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 PM2.5, Montreal was the only city with a higher-than-usual seasonal decline, whereas for O3 all four cities remained within the previous decadal range. In order to isolate the impact of lockdown-related emission changes from other factors such as seasonal changes in meteorology and emissions and meteorological variability, two emission scenarios were performed with the GEM-MACH air quality model. The first was a Business-As-Usual (BAU) scenario with baseline emissions and the second was a more realistic simulation with estimated COVID-19 lockdown emissions. NO2 surface concentrations for the COVID-19 emission scenario decreased by 31 to 34% on average relative to the BAU scenario in the four metropolitan areas. Lower decreases ranging from 6 to 17% were predicted for PM2.5. O3 surface concentrations, on the other hand, showed increases up to a maximum of 21% close to city centers versus slight decreases over the suburbs, but Ox (odd oxygen), like NO2 and PM2.5, decreased as expected over these cities.

Effect of COVID-19 pandemic restrictions on air pollution at a local scale in urban areas affected by high-intensity vehicle traffic in Poland

“…Many publications indicate that the lockdown in 2020 implemented due to the SARS-CoV-2 pandemic caused a significant improvement in air quality at a global scale, for example, in Europe (Filonchyk et al 2020 ; Gama et al 2021 ; Higham et al 2021 ; Wiśniewski et al 2021 ; Ródenas et al 2022 ; Baldasano 2020 ; Skirienė and Stasiškienė 2021 ; Jakovljevoć et al 2021 ; Bar et al 2021 ; Rogulski and Badyda 2021 ; Mikulski et al 2021 ), USA (Bar et al 2021 ), Canada (Mashayekhi et al 2021 ), Mexico (Kutralam-Muniasamy et al 2021 ), and China (Xu et al 2020 ; Bauwens et al 2020 ). This short-term improvement in air quality has a positive impact on human health in terms of reducing respiratory and other diseases, saving many thousands of lives, as annually approximately 7 million deaths occur due to global air pollution (WHO 2018 ).…”

COVID-19 Lockdown in Belgrade: Impact on Air Pollution and Evaluation of a Neural Network Model for the Correction of Low-Cost Sensors’ Measurements

“…The French National Institute (INERIS) has conducted a comprehensive study related to NO 2 and PM 10 around Europe, and a decrease in NO 2 pollution was also noticed, but the PM 10 pollution was shown to depend on the observed region (an increase/decrease was observed) [6]. The same behavior, regarding NO 2 and PM pollution levels, is also noticed in Canada and presented in [7]. The impact of the COVID-19 lockdown on traffic-related air pollution (PM 2.5 , black carbon (BC), NO, NO 2 and CO) in a northwestern US city is evaluated in [8].…”

The Interplay between Housing Environmental Attributes and Design Exposures and Psychoneuroimmunology Profile—An Exploratory Review and Analysis Paper in the Cancer Survivors’ Mental Health Morbidity Context

“…Lockdown dates over different countries resulted in drastic reductions in global-level air pollutants compared to those expected for the time of year; however, variations in air quality were dependent on the specific implemented measures and timing of lockdowns [122][123][124]. Overall, whereas ambient air pollution levels decreased in most of the forms, an increase of ozone concentrations were reported in several regions of Europe, including Spain [125], France, Italy [126], Netherlands [127], and the UK [128,129], as well as China [126,130], South and Southeast Asia [131,132], Canada [133], the United States (US) [134,135] and Mexico [136], despite different lockdown measures being implemented. Residential environments remained a significant risk source to indoor air emissions [137,138].…”