Table 9.

Comparison of results to other studies that quantified air pollution changes during lockdowns in 2020.

Study	Region	Time period	Pollutant	Reported estimate	Our estimate
Adams (2020)	Ontario, Canada	22-Mar–25-Apr	NO${}_2$	−2 ppb	−1.9 ppb
Adams (2020)	Ontario, Canada	22-Mar–25-Apr	PM2.5	0 $\mathrm{\mu }\mathrm{g}$/m${}^3$	−0.6 $\mathrm{\mu }$g/m${}^3$
Adams (2020)	Ontario, Canada	22-Mar–25-Apr	O${}_3$	−1 ppb	1.1 ppb
Archer et al. (2020)	United States	1-Apr–30-Apr	NO${}_2$	−2.02, $-1.3$ ppba	−2.5 ppb
Archer et al. (2020)	United States	1-Apr–30-Apr	PM2.5	0.05, $0.28\mathrm{\mu }\mathrm{g}$/m${}^3$a	−0.1 $\mathrm{\mu }$g/m${}^3$
Berman and Ebisu (2020)	United States	8-Jan–12-Mar	NO${}_2$	−1.17 ppb	−0.6 ppb
Berman and Ebisu (2020)	United States	13-Mar–21-Apr	NO${}_2$	−4.76 ppb	−2.9 ppb
Berman and Ebisu (2020)	United States	8-Jan–12-Mar	PM2.5	−0.29 $\mathrm{\mu }$g/m${}^3$	−0.6 $\mathrm{\mu }$g/m${}^3$
Berman and Ebisu (2020)	United States	13-Mar–21-Apr	PM2.5	−0.28 $\mathrm{\mu }$g/m${}^3$	−0.1 $\mathrm{\mu }$g/m${}^3$
Connerton et al. (2020)	Los Angeles, USA	1-Mar–31-Mar	PM2.5	−2.99 $\mathrm{\mu }$g/m${}^3$	−1.9 $\mathrm{\mu }$g/m${}^3$
Connerton et al. (2020)	New York, USA	1-Mar–31-Mar	PM2.5	−2.03 $\mathrm{\mu }$g/m${}^3$	−4.5 $\mathrm{\mu }$g/m${}^3$
Connerton et al. (2020)	Paris, France	1-Mar–31-Mar	PM2.5	−2.56 $\mathrm{\mu }$g/m${}^3$	−2.4 $\mathrm{\mu }$g/m${}^3$
Connerton et al. (2020)	São Paulo, Brazil	1-Mar–31-Mar	PM2.5	−0.54 $\mathrm{\mu }$g/m${}^3$	−0.3 $\mathrm{\mu }$g/m${}^3$
Jia et al. (2020)	Memphis, USA	25-Mar–4-May	PM2.5	0.3 $\mathrm{\mu }\mathrm{g}$/m${}^3$	0.1 $\mathrm{\mu }\mathrm{g}$/m${}^3$
Jia et al. (2020)	Memphis, USA	25-Mar–4-May	O${}_3$	−1.9 ppb	−1.6 ppb
Ordóñez et al. (2020)	Europe	15-Mar–30-Apr	NO${}_2$	−9.2, −13.1 $\mathrm{\mu }$g/m${}^3$b	−10.7 $\mathrm{\mu }$g/m${}^3$
Ordóñez et al. (2020)	Europe	15-Mar–30-Apr	O${}_3$	6.2, $0.1\mathrm{\mu }\mathrm{g}$/m${}^3$b	$4.5\mathrm{\mu }\mathrm{g}$/m${}^3$
Petetin et al. (2020)	Spain	14-Mar–29-Mar	NO${}_2$	−3.4, −5.6 ppbc	−5.9 ppb
Petetin et al. (2020)	Spain	30-Mar–9-Apr	NO${}_2$	−5.2, −7.4 ppbc	−6.8 ppb
Petetin et al. (2020)	Spain	10-Apr–23-Apr	NO${}_2$	−4.3, −6.8 ppbc	−6.1 ppb
Ropkins and Tate (2021)	United Kingdom	10-Mar–10-Apr	NO${}_2$	−4.16, −7.58 $\mathrm{\mu }$g/m${}^3$d	−8.1 $\mathrm{\mu }$g/m${}^3$
Ropkins and Tate (2021)	United Kingdom	10-Mar–10-Apr	PM2.5	4.79, $5\mathrm{\mu }\mathrm{g}$/m${}^3$d	−1.7 $\mathrm{\mu }$g/m${}^3$
Ropkins and Tate (2021)	United Kingdom	10-Mar–10-Apr	O${}_3$	6.96, 7.39 $\mathrm{\mu }\mathrm{g}$/m${}^3$d	5.8 $\mathrm{\mu }\mathrm{g}$/m${}^3$
Tanzer-Gruener et al. (2020)	Pittsburgh, USA	14-Mar–30-Apr	PM2.5	−2.8 $\mathrm{\mu }$g/m${}^3$	−1.7 $\mathrm{\mu }$g/m${}^3$
Venter et al. (2020)	China	24-Jan–15-May	PM2.5	−16 $\mathrm{\mu }$g/m${}^3$	−9.2 $\mathrm{\mu }$g/m${}^3$
Venter et al. (2020)	India	29-Feb–15-May	PM2.5	−15 $\mathrm{\mu }$g/m${}^3$	−15.6 $\mathrm{\mu }$g/m${}^3$
Zheng et al. (2020)	Wuhan, China	23-Jan–22-Feb	PM2.5	−24.8 $\mathrm{\mu }$g/m${}^3$	−28.9 $\mathrm{\mu }$g/m${}^3$

^aComparison to 2015–2019 and trend-adjusted change, respectively.

^bComparison to 2015–2019 and meteorology-adjusted change, respectively.

^cMeteorology-normalised changes at background and traffic sites, respectively.

^dBreak-point/segment analyses for urban background and traffic sites, respectively.