Table 4.

Risk ratios (RRs) and 95% confidence intervals (CIs) from log-binomial regression models, between air pollution at residence and COVID-19 disease among the total COVICAT population and subgroups with serological testing and positive antibodies for SARS-CoV-2 infection.

Population/air pollutant	RR (95% CI)a	RR (95% CI)b
Total population ($N$)	9,605	9,088
${\mathrm{NO}}_2$	1.14 (1.00, 1.29)	1.16 (1.01, 1.32)
${\mathrm{PM}}_{2.5}$	1.17 (1.03, 1.32)	1.16 (1.02, 1.32)
BC	0.99 (0.89, 1.12)	1.00 (0.89, 1.13)
${\mathrm{O}}_3$	0.92 (0.83, 1.03)	0.91 (0.82, 1.02)
Participants with serology ($N$)	4,103	3,922
${\mathrm{NO}}_2$	1.31 (1.07, 1.62)	1.35 (1.10, 1.67)
${\mathrm{PM}}_{2.5}$	1.30 (1.06, 1.60)	1.29 (1.05, 1.60)
BC	0.98 (0.81, 1.18)	0.99 (0.82, 1.19)
${\mathrm{O}}_3$	0.81 (0.68, 0.98)	0.80 (0.66, 0.97)
Participants with SARS-CoV-2 infection ($N$)	743	702
${\mathrm{NO}}_2$	1.23 (0.96, 1.56)	1.26 (0.99, 1.60)
${\mathrm{PM}}_{2.5}$	1.19 (0.93, 1.52)	1.13 (0.90, 1.43)
BC	1.07 (0.86, 1.32)	1.07 (0.86, 1.32)
${\mathrm{O}}_3$	0.89 (0.72, 1.10)	0.88 (0.71, 1.09)

Note: Associations reported per interquartile range. BC, black carbon; COVICAT, COVID-19 cohort in Catalonia study; ${\mathrm{NO}}_2$, nitrogen dioxide; ${\mathrm{O}}_3$, ozone; ${\mathrm{PM}}_{2.5}$, particulate matter.

^a Adjusted for age, sex, education (less than primary/primary/secondary/university), deprivation index (quintiles), population density, and type of survey (online/telephone).

^b Adjusted for age, sex, education (less than primary/primary/secondary/university), deprivation index (quintiles), smoking (never/ex-smoker/smoker), physical activity (low/moderate/high), population density, and type of survey (online/telephone).