Table 6.

Risk ratios (RRs) and 95% confidence intervals (CIs) from log-binomial regression models, between prepandemic air pollution levels at residence and COVID-19 disease stratified by participant characteristics, COVICAT study.

Category/air pollutant	RR (95% CI)a	RR (95% CI)a	$p$-Valueb
Age [y ($N$)]	$<60$ (6,823)	$\ge 60$ (2,782)	—
${\mathrm{NO}}_2$	1.12 (0.98, 1.29)	1.21 (0.91, 1.61)	0.625
${\mathrm{PM}}_{2.5}$	1.14 (0.99, 1.30)	1.33 (0.99, 1.79)	0.317
BC	1.02 (0.90, 1.16)	0.89 (0.70, 1.12)	0.281
${\mathrm{O}}_3$	0.94 (0.83, 1.05)	0.86 (0.67, 1.10)	0.529
Sex ($N$)	Female (5,656)	Male (3,949)	—
${\mathrm{NO}}_2$	1.16 (1.00, 1.35)	1.09 (0.89, 1.33)	0.575
${\mathrm{PM}}_{2.5}$	1.15 (0.99, 1.33)	1.20 (0.98, 1.48)	0.705
BC	0.97 (0.84, 1.10)	1.06 (0.88, 1.28)	0.399
${\mathrm{O}}_3$	0.88 (0.77, 1.01)	1.00 (0.84, 1.19)	0.244
Educational level ($N$)c	High (4,454)	Low (5,151)	—
${\mathrm{NO}}_2$	1.06 (0.89, 1.27)	1.19 (1.01, 1.40)	0.319
${\mathrm{PM}}_{2.5}$	1.04 (0.87, 1.23)	1.28 (1.09, 1.51)	0.065
BC	0.96 (0.82, 1.13)	1.02 (0.88, 1.19)	0.570
${\mathrm{O}}_3$	0.95 (0.82, 1.11)	0.90 (0.78, 1.03)	0.542
Area-level deprivation ($N$)d	High (3,842)	Low (5,763)	—
${\mathrm{NO}}_2$	1.04 (0.84, 1.28)	1.17 (1.01, 1.35)	0.347
${\mathrm{PM}}_{2.5}$	1.12 (0.91, 1.38)	1.18 (1.02, 1.36)	0.682
BC	0.95 (0.81, 1.12)	1.02 (0.89, 1.18)	0.509
${\mathrm{O}}_3$	0.97 (0.81, 1.16)	0.91 (0.80, 1.04)	0.561
Previous diagnosis of chronic disease ($N$)e	No (7,880)	Yes (1,725)	—
${\mathrm{NO}}_2$	1.18 (1.02, 1.35)	0.97 (0.76, 1.24)	0.166
${\mathrm{PM}}_{2.5}$	1.17 (1.02, 1.34)	1.13 (0.88, 1.45)	0.818
BC	1.01 (0.89, 1.14)	0.94 (0.76, 1.18)	0.606
${\mathrm{O}}_3$	0.89 (0.79, 1.01)	1.06 (0.87, 1.30)	0.137
Obesity [$\text{BMI}\ge 30{\mathrm{kg}/\mathrm{m}}^2$ ($N$)]	No (7,955)	Yes (1,631)	—
${\mathrm{NO}}_2$	1.12 (0.97, 1.29)	1.15 (0.91, 1.46)	0.862
${\mathrm{PM}}_{2.5}$	1.13 (0.98, 1.30)	1.28 (1.00, 1.63)	0.368
BC	0.97 (0.86, 1.10)	1.07 (0.85, 1.34)	0.455
${\mathrm{O}}_3$	0.93 (0.82, 1.05)	0.92 (0.75, 1.13)	0.938
Degree of urbanization ($N$)	Suburb or rural (955)	City (8,650)	—
${\mathrm{NO}}_2$	0.98 (0.59, 1.61)	1.17 (1.01, 1.36)	0.495
${\mathrm{PM}}_{2.5}$	1.00 (0.70, 1.43)	1.21 (1.05, 1.40)	0.332
BC	0.80 (0.43, 1.49)	0.99 (0.88, 1.12)	0.502
${\mathrm{O}}_3$	1.11 (0.82, 1.50)	0.89 (0.78, 1.02)	0.186
Population density ($N$)f	Low (5,763)	High (3,842)	—
${\mathrm{NO}}_2$	1.13 (0.98, 1.30)	1.15 (0.86, 1.52)	0.923
${\mathrm{PM}}_{2.5}$	1.13 (0.98, 1.30)	1.29 (0.99, 1.68)	0.391
BC	1.02 (0.89, 1.16)	0.87 (0.68, 1.11)	0.275
${\mathrm{O}}_3$	0.93 (0.82, 1.04)	0.92 (0.72, 1.19)	0.980

Note: Associations reported per interquartile range. —, no data available; BC, black carbon; BMI, body mass index; COVICAT, COVID-19 cohort in Catalonia study; ${\mathrm{NO}}_2$, nitrogen dioxide; ${\mathrm{O}}_3$, ozone; ${\mathrm{PM}}_{2.5}$, particulate matter; Q, quintile.

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

^b $p$-Value for likelihood ratio test for interaction.

^c University is considered as high educational level.

^d Low deprivation: Q3–Q5 of deprivation score; high deprivation: Q1–Q2 of deprivation score.

^e Previous diagnosis of any of the following: respiratory, cardiometabolic, kidney, or immune-related diseases.

^f Low density: Q1–Q3 of population density; high density: Q4–Q5 of population density.