Table 2.
Adjusted associations between long-term air pollutants and COVID-19-related outcomes in single and two-pollutant models
| COVID-19 hospital admission* | COVID-19 ICU admission* | COVID-19 death* | Hospital length of stay* | ||
|---|---|---|---|---|---|
| Exposure | HR (95% CI) | HR (95% CI) | HR (95% CI) | IRR (95% CI) | |
| COVAIR-CAT models | |||||
| NO2 (IQR increase: 16.1) | Single-pollutant | 1.25 (1.22–1.29) | 1.42 (1.30–1.55) | 1.18 (1.10–1.27) | 1.06 (1.03–1.09) |
| PM2.5 (IQR increase: 3.2) | Single-pollutant | 1.19 (1.16–1.21) | 1.16 (1.09–1.24) | 1.13 (1.07–1.19) | 1.06 (1.04–1.08) |
| COVAIR-CAT models | |||||
| NO2 (IQR increase: 16.1) | Adjusted for PM2.5 | 1.12 (1.08–1.17) | 1.51 (1.33–1.72) | 1.10 (0.99–1.22) | 0.99 (0.95–1.03) |
| NO2 (IQR increase: 16.1) | Adjust for O3 | 1.24 (1.19–1.29) | 1.58 (1.39–1.79) | 1.19 (1.08–1.31) | 1.07 (1.03–1.12) |
| PM2.5 (IQR increase: 3.2) | Adjusted for NO2 | 1.12 (1.08–1.15) | 0.93 (0.85–1.03) | 1.08 (1.00–1.16) | 1.07 (1.04–1.10) |
| PM2.5 (IQR increase: 3.2) | Adjust for O3 | 1.16 (1.13–1.19) | 1.13 (1.04–1.22) | 1.12 (1.05–1.19) | 1.07 (1.05–1.10) |
*The analyses of COVID-19 hospital admission, ICU admission, and death were conducted in the whole population, while hospital length of stay was conducted among those with COVID-19 hospital admission. Estimates from Model 4, which included: age (continuous term, penalized spline with 6 df) + sex (strata, 2 categories) + smoking status (factor, 3 categories) + individual income (factor, 3 categories) + health risk group (factor, 4 categories) + small area socioeconomic index (continuous term) + percentage of non-Spanish nationals (continuous term) + distance to the closest primary care unit (continuous term) + urbanicity (strata, 3 categories) + average weekly of test-positive proportion (continuous term) + health region (strata, 7 categories).