Table 3.
Correlation between epidemic growth of COVID-19 and ambient environmental factors.
| Variable | Ratio unit | Univariate |
Multivariable |
||
|---|---|---|---|---|---|
| RRR (95% CI) | p value | Adjusted RRR (95% CI) | p value | ||
| Mean temperature | 1 °C | 1.03 (1.00–1.06) | 0.056 | 1.04 (1.01–1.08) | 0.018* |
| Mean daily minimum temperature | 1 °C | 1.02 (1.00–1.04) | 0.053 | 1.03 (1.00–1.06) | 0.037* |
| Mean daily maximum temperature | 1 °C | 1.04 (1.00–1.08) | 0.060 | 1.04 (1.01–1.08) | 0.020* |
| Precipitation | 1 mm | 0.99 (0.98–1.00) | 0.091 | 0.99 (0.98–1.00) | 0.060 |
| Sunshine hours | 1 h | 1.03 (1.00–1.05) | 0.035* | 1.03 (1.01–1.05) | 0.011* |
| Mean wind speed | 1 m/s | 1.13 (1.04–1.23) | 0.005** | 1.06 (0.96–1.16) | 0.238 |
| Mean relative humidity | 5% | 0.98 (0.95–1.02) | 0.344 | 0.97 (0.94–1.01) | 0.105 |
| Mean daily minimum relative humidity | 5% | 0.98 (0.95–1.01) | 0.220 | 0.98 (0.96–1.00) | 0.058 |
| Mean absolute humidity | 1 g/kg, DA | 1.03 (0.98–1.09) | 0.259 | 1.04 (0.98–1.11) | 0.159 |
| NO | 1 ppb | 0.96 (0.90–1.02) | 0.200 | 1.04 (0.97–1.10) | 0.278 |
| NO2 | 1 ppb | 0.98 (0.97–1.00) | 0.033* | 1.01 (0.99–1.02) | 0.540 |
| Ox | 1 ppb | 1.02 (1.00–1.04) | 0.082 | 1.01 (0.99–1.03) | 0.402 |
| SPM | 1 μg/m3 | 1.01 (0.98–1.05) | 0.356 | 1.03 (1.00–1.05) | 0.026* |
| PM2.5 | 1 μg/m3 | 1.01 (0.98–1.04) | 0.698 | 1.03 (1.00–1.06) | 0.083 |
Values are expressed as ratios of rate ratios (95% CIs) and 2-sided p values. Significant at * p < 0.05, ** p < 0.01. Multivariable analysis is adjusted for male inhabitant, inhabitants aged ≥65 years, urban density, taxable income, health expenditure, and life expectancy at birth; Abbreviations: DA, dry air; CI, confidence interval; RRR, ratio of rate ratio; NO, nitrogen monoxide; NO2, nitrogen dioxide; Ox, photochemical oxidant; SPM, suspended particulate matter; PM2.5, fine particulate matter.