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. 2021 Jan 22;195:110777. doi: 10.1016/j.envres.2021.110777

Table 2.

Multivariable estimates of incidence rate ratios (IRRs) for COVID-19 in Lombardy municipalities between February 20th and April 16th, 2020, according to demographic, socioeconomic and community variables and air pollutants concentrations.

Model with PM2.5 Model with PM10
IRRa 95% CI p-value IRRa 95% CI p-value
Demographic, socioeconomic and community variables
Population sizeb 0.90 0.83–0.98 0.01 0.90 0.83–0.98 0.01
Population densityb 0.92 0.83–1.01 0.07 0.92 0.84–1.01 0.10
Sex ratioc 0.99 0.94–1.05 0.83 1.00 0.94–1.05 0.87
Proportion of population over 75 years oldc 1.08 1.01–1.15 0.02 1.09 1.02–1.16 0.01
Average family sizec 1.01 0.95–1.08 0.79 1.03 0.97–1.10 0.33
House crowding index (high vs low) 0.93 0.84–1.03 0.19 0.92 0.83–1.02 0.12
High to low education ratiob 0.76 0.72–0.81 <0.01 0.76 0.72–0.81 <0.01
IRPEF per capitac 1.19 1.12–1.27 <0.01 1.18 1.11–1.26 <0.01
Percentage of private mobility usec 0.85 0.81–0.88 <0.01 0.85 0.81–0.89 <0.01
Number of beds in nursing homes (>80 vs 0) 1.49 1.32–1.69 <0.01 1.49 1.32–1.68 <0.01
Distance to the closest hospitalc 0.92 0.87–0.97 <0.01 0.92 0.88–0.97 <0.01
Number of employees in bars, restaurants and mobile catering activities per capita (>14 vs ≤ 9 per 1000 inhabitants) 1.11 1.00–1.23 0.04 1.12 1.02–1.24 0.02
Number of employees in health and social assistance activities per capita (>0.6 vs 0 per 1000 inhabitants) 1.02 0.92–1.14 0.70 1.02 0.92–1.14 0.66
Number of employees in sports, entertainment and recreational activities per capita (>0.9 vs ≤ 0.4 per 1000 inhabitants) 1.18 1.07–1.30 <0.01 1.18 1.07–1.31 <0.01
Air pollutants concentrations
PM (per 10 μg/m3) 1.58 1.31–1.90 <0.01 1.34 1.16–1.55 <0.01
NO2 (per 10 μg/m3) 0.93 0.88–0.99 0.02 0.95 0.89–1.00 0.07

Abbreviations: CI, confidence interval; IRPEF, Imposta Regionale Persone Fisiche; IRR, incidence rate ratio; NO2, nitrogen dioxide; PM, particulate matter.

a

Adjusted by weeks since first COVID-19 case report (a proxy for epidemic stage), winter average temperature and winter average absolute humidity as modelled through a 3-knots restrcited cubic spline (Fig. 4).

b

Variable was log2- transformed and standardized.

c

Variable was standardized.