Table 3.

Stratified analysis of ambient air pollutants and/or meteorological factors’ interaction effects on COVID-19 confirmed cases

Variable group	Variable	Stratified factor	β	Lower 95% CI	Upper 95% CI	P
Effect of air pollutants stratified in meteorological factors	CO	HS < P50	3.321	−0.230	6.873	0.067
		HS ≥ P50	1.115	−0.247	2.478	0.108
	CO	DTR < P50	5.763	2.402	9.124	0.001
		DTR ≥ P50	0.931	0.066	1.796	0.035
	CO	RH < P50	0.930	−0.574	2.434	0.226
		RH ≥ P50	6.045	3.247	8.844	<0.001
	SO2	AP < P50	−0.006	−0.052	0.041	0.812
		AP ≥ P50	−0.243	−0.307	−0.178	<0.001
	PM2.5	PRE < P50	0.004	−0.019	0.027	0.727
		PRE ≥ P50	0.049	−0.009	0.107	0.100
Effect of air pollutants stratified in other air pollutants	PM2.5	CO < P50	0.003	−0.012	0.019	0.665
		CO ≥ P50	0.018	−0.035	0.071	0.504
	PM2.5	NO2 < P50	0.021	−0.007	0.050	0.142
		NO2 ≥ P50	0.005	−0.016	0.026	0.633
	CO	NO2 < P50	5.024	3.087	6.962	<0.001
		NO2 ≥ P50	−0.987	−2.323	0.349	0.148
	CO	SO2 < P50	7.081	3.923	10.239	<0.001
		SO2 ≥ P50	0.237	−1.130	1.604	0.734
	CO	O3 < P50	−0.306	−1.460	0.848	0.603
		O3 ≥ P50	4.074	2.301	5.847	<0.001
	SO2	O3 < P50	−0.129	−0.207	−0.052	0.001
		O3 ≥ P50	−0.036	−0.094	0.022	0.224
Effect of meteorological factors stratified in other meteorological factors	HS	PRE < P50	0.183	−0.032	0.399	0.095
		PRE ≥ P50	0.507	−0.218	1.231	0.170
	WV	RH < P50	0.013	−0.679	0.705	0.970
		RH ≥ P50	−0.506	−0.866	−0.147	0.006
	DTR	RH < P50	0.065	−0.141	0.272	0.535
		RH ≥ P50	0.052	−0.265	0.369	0.749