Table 1.

Associations of PM_2.5, synoptic weather types (SWTs), and their interactions with daily cardiovascular mortality.

Variable	Risk Ratio (RR) for Cardiovascular Mortality
	Model without SO2, NO2		Model with SO2, NO2
	RR (95% CI)	P-Value	RR (95% CI)	P-Value
PM2.5 (per 10 μ g/m3)	1.0126 (1.0040, 1.0212)	0.004	1.0121 (1.0027, 1.0215)	0.011
SO2			1.0007 (0.9993, 1.0021)	0.310
NO2			0.9998 (0.9990, 1.0005)	0.544
Synoptic weather types
Hot dry (Ref)
Warm humid	0.9945 (0.9359, 1.0567)	0.858	0.9971 (0.9378, 1.0603)	0.927
Cold dry	0.9894 (0.9191, 1.0651)	0.778	0.9861 (0.9149, 1.0628)	0.714
Cool dry	0.9954 (0.9308, 1.0645)	0.893	0.9978 (0.9327, 1.0674)	0.948
Cool humid	1.0369 (0.9666, 1.1123)	0.311	1.0378 (0.9675, 1.1133)	0.300
Cold humid	1.0138 (0.9438, 1.0891)	0.707	1.0157 (0.9451, 1.0914)	0.672
Day of week
Sunday (Ref)
Monday	1.0269 (0.9963, 1.0585)	0.085	1.0269 (0.9963, 1.0585)	0.086
Tuesday	1.0178 (0.9874, 1.0491)	0.254	1.0182 (0.9876, 1.0497)	0.246
Wednesday	1.0350 (1.0043, 1.0667)	0.025	1.0352 (1.0041, 1.0672)	0.026
Thursday	1.0139 (0.9835, 1.0453)	0.373	1.0143 (0.9837, 1.0458)	0.363
Friday	1.0058 (0.9756, 1.0369)	0.712	1.0065 (0.9761, 1.0378)	0.681
Saturday	1.0315 (1.0008, 1.0632)	0.044	1.0320 (1.0012, 1.0637)	0.042
Interaction
PM2.5 × Hot dry (Ref)
PM2.5 × Warm humid	0.9924 (0.9822, 1.0027)	0.149	0.9926 (0.9822, 1.0030)	0.162
PM2.5 × Cold dry	0.9853 (0.9761, 0.9946)	0.002	0.9852 (0.9758, 0.9946)	0.002
PM2.5 × Cool dry	0.9905 (0.9802, 1.0009)	0.074	0.9904 (0.9800, 1.0009)	0.072
PM2.5 × Cool humid	0.9889 (0.9762, 1.0019)	0.093	0.9893 (0.9764, 1.0022)	0.104
PM2.5 × Cold humid	0.9855 (0.9764, 0.9948)	0.002	0.9853 (0.9760, 0.9946)	0.002

Ref, reference group; CI, confidence interval, Bold items, variables with statistical significance (P-value < 0.05).