Table 3. Subgroup-analysis of each pollutant and cardiovascular mortality.

Pollutant	Outcome	Number of estimates	Heterogeneity I2 (%)	Statistics Model	Summary ER (%) (95% CI)
PM2.5
	Lag 0	4	49	Random-effect	0.40 [0.23, 0.58]
	Lag 1	3	90	Random-effect	0.14 [−0.23, 0.52]
	Lag 2	2	77	Random-effect	−0.01 [−0.22, 0.01]
	Lag 0–1	2	71	Fixed-effect	0.77 [0.42, 1.12]
	Warm	2	19	Fixed-effect	0.67 [0.21, 1.14]
	Cool	2	75	Random-effect	0.68 [−0.35, 1.71]
PM10
	Lag 0	9	76	Random-effect	0.27 [0.10, 0.44]
	Lag 1	6	80	Random-effect	0.35 [0.12, 0.59]
	Lag 2	4	63	Random-effect	0.03 [−0.21, 0.27]
	Lag 0–1	12	84	Random-effect	0.47 [0.30, 0.64]
	Male	3	73	Random-effect	0.30 [0.06, 0.55]
	Female	3	80	Random-effect	0.56 [0.14, 0.97]
	Warm seasons	4	73	Random-effect	0.44 [−0.07, 0.96]
	Cool seasons	4	80	Random-effect	0.46 [0.18, 0.73]
	Age > 65 years	5	78	Random-effect	0.50 [0.23, 0.76]
	Age ≤ 65 years	5	80	Random-effect	0.33 [0.01, 0.65]
NO2
	Lag 0	3	75	Random-effect	0.44 [−0.46, 1.34]
	Lag 1	2	77	Random-effect	1.11 [0.12, 2.11]
	Lag 0–1	8	86	Random-effect	1.33 [0.73, 1.93]
	Male	3	86	Random-effect	0.80 [0.08, 1.51]
	Female	3	64	Random-effect	1.08 [0.48, 1.69]
	Warm seasons	3	0	Fixed-effect	0.13 [−0.25, 0.50]
	Cool seasons	3	90	Random-effect	1.96 [0.33, 3.60]
	Age > 65 years	4	86	Random-effect	1.27 [0.55, 1.99]
	Age ≤ 65 years	4	50	Fixed-effect	0.40 [0.20, 0.61]
SO2
	Lag 0	3	87	Random-effect	0.38 [−0.45, 1.20]
	Lag 1	4	87	Random-effect	0.72 [0.05, 1.39]
	Lag 2	2	41	Fixed-effect	0.12 [−0.13, 0.38]
	Lag 0–1	8	82	Random-effect	0.61 [0.23, 1.00]
	Male	2	59	Random-effect	0.56 [0.08, 1.04]
	Female	2	87	Random-effect	0.99 [−0.10, 2.09]
	Warm seasons	3	3	Fixed-effect	0.21 [−0.01, 0.43]
	Cool seasons	3	86	Random-effect	1.28 [0.39, 2.18]
O3
	Lag 2	2	81	Random-effect	0.40 [−0.04, 0.84]
	Lag 0–1	2	76	Random-effect	1.51 [−1.32, 4.33]
	Warm seasons	3	36	Fixed-effect	0.43 [0.15, 0.71]
	Cool seasons	4	91	Random-effect	1.72 [−0.71, 4.15]

ER, Excess risk (ER) percentages and 95% confidence intervals for different lag times of mortality, different age groups, different genders and different temperature for each increment of 10 μg/m3 in pollutant concentrations. CI, confidence interval. PM, Particulate matter