Table 2.

Stroke risk ratios associated with an inter quartile range (IQR) increase in the levels of air pollutants including PM_2.5, O₃, SO₂, and NO₂.

Model	Pollutants	Lag 0 Model		Lag 1 Model
		RR	95% CI	RR	95% CI
Single-pollutant model	PM2.5 only	1.0270 *	(1.0174, 1.0366)	1.0309 *	(1.0212, 1.0406)
	O3 only	1.0173 *	(1.0079, 1.0268)	1.0213 *	(1.0119, 1.0307)
	SO2 only	1.0363 *	(1.0262, 1.0465)	1.0317 *	(1.0216, 1.0419)
	NO2 only	1.0446 *	(1.0348, 1.0543)	1.0435 *	(1.0338, 1.0532)
Two-pollutant model	PM2.5 adjusted for O3	1.0238 *	(1.0133, 1.0345)	1.0263 *	(1.0157, 1.0370)
	O3 adjusted for PM2.5	1.0072	(0.9968, 1.0176)	1.0106 *	(1.0004, 1.0209)
	PM2.5 adjusted for SO2	1.0082	(0.9959, 1.0206)	1.0193 *	(1.0067, 1.0321)
	SO2 adjusted for PM2.5	1.0307 *	(1.0176, 1.0439)	1.0183 *	(1.0051, 1.0317)
	PM2.5 adjusted for NO2	0.9856	(0.9716, 0.9998)	0.9942	(0.9798, 1.0089)
	NO2 adjusted for PM2.5	1.0560 *	(1.0411, 1.0712)	1.0481 *	(1.0331, 1.0633)
	O3 adjusted for SO2	1.0052	(0.9952, 1.0154)	1.0119 *	(1.0019, 1.0220)
	SO2 adjusted for O3	1.0342 *	(1.0233, 1.0451)	1.0269 *	(1.0160, 1.0379)
	O3 adjusted for NO2	1.0046	(0.9949, 1.0144)	1.0110 *	(1.0014, 1.0207)
	NO2 adjusted for O3	1.0431 *	(1.0329, 1.0534)	1.0406 *	(1.0306, 1.0506)
	SO2 adjusted for NO2	1.0115	(0.9988, 1.0244)	1.0044	(0.9916, 1.0173)
	NO2 adjusted for SO2	1.0374 *	(1.025, 1.0500)	1.0408 *	(1.0283, 1.0534)
Multi-pollutant model	PM2.5 adjusted for O3, SO2 and NO2	0.9768 *	(0.9617, 0.9922)	0.9858	(0.9700, 1.0019)
	O3 adjusted for PM2.5, SO2 and NO2	1.0066	(0.9962, 1.0172)	1.0136 *	(1.0031, 1.0241)
	SO2 adjusted for PM2.5, O3 and NO2	1.0161 *	(1.0024, 1.0300)	1.0035	(0.9896, 1.0174)
	NO2 adjusted for PM2.5, O3 and SO2	1.0509 *	(1.0353, 1.0668)	1.0490 *	(1.0332, 1.0651

* p < 0.05, RR = relative risk, CI = confidence interval, IQR = interquartile range.