Table 3.

Adjusted percent change (95% CIs) in HRV and HR associated with PM_2.5 (μg/m³)

Main effect of PM2.5	24-hr†				Day‡				Night‡
	SDNN	Power¶	HR	Power¶	SDNN	Power¶	HR	Power¶	SDNN	Power¶	HR	Power¶
PM2.5 (μg/m3)§	0.07 (−0.15 to 0.29)	0.9066	−0.13 (−0.20 to −0.06)	0.9999	−0.18 (−0.43 to 0.06)	0.9997	0.16 (0.08 to 0.24)	0.9671	−8.42 (−11.36 to −5.49)	0.9999	1.88 (1.12 to 2.65)	0.9982
PM2.5 (tertile, μg/m3)
Low (<5.97)	Reference		Reference		Reference		Reference		Reference		Reference
Medium (5.97–14.5)	−3.78 (−7.00 to −0.44)	0.9999	1.83 (0.92 to 2.74)	0.9778	−6.00 (−9.08 to −2.87)	0.9999	1.85 (0.72 to 3.00)	0.8944	−9.96 (−16.39 to −3.04)	0.9999	3.69 (1.89 to 5.52)	0.9817
High (>14.5)	−5.92 (−8.55 to −3.22)	0.9999	1.50 (0.41 to 2.59)	0.7734	−7.53 (−10.97 to −3.96)	0.9999	2.49 (1.18 to 3.82)	0.9634	−34.10 (−41.30 to −26.02)	0.9999	8.98 (5.99 to 12.06)	0.9999
P for trend	0.0129	0.7019	0.0034	0.9999	<0.0001	0.9838	0.0002	0.9999	<0.0001	0.9999	<0.0001	0.9999

^†Adjusted for age, gender, smoking status, use of statin, NSAIDs, hypertensive medication (beta blocker, calcium channel blocker or ACE inhibitors/angiotensin receptor blockers), aspirin, and time of day.

^‡Adjusted for age, gender, smoking status, use of statin, NSAIDs, hypertensive medication (beta blocker, calcium channel blocker or ACE inhibitors/angiotensin receptor blockers), and aspirin.

^§Per IQR (13.6 μg/m³) increase in PM_2.5.

^¶$\text{Observed Power}=1-\Phi \left(\frac{\beta }{\mathit{SE}}-1.96\right)$, where β and SE are the estimated regression coefficient and its standard error from mixed analysis [25].