Table 3.

Results of stratified analyses by habitual exercise or PM_2.5 concentration quartiles in Taiwanese adults

Subgroup	HR (95% CI)		P	HR (95% CI)		P	HR (95% CI)		P
Effects of exercise: stratified by PM2.5 concentration	Low—PM2.5 concentration			Moderate—PM2.5 concentration			High—PM2.5 concentration
Inactive (0 MET-h)	Reference			Reference			Reference
Moderate (0.01–8.75 MET-h)	0.87	(0.83, 0.92)	<0.001	0.90	(0.86, 0.95)	<0.001	0.95	(0.90, 1.00)	0.05
High (>8.75 MET-h)	0.68	(0.64, 0.72)	<0.001	0.75	(0.71, 0.80)	<0.001	0.77	(0.73, 0.81)	<0.001
Test for trend a	0.82	(0.80, 0.85)	<0.001	0.87	(0.85, 0.89)	<0.001	0.88	(0.86, 0.90)	<0.001
Effects of PM 2.5 : stratified by exercise	Inactive			Moderate-exercise level			High – exercise level
Low (≤22.37 μg/m3)	Reference			Reference			Reference
Moderate (22.37–25.96 μg/m3)	1.27	(1.21, 1.34)	<0.001	1.31	(1.24, 1.39)	<0.001	1.42	(1.34, 1.50)	<0.001
High (>25.96 μg/m3)	1.63	(1.52, 1.75)	<0.001	1.83	(1.70, 1.97)	<0.001	2.01	(1.85, 2.18)	<0.001
Test for trend a	1.28	(1.23, 1.32)	<0.001	1.34	(1.30, 1.39)	<0.001	1.42	(1.36, 1.47)	<0.001
Per 10 μg/m3 increment	1.74	(1.63, 1.86)	<0.001	1.92	(1.80, 2.05)	<0.001	2.16	(2.02, 2.30)	<0.001

All results were fully adjusted for age, sex, educational level, season, baseline calendar year, physical labor at work, smoking status, alcohol consumption, occupational exposure, vegetable intake, fruit intake, BMI, hypertension, diabetes, self-reported cardiovascular disease, and self-reported cancer.

^aThe trend test was performed by entering 1, 2, and 3 as continuous variables in the models for inactive exercise level/low PM_2.5 concentration_, moderate exercise level/moderate PM_2.5 concentration, and high exercise level/high PM_2.5 concentration, respectively.

95% CI, 95% confidence interval; HR, hazard ratio.