Risk/benefit tradeoff of habitual physical activity and air pollution on chronic pulmonary obstructive disease: findings from a large prospective cohort study

Table 4 Associations between PM_2.5 levels and COPD incidence when exposed to different self-reported physical activity (PA) levels

PM_2.5 levels ^a		Low-level PA		Moderate-level PA		High-level PA
PM_2.5 levels ^a	Case	HR (95% CI) ^b	P	HR (95% CI) ^b	P	HR (95% CI) ^b	P
Low	1959	1.000	–	1.000	–	1.000	–
Moderate	2164	1.071 (0.942, 1.218)	0.296	1.004 (0.909, 1.109)	0.940	1.084 (0.980, 1.199)	0.117
High	2311	1.053 (0.920, 1.206)	0.450	1.048 (0.945, 1.163)	0.370	1.099 (0.989, 1.222)	0.081
Trend test	–		0.464		0.364		0.081

Abbreviations: HR hazard ratio, CI confidence interval, PA physical activity, COPD chronic obstructive pulmonary disease, PM_2.5 particulate matter with aerodynamic diameter < 2.5 μm
^a PM_2.5 exposure levels (low, moderate, and high) were defined by PM_2.5 tertiles (< 9.48 μg/m³, 9.48 to 10.27 μg/m³, and ≥ 10.27 μg/m³), and self-reported PA levels were defined according to a standard scoring criteria of International Physical Activity Questionnaire (IPAQ): low (< 600 MET-min/week), moderate (600 to 3000 MET-min/week), and high (≥ 3000 MET-min/week)
^b All results were calculated fully adjusted by covariates in Model 3: age at enrolment, sex, ethnicity, household income, employment status, education, Townsend deprivation index, smoking status, alcohol intake frequency, fruit and vegetable intake, body mass index (BMI), and secondhand smoke exposure

ISSN: 1741-7015