PA levels a | Â | Low-level PM2.5 | Moderate-level PM2.5 | High-level PM2.5 |
---|
Case | HR (95% CI) b | P | HR (95% CI) b | P | HR (95% CI) b | P |
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Self-reported PA |
 Low | 1495 | 1.000 | – | 1.000 | – | 1.000 | – |
 Moderate | 2530 | 0.786 (0.698, 0.884) | <0.0001 | 0.727 (0.65, 0.812) | <0.0001 | 0.792 (0.711, 0.882) | <0.0001 |
 High | 2409 | 0.714 (0.633, 0.806) | <0.0001 | 0.707 (0.631, 0.792) | <0.0001 | 0.751 (0.672, 0.84) | <0.0001 |
 Trend test | – |  | <0.0001 |  | <0.0001 |  | <0.0001 |
Objectively measured PA |
 Low | 253 | 1.000 | – | 1.000 | – | 1.000 | – |
 Moderate | 434 | 0.835 (0.651, 1.072) | 0.157 | 0.696 (0.549, 0.883) | 0.003 | 0.752 (0.587, 0.962) | 0.024 |
 High | 403 | 0.656 (0.489, 0.881) | 0.005 | 0.571 (0.429, 0.76) | <0.0001 | 0.696 (0.523, 0.927) | 0.013 |
 Trend test | – |  | 0.005 |  | 0.007 |  | 0.001 |
- The bold type represents the statistically significant differences (p < 0.05)
- Abbreviations: PM2.5 particulate matter with aerodynamic diameter < 2.5 μm, HR hazard ratio, CI confidence interval, PA physical activity, COPD chronic obstructive pulmonary diseases
- a 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), and objectively measured PA levels were defined by objectively measured PA tertiles [< 24.32 milli-gravity (mg), 24.32 to 30.70 mg, and ≥ 30.70 mg]
- bAll 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