What is the clinical evidence from this study?

Study design: Cohort. Population: Chronic obstructive pulmonary disease (COPD) (n=467944). Intervention: Total physical activity vs. Lowest quartile of physical activity (<10.7 MET-h/d). Primary outcome: Incident COPD hospitalization (HR 0.80, 95% CI 0.70-0.92, p=<0.001).

September 1, 2025The Lancet Regional Health - Western Pacific1 citationsOpen Access

Effect modification of long-term air pollution exposure on the association of physical activity with COPD hospitalization: a prospective cohort study of 0.5 million Chinese adults

Q: What are the key findings of this study?

High physical activity (≥29.8 MET-h/d) was associated with a 20% lower risk of COPD hospitalization (HR 0.80) in low PM2.5 areas, but this benefit was attenuated in high PM2.5 areas (HR 1.08, p-interaction <0.001).

XXXi XiaSun Yat-sen University CLCong LiuChangjiang Water Resources Commission YNYue NiuShanghai Jiao Tong University

Key Result

High physical activity (≥29.8 MET-h/d) was associated with a 20% lower risk of COPD hospitalization (HR 0.80) in low PM2.5 areas, but this benefit was attenuated in high PM2.5 areas (HR 1.08, p-interaction <0.001).

Study Design

Type

Cohort (n=467,944)

Multicenter

Yes

Structured PICO

Does long-term ambient air pollution exposure modify the benefits of physical activity against COPD hospitalization in Chinese adults?

Population

467,944 Chinese adults aged 30-79 years without evident airflow obstruction at baseline, followed for a mean of 12.5 years.

Exposure

Physical activity

Comparator

Varying levels of long-term ambient air pollution exposure

Outcome

COPD hospitalizationhard clinical

Long-term exposure to ambient air pollution attenuates the protective effects of physical activity against COPD hospitalization.

Main Result

Hazard Ratio: 0.8 (95% CI 0.7–0.92)

p-value: p=<0.001

Limitations

Physical activity was estimated based on self-reported information at baseline, which may be subject to measurement error or changes over time.
Could not distinguish between indoor and outdoor physical activity or time spent outdoors.
Incidents recorded captured only more severe cases requiring hospitalization, not mild cases diagnosed in outpatient settings.
Ambient air pollution was estimated at the residential neighborhood level, leading to potential exposure misclassification.
Potential residual confounding from measured or unmeasured factors.

Abstract

Background: Little is known about how long-term ambient air pollution exposure modifies the potential benefits of physical activity against chronic obstructive pulmonary disease (COPD). We aimed to examine the interaction between ambient air pollution and physical activity in relation to risk of COPD hospitalization. Methods: ), respectively, using multivariable Cox regression. Findings: ). The effect modification strengthened when stratifying participants by higher cut-offs of air pollution exposure. Interpretation: Long-term exposure to ambient air pollution is associated with attenuation of the potential benefits of physical activity against COPD in Chinese adults. Funding: Sino-British Fellowship Trust, National Key Research and Development Program of China, Kadoorie Charitable Foundation, Wellcome, Noncommunicable Chronic Diseases-National Science and Technology Major Project, National Natural Science Foundation of China, UK Medical Research Council, Cancer Research UK, British Heart Foundation.

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