A Study of the Combined Effects of Physical Activity and Air Pollution on Mortality in Elderly Urban Residents: The Danish Diet, Cancer, and Health Cohort
Background: Physical activity reduces, whereas exposure to air pollution increases, the risk of premature mortality. Physical activity amplifies respiratory uptake and deposition of air pollutants in the lung, which may augment acute harmful effects of air pollution during exercise.
Objectives: We aimed to examine whether benefits of physical activity on mortality are moderated by long-term exposure to high air pollution levels in an urban setting.
Methods: A total of 52,061 subjects (50–65 years of age) from the Danish Diet, Cancer, and Health cohort, living in Aarhus and Copenhagen, reported data on physical activity in 1993–1997 and were followed until 2010. High exposure to air pollution was defined as the upper 25th percentile of modeled nitrogen dioxide (NO2) levels at residential addresses. We associated participation in sports, cycling, gardening, and walking with total and cause-specific mortality by Cox regression, and introduced NO2 as an interaction term.
Results: In total, 5,534 subjects died: 2,864 from cancer, 1,285 from cardiovascular disease, 354 from respiratory disease, and 122 from diabetes. Significant inverse associations of participation in sports, cycling, and gardening with total, cardiovascular, and diabetes mortality were not modified by NO2. Reductions in respiratory mortality associated with cycling and gardening were more pronounced among participants with moderate/low NO2 [hazard ratio (HR) = 0.55; 95% CI: 0.42, 0.72 and 0.55; 95% CI: 0.41, 0.73, respectively] than with high NO2 exposure (HR = 0.77; 95% CI: 0.54, 1.11 and HR = 0.81; 95% CI: 0.55, 1.18, p-interaction = 0.09 and 0.02, respectively).
Conclusions: In general, exposure to high levels of traffic-related air pollution did not modify associations, indicating beneficial effects of physical activity on mortality. These novel findings require replication in other study populations.
1Center for Epidemiology and Screening, Department of Public Health, University of Copenhagen, Copenhagen, Denmark; 2Danish Cancer Research Center, Danish Cancer Society, Copenhagen, Denmark; 3Centre for Environmental Policy, Imperial College London, London, United Kingdom; 4Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; 5Center for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; 6Universitat Pompeu Fabra, Barcelona, Spain; 7CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain; 8Department of Environmental Science, Aarhus University, Roskilde, Denmark; 9Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark; 10Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark
Recommended Citation:
Zorana Jovanovic,ersen,1,et al. A Study of the Combined Effects of Physical Activity and Air Pollution on Mortality in Elderly Urban Residents: The Danish Diet, Cancer, and Health Cohort[J]. Environmental Health Perspectives,2015-01-01,Volume 123(Issue 6):557