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Higher fine particulate matter and temperature levels impair exercise capacity in cardiac patients
  1. Paolo Giorgini1,
  2. Melvyn Rubenfire2,
  3. Ritabrata Das3,
  4. Theresa Gracik4,
  5. Lu Wang3,
  6. Masako Morishita4,
  7. Robert L Bard2,
  8. Elizabeth A Jackson2,
  9. Craig A Fitzner5,
  10. Claudio Ferri1,
  11. Robert D Brook2
  1. 1Department of Life, Health and Environmental Sciences, Division of Internal Medicine and Nephrology, University of L'Aquila, L'Aquila, Italy
  2. 2Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA
  3. 3Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
  4. 4Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan, USA
  5. 5Air Quality Division, Department of Environmental Quality, Lansing, Michigan, USA
  1. Correspondence to Dr Robert D Brook, Professor of Medicine Division of Cardiovascular Medicine, University of Michigan Medical School, 24 Frank Lloyd Wright Dr, PO Box 322, Ann Arbor MI 48106, USA; robdbrok{at}umich.edu

Abstract

Objective Fine particulate matter (PM2.5) air pollution and variations in ambient temperature have been linked to increased cardiovascular morbidity and mortality. However, no large-scale study has assessed their effects on directly measured aerobic functional capacity among high-risk patients.

Methods Using a cross-sectional observational design, we evaluated the effects of ambient PM2.5 and temperature levels over 7 days on cardiopulmonary exercise test results performed among 2078 patients enrolling into a cardiac rehabilitation programme at the University of Michigan (from January 2003 to August 2011) using multiple linear regression analyses (controlling for age, sex, body mass index).

Results Peak exercise oxygen consumption was significantly decreased by approximately 14.9% per 10 μg/m3 increase in ambient PM2.5 levels (median 10.7 μg/m3, IQR 10.1 μg/m3) (lag days 6–7). Elevations in PM2.5 were also related to decreases in ventilatory threshold (lag days 5–7) and peak heart rate (lag days 2–3) and increases in peak systolic blood pressure (lag days 4–5). A 10°C increase in temperature (median 10.5°C, IQR 17.5°C) was associated with reductions in peak exercise oxygen consumption (20.6–27.3%) and ventilatory threshold (22.9–29.2%) during all 7 lag days. In models including both factors, the outcome associations with PM2.5 were attenuated whereas the effects of temperature remained significant.

Conclusions Short-term elevations in ambient PM2.5, even at low concentrations within current air quality standards, and/or higher temperatures were associated with detrimental changes in aerobic exercise capacity, which can be linked to a worse quality of life and cardiovascular prognosis among cardiac rehabilitation patients.

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