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Air pollution and ST-segment depression in elderly subjects
Diane R Gold1, Augusto A Litonjua, Antonella Zanobetti
1Channing Laboratory, Brigham and Women's Hospital, Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA. diane.gold@channing.harvard.edu
Environmental Health Perspectives
|July 9, 2005
Summary
Exposure to traffic-related air pollution, measured by black carbon (BC), is linked to ST-segment depression, a heart rhythm change. This finding suggests a connection between air quality and cardiovascular health in older adults.
Area of Science:
- Environmental Health
- Cardiology
- Epidemiology
Background:
- Ambient particle pollution is associated with cardiovascular morbidity.
- Black carbon (BC) quantifies traffic-related particle exposure.
- Previous studies indicate a link between air pollution and cardiovascular events.
Purpose of the Study:
- To investigate the association between ambient pollution, specifically black carbon (BC), and ST-segment levels during a monitored protocol.
- To determine if traffic-related particle exposure impacts cardiac electrical activity.
Main Methods:
- A repeated-measures study involving 24 active older adults (61-88 years) with 269 observations.
- Continuous Holter electrocardiogram monitoring during rest, standing, exercise, recovery, and paced breathing.
- Analysis of ST-segment levels in relation to preceding black carbon (BC) levels (12-hr mean and 5-hr pre-test).
Main Results:
- Elevated mean BC levels in the preceding 12 hours and 5 hours predicted ST-segment depression.
- The strongest association was observed during post-exercise periods.
- An elevated BC level was associated with -0.1 mm ST-segment depression during post-exercise rest (p=0.001 for 5-hr BC).
- Elevated BC also predicted an increased risk of significant ST-segment depression (> or = 0.5 mm).
- Carbon monoxide did not confound the observed association.
Conclusions:
- Increased exposure to traffic-related particles (black carbon) is associated with ST-segment depression.
- ST-segment depression may indicate myocardial ischemia or inflammation.
- Findings highlight the cardiovascular impact of ambient air pollution from traffic sources.