Unexplained Atrial Fibrillation is Associated with High Ambient Ozone

David Q. Rich, Sc.D, Frank E. Speizer, MD, Diane Gold, MD, D.Sc., MPH, Joel Schwartz, Ph.D., and Douglas W. Dockery, Sc.D.
Harvard School of Public Health
P01ES09825, P30ES00002, and T32ES7069

Background: Atrial fibrillation (AF) is defined as a heart arrhythmia in which electrical activity in the atria is disorganized resulting in an irregular ventricular rhythm. At least 2.3 million adults in the United States have some form of atrial fibrillation; however, this number is likely an underestimate because many people with this condition are asymptomatic. AF is a risk factor for stroke and is usually associated with one or a combination of pre-existing conditions such as hypertension, ischaemic heart disease, heart failure, cardiomyopathy, mitral valve disease, and prior myocardial infarction. When AF occurs in the absence of another condition, it is called paroxysmal atrial fibrillation (PAF). The symptoms of paroxysmal AF are often devastating because of its unpredictable nature and dramatic changes of heart rate and regularity. There exists an increasing body of evidence that exposure to certain ambient air pollutants at levels that occur frequently in large urban environments is associated with (AF). Previous studies by this NIEHS-supported laboratory at the Harvard School of Public Health have found associations between PAF and episodes of high levels of black carbon and nitrogen dioxide in ambient air.

Advance: In an epidemiologic study with 202 participants in the Boston metropolitan area, these investigators examined the link between community air pollution and 91 confirmed cases of PAF in 29 subjects. They report a positive association between episodes of PAF and increased ozone concentration. The risk of arrhythmia was two-fold higher within one hour of high ozone exposure. The risk estimate for a longer moving average was decreased suggesting a more immediate effect.

Implications: Ozone is known to be an acute lung irritant and has been associated with acute myocardial infarction and exacerbation of asthma and other respiratory conditions. The results from this study identify ozone air pollution as a potential precipitant of ventricular arrhythmia. These findings add to the evidence that poor air quality is a risk factor for atrial fibrillation. They also indicate that persons with pre-existing AF and other heart conditions should reduce activity and remain indoors during periods of high ambient ozone concentration.

Citation: Rich DQ, Mittleman MA, Link MS, Schwartz J, Luttmann-Gibson H, Catalano PJ, Speizer FE, Gold DR, Dockery DW. Increased risk of paroxysmal atrial fibrillation episodes associated with acute increases in ambient air pollution. Environ Health Perspect. 2006 Jan;114(1):120-3.