Exposure to Air Pollution and Particle Radioactivity With the Risk of Ventricular Arrhythmias

Abstract

Background: Individuals are exposed to air pollution and ionizing radiation from natural sources through inhalation of particles. This study investigates the association between cardiac arrhythmias and short-term exposures to fine particulate matter (PM_2.5) and particle radioactivity. Methods: Ventricular arrhythmic events were identified among 176 patients with dual-chamber implanted cardioverter-defibrillators (ICDs) in Boston, Massachusetts between September 2006 and June 2010. Patients were assigned exposures based on residential addresses. Daily PM_2.5 level was estimated at 1-km×1-km grid cells from a previously validated prediction model. Particle gross β activity was used as a surrogate for particle radioactivity and was measured from several monitoring sites by the U.S. Environmental Protection Agency's monitoring network. The association of the onset of ventricular arrhythmias (VA) with 0-21 day moving averages of PM_2.5 and particle radioactivity (two single-pollutant models and a two-pollutant model) prior to the event were examined using time-stratified case-crossover analyses, adjusted for dew point and air temperatures. Results: A total of 1,050 VA were recorded among 91 patients, including 123 sustained VA among 25 of these patients. In the single-pollutant model of PM_2.5, each interquartile range (IQR) increase in daily PM_2.5 levels for a 21-day moving average was associated with 39% higher odds of a VA event (95% CI: 12% to 72%). In the single-pollutant model of particle radioactivity, each IQR increase in particle radioactivity for a 2-day moving average was associated with 13% higher odds of a VA event (95% CI: 1% to 26%). In the two-pollutant model, for the same averaging window of 21-days, each IQR increase in daily PM_2.5 was associated with an 48% higher odds of a VA event (95% CI: 15 to 90%), and each IQR increase of particle radioactivity with a 10% lower odds of a VA event (95% CI: -29% to 14%). We found that with higher levels of particle radioactivity, the effect of PM_2.5 on ventricular arrhythmias is reduced. Conclusions: In this high-risk population, intermediate (21-day) PM_2.5 exposure was associated with higher odds of a ventricular arrhythmia event onset among patients with known cardiac disease and indication for ICD implantation independently of particle radioactivity.