['Previous studies have observed that short-term exposure to elevated concentrations of particulate matter (PM) air pollution increases risk of acute ischemic heart disease events and heart failure hospitalization, alters cardiac autonomic function, and increases risk of arrhythmias. This study explored the potential associations between short-term elevations in PM exposure and atrial fibrillation (AF).', 'A case-crossover study design was used to explore associations between fine PM (PM2.5, particles with an aerodynamic diameter ≤2.5 μm) and 10,457 AF hospitalizations from 1993 to 2008 of patients who lived on Utah’s Wasatch Front. Patients were hospitalized at Intermountain Healthcare facilities with a primary diagnosis of AF. Concurrent day exposure and cumulative lagged exposures for up to 21 days were explored and the data were stratified by sex, age, and previous or subsequent admission for myocardial infarction. Although the estimated associations between PM2.5 and AF hospitalizations for the various lag structures and strata were consistently positive suggestive of risk, they were not statistically significant and they were extremely small compared to previously observed associations with ischemic heart disease events and heart failure hospitalizations. Further, we observed no additive risk between PM2.5 and AF hospitalization in those with respiratory disease or sleep apnea.'] Is atrial fibrillation hospitalization increased with short-term elevations in exposure to fine particulate air pollution?