Atrial fibrillation (AF) is the most common cardiac arrhythmia seen in clinical practice, and makes an important contribution to cardiovascular disease (CVD) and all-cause mortality. The focus of AF research has recently shifted, from concentrating on treatments and complications, to the evaluation of putative risk factors including ambient air pollution. Although the present study pertains specifically to AF, much of its content is drawn from, and therefore is applicable to, the study of other arrhythmias, the conduct of which is confronted by many of the same challenges. Meeting these challenges involves recognising the collective importance of 1. large, ethnically and geographically diverse, clinically well-characterised populations; 2. methods for reducing uncertainty in outcome ascertainment, distinguishing effects of pervasive environmental exposures and improving their estimation; 3. approaches to evaluation of susceptibility; and 4. strategies for informing regulatory policies designed to help control population-level risks for CVD.