This article is a commentary on the following study: Devlin RB, Ghio AJ, Kehrl H, Sanders G, Cascio W. Elderly humans exposed to concentrated air pollution particles have decreased heart rate variability. Eur Respir J Suppl. 2003 May;40:76s-80s. The objective is to identify a possible association between exposure to PM2.5 particles and heart rate variability in healthy elderly subjects and in young adults. This study is very interesting because it supports an intriguing hypothesis regarding the role of particulate matter in causing heart rhythm disorders and, consequently, cardiovascular diseases. However, it should be supplemented by studies that account for additional confounding factors and include a larger sample size to strengthen confidence in the results.