Keith Palmer, Editor AIR POLLUTION AND VENTRICULAR ARRHYTHMIAS

Episodes of particulate air pollution have been associated with increased cardiovas-cular mortality and morbidity, while a number of studies indicate short term changes in heart rate variability and a liability to ventricular arrhythmias. Rich et al1 have assessed the last of these effects among a cohort of patients with implantable cardioverter defibrillators. These devices, which are designed to detect and treat life-threatening ventricular arrhythmias, offer a research opportunity to monitor heart rhythm during pollution episodes. A case-crossover design was used to compare periods in which ventricular arrhythmias occurred with control periods matched on week day, hour of day, and calendar month, with adjustment for various climatic factors. The authors estimate a significant 24 % increase in risk for each 5 ppb increase in mean sulphur dioxide, and non-significant rises in relation to nitrogen dioxide and elemental carbon in the previous 24 hours. Their findings are consistent with earlier observations, even though the constituent pollutants are likely to have varied between studies. An accompanying editorial discusses the issues raised.2 NOISE AND CHILDREN’S BLOOD PRESSUR