In January 1985, an air pollution episode occurred throughout Central Europe (8), resulting in an elevated number of hospital admissions for cardiovascular diseases that were attributed to admissions for acute coronary syndromes and arrhythmia (9). Concurrently, the first MONICA survey (monitoring of trends and determinants in cardiovascular disease) was carried out in Augsburg (southern Germany) (10). This survey provides the unique opportunity to study the impact of an air pollution episode on markers of early biologic effects or altered function of the heart in a random sample of the adult population. Of particular interest are markers that could explain the increase in hospital admissions for cardiovascular diseases in association with air pollution (11, 12). An elevated resting heart rate has been recognized as a risk factor for all-cause mortality as well as cardiovascular mortality independent of other major risk factors (13—15). This paper assesses whether accelerations in heart rate, as a marker for altered autonomic control of the heart (16), can be observed in association with elevated levels of air pollution.