The purpose of the study is to investigate the nature, frequency, and possible causes of reported episodes of marked increases in the incidence of certain respiratory conditions in the New Orleans area. The study has been restricted to persons admitted for acute respiratory embarrassment to the Charity Hospital emergency clinic and to the period since December 1, 1957. The objectives are to determine the demographic and clinical characteristics of the persons under study, to determine the temporal and geographic aspects of acute respiratory embarrassment, to identify local point and area sources of air pollution, and to determine whether relationships exist between weather variables for the period in the geographic and temporal characteristics of the admissions.