New Orleans asthma : II. Relationship of climatologic and seasonal factors to outbreaks

Outbreaks of obstructive pulmonary disease in the city of New Orleans, which occur in epidemic proportions, are generally seasonal, occurring with greater frequency and magnitude during the months of September, October, and November. These fall outbreaks are associated with minimum temperatures and minimum humidities. Involved individuals are not symptomatic exclusively during outbreaks, and previously observed similarities between involved and noninvolved asthmatic subjects are due to the overlap of these groups. In light of previous observations that New Orleans asthma affects a homogeneous group of allergic individuals and is not related to measurable increases in specific chemical pollutants, the observed climatological and seasonal variations suggest that it does not differ from conventional "extrinsic" bronchial asthma.