Spirometric Standards for Healthy Nonsmoking Adults

Previous studies designed to establish normal standards for ventilatory testing have usually included substantial numbers of cigarette smokers and hospital patients. Forced expiratory flows and volumes were measured in 988 healthy nonsmoking men and women who had relatively little exposure to any form of air pollution. Negative correlations were obtained with age and positive correlations with height. Prediction formulas were derived and nomograms were constructed for 4 standard ventilatory measurements. Comparisons were made with prediction formulas of other workers. There was progressive decline in ventilatory function with age; larger values in men were present at all ages. Wide variation was encountered and was not attributable to age, sex, or height. This was most marked in the two forced expiratory flows, which had low multiple correlations and large standard errors of estimate. The wide range of normal values seriously impairs the usefulness of spirometry in reliably detecting impairment of ventila...