Objective.—The prevalence of airflow obstruction in recreational self-contained underwater breathing apparatus (SCUBA) divers is unknown. Since airflow obstruction is a relative contraindication for diving, we conducted a study to determine its prevalence and magnitude in a cohort of recreational divers in Saba, Netherlands Antilles.

Methods.—Prior to diving, divers were asked to complete a diving/health questionnaire and then to perform spirometry administered by trained dive store personnel. Spirometry instrumentation provided immediate feedback regarding test quality.

Results.—Of 8365 eligible divers during the study period (November 1997–March 1999), 668 enrolled and completed questionnaires. Of those completing questionnaires, 46% reported a history of smoking, 13% were current smokers, 15% wheezed, 6% had asthma, 4% used bronchodilators, and 3% took oral steroids. Of 654 completing spirometry, 231 had acceptable spirometry quality and complete questionnaires. By forced expiratory volume in 1 second/forced vital capacity, 10% had mild, 1.7% had moderate, and 0.4% had severe airflow obstruction.

Conclusions.—The prevalence of airflow obstruction was 6% to 15% by report and 12% by spirometry, approximating the combined prevalence of asthma and chronic obstructive pulmonary disease in the general population. Study limitations include possible self-selection and low enrollment rate. Prospective lung function testing can be conducted at remote sites using nonmedical personnel as “testers.” This study could guide future investigations to determine if asthma is a risk factor for decompression illness.