Lung function over the first 3 years of a professional diving career.

OBJECTIVES: To characterise diving exposure and pulmonary function in professional divers at the start of their formal education and during the first 3 years of their professional career. METHODS: The study included 87 men at the start of their education as professional divers. At follow up 1 and 3 years after the school 83 and 81 divers respectively were re-examined. Assessment of lung function included dynamic lung volumes and flows and transfer factor for carbon monoxide (Tl(CO)). RESULTS: 69 Divers had preschool SCUBA diving experience and had a median number of 70 dives (range 2-3000) to a median maximal depth of 40 (range 10-73) metres. During the 15 week introductory diving course, they had 44 dives (range 38-50) in the depth range 10-50 metres. The median number of dives over the follow up period was 95 (range 0-722) to a maximal median depth of 38 (range 0-98) metres. At the start of the diving course there were no differences in forced vital capacity (FVC), forced expired volume in 1 second (FEV(1)), and in Tl(CO) between the 69 pre-exposed divers and the 18 never exposed divers. The FVC was significantly larger than predicted in both groups. At follow up at 3 years there was a significant reduction in mean (SD) FEV(1) of 1.8% (6.5), in forced mid-expiratory flow rate (FEF(25-75%)) of 6.5% (11.7) and in forced expiratory flow at 75% of FVC expired (FEF(75%)) of 10.4% (16. 8). There was no change in FVC. The Tl(CO) was significantly decreased by 4.6% (8.8). No significant effects were found of cumulative diving exposure, including the number of dives, on the relative changes of any of the lung function variables. CONCLUSIONS: The results indicate that divers initially belong to a selected group with large FVC. Exposure to diving may contribute to changes in pulmonary function, mostly affecting small airways conductance.