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

Objectives-To characterise diving exposure and pulmonary function in profes sional 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 profes sional divers. At follow up 1 and 3 years after the school 83 and 81 divers respectively were re-examined. Assessment of lung function included dynami c lung volumes and flows and transfer factor for carbon monoxide Results-69 Divers had preschool SCUBA diving experience and had a median nu mber of 70 dives (range 2-3000) to a median maximal depth of 40 (range 10-7 3) 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 di fferences in forced vital capacity (FVC), forced expired volume in 1 second (FEV1), and in T1(CO), between the 69 pre-exposed divers and the 18 never exposed divers. The FVC was significantly larger than predicted in both gro ups. At follow up at 3 years there was a significant reduction in mean (SD) FEV1 of 1.8% (6.5), in forced mid-expiratory flow rate (FEF25-75%) of 6.5% (11.7) and in forced expiratory flow at 75% of FVC expired (FEF75% )of 10. 4% (16.8). There was no change in FVC. The T1(CO) was significantly decreas ed by 4.6% (8.8). No significant effects were found of cumulative diving ex posure, including the number of dives, on the relative changes of any of th e 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 pulm onary function, mostly affecting small airways conductance.