The influence of wetsuit thickness (≥ 7 mm) on lung volumes in scuba divers.

Introduction: We hypothesised that although thicker (≥ 7 mm) wetsuits delay hypothermia and allow divers to dive in cooler waters, they may hinder pulmonary function. The aim of this study was to investigate whether thicker wetsuits worn by Tasmanian divers affected lung volumes, primarily the forced vital capacity (FVC) and forced expiratory volume, one second (FEV1).

Methods: Sixty-two volunteer active divers were recruited from recreational dive clubs and Tasmania's occupational diving industry. After confirming fitness and that the divers were currently active, spirometry testing was performed with and without the divers' usual wet suits, in a controlled dry environment. Suits were of varying thickness, but all were ≥ 7 mm thickness.

Results: All divers had significantly reduced lung volumes when wearing ≥ 7 mm wetsuits. Recreational divers had greater decrements (-7% FVC and -5% FEV1), compared to occupational divers (-3% FVC, -3% FEV1). Males' lung volumes declined -4% FVC and -4 % FEV1, whereas females declined -7 % FVC and -6 % FEV1. Female recreational divers experienced the greatest negative impact from thicker wetsuits (up to 15% reduction in FVC), and this group also demonstrated an inverse relationship between increasing wetsuit thickness and declining lung volumes.

Conclusions: Wearing thicker wet suits aids in thermal protection in temperate water diving but this study suggests it has negative effects on lung volumes. The real-life impact of this negative effect may be minor in fit healthy divers but might add additional risk to a less fit, recreational diving population with medical comorbidities.