Formal guidelines on deciding respiratory fitness for subaqua diving are available to physicians and GPS for the first time from the British Thoracic Society. Diving as a sport is booming, and doctors will be asked to assess fitness to dive more often and more stringently. They now have ready access to practical evidence based advice and guidance on when to seek specialist opinion. Both evidence and recommendations are graded according to SIGN criteria, and the guidelines will be audited for their usefulness.

The diving environment and its physiological effects pose special risks to divers. Pressure effects, decompression illness, and pulmonary oedema are all direct hazards. Then there are the effects of pre-existing respiratory illness and the potential need to be able to rescue another diver in difficulty. All are brought to bear in assessing fitness to dive.

Essentially, anyone without existing respiratory symptoms or previous lung disease or injury is fit to dive if respiratory examination and spirometric and PEFR measurements show no abnormalities, otherwise they are not. Anyone with respiratory symptoms or previous lung disease or injury is fit to dive if these measurements, plus chest and x ray examination, are normal, unless the condition is one that precludes diving or needs further specialist advice. Such conditions are lung bullae or cysts, previous spontaneous pneumothorax, some types of asthma, COPD, active sarcoidosis or tuberculosis and other serious lung conditions. Whatever the respiratory picture, though, ruling out other conditions that might compromise diver safety— diabetes or epilepsy—is essential.