For most of the conditions caused by contaminated air, the first step is to replace the contaminated air supply with an appropriate uncontaminated breathing gas. Underwater, this will mean reverting to an alternative source. On the surface, breathing fresh air may suffice in mild cases. However, rest, breathing high concentration oxygen and general first aid measures may be required. In more severe cases, resuscitation may be needed.
It is generally believed that patients with serious cases of carbon monoxide toxicity benefit from hyperbaric oxygen therapy, and this is widely used.
Treatment of nitrogen dioxide poisoning requires rest in all cases. This may prevent the condition from progressing. If the exposure was thought to be to a toxic concentration or if the patient develops further symptoms, then 100 per cent oxygen is indicated. If pulmonary oedema develops, it should be appropriately managed.