Table 3. Disabling agents in a scuba diving fatality .

Disabling agents

Definition: A disabling agent (as used here) is an action or circumstance (associated with the trigger) that caused injury or illness. It may be an action of the diver or other persons, reaction of the equipment, effect of a medical condition or a force of nature.

Gas supply-related: Includes any problem relating to the on-going supply, purity and suitability of the breathing gas but not loss of gas supply due to equipment failure.

• Inappropriate breathing gas mixture;

• Contamination;

• Exhaustion of breathing gas supply.

Ascent-related: Includes any problem that was likely precipitated by or associated with the ascent from a dive. This may include but is not restricted to:

• Breath holding during ascent;

• Gas sharing during ascent;

• Rapid ascent.

Medical-related: Includes any problem that was likely precipitated by or associated with a pre-existing or imminent medical condition (which may or may not be the same as the disabling injury). It may include but is not restricted to:

• Cardiovascular disease;

• Other medical condition.

Buoyancy-related: Includes buoyancy problems related to poor knowledge or skills and secondary to some trigger. It can also include loss of buoyancy control subsequent to equipment failure (e.g., loss of buoyancy subsequent to a faulty BCD).

• Inadequate buoyancy control underwater;

• Lack/loss of buoyancy on surface;

• Drysuit 'blow-up' subsequent to equipment failure.

Environment-related: Includes problems where a diver is disabled as a result of environmental circumstances such as:

• Adverse sea conditions;

• Entrapment − this entrapment is secondary to an initial trigger such as narcosis, silting, poor buoyancy or surge. It often leads to exhaustion of the breathing gas (in which case, the disabling agent is recorded as environmental – entrapment, then out of breathing gas.

• Impact with watercraft, rocks, reef;

• Dangerous marine animal contact (e.g., shark attack).

Equipment-related: Includes a consequence of a problem associated with an item of the diver’s equipment, but secondary to some accident trigger.

Other: Includes anything that cannot appropriately be allocated to one of the defined categories. This category should be used sparingly and only after a serious attempt to utilise an existing category.

Unknown: There is insufficient information on which to make a reasonable suggestion of a possible disabling agent.