The indigenous fisherman divers of Thailand: diving-related mortality and morbidity.

The Urak Lawoi are indigenous fishermen on Thailand's west coast. The population includes an estimated 400 divers who dive using surface-supplied compressed air. In a cross-sectional survey conducted among the 6 major communities of Urak Lawoi, questionnaire-based interviews were administered to active divers, ex-divers, and families or colleagues of divers who had died in the previous 5 years. Six deaths resulting from diving-related accidents were identified, indicating a diving-related mortality rate of approximately 300 per 100,000 person-years, while in the same 5-year period 11 divers had been disabled owing to diving-related events, indicating a diving-related disabling event rate of approximately 550 per 100,000 person-years. Among 342 active divers interviewed, one third reported having suffered from decompression illness, although based on reported current symptoms over 50% were classified as suffering from recurring non-disabling decompression illness. Physical examination conducted on a subset of 98 active divers revealed the presence of spinal injury (clonus, raised muscle tone, and heightened reflexes) and of joint damage (pain in one or more joint, crepitus, or restricted movement) in 24 and 30% respectively. Improved primary prevention and medical treatment are needed to reduce mortality and morbidity among this population.

The indigenous fisherman divers of Thailand: diving practices.

Diving practices of a group of indigenous people living on Thailand's west coast were investigated. Village chiefs were first interviewed using a questionnaire. Three hundred and forty-two active divers were then interviewed by health care workers using a second questionnaire. Field observation was used to further develop information and confirm diving practices. Divers in 6 villages, whose basic means of making a living is from diving for marine products such as fish and shellfish, have diving patterns that put them at substantial risk of decompression illness. Breathing air from a primitive compressor through approximately 100 m of air hose, these divers have long bottom times coupled with short surface intervals. Forty-six point two percent of the divers indicated that they would not make a stop during ascent from a long deep dive (40 m for 30 min). When comparing their previous day of diving to the U.S. Navy Standard Air Decompression Table (U.S. Navy, 1993), 72.1% exceeded the no-decompression limits set by the tables. Diving patterns point to a need for more in-depth research into the diving patterns of this indigenous group. Future research should include the use of dive logging devices to record depths and times. There is also a need to provide divers with information and training to reinforce positive practices and strengthen knowledge of the risks associated with their current diving practices.

The indigenous Sea Gypsy divers of Thailand's west coast: measurement of carbon monoxide in the breathing air.

Approximately 400 indigenous divers live and work on Thailand's west coast. They dive with surface supplied air from primitive compressor units mounted on open boats which measure from seven to 11 meters in length. It was suspected that carbon monoxide was present in the breathing air of at least the gasoline-driven compressor units. To determine the presence of carbon monoxide gas in the breathing air, compressed air from the compressor was pumped through the diver air supply hose through a plenum (monitoring) chamber established on the boat. After a compressor warm-up of 15 minutes, the diving air was measured with the boat at eight different bearings to the wind, each 45 degrees apart at intervals of five minutes. Three of the four gasoline-driven compressor units tested showed presence of carbon monoxide in the breathing air. One diesel-driven unit showed a very low concentration of carbon monoxide (3-4 ppm) and six diesel-driven units showed no detectable carbon monoxide. Although not tested, diesel exhaust emissions could also enter the breathing air by the same route. A locally made modification to the compressor air intake was designed and successfully tested on one gasoline-driven compressor unit. An information sheet on the hazards of carbon monoxide as well as on the modification has been developed for distribution among the villages.

The indigenous fisherman divers of Thailand: in-water recompression.

BACKGROUND: The Urak Lawoi, part of the Sea Gypsies of Thailand, have been diving using surface-supplied compressed air for more than 30 years. Their dive sites range from one hour to several days from their villages. Similar to other indigenous fisherman divers, the Urak Lawoi suffer from a high incidence of decompression illness. Their methods of in-water recompression were investigated. METHODS: In December 1998, available divers in two Urak Lawoi villages were asked if they had ever been treated using in-water recompression following decompression illness. If the divers responded positively, a questionnaire-based interview was carried out. Divers were asked to recall the cause of the accident, their diving patterns of the day, the parts of the body affected, the depths and times of in-water recompression and whether the problems were resolved as a direct result of this action. RESULTS: Eleven divers, aged 19-52, were interviewed. Causal factors listed by the divers included diving pattern 55% (6/11), rapid ascent 27% (3/11), and equipment failure 18% (2/11). Divers were recompressed in water using surface-supplied compressed air. The time between surfacing from the accident-related dive and being put back in the water ranged from immediately to 60 minutes. Depth and duration of in-water recompression ranged from 4 to 30 meters and 5 to 120 minutes. Outcomes reported by the divers were: improved or resolved at depth with no return of symptoms at surface in 64% (7/11), improved or resolved at depth with a return of symptoms at surface in 18 (2/11), and not resolved at depth in 18% (2/11). DISCUSSION: Health-care workers in the villages may be able to provide basic first aid but, for some villages, a medical doctor may be as much as 10 hours away and a recompression facility as far as 16 hours in good weathier. In-water recompression has, within the diving population, proved to be an appropriate first-aid measure for decompression illness. A future project activity will develop consensus guidelines for determining under what circumstances in-water recompression using surface-supplied air should be carried out and identify appropriate methods that the Urak Lawoi can apply.