"After the Sunset" actress Salma Hayek spent hours in a decompression chamber after she experienced "fatigue and exhaustion" while diving, a spokesperson for the film being shot in New Providence said on Monday.

"As a precaution, the doctor recommended she enter the decompression chamber."

Sources said the 35-year-old Mexican actress, who the spokesperson said is a certified diver, had been taken to Paradise Island on Sunday, where she was to have filmed a beach scene with co-star Pierce Brosnan. They said she was then taken by ambulance to Lyford Cay, where the medical centre has the only chamber on the island, which can be used to stabilise divers who have developed the bends or embolisms.

Both conditions can result from surfacing too quickly from the increased water and air pressure a diver encounters.

While she was being treated, some people involved in the beach scene were kept on standby.

The production spokesperson said filming continued both Sunday and Monday, and the movie is expected to wrap up in The Bahamas on Friday. She said everything is running on schedule.

"We move to Los Angeles and we will shoot in January," she said, before the film is scheduled to be complete on Feb. 6.

Professional divers describe decompression as unpleasant but necessary for several conditions.

When one breathes from a scuba tank, the air has the same pressure as the water is exerting. It has to, or it won't come out of the tank. Therefore, when scuba diving, the air in lungs at a 33-foot depth has twice the pressure of air on land. At 66 feet, it has three times the pressure, and so on.

When high-pressure gases contact water, they dissolve and some of the nitrogen from air will dissolve in the water in the body. If a bdiver were to swim quickly to the surface, it is like uncapping a bottle of soda as the gas is released. This can be very painful and sometimes fatal.

To avoid the effects of quick decompression, the diver must rise slowly and/or make intermittent decompression stops on the way so the gas can come out of solution slowly. If the diver does rise too fast, the only cure is to enter the chamber in which the air pressure matches that at depth (breathing 100-per-cent oxygen on the way to the chamber also helps). Then, the pressure is released slowly.

An embolism is an air bubble in the blood, which can be caused by a rupture of small blood vessels in the lungs as the diver rises too fast for the gradual change in pressure that avoids problems.

Posted: Tuesday December 16,2003