Grammy-winning jazz singer Al Jarreau was rushed to the hospital before a concert in France today when he began having problems breathing.  Mr. Jarreau's British agent blamed the high altitude of Barcelonnette, in the Alps, for the 70-year old's condition.  He was rushed to a hospital with an intensive care unit in nearby Gap and was listed in critical condition, although by press time he had been taken off assisted breathing and was showing some improvement.  Doctors were still unsure of the cause of Jarreau's condition but said that fatigue, combined with the thin air in the Alps were the most probable suspects.  They recommended that the singer take some time off to recover and rest before resuming his current tour.