The nation's deep recession is helping to alleviate the decade-long nursing shortage, as workers who had left the field are returning. Nearly a quarter-million nurses entered the work force in 2007-08, an 18% surge that was the largest two-year increase in at least three decades, according to a study. Many nurses who had left the field have re-entered the work force to compensate for a spouse's lost income or health benefits, the study said.