BATON ROUGE, Louisiana (CNN) -- Two of the main hospitals serving New Orleans are unsalvageable, and it will cost hundreds of millions of dollars to replace them, the head of the hospitals said Wednesday."The big Charity and University hospital buildings were issued their 'death warrant' by Katrina and the cataclysmic floods it spawned," said Donald R. Smithburg, the chief executive of Louisiana State University Health Care Services Division. "Both facilities are dangerous, dangerous places."Charity Hospital, the main trauma center for southeastern Louisiana, and University Hospital sustained major damage during Hurricane Katrina and its aftermath. Charity's basement, where the morgue was, was so flooded that workers resorted to storing bodies in stairwells.The hospitals have been vacant since the storm, and inspectors have been assessing the damage."The buildings have unsafe air to breathe, pervasive mold growing, and mechanical systems that were completely destroyed by the storm," Smithburg said before the LSU Board of Supervisors in Baton Rouge.Both hospitals, which treated a total of more than 500,000 patients a year, are damaged beyond repair and must be replaced, he said. Smithburg estimated damage at Charity Hospital at more than $340 million; at University Hospital around $105 million.Smithburg noted that the main Charity building was built in the 1930s, and University Hospital in the 1960s. "Even before the storms, these old facilities were on the ropes," he said.He added that the buildings do not have the environmental, structural or mechanical capacity needed by 21st century health care facilities and that new facilities are needed."We are going to build newer, more modern facilities that will withstand the test of time. They will withstand the next storm, and the one after that," Smithburg said. "Charity and University have anchored the health care system of southern Louisiana for over 100 years," he said. "We believe they should be replaced quickly to ensure they provide health care for the next 100 years and beyond."