Next week, Duke will come up with a plan to treat the mold, which the university described as a common form that typically grows outdoors. Eddie Hull, dean of residence life and executive director of housing services, said the mold does not appear to be a serious health risk to students, and no students have been relocated.

Hull sent e-mail Friday to students in Edens 2A on the West Campus, informing them that mold had been found in four rooms on the fifth floor.

Hull said Duke's Occupational and Environmental Safety Office was contacted and that inspectors from that office are collecting air and surface samples inside and outside the building. "We won't know for sure until Monday how serious the problem may be. At this point, it does not appear to be an exposure problem," Hull said. "We take these things very seriously."

Students reported a dirtlike substance being blown through air vents.

Last fall, mold was found in two of the five buildings in Edens Quad. Air handlers in the buildings were cleaned, coated with paint and equipped with new diffusers.