DURHAM, N.C. -- Homes and businesses sitting empty after Hurricanes Katrina and Rita are at high risk for mold growth and people should exercise caution when entering these buildings, says Duke University Medical Center professor and mold expert Wayne Thomann, Dr.P.H.

"Normally, our response is to immediately remove wet materials before mold growth starts, but people may not have been able to get into their property to effectively mitigate potential problems with microbial growth. There is also a risk associated with residual, contaminated flood waters. People should be aware that these storms were very different – there is an increased probability that their buildings, their furnishings and contents will have experienced mold growth," Thomann said.

Even homes not directly affected by flooding may have mold because the high heat and humidity in the Gulf Coast states can trigger microbial growth, and many houses have not had air-conditioning for several weeks, said Thomann, assistant clinical professor of community and family medicine in Duke's division of occupational and environmental medicine. Thomann has more than 20 years experience assessing homes for mold damage after flooding and other natural disasters, including hurricanes and tornadoes.

Thomann recommends returning evacuees stay attuned to their environment, and be cautious and careful in their initial inspections of homes and workplaces.

"Watch for signs of visible mold, and the musty odor that signifies microbial growth. We really emphasize prevention, and we don't want people putting themselves in situations where they will experience symptoms, either from allergic reactions or irritation," Thomann said.

"In many cases in may be necessary to get professional help with mold cleanup. Homeowners should discuss remediation with their insurance agent and make sure they do a background check on anybody they bring in to help," Thomann said.

Thomann suggests following guidelines on mold and mold cleanup, with special attention to the  personal safety considerations, from the Environmental Protection Agency.

The American Red Cross also has a brochure on repairing flooded homes. Click here.