WebMD's Paul Enright, MD

If you have asthma or allergies, don't enter flood-damaged buildings.

Katrina took the roofs off tens of thousands of homes and buildings, and then flooding damaged additional tens of thousands. Almost all of these buildings now have mold growing on the remaining wallboard, even a foot higher than the flood water line. If the building smells "funny" (musty, earthy, or moldy), get out of it. Salvage of items from these buildings and removal of water-damaged items will result in the release of millions of microscopic mold particles (spores) into the air. Those who have become allergic to molds will experience many hours of respiratory symptoms if they inhale those particles. More than one-third of people with hay fever, allergies, sinusitis, and asthma are allergic to molds, although many of them don't know it. Mold allergies affect all age groups, but older folks are more likely to suffer the most from worsening of asthma and other lung diseases when exposed to mold spores.

The respiratory symptoms of mold exposure include a runny or congested nose, sinus pain, a sore throat, cough, wheezing, chest tightness, and shortness of breath. You can also get headaches, a fever, a skin rash, eye irritation, and a generally ill feeling (like you have the flu) from large mold exposures. The effects of small or short-term mold exposures vary widely from person to person, but exposure to high levels of indoor mold growth can eventually cause health problems for anyone.

Volunteers who are responding to the destruction, as well as returning home owners, should worry about airborne mold exposures from water-damaged homes and other buildings. After they get wet, molds grow within two days on items such as: wallboard (fiberboard or sheetrock), carpets, carpet padding, upholstered furniture (sofas and chairs), bedding (mattresses and blankets), paper (books and magazines), foods, insulation (fiberglass and cellulose), ceiling tiles, and wood. Moving any of these items will release mold spores, which are concentrated indoors. Even if you don't smell it, look for evidence of mold growth: areas of discoloration, staining, and fuzzy growth. Molds can be many colors: white, grey, brown, black, yellow or green.

For those who simply must enter hurricane-damaged buildings and who do not have allergies, asthma, or smoking-related lung disease (COPD or emphysema), take precautions. Don't operate fans within the building, as this will cause the spores to become airborne. Wear protective clothing and gear: rubber gloves, eye goggles, a well-fitting N-95 respirator (dust mask), a long-sleeved shirt, long pants, and boots which won't easily be punctured when you step on a nail. Enclose moldy items in plastic (garbage bags or plastic sheets sealed with tape) before you carry them from the building. After working, remove your contaminated clothing, place them in a plastic bag, and wash them separately. Take a shower and shampoo your hair. Almost all of the materials listed in the table must be bagged and discarded. Hot water heaters have insulation, so the entire heater must usually be discarded if it has become wet.

Mold can also grow on relatively hard items like plastic, tile, flooring, concrete, solid wood, glass, and metal. Such mold can be killed by using a true steam cleaner (not just hot water), but then it must be wiped up before it dries. Alternatively, if the material is near an open window or outdoors, use detergent to clean the surface and then apply a diluted bleach solution (one-fourth cup of bleach to one gallon of water) using rubber gloves and while wearing goggles. Wipe up the wet gunk with a sponge or wet mop, or remove it with a wet/dry vacuum. Don't use cleaning solutions with ammonia. Avoid ozone generators.

See the EPA and State of Minnesota and State of Texas mold web sites and the excellent book My House is Killing Me for details of finding moldy materials and cleaning or discarding them safely. Take your time and be careful. It can take months to thoroughly dry a building, even after "doing all the right things." Mold can remain hidden in enclosed spaces which are hard to examine (like crawl spaces, attics, inside walls, and heating/cooling ducts). Mold test kits and "services" are unreliable. Some water-damaged buildings can never be made safe for mold-sensitive people.

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Published September 6, 2005.