Q: Our basement was flooded last year due to excessive rain. Because it was also very humid, it was prime for mold and mildew growth. We had extensive mildew on old cabinets and on beams. Now that the basement is cold and dry, it appears that the mildew is gone. Do we still need to remediate or are the mildew spores dead? I'm concerned that it will just reappear every summer when the weather becomes humid.

A: Like the old soldier that never dies, mold takes a lot to kill. Dry, cold conditions don’t necessarily kill fungal growth. Spores become dormant; however when the environmental conditions reoccur that are conducive to growth, the existing mold colonies continue to grow and new ones become established.

Another aspect of mold contamination is that dead mold isn’t necessarily safe mold. Depending on the type of mold present, the mold toxins (mycotoxins) associated with the living mold do not go away or break down when the fungi die. Mold toxins are chemicals and are not alive, therefore the only way to get rid of them is to remove or denature them. Denaturing can be done with disinfectants or, in some cases, ultraviolet light. If the item that is moldy is porous, such as upholstered furniture, carpeting or gypsum board, then removal and disposal is often the most cost-effective method for dealing with the mold. If a mold-contaminated object has value, remediation can be effective. Solid wood items should be cleaned with a HEPA-filtered vacuum, sanded with a HEPA-filtered sander (if needed), disinfected and then encapsulated with an anti-fungal sealant.

The most important step to prevent a reoccurrence of last year’s mold problems is to prevent the conditions that occurred last year that allowed the flooding. Flooding in the basement can often be addressed by altering landscaping so that water drains away from the house, redirecting roof drains away from the house, and sealing/insulating the foundation. French drains can be installed either outside or inside a building in order to drain water away. Also, dehumidifiers can be useful tools in reducing humidity levels in a basement. Almost any house with a basement needs dehumidification in the warm, humid season, and reducing the moisture level in the air will certainly reduce the potential for mold growth.

Thanks to Mark Goldman, who is a senior air quality scientist for Engineering and Fire Investigations (EFI), a firm that provides mold investigation and indoor air quality services nationwide. Mark can be reached at mark_goldman@efiglobal.com.

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