When authorities could find no evidence of microbial growth in an apartment complex in the German province of Nordrhein-Westfalen, they turned to an expert. Oskar, the mold dog. Dogs have been long used to find missing people, weapons and the presence of accelerants used to set fires. Now man's best friend is being used in another search—the search for mold inside buildings.

"The use of rescue dogs after earthquakes or other catastrophes and the use of tracker dogs to find hidden drugs or explosives is well known," Thomas Diederich, Dipl.-Ing., said. "Swedish dog-leaders were the first to develop the idea of using dogs to find hidden microbial damage."

Diederich presented a paper on How to Find Hidden Microbial Growth With a Mold Dog, at the IAQ 2001 conference, Moisture, Microbes and Health Effects: Indoor Air Quality and Moisture in Buildings, held last week in San Francisco, Calif.

The conference is sponsored by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Microorganisms, such as mold, often grow in hidden places and are not visible. Dogs can be used to search for microbial odor and detect the source, he said.

For example, shortly after several families moved into the apartment complex, health complaints, including tiredness, headache, skin problems, breathing problems and painful joints, were made. "Investigation showed that mold was present," Diederich said. "But only a small amount was found in a few apartments, such as near bathroom windows and behind a cupboard."

Oskar was brought in and indicated the presence of mold on the wall. The surface paint was analyzed and a variety of microorganisms were found, he said. Diederich said the use of mold dogs is the most effective method of examining big objects, such as office buildings. A search of an office building with 200 rooms took one dog eight hours.

"To use only measurements of moisture would have lasted several days, probably without any result," he said.