WILKES-BARRE, Pa. - (AP) - In the battle to find unhealthy mold in houses, a low-tech option is gaining favor among some homeowners: dogs with sensitive sniffers trained for hunting down the illness-causing spores.

Bootz, a Labrador-Great Dane mix, is one of about 40 mold-sniffing dogs in the United States and works in northeastern Pennsylvania.

"He's found mold behind Sheetrock ... up in the ceiling," said his handler and owner, Michelle Gerhard, of Shavertown, Luzerne County.

Bootz is a graduate of a school in Clearwater, Fla., that rescues dogs from shelters and puts them through 1,000 hours of training to use their sharp sense of smell to find mold. Dogs have been used to find mold for more than two decades in Europe, though they have been used more commonly in the United States to locate explosives and drugs.

So-called mold dogs offer a faster and cheaper alternative to other forms of mold detection, which can involve specialized technology and equipment to sample air for microscopic mold spores or particles. Mold can aggravate asthma and cause breathing and respiratory problems.

At one job, Bootz "wouldn't get his nose off the carpet," initially causing his owner to suspect he picked up the scent of another dog. However, thanks to the dog's persistence, further investigation found that the underside of the floor was covered with mold, Gerhard said.

Commanded to "seek," Bootz starts to sniff around. If he finds something, he sits. Commanded by Gerhard to "show me," he often licks the spot - then gets a treat.

"It's all a game to (him)," Gerhard said.

The designated area is sampled and the sample is sent to a laboratory for analysis. An inspection for a 2,000-square-foot house costs $245. Gerhard's company, Pennsylvania Mold Dog, doesn't perform mold remediation because of conflict-of-interest prohibitions. The dog undergoes quarterly recertification by the school.

Other ways to locate mold include use of a hand-held device to measure moisture, as well as taking air samples to measure the spore count.

A report released last week by the National Academies of Science said scientific evidence linked mold and damp conditions in buildings to certain respiratory problems in healthy people. It also associated mold and damp conditions with asthma symptoms in asthmatics sensitive to mold.