The dog's remarkably keen sense of smell leads him to sniff for clues in strange places: on top of a forgotten basement safe, along a shelf of musty books, behind dingy walls and water-stained ceilings.
Barney, a chocolate Labrador/German pointer mix, is not after bombs or drugs or evidence in a grisly crime. The 2 1/2-year-old canine detective is tracking down mold.
David Marcelli of Mold Trackers points to an area in a roof where mold could grow easily.
(Photos Len Spoden For The Washington Post)
Owned by David and Rondra Marcelli of Mold Trackers LLC of Westminster, Md., Barney is one of a growing number of "mold dogs" trained to help find the silently spreading organisms that worry homeowners, home builders and housing insurers alike (call 800-342-0133 or visit www.trustmynose.com on the Web).
The Marcellis are among 50 dog handlers in this country who are certified in mold-detection services; last year, the couple helped found the International Mold Detection Dog Association.
David Marcelli, 40, a former firefighter, has followed Barney through old houses, newly built housing developments, churches and courthouses. He says he never knows where the dog's nose will take him. In a home near Towson, he says, "the dog went bonkers and literally dragged me down a flight of stairs and then climbed on top of the basement safe. It turned out that after having a water problem, the homeowner had waterproofed everywhere but the safe. That's where we found the mold."
In a house north of Baltimore, Barney found toxic spores growing on the pages of books in a basement family room. "The owner had been reading them," says Marcelli, "but no mold was visible so no one suspected that the books were the source."
For years, musty smells and ailing employees in the old stone courthouse in Ellicott City aroused suspicions of a chronic mold problem. Last week, Margaret Rappaport, circuit court clerk of Howard County, called in Barney. The dog's signaled "alerts" in offices and file rooms erased any doubt that spores linger behind walls and ceilings in the building. "Before starting to renovate our offices next month," says Rappaport, "I wanted to know exactly where the mold was."
Pinpointing mold is the newest mission for animals long valued for their acute abilities to sniff out explosives and narcotics. Dog detection of mold was originally pioneered in Sweden and has been used in Europe for about two decades.
According to scientist Paul Waggoner, interim director of Auburn University's Canine and Detection Research Institute, a dog's sense of smell is at least a thousand times more sensitive than a human's. "Dogs are capable of detecting one drop of Kool-Aid in a large auditorium," Waggoner says.
"Their reliability depends on their training. Under the right conditions and right training, dogs are able to be 90 percent accurate in identifying a substance like mold."
David Marcelli has seen that accuracy in action.
"Dogs have an incredible sense of smell that we can't even comprehend," says Marcelli. "They've been used for years to detect bombs, drugs and [arson] accelerants like gasoline and lighter fluid. They can tell where mold starts and ends."
Barney has been trained to smell 18 species of mold plus bacteria related to wood rot. These range from a toxic strain of aspergillus to the "killer" black mold Stachybotrys chartarum, which has been linked to allergic reactions and respiratory illnesses.
Molds typically flourish where moisture is present on drywall, carpet, ceiling tiles and other fibrous building materials. They have become a major concern in the home-building industry in recent years as lawsuits and insurance claims related to mold have jumped. The heightened concern has prompted some insurers to increase rates, reduce coverage or stop writing homeowner policies altogether.
Mold growth is often difficult to detect. Frequently, the spreading organisms are hidden in walls and ceilings so that finding them requires removing layers of wallboard and other finishes. The advantage of using a dog over more conventional methods, Marcelli says, is that the animal can more quickly identify the source of the mold than drilling into the walls or sampling the air for mold by sucking it into filters with a vacuum pump and sending the filters to labs for testing.
"A lot of people get duped by air samples. They don't tell you where the mold is or how much of the room is involved," he says. "A dog gives you faster and more accurate detection that ultimately saves money on mold remediation."
On a typical residential job, Marcelli walks Barney clockwise through each room of the house. The leashed dog waits for his owner's command -- "Barney, seek" -- to start sniffing about. Once Barney sits down and points with his nose, Marcelli knows mold is there. In some cases, he removes a sample from the suspicious spot and sends it to a lab in Oregon for testing.
A typical house call takes a couple of hours on average and costs about $300 to $400, not including the cost of testing. Analyzing a sample taken from the home runs about $100 per sample and takes about two days for results.
Removing the mold is left to the homeowner. "Our mission is to find where the problem lies so it can be corrected. We don't do any form of cleaning. I got out of mold remediation because it was expensive to stay insured and find good help," says Marcelli, who also runs a second company, Guardian Environmental Services, that cleans air ducts but not mold.
The Marcellis purchased Barney from Bill Whitstine, a retired fire marshal and owner of Mold Dog (www.mold-dog.com), a subsidiary of the Florida Canine Academy in Safety Harbor, Fla., which trains shelter-rescued dogs for sniffing out arson, explosives and termites.
The animals are given between 800 and 1,000 hours of intense training, learning to respond to scents produced by hundreds of different mold spores. "It took a lot of research to develop the training aids," says Whitstine, who is now developing dog-detection of cancer and contaminated meats. "Mold changes so rapidly that we had to figure out ways of keeping samples correct."
Whitstine charges $12,500 per mold-sniffing dog and 60 hours of training for handlers such as the Marcellis, who take refresher courses and are recertified annually. Over the past two years, he has trained about 50 mold dog owners who work in this country, plus several in Canada, Finland and Japan. Many belong to the newly formed International Mold Detection Dog Association.
According to Rondra Marcelli, 43, who sits on the group's board of directors, the organization has about 35 members and is planning to hold its first conference next March.
"The intent is to establish guidelines in training and certification. It's also a network for the dog owners," says Rondra, who works part-time as a registered nurse. David Marcelli says his wife has a special affinity for dogs: She was named after her grandmother's German shepherd.
Among the Marcellis' frequent customers are home builders in Maryland, who want to make sure their new houses are free of mold. "Home builders are becoming more proactive about mold. We usually go in prior to the installation of drywall or any time there's been excessive exposure to water," says David Marcelli.
Business is so brisk, he says, the couple is thinking about getting a second mold dog.