## 1 Introduction  
Mold spores and conidia are virtually ubiquitous, spreading though the air all over the world. They are often deposited indoors, and, in the right indoor conditions, mold can flourish and become a serious problem to the building's inhabitants. The most important factor governing mold growth is moisture conditions. Fungal growth begins at a water activity near 0.8 aw, and significant quantities of mycotoxins are produced when aw reaches 0.95. Mold growth is most conducive under a scenario where a water intrusion takes place. Molds flourish under these conditions, and upon dry conditions, spores and conidia are released, dispersed and deposited around the building [1]. It has been reported that there is an association between human upper respiratory tract symptoms and damp mold infested buildings [2]. A few common genera of indoor molds are _Penicillium, Aspergillus, Alternaria, Stachybotrys,_ and _Cladosporium_. Mycotoxins are secondary metabolites produced by molds that act as a defense against plants, bacteria, and other fungi. The World Health Organization International Agency for Research on Cancer studied various mycotoxins for their carcinogenic potentials, and concluded that many were indeed carcinogenic or cancer promoting [3]. Recent studies in mice exposed to mycotoxin have shown severe neurotoxicity and inflammation within the nose and brain [4]. Molds also produces MVOCs that are less toxic than mycotoxins. However, studies have shown that children living in homes with elevated MVOC levels have a higher prevalence of asthma, hay fever, and eye irritation [5]. MVOCs are emitted into the air and can be inhaled. More than 500 different MVOCs have been identified and used to identify hidden sources of fungal contamination [6, 7]. The MVOCs comprising the odor signatures of a given species of mold can vary based on the substrate on which it is growing [8, 9]. MVOCs are emitted during all stages of mold growth. Some have very low odor thresholds, where they may be detectable by unaided human olfaction. Different MVOCs vary in toxicity, and one of the most cytotoxic is 1-octen-3-ol [10]. Recently in the United States, interest in the mold detection industry has increased due to an increased awareness of the possible harmful effects of human exposure to toxic indoor molds and property damage that occurs as a result of a mold infestation. Preliminary sampling of indoor mold  
Figure 1: Visible mold growth in Florida home. can be done by a variety of methods, such as moisture meters, laser particle counters, IR thermometers, and air sampling. Most methods used today involve taking random samples throughout the building in an attempt to locate the source of the mold spores. These techniques are very expensive and time consuming. Though high concentrations of mold may present in buildings, but because of their oftentimes invisible nature, locating the mold is a major problem. It is important to know the hot spots of mold growth for precise sampling and remediation procedures. Canines have been widely used by law enforcement and forensic investigators in detecting accelerants, drugs, explosives, and human remains for years. Dogs have an exceptional sense of smell due to their increased number of olfactory receptors, allowing them to be specially trained to smell compounds that are virtually undetectable by human smell. They are also ideal since they will work solely for a reward or praise from their handler. The specialized mammalian behavior \"sniffing\" improves the canine's olfactory abilities by causing turbulence in the nasal passages, effectively increasing transport of the odor molecules to the olfactory receptors. It is known that detector dogs are capable of detecting parts per million to parts per billion of volatile organic compounds and recent studies have begun to definitively identify the odor signature chemicals and thresholds of canine detection for a variety of specimens [11].