Indoor Mold Growth
Influenced More by Latitude Than Building Type
In a surprising study result, it was found that more numerous and diverse varieties of fungi inhabit temperate zone households than dwellings in tropical climes. Recent studies that used culture-independent sampling methods demonstrated a high diversity of indoor fungi distinct from that of outdoor environments. Contrary to common ecological patterns, fungal diversity is significantly higher in temperate zones than in the tropics, with distance from the equator being the best predictor of phylogenetic community similarity. Remarkably, building function has no significant effect on indoor fungal composition, despite stark contrasts between architecture and materials of some buildings in close proximity. The results suggest that factors driving fungal composition are primarily global rather than mediated by building design or function.
According to James Scott, professor of occupational and environmental health at the University of Toronto, "Over the last couple of decades we've really started to appreciate how important the indoor environment is to our health, particularly the health of kids." Scott noted that the study used a fairly small sample set, and only included three locations sampled between the tropics of Cancer and Capricorn compared with nine locations sampled in temperate regions. "But it's the first look at something that is of huge interest from an environmental health standpoint," Scott says.
Scott noted that there are a lot of mixed findings about exposures to indoor fungi and their links to disease. "For the last 50 to 60 years, people interested in indoor environment and health have collected samples from the indoor environment in a certain manner. What this study highlights is that those sampling methods that have been used for quite some time were probably missing 90 to 95 percent of the biodiversity," Scott says.
"It's shocking, really. We need to start rethinking how we measure," Scott says.
As Florida's climatical zone is defined as "subtropical", the study is of interest to its residents. Mold and other types of fungi are naturally found everywhere, indoors or out, and for the most part these organisms cause humans little harm. However, some fungal species can spoil food, rot buildings, as well as cause allergies, asthma or other ailments in humans. The American College of Occupational and Environmental Medicine estimates that approximately 5 percent of the U.S. population suffers from mold allergies. Symptoms can include sneezing, itchy and watery eyes, nasal congestion, and rash or hives.
Human indoor exposure to microbes is of prime importance because the average person in an industrialized nation spends approximately 90 percent of his or her life inside. Many questions remain as to which fungal species colonize human dwellings as well as how they impact human health.
