The Southeast United States is unique in many ways. Unfortunately for residential and commercial property owners, mold is at the top of that list. The seasonal dynamics of the region drives changes in fungal species composition and spore abundance both indoors and outdoors. Now that the transition between summer and fall has started, hot humid weather turns warm and dry. Dry weather triggers the senescence of indoor surface mold in homes with excessive humidity, but spore release may continue for some time. The weather also triggers a flush in outdoor fungal activity, especially the mushroom producing fungi, which is why fall is known by professional and amateur mycologists (http://en.wikipedia.org/wiki/Mycology) alike as the pinnacle of mushroom diversity. Locations like the Great Smoky Mountain National Park (http://www.nps.gov/grsm/index.htm) are a textbook example of the Southeast’s mushroom producing capability.
Mushrooms are most prevalent in forested areas, parks, and mulch beds that border urban development. Their fruiting bodies become the primary source of outdoor spores in the fall; however, there are exceptions like agricultural communities that become inundated by plant pathogen and mold spores during harvest. The fall is also the time to open window and let homes breathe. However, residences that have occupants who suffer from mold allergies may benefit by limiting open windows to a few hours each day. Also, setting the thermostat to run the fan during the day will capture residual surface mold spores and outdoor mushroom spores that have entered the home. As fall passes into winter the mushroom decay to detritus, but soon it will be time for another mold phenomenon to unfold when the heat is switched on.