There is an interesting new (and open access) paper out: Geographic Distribution of Environmental Relative Moldiness Index Molds in USA Homes. Before the Indoor Air 2011 meeting I just returned from, I would not have understood as much of what is discussed in the paper as I do now. But I think the paper does a pretty good job of laying out the issues even for those who did not attend.
In essence what they looked at was quantitative PCR (qPCR) data on the relative abundance of 36 different kinds of molds in dust samples from buildings. qPCR surveys of these molds are used for something called the “Environmental Relative Moldiness Index (ERMI)”. What the authors did here was try to develop and use a standardized protocol for sampling (i.e., collecting dust) and DNA analysis in order to carefully compare values across buildings found throughout the US. And then they use this to basically do biogeography of molds in buildings.
This paper is definitely worth a look for those interested in microbial ecology of buildings and/or surveys of molds in buildings. Standardization is a critical tool to allow for comparisons across space and time.