“…In the case of mite density, the number of mites per gram of dust may range from a few to 16,000 or more, although the results of the surveys are difficult to compare and evaluate because of the lack of standardization of both dust collecting methods and reporting procedures. It has been shown, however, that occurrence and abundance of house dust mites may vary in particular topographical regions and are associated to a large degree with the climate of a region, and especially with outdoor and indoor humidity (Korsgaard, 1998;Mumcuoglu, 1976;Mumcuoglu et al, 1999;Colloff, 2009). Ratios of numbers of the particular pyroglyphid dust mite species, especially between D. pteronyssinus and D. farinae, are different in separate regions of the world (Fain et al, 1990;Mumcuoglu, et al 1999).…”