In an effort to better understand the relationship between different fungal sampling methods in the indoor environment, four methods were used to quantify mold contamination in 13 homes with visible mold. Swab, fungal spore source strength tester (FSSST), and air samples (total of 52 samples) were analyzed using both the microscopic (total spore count) and culture-based (CFU count) enumeration techniques. Settled dust samples were analyzed for culturable fungi only, as the microscopic enumeration was restricted by the masking effect. The relationships between the data obtained with the different sampling methods were examined using correlation analysis. Significant relationships were observed between the data obtained from swab and FSSST samples both by the total counting (r = 0.822, p <0.05) and by the CFU counting (r = 0.935, p <0.01). No relationships were observed between air and FSSST samples or air and settled dust samples. Percentage culturability of spores for each sampling method was also calculated and found to vary greatly for all three methods (swab: 0.03% to 63%, FSSST: 0.1% to >100%, air: 0.7% to 79%). These findings confirm that reliance on one sampling or enumeration method for characterization of an indoor mold source might not provide an accurate estimate of fungal contamination of a microenvironment. Furthermore, FSSST sampling appears to be an effective measurement of a mold source in the field, providing an upper bound estimate of potential mold spore release into the indoor air. Because of the small sample size of this study, however, further research is needed to better understand the observed relationships in this study.
Keywords air sampling; indoor fungi; settled dustIt has been estimated that 20% to 40% of homes in Northern Europe and Canada have mold contamination. (1) This number is likely to be much higher in tropical and subtropical countries. (2,3) In the United States, as many as 40% of homes have mold problems. (1,4) Various health effects, such as respiratory symptoms, allergic rhinitis, asthma, and hypersensitivity pneumonitis, are associated with mold exposure. (5)(6)(7)(8)(9)(10)(11)(12) A case control study conducted in Europe suggested a relationship between increases in symptoms in asthmatic patients and increased mold and moisture problems in the home. (13) Other studies have shown that exposure to visible mold, or excessive moisture, which promotes mold growth, leads to an increase in allergic symptoms. (6,8,(14)(15)(16)(17)(18)(19)(20) Toxicity caused by exposure to the metabolites of certain molds have also been linked to health effects. (6,21) However, the relationship between specific health effects and the mold spore concentration has not been well defined. (6) It has been criticized that the methodologies for sampling and analysis are neither