This is the first study to report that indoor exposure to high levels of (1-3)-beta-D-glucan (concentration >60 microg/g) is associated with decreased risk for recurrent wheezing among infants born to atopic parents. This effect was more pronounced in the subgroup of allergen-sensitized infants.
The results of a traditional visual mold inspection were compared to a mold evaluation based on the Relative Moldiness Index (RMI). The RMI is calculated from mold-specific quantitative PCR (MSQPCR) measurements of the concentration of 36 species of molds in floor dust samples. These two prospective mold evaluations were used to classify the mold condition in 271 homes of infants. Later, the development of respiratory illness was measured in the infants living in these homes and the predictive value of each classification system was evaluated.The binary classification of homes as either moldy or non-moldy by on-site visual home inspection was not predictive of the development of respiratory illness (wheeze and/or rhinitis) (P = 0.27). Conversely, a method developed and validated in this paper, using the RMI index fit to a logistic function, can be used to predict the occurrence of illness in homes and allows stake-holders the choice among various levels of risk.
Characterizing the variation in bioaerosol concentrations is important for the estimation of health effects associated with bioaerosols and planning exposure assessment strategies. This investigation was conducted in order to develop a better understanding of exposure to fungal spores, pollen, and (1?3)-b-D-glucan, by determining the variations of their concentrations between and within homes. In the study, 24-h air sampling was performed on five consecutive days in four Cincinnati area homes. The samples (a total of 160) were taken simultaneously in four different rooms inside each home and at four different outside locations near the home using Button Personal Inhalable Aerosol Samplers. The relative sizes of the between-and within-home variability to the total variability were calculated for each outcome. The relative sizes of the betweenand within-home variability in indoor air ranged from 0.10 to 0.52 and 0.09 to 0.10, respectively. For outdoor air, the between-and within-home variability ranged from 0.27 to 0.50 and 0.09 to 0.10, respectively. Thus, the ranges of within-home variability, both indoors and outdoors, were much less than the variability between different homes. The results suggest that, if long-term sampling methods are employed to characterize the bioaerosol exposure for a population, the sampling should be repeated in a larger number of homes as an alternative to replicate sampling in a fewer number of homes. When characterizing exposure within one home, the sampling should be repeated in different rooms, rather than repeating it on different days.
In this exploratory study, indoor and outdoor airborne fungal spores, pollen, and (1fi3)-b-D-glucan levels were determined through long-term sampling (24-h) using a Button Personal Inhalable Aerosol Sampler. The air samples were collected in five Cincinnati area homes that had no visible mold growth. The total count of fungal spores and pollen in the collected samples was conducted under the microscope and Limulus Amebocyte Lysate (LAL) chromogenic assay method was utilized for the determination of the (1fi3)-b-D-glucan concentration. For the combined number concentration of fungal spores and pollen, the indoor and outdoor geometric mean values were 573 and 6,435 m -3 , respectively, with a geometric mean of the Indoor/Outdoor (I/O) ratio of .09. The geometric means of indoor and outdoor (1fi3)-b-D-glucan concentrations were .92 and 6.44 ng m -3 , respectively, with a geometric mean of the I/O ratio equal to .14. The I/O ratio of (1fi3)-b-D-glucan concentration was found to be marginally greater than that calculated based on the combined number concentration of fungal spores and pollen. This suggests that (1fi3)-b-D-glucan data are affected not only by intact spores and pollen grains but also by the airborne fragments of fungi, pollen, and plant material, which are ignored by traditional enumeration methodologies. Since the (1fi3)-b-Dglucan level may elucidate the total exposure to fungal spores, pollen, and fungal fragments, its I/O ratio may be used as a risk marker for mold and pollen exposure in indoor environments.
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