The development and application of the Environmental Relative Moldiness Index (ERMI).

The prevalence of asthma in the United States (U.S.) has doubled since 1970, coinciding with the increased use of gypsum-drywall in home construction. Mold growth is promoted when gypsum-drywall gets wet. Since asthma is linked to mold exposures, accurate quantification of mold contamination in homes is critical. Therefore, qPCR assays were created and then used to quantify 36 common molds in dust collected in representative U.S. homes during the first American Health Homes Survey (AHHS). The concentrations of the 36 molds, i.e. 26 water-damage molds (Group 1) and 10 outside molds (Group 2), were used in the formulation of a home's Environmental Relative Moldiness Index (ERMI) value. The ERMI values for each of the AHHS homes were assembled from lowest to highest to create the ERMI scale, which ranges from -10 to 20. Subsequent epidemiological studies consistently demonstrated that higher ERMI values were linked to asthma development, reduced lung capacity or occupant asthma. Reducing mold exposures by remediation or with HEPA filtration resulted in a reduced prevalence of asthma and improvements in respiratory health. The ERMI scale has also been successfully applied in evaluating mold concentrations in schools and large buildings and appears to have applications outside the U.S.

The relationship between childhood atopic dermatitis and asthma in an under resourced community.

Background: Atopic dermatitis (AD) is an inflammatory skin disease caused by allergen exposures and estimated to affect ∼20% of children. Children in urban areas have a higher prevalence of AD compared with those living outside of urban areas. AD is believed to lead to asthma development as part of the "atopic march." Objective: Our objective was to determine the sequential and chronological relationships between AD and asthma for children in an under-resourced community. Methods: The progression from AD to asthma in the under-resourced, urban community of Sun Valley, Colorado, was examined by assessing Medicaid data for the years 2016 to 2019 for a diagnosis of AD or asthma in children 6 and 7 years old. Results: Pearson correlations between AD and asthma diagnoses were significant only with respect to AD at age 6 years compared with asthma 1 year later, at age 7 years. Conclusion: By studying a susceptible community with a consistent but mixed genetic background, we found sequential and chronological links between AD and asthma.

HEPA filtration intervention in classrooms may improve some students' asthma.

OBJECTIVE: The School Inner-City Asthma Intervention Study 2 (SICAS 2) tested interventions to reduce exposures in classrooms of students with asthma. The objective of this post-hoc analysis was limited to evaluating the effect of high-efficiency particulate (HEPA) filtration interventions on mold levels as quantified using the Environmental Relative Moldiness Index (ERMI) and the possible improvement in the students' asthma, as quantified by spirometry testing. METHODS: Pre-intervention dust samples were collected at the beginning of the school year from classrooms and corresponding homes of students with asthma (n = 150). Follow-up dust samples were collected in the classrooms at the end of the HEPA or Sham intervention. For each dust sample, ERMI values and the Group 1 and Group 2 mold levels (components of the ERMI metric) were quantified. In addition, each student's lung function was evaluated by spirometry testing, specifically the percentage predicted forced expiratory volume at 1 sec (FEV1%), before and at the end of the intervention. RESULTS: For those students with a higher Group 1 mold level in their pre-intervention classroom than home (n = 94), the FEV1% results for those students was significantly (p < 0.05) inversely correlated with the Group 1 level in their classrooms. After the HEPA intervention, the average Group 1 and ERMI values were significantly lowered, and the average FEV1% test results significantly increased by an average of 4.22% for students in HEPA compared to Sham classrooms. CONCLUSIONS: HEPA intervention in classrooms reduced Group 1 and ERMI values, which corresponded to improvements in the students' FEV1% test results.

Hot water plumbing in residences and office buildings have distinctive risk of Legionella pneumophila contamination.

AIM: To observe how Legionella pneumophila, the causative agent for legionellosis, can transmit through the hot water plumbing of residences and office buildings. METHOD AND RESULTS: Using qPCR, L. pneumophila and L. pneumophila Serogroup (Sg)1 were measured in hot water samples collected from 100 structures, consisting of 70 residences and 30 office buildings. The hot water samples collected from office buildings had a higher L. pneumophila detection frequency of 53% (16/30) than residences, with a 103 GU/L (median) concentration. An office building's age was not a statistically significant predictor of contamination, but its area (>100,000 sq. ft.) was, P = <0.001. Hot water samples collected at residences had a lower L. pneumophila detection frequency of 36% (25/70) than office buildings, with a 100 GU/L (median) concentration. A residence's age was a significant predictor of contamination, P = 0.009, but not its area. The water's secondary disinfectant type did not affect L. pneumophila detection frequency nor its concentration in residences, but the secondary disinfectant type did affect results in office buildings. Legionella pneumophila's highest detection frequencies were in samples collected in March-August for office buildings and in June-November for residences. CONCLUSION: This study revealed that the built environment influences L. pneumophila transport and fate. Residential plumbing could be a potential "conduit" for L. pneumophila exposure from a source upstream of the hot water environment. Both old and newly built office buildings had an equal probability of L. pneumophila contamination. Legionella-related remediation efforts in office buildings (that contain commercial functions only) might not significantly improve a community's public health.

Characterization of fungal exposure and dectin-1 expression in healthy horses and horses with severe asthma.

OBJECTIVE: To quantify dectin-1 expression in bronchoalveolar lavage fluid (BALF), create polyclonal antibodies against equine dectin-1 and localize it in tissues, and quantify fungal exposure in pastured and stabled asthmatic and nonasthmatic horses. SAMPLES: BALF samples from 6 controls and 6 horses with severe asthma. Stored lung and nasal wash samples. PROCEDURES: Dectin-1 expression was quantified by quantitative PCR (qPCR). Purified peptide from equine dectin-1 was used to generate polyclonal antibodies and was confirmed with immunological testing. Fungal exposure was quantified in BALF samples by counting fungal-like intracellular particles in phagocytic cells, by qPCR quantification of the "universal" 18S rRNA fungal gene, and by quantifying 36 specific fungi in equine and dust samples using qPCR assays. RESULTS: Equine dectin-1 was localized in tissues and cells, and functional isoforms were upregulated significantly in BALF after stabling. Pastured horses from both groups had low levels of fungi in BALF, and there was a significant increase in some specific fungi, most notably for Eurotium amstelodami, Wallemia sebi, and Aspergillus niger after stabling. However, stabled asthmatic horses had fewer phagocytized particles, less 18S rRNA signal, and fewer specific fungi compared to nonasthmatic horses. CLINICAL RELEVANCE: Stabling increases exposure to fungi, but asthmatic horses had fewer fungi reaching their lower airways, presumably resulting from congestion and narrowing of the airways. Exposure to fungi could contribute to airway inflammation by increasing dectin-1 functional isoforms, and exposure to indoor molds should be avoided.

Asthma Prevalence and Mold Levels in US Northeastern Schools.

BACKGROUND: Asthma is among the most common chronic diseases of children in the United States (US). Mold exposures have been linked to asthma development and exacerbation. In homes, mold exposures have been quantified using the Environmental Relative Moldiness Index (ERMI), and higher home ERMI values have been linked to occupant asthma. OBJECTIVE: In this analysis of the School Inner-City Asthma Study (SICAS), we aimed to evaluate the ERMI's applicability to measuring mold in schools compared with homes and to examine the prevalence of asthma in relationship to students' demographics and the physical characteristics of school buildings. METHODS: Northeastern US schools (n = 32) and homes (n = 33) were selected, and the 36 ERMI molds were quantified in a dust sample from each classroom (n = 114) or home. School building characteristics data were collected from SICAS. Asthma prevalence and student demographics data were obtained from government websites. Linear regression and mixed models were fit to assess the association of the current asthma prevalence and physical characteristics of the school, make-up of the student body, and the ERMI metric. RESULTS: Levels of outdoor group 2 molds were significantly (P < .01) greater in schools compared with homes. The presence of air-conditioning in school buildings correlated significantly (P = .02) with lower asthma prevalence. CONCLUSION: The prevalence of asthma in student bodies is associated with many factors in schools and homes.

ß-Glucan exacerbates allergic asthma independent of fungal sensitization and promotes steroid-resistant TH2/TH17 responses.

BACKGROUND: Allergic sensitization to fungi has been associated with asthma severity. As a result, it has been largely assumed that the contribution of fungi to allergic disease is mediated through their potent antigenicity. OBJECTIVE: We sought to determine the mechanism by which fungi affect asthma development and severity. METHODS: We integrated epidemiologic and experimental asthma models to explore the effect of fungal exposure on asthma development and severity. RESULTS: We report that fungal exposure enhances allergen-driven TH2 responses, promoting severe allergic asthma. This effect is independent of fungal sensitization and can be reconstituted with ß-glucan and abrogated by neutralization of IL-17A. Furthermore, this severe asthma is resistant to steroids and characterized by mixed TH2 and TH17 responses, including IL-13+IL-17+CD4+ double-producing effector T cells. Steroid resistance is dependent on fungus-induced TH17 responses because steroid sensitivity was restored in IL-17rc-/- mice. Similarly, in children with asthma, fungal exposure was associated with increased serum IL-17A levels and asthma severity. CONCLUSION: Our data demonstrate that fungi are potent immunomodulators and have powerful effects on asthma independent of their potential to act as antigens. Furthermore, our results provide a strong rationale for combination treatment strategies targeting IL-17A for this subgroup of fungus-exposed patients with difficult-to-treat asthma.

Nationwide reconnaissance of contaminants of emerging concern in source and treated drinking waters of the United States.

When chemical or microbial contaminants are assessed for potential effect or possible regulation in ambient and drinking waters, a critical first step is determining if the contaminants occur and if they are at concentrations that may cause human or ecological health concerns. To this end, source and treated drinking water samples from 29 drinking water treatment plants (DWTPs) were analyzed as part of a two-phase study to determine whether chemical and microbial constituents, many of which are considered contaminants of emerging concern, were detectable in the waters. Of the 84 chemicals monitored in the 9 Phase I DWTPs, 27 were detected at least once in the source water, and 21 were detected at least once in treated drinking water. In Phase II, which was a broader and more comprehensive assessment, 247 chemical and microbial analytes were measured in 25 DWTPs, with 148 detected at least once in the source water, and 121 detected at least once in the treated drinking water. The frequency of detection was often related to the analyte's contaminant class, as pharmaceuticals and anthropogenic waste indicators tended to be infrequently detected and more easily removed during treatment, while per and polyfluoroalkyl substances and inorganic constituents were both more frequently detected and, overall, more resistant to treatment. The data collected as part of this project will be used to help inform evaluation of unregulated contaminants in surface water, groundwater, and drinking water.

Microbial pathogens in source and treated waters from drinking water treatment plants in the United States and implications for human health.

An occurrence survey was conducted on selected pathogens in source and treated drinking water collected from 25 drinking water treatment plants (DWTPs) in the United States. Water samples were analyzed for the protozoa Giardia and Cryptosporidium (EPA Method 1623); the fungi Aspergillus fumigatus, Aspergillus niger and Aspergillus terreus (quantitative PCR [qPCR]); and the bacteria Legionella pneumophila (qPCR), Mycobacterium avium, M. avium subspecies paratuberculosis, and Mycobacterium intracellulare (qPCR and culture). Cryptosporidium and Giardia were detected in 25% and in 46% of the source water samples, respectively (treated waters were not tested). Aspergillus fumigatus was the most commonly detected fungus in source waters (48%) but none of the three fungi were detected in treated water. Legionella pneumophila was detected in 25% of the source water samples but in only 4% of treated water samples. M. avium and M. intracellulare were both detected in 25% of source water, while all three mycobacteria were detected in 36% of treated water samples. Five species of mycobacteria, Mycobacterium mucogenicum, Mycobacterium phocaicum, Mycobacterium triplex, Mycobacterium fortuitum, and Mycobacterium lentiflavum were cultured from treated water samples. Although these DWTPs represent a fraction of those in the U.S., the results suggest that many of these pathogens are widespread in source waters but that treatment is generally effective in reducing them to below detection limits. The one exception is the mycobacteria, which were commonly detected in treated water, even when not detected in source waters.

Assessing the allergenic potential of molds found in water-damaged homes in a mouse model.

Damp/moldy indoor environments, which have resulted from flooding events and may increase as a result of climate change, have been associated with asthma exacerbation. Certain molds found in significantly higher or lower concentrations in asthmatics' homes compared to control homes have been categorized as Group 1 (G1) and Group 2 (G2) molds, respectively. We have compared the allergic potential of selected G1/G2 molds to house dust mite (HDM) in a mouse model. BALB/c mice were exposed to mold (0-80 µg) or HDM (20 µg) extract by intratracheal aspiration either 4X over 4 weeks (allergenicity) or 1X (non-specific responses). Airflow limitation (methacholine challenge) was measured (Day 1) and serum and bronchoalveolar lavage fluid were collected (Day 2) after the final exposure. The G1 molds induced low-to-moderate responses and required higher doses to achieve antigen-specific IgE results similar to those induced by HDM. Compared to HDM responses, the G2 mold in this study required lower doses to induce a similar response. Acute exposure responses suggest some molds may exacerbate asthmatic responses. These studies demonstrate the differing capacities of molds to induce responses associated with allergic asthma, including differences in the threshold dose for allergy induction. Therefore, molds must be evaluated individually for allergic/asthmatic potential. These studies along with our previous studies with G1 (Stachybotrys chartarum)/G2 (Penicillium chrysogenum) molds suggest that the G1/G2 categorization is not indicative of allergic potential but they do not preclude this categorization's utility in determining unhealthy building dampness.

Widespread molecular detection of Legionella pneumophila Serogroup 1 in cold water taps across the United States.

In the United States, 6,868 cases of legionellosis were reported to the Center for Disease Control and Prevention in 2009-2010. Of these reports, it is estimated that 84% are caused by the microorganism Legionella pneumophila Serogroup (Sg) 1. Legionella spp. have been isolated and recovered from a variety of natural freshwater environments. Human exposure to L. pneumophila Sg1 may occur from aerosolization and subsequent inhalation of household and facility water. In this study, two primer/probe sets (one able to detect L. pneumophila and the other L. pneumophila Sg1) were determined to be highly sensitive and selective for their respective targets. Over 272 water samples, collected in 2009 and 2010 from 68 public and private water taps across the United States, were analyzed using the two qPCR assays to evaluate the incidence of L. pneumophila Sg1. Nearly half of the taps showed the presence of L. pneumophila Sg1 in one sampling event, and 16% of taps were positive in more than one sampling event. This study is the first United States survey to document the occurrence and colonization of L. pneumophila Sg1 in cold water delivered from point of use taps.

Higher environmental relative moldiness index values measured in homes of adults with asthma, rhinitis, or both conditions.

Higher values of the environmental relative moldiness index (ERMI), a DNA-based method for quantifying indoor molds, have been associated with asthma in children. In this study, settled dust samples were collected from the homes of adults with asthma, rhinitis, or both conditions (n=139 homes) in Northern California. The ERMI values for these samples were compared to those from dust collected in homes from the same geographic region randomly selected as part of the 2006 American Healthy Home Survey (n=44). The median ERMI value in homes of adult with airway disease (6) was significantly greater than median ERMI value (2) in the randomly selected homes (p<0.0001). In this study in Northern California, the homes of adults with asthma had ERMI values consistent with a heavier burden of indoor mold than that measured in other homes from the same region.

Decreased pulmonary function measured in children exposed to high environmental relative moldiness index homes.

BACKGROUND: Exposures to water-damaged homes/buildings has been linked to deficits in respiratory health. However, accurately quantifying this linkage has been difficult because of the methods used to assess water damage and respiratory health. PURPOSE: The goal of this analysis was to determine the correlation between the water-damage, as defined by the Environmental Relative Moldiness Index (ERMI) value in an asthmatic child's home, and the child's pulmonary function measured by spirometry, "forced expiratory volume in one second, percent predicted" or FEV1%. METHODS: This analysis utilized data obtained from the "Heads-off Environmental Asthma in Louisiana" (HEAL) study. The children (n= 109), 6 to 12 years of age, who had completed at least one spirometry evaluation and a dust sample collected for ERMI analysis from the home at approximately the same time as the spirometry testing, were included in the analysis. Statistical evaluation of the correlation between ERMI values and FEV1% was performed using the Spearman's Rank Correlation analysis. The relationship between ERMI values and FEV1% was performed using B-spline regression. RESULTS: The average ERMI value in the HEAL study homes was 7.3. For homes with ERMI values between 2.5 and 15, there was a significant inverse correlation with the child's lung function or FEV1% measurement (Spearman's rho -0.23; p= 0.03), i.e. as the ERMI value increased, the FEV1% value decreased. CONCLUSIONS: Measures of water-damage (the ERMI) and clinical assessments of lung function (FEV1%) provided a quantitative assessment of the impact of water-damaged home exposures on children's respiratory health.

Infant origins of childhood asthma associated with specific molds.

BACKGROUND: The specific cause or causes of asthma development must be identified to prevent this disease. OBJECTIVE: Our hypothesis was that specific mold exposures are associated with childhood asthma development. METHODS: Infants were identified from birth certificates. Dust samples were collected from 289 homes when the infants were 8 months of age. Samples were analyzed for concentrations of 36 molds that comprise the Environmental Relative Moldiness Index (ERMI) and endotoxin, house dust mite, cat, dog, and cockroach allergens. Children were evaluated at age 7 years for asthma based on reported symptoms and objective measures of lung function. Host, environmental exposure, and home characteristics evaluated included a history of parental asthma, race, sex, upper and lower respiratory tract symptoms, season of birth, family income, cigarette smoke exposure, air conditioning, use of a dehumidifier, presence of carpeting, age of home, and visible mold at age 1 year and child's positive skin prick test response to aeroallergens and molds at age 7 years. RESULTS: Asthma was diagnosed in 24% of the children at age 7 years. A statistically significant increase in asthma risk at age 7 years was associated with high ERMI values in the child's home in infancy (adjusted relative risk for a 10-unit increase in ERMI value, 1.8; 95% CI, 1.5-2.2). The summation of levels of 3 mold species, Aspergillus ochraceus, Aspergillus unguis, and Penicillium variabile, was significantly associated with asthma (adjusted relative risk, 2.2; 95% CI, 1.8-2.7). CONCLUSION: In this birth cohort study exposure during infancy to 3 mold species common to water-damaged buildings was associated with childhood asthma at age 7 years.

Some chronic rhinosinusitis patients have elevated populations of fungi in their sinuses.

OBJECTIVES/HYPOTHESIS: To measure the populations of 36 fungi in the homes and sinuses of chronic rhinosinusitis (CRS) and non-CRS patients. STUDY DESIGN: Single-blind cross-sectional study. METHODS: Populations of 36 fungi were measured in sinus samples and in the home vacuum cleaner dust of CRS (n = 73) and non-CRS patients (n = 16) using quantitative polymerase chain reaction. Etest strips containing amphotericin B, anidulafungin, caspofungin, fluconazole, and voriconazole were used to test the susceptibility of seven potentially relevant fungi. RESULTS: Seven fungi (Alternaria alternata, Cladosporium cladosporioides types 1 and 2, Cladosporium herbarum, Penicillium brevicompactum, Penicillium crustosum, and Penicillium chrysogenum type 2) were discovered at very high concentrations in some CRS patients. In vitro antifungal susceptibility testing of these seven fungi demonstrated species specific sensitivities. Four CRS patients with marked elevations of fungal populations in their sinus samples underwent endoscopic sinus surgery. After surgical treatment, the fungal populations were reduced by several orders of magnitude. CONCLUSIONS: Seven fungi were found in very high concentrations in the sinuses of some CRS patients. Not one of the five common antifungal agents could control all seven of these fungi based on in vitro tests.

Production and characterization of IgM monoclonal antibodies against hyphal antigens of Stachybotrys species.

Stachybotrys is a hydrophilic fungal genus that is well known for its ability to colonize water-damaged building materials in indoor environments. Personal exposure to Stachybotrys chartarum allergens, mycotoxins, cytolytic peptides, and other immunostimulatory macromolecules has been proposed to exacerbate respiratory morbidity. To date, advances in Stachybotrys detection have focused on the identification of unique biomarkers that can be detected in human serum; however, the availability of immunodiagnostic reagents to Stachybotrys species have been limited. In this study, we report the initial characterization of monoclonal antibodies (MAbs) against a semi-purified cytolytic S. chlorohalonata preparation (cScp) derived from hyphae. BALB/c mice were immunized with cScp and hybridomas were screened against the cScp using an antigen-mediated indirect ELISA. Eight immunoglobulin M MAbs were produced and four were specifically identified in the capture ELISA to react with the cScp. Cross-reactivity of the MAbs was tested against crude hyphal extracts derived from 15 Stachybotrys isolates representing nine Stachybotrys species as well as 39 other environmentally abundant fungi using a capture ELISA. MAb reactivity to spore and hyphal antigens was also tested by a capture ELISA and by fluorescent halogen immunoassay (fHIA). ELISA analysis demonstrated that all MAbs strongly reacted with extracts of S. chartarum but not with extracts of 39 other fungi. However, four MAbs showed cross-reactivity to the phylogenetically related genus Memnoniella. fHIA analysis confirmed that greatest MAb reactivity was ultrastructurally localized in hyphae and phialides. The results of this study further demonstrate the feasibility of specific MAb-based immunoassays for the detection of S. chartarum.

Aeromonas caviae strain induces Th1 cytokine response in mouse intestinal tract.

Aeromonas caviae has been associated with human gastrointestinal disease. Strains of this species typically lack virulence factors (VFs) such as enterotoxins and hemolysins that are produced by other human pathogens of the Aeromonas genus. Microarray profiling of murine small intestinal extracts, 24 h after oral infection with an A. caviae strain, provides evidence of a Th1 type immune response. A large number of gamma-interferon (gamma-IFN) induced genes are up-regulated as well as several tumor necrosis factor-alpha (TNF-alpha) transcripts. Aeromonas caviae has always been considered an opportunistic pathogen because it lacks obvious virulence factors. This current effort suggests that an A. caviae strain can colonize the murine intestinal tract and cause what has been described by others as a dysregulatory cytokine response. This response could explain why a number of diarrheal waterborne disease cases have been attributed to A. caviae even though it lacks obvious enteropathogenic properties.

Human serum IgE reacts with a Metarhizium anisopliae fungal catalase.

BACKGROUND: Previous studies have demonstrated that Metarhizium anisopliae extract can induce responses characteristic of human allergic asthma in a mouse model. The study objectives were (1) to identify and characterize the M. anisopliae mycelia extract (MYC) proteins that are recognized by mouse serum IgE, (2) to determine if human serum IgE reacts with these proteins, and (3) to determine if these IgE-reactive proteins are found in other fungi. METHODS: Asthmatic human serum IgE, M. anisopliae crude antigen (MACA) immunized mouse serum IgE, and anti-catalase antibodies were used to probe one- and two-dimensional gel electrophoresis blots of MYC. RESULTS: Mass spectrometry analysis identified catalase as a mouse IgE-reactive protein. This identification was confirmed by assaying catalase activity in the extract and extract immunoblots probed with anti-catalase antibody. Six adult asthmatic sera contained IgE, but not IgG, that was reactive with mycelia extract proteins. A similar protein profile was seen when blots were probed with either mouse anti-MACA IgE or anti-bovine liver catalase antibodies. Furthermore, these mouse anti-MACA and anti-catalase antibodies were cross-reactive with other mold extracts (skin prick testing mix) and Aspergillus niger catalase. CONCLUSIONS: Some human asthmatics have developed IgE that reacts with an M. anisopliae catalase, most likely due to cross-reactivity (minimal IgG development). The cross-reactivity among fungal catalases suggests that IgE-reactive catalase might be useful for exposure assessment. Additionally, the similarity of protein profiles visualized with both human and mouse serum IgE suggests that allergy hazard identification can be facilitated using a mouse model.

Mold species in dust from the International Space Station identified and quantified by mold-specific quantitative PCR.

Dust was collected over a period of several weeks in 2007 from HEPA filters in the U.S. Laboratory Module of the International Space Station (ISS). The dust was returned on the Space Shuttle Atlantis, mixed, sieved and the DNA was extracted. Using a DNA-based method called mold-specific quantitative PCR (MSQPCR), 39 molds were measured in the dust. Potential opportunistic pathogens Aspergillus flavus and Aspergillus niger and potential moderate toxin producers Penicillium chrysogenum and Penicillium brevicompactum were noteworthy. No cells of the potential opportunistic pathogens Aspergillus fumigatus, Aspergillus terreus, Fusarium solani or Candida albicans were detected.

Comparison of mold concentrations quantified by MSQPCR in indoor and outdoor air sampled simultaneously.

Mold specific quantitative PCR (MSQPCR) was used to measure the concentrations of the 36 mold species in indoor and outdoor air samples that were taken simultaneously for 48 h in and around 17 homes in Cincinnati, Ohio. The total spore concentrations of 353 per m(3) of indoor air and 827 per m(3) of outdoor air samples were significantly different (por=0.5). These results suggest that interpretation of the meaning of short-term (<48 h) mold measurements in indoor and outdoor air samples must be made with caution.