E. Ziegler, R. Sahay, Pure Air Control Services, Clearwater, FL.
Indoor, as well as outdoor, air samples from commercial and residential buildings were collected by spore trap technique over a period of 10 years throughout the North America. Approximately four thousand (4,000) samples collected from the above technique were than analyzed to determine the quality and quantity of the air trapped bio-particulate with special reference to air-borne fungi. A comparison is made between indoor air-borne fungi with that of the outdoor air-borne fungi to find out the biodiversity and quantitative value in terms of sampling site. The study concludes that despite the ubiquitous nature of air-borne fungi, some fungi does influence the indoor air quality both quantitatively and qualitatively in spite of building types (commercial or residential). The data collected during this endeavor helps in determining the base line conditions of a building under normal conditions.
M. Hodgson, Clayton-Bureau Veritas, Edison, NJ.
Evaluation of bioaerosol sampling data is typically performed based on a comparison between the indoor and outdoor air, as recommended by several publications including the ACGIH, Bioaerosols Assessment and Control. Typically these comparisons look at total concentrations, rank order, and biodiversity to compare sampling data sets without consideration for the very high variances observed in the two data sets. This presentation looks at the variance that is to be anticipated in the data sets generated and presents several statistical tools that can be used to make comparisons of the data sets. Working from case histories the author will show many of the common mistakes made in interpreting data sets and make suggestions as to how the errors can be avoided. The paper will additionally look at the scale of error typically found in bioaerosol data and how this impacts the interpretation of the data.
L. Taylor, CDC/NIOSH/Harvard University, Cincinnati, OH; K. Wallingford, M. Hein, CDC/NIOSH, Cincinnati, OH; H. Burge, R. Herrick, Harvard University, Boston, MA.
To date, there is limited research regarding the identification of specific fungal genera on commercial passenger aircraft. We have studied concentrations of genera/species of airborne culturable fungi and total spore concentrations by genus or larger group on a series of twin aisle wide-body aircraft. Twelve flights on B-767 aircraft between 4.5 and 6.5 hours in duration were evaluated. Using N-6 impactor and spore traps, triplicate samples were collected in the front and rear of coach class during six sampling intervals throughout each flight: boarding, mid-climb, early cruise, mid-cruise, late cruise, and deplaning. Comparison samples were also collected inside and outside airport terminals at the origin and destination cities. Data were analyzed using both frequency (percentage of samples in which genus/species was detected) and peak concentration methodologies within the different sampling intervals. A total of 522 culturable and 517 spore samples were collected on twelve aircraft flights and inside and outside airport terminals. A variety of 46 genus/species were observed in both the culturable and total spore samples. The composition of fungal genera varied between inside and outside the airport terminal locations. The genera also differed between sampling intervals on the aircraft, specifically between boarding or deplaning compared to the cruise intervals. A frequency analysis of the fungal data indicated that Cladosporium, Aspergillus and Pencillium were predominant genera in the culturable samples whereas Cladosporium, Basidiospores, Pencillium/Aspergillus, and Ascospores were predominant in the total spore samples. The peak analysis revealed isolated genera/species spike events observed on particular flights. The analysis of genera indicates that fungi from both inside and outside the terminal are migrating onto the aircraft while the aircraft is attached to the gate. Other probable sources for the fungal concentrations are likely human shedding from the passengers themselves or reservoirs contained within the aircraft.
R. Spicer, Centrenel, Inc., Haddonfield, NJ; H. Gangloff, Hudson International, Wayne, PA.
Culturable airborne fungal spore sampling (Andersen N-6; MEA culture media) at five building sites during the period 2002-2005 provided a bank of data to evaluate the influence of time lag between indoor and outdoor samples when utilizing bioaerosol levels for building investigation. Differences in detection frequency above the median concentration of the combined indoor and outdoor levels (for each fungal species) was used as the criterion to evaluate the data. Under the test hypothesis that indoor and outdoor air are from the same population, differences that could occur at a random probability of 0.10 (10%) or less were deemed significant (equivalent to a probability equal to or greater than 0.90 [90%] that the airborne levels in the test zone exceed the outdoor air). A base data set of indoor and outdoor air samples were collected during the same general time period throughout the day at each site; all buildings had some degree of recent water damage and/or visible mold. The indoor and outdoor base data set (approximately 33-40 samples) for each site was then subdivided by start and stop times to create “overlap” data sets, so that indoor air sampling began and terminated approximately one or two hours after outdoor air sampling. Thus, each site was represented by indoor and outdoor air samples collected contemporaneously, as well as “offset” data. Significant differences in levels of usual “indicator” fungi (most often species of Penicillium and Aspergillus) that appeared indoors during sampling in the same time period outdoors, also generally occurred in the one and two hour “offset” periods. This indicates the influence of a lag in infiltration and/or reduction in indoor bioaerosols through HVAC filtration within a two hour time frame is minimal.
H. Burge, K. Ramanathan, D. Gallup, Environmental Microbiology Laboratory, Inc., San Bruno, CA.
Outdoor spore populations vary widely over short periods of time especially during changes in weather. Understanding this variability is crucial if indoor/outdoor ratios are to be used for data interpretation. We have developed the MoldRange, which is a database compiled from outdoor spore trap samples collected across the country and throughout the year. All samples were collected by field investigators using their own protocols, and analyzed in our lab following our standard protocols and subject to our quality control processes. The database differentiates between sampler types and provides some information on local weather conditions during sampling. Spores were identified and tabulated by genus or higher grouping, and relative amounts of background debris were noted. Tabulations were entered directly into a database, compiled by date and state, and analyzed for range and percentiles by state and by month. As of September 2005, the database includes approximately 90,000 samples collected from 47 states, and for every month of the year. Separate analyses have been conducted by state and by month, although within-state comparisons have been done for a few states. MoldRange is presented to the originating investigator as a table that allows comparison with his/her outdoor counts to the range and percentiles for his state and for the appropriate month. In a broader sense, the data can be used for investigations of the prevalence of specific spore types across the United States, seasonality of fungal aerosol populations by state, and many other purposes. MoldRange is probably the largest outdoor spore database and the most consistently collected and analyzed. It should provide a valuable tool for increasing understanding of the outdoor fungal aerosol.
D. Gallup, D. Bell, H. Burge, Environmental Microbiology Laboratory, San Bruno, CA.
Increased awareness of problems associated with indoor fungal growth has driven a tremendous growth in mold investigations and an increasingly diverse population of investigators with ever widening levels of experience, knowledge, and backgrounds. As a result, interpretations from the same set of data vary tremendously. Because widely accepted numerical standards for fungal aerosols do not exist, reliance is often placed on comparisons with the outdoor aerosol. We have develop the MoldScore which compares individual spore types indoors and out, assesses the likelihood that a particular spore type will ever be produced indoors, and calculates a score that can be used as part of the decision process for indoor contamination decisions. We have compared the MoldScore with other commonly used approaches to indoor/outdoor interpretations, including inside to outside concentration ratios (I/O >1 and I/O >10), the IESO standard, population agreement ratios, and Spearman’s rank correlation, and we have compared each of these approaches to decisions by a panel of 10 experts each with over 10 years of experience. Initial data analysis on 19 data sets has documented that the MoldScore agrees with highly experienced investigators 95% of the time; I/O >1 agrees 56% of the time; I/O>10 agrees 74% of the time; and I/O or marker spore type I/O >1 agrees 68% of the time. These initial analyses are being expanded to include 100 data sets and comparisons with the other commonly used indoor/outdoor comparison approaches. Based on these initial comparisons, and our ongoing experience, we believe that the MoldScore provides a scientifically valid and very useful tool for comparing indoor and outdoor fungal aerosol populations.
T. Godish, D. Godish, Ball State University, Muncie, IN.
This study was designed to systematically evaluate the count performance of selected commercial laboratories, a reference laboratory, and the authors’ laboratory for total airborne mold samples collected on Air-O-Cell cassettes. Six rounds of samples were sent to each of 10 selected laboratories based on EMLAP accreditation, relative prominence, geographic location, and analyses costs. In individual sampling rounds reported count concentrations varied by an order of magnitude among the ten commercial laboratories and the reference laboratory. The application of Friedman’s nonparametric test indicated three count populations, seven with relatively low count values that were not significantly different from each other, four laboratories (including the reference laboratory) that were significantly different from the first population but not significantly different from each other, and the authors’ laboratory which reported count values significantly higher than all other laboratories (approximately three times higher than those reported by laboratories in the upper of the count range). Notably, laboratories with the highest analyses cost reported the highest count values for the commercial laboratory population. The relationship between analyses costs and reported count values were observed to be moderately to strongly correlated (r2 = 0.49). Total airborne mold counts were compared to culturable-viable counts of samples collected on malt extract agar (MEA) and dicloran glycerol agar (DG-18). Values ≥ to reported total airborne mold values varied from 10–35% for four rounds of samples on MEA and 30–60% for four rounds of sampling on DG-18. The broad range of reported count values for co-located, concurrently collected total airborne mold samples, the relationship between count values and analyses costs, and the relatively high numbers of culturable-viable count values ≥ than total airborne mold count values indicates that count values reported by commercial laboratories (viewed as a group) cannot be used reliably as a measure of total airborne mold levels.
D. Gallup, M. Moody, H. Burge, Environmental Microbiology Laboratory, San Bruno, CA.
In this era of heightened concern about indoor fungal aerosols, we tend to forget that molds are everywhere, and that limited activity can induce very intense and often unusual aerosols to which we are exposed. We have begun to evaluate such aerosols by monitoring spore populations using spore trap cassettes. Our initial experiments involved tossing moldy fruit and moldy flowers into a garbage container. Baseline samples were collected outdoors (0.15m3), then 0.15m3 samples indoors before the activity. We then performed the activity and immediately collected another 0.15m3 sample, followed by similar samples at 30 and 60 minutes. Samples were analyzed microscopically, and results tabulated by genus or by larger morphological grouping. Data were converted to spores of each type/cubic meter of air. Increases in total spore concentrations ranged from 1,000 to almost 200,000 spores/m3 of air. Largest increases involved tossing moldy strawberries. In addition to increases in total spore concentrations, spore populations varied qualitatively. For strawberries, the common contaminating mold is Botrytis, and this was the largest contributor to the activity aerosol. Cladosporium and Penicillium/Aspergillus concentrations also increased. In another case, Cladosporium, ascospores, and basidiospores increased with the activity. Decay rate for the generated aerosols depended, as expected, on spore size, with, for example, Botrytis aerosols decaying more rapidly than those of Penicillium/Aspergillus. These data provide evidence that some usual daily activities can produce aerosols in excess of those considered “elevated” in indoor air investigations. Such activities that occur during investigations could lead to false conclusions about the status of the environment, and indicate that routine exposure does occur to intense and sometimes unusual fungal aerosols.
H. Burge, Environmental Microbiology Laboratory, Inc., San Bruno, CA.
The trend in indoor fungal investigations is away from culture and toward spore trap sampling. This approach is often successful, but there are reasons why one might like to know the species of fungi, especially when tracking sources. We have evaluated a series of data from 10 field investigations that utilized spore trap sampling to compare concentrations of Cladosporium and Penicillium/Aspergillus outdoors and at several indoor locations. The specific aim was to determine how often knowing the species of these fungi would have aided in interpretation of the data, and improvement of the ability to make remediation recommendations. All of the investigators used spore trap cassettes, and all sampled for 10 minutes at 15 liters/minute as specified by the manufacturer. Samples were analyzed at our laboratories and analysis was subject to our quality control protocols. In this small series of investigations, 80% would have benefited from having more detailed information on the types of Cladosporium and Penicillium/Aspergillus spores that were present. Examples of comparisons that would have been enhanced are indoor Pen/Asp at 107, outdoor at 160; indoor clad at 6800, outdoor at 11800; indoor Cladosporium at 267 and 533, outdoor at 373 and 213. In each of these cases, there is no way to determine whether or not the outdoor air was the primary source for the aerosol, or whether indoor growth was responsible. If indoor/outdoor comparisons or site to site comparisons indoors are to be made, it is essential that species identifications be performed, at least for taxa such as Cladosporium, Penicillium, and Aspergillus that are ubiquitous both indoors and out.
C. Leathers, V. Crow, Dominion Environmental Consultants, Inc., Phoenix, AZ.
Since January of 2002, more than 100 thousand mold specimens have been studied from indoor environments throughout the United States. Among these are genera of known human and/or animal pathogens which have rarely, or never before, been reported as growing in indoor environments. Included are species of Ascotricha, Epidermophyton, Geotrichum, Histoplasma, Microsporum, Sarcinomyces, Sclerococcum, and Sporotrichum, among others. Specimens were obtained directly from water-damaged, indoor surfaces by the tape-lift method, and showed evidence of growth by the presence of hyphae and sporulation directly on each substrate. Substrata included moist drywall, carpeting, ceramic tiles, vinyl flooring, wooden studs and trusses. Buildings included residential homes, schools, commercial warehouses, and retail establishments. Although the genera represented in this study are commonly recognized to contain pathogenic species, testing for pathogenicity of each specimen was not feasible, due to the nature of the collection procedure (tape lift). However, most of the identified species are well known pathogens in outdoor environments, and their pathogenicity should be considered potential, when encountered indoors. As a result of this study, building inspectors are encouraged to keep in mind that such pathogens may occur in any building given the right conditions for their establishment, especially available moisture, an appropriate temperature range and nutrient-containing substrata.
T. Ryan, Ohio University, Athens, OH; C. Taylor, Premier Industries, Inc., Columbus, OH.
Many field surveys for mold contamination employ bioaerosol quantification as a tool. Associating Microbial Volatile Organic Compounds (MVOCs) with the mold species producing them might allow a more rapid, less invasive, method of mold detection, especially for molds hidden in wall cavities. The hypothesis tested here was: Do MVOCs present in an environment consistently correlate with the dominant mold species present? To answer this question, 23 homes were sampled during the months of June-August. Two (2) MVOC samples were collected in each house, from the main floor living area and in a basement location. Andersen N-6 samplers were used to collect bioaerosols onto malt extract agar, followed by analysis by a third-party AIHA-EMLAP qualified laboratory. MVOC area samples were collected by active sampling onto stainless steel siliconized tubes containing Tenax TA and Carbopack B, which were then analyzed by GC/MS. Concentrations and prevalence of 19 indisputable MVOCs were compared with the bioaerosol data. While over 20 different genera of molds were identified, the predominant genera (ranked occurrences) were Cladosporium, Penicillium, Basidiomycetes, and Aspergilli. All MVOCs studied were found in the sample set, with 2-octen-1-ol, 3-octenone, 2-heptanone, 1-octen-3-ol, and 1-butanol showing the highest average concentrations (10-20 µg/m3). Differences in MVOC occurrence were greatest between homes, with MVOCs found in basement locations also typically occurring in living areas at lower concentrations. There was no statistically significant difference between basement and living area MVOC concentrations (p=0.05), although the C8 compound averages approached significance in two instances (3-octanone, p=0.10, and 2-octen-1-ol, p=0.08). The noted MVOCs borneol and terpineol were often detected, but only infrequently at elevated concentrations. Based on these findings and other published reports, 1-butanol and 2-heptanone should be examined further as good indicators of fungal growth of the most frequently found mold genera.
Posted May 30, 2006