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CULTURABLE FUNGI IN SETTLED DUST FROM NORMAL RESIDENTIAL ENVIRONMENTS.
J. Hicks, E. Lu, Exponent Inc., Oakland, CA.
Collection and fungal culture analysis of dust from surfaces inside the built environment is sometimes used to determine the presence of fungal contamination. From this analysis, some investigators make decisions about the presence of unusual types and concentrations of fungi, the need for fungal remediation activities, and in some situations, exposures that occupants may have encountered. There is little information about the presence of culturable fungi in settled dust from environments where there is no history of water intrusion, fungal growth, or other unusual reservoirs of fungi. This study presents the results of collection and analysis of dust from horizontal surfaces in 26 residential environments that had been pre-screened to eliminate structures that had any indications of past water intrusion, water stains, flooding, mold growth sites, or air sampling results that suggested unusual mold spore types and concentrations. Pre-screening included occupant interviews, visual inspections, and air sampling and analysis. If a structure passed the pre-screening step, surface samples were then collected from three types of surfaces (e.g., high traffic carpeted areas, low traffic carpeted areas, and furniture). A total of 74 dust samples were collected and analyzed. Analysis included the use of three different types of culture media, each at four different dilutions. The results are presented in terms of colony forming units per gram of collected dust, and in terms of colony forming units per square foot of surface area. The results revealed a diversity of fungal types and concentrations, including organisms routinely associated with water intrusion damage, and total fungal levels exceeding 107 colony-forming units per gram of dust. A set of eight samples collected side-by-side revealed generally similar organisms, but levels varied by approximately 10-fold. The results from this study serve as a useful comparison for surface dust collected for fungal culture analysis.
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NUMERICAL GUIDELINES FOR TOTAL FUNGI IN CARPET DUST FOR IICRC CONDITIONS 1–3.
D. Bridge, Rimkus Consulting Group Inc., Houston, TX; M. Krotenberg, Rimkus Consulting Group Inc., Phoenix, AZ.
In 2003, the Institute of Inspection, Cleaning, and Restoration Certification (IICRC) published IICRC S520 Standard and Reference Guide for Professional Mold Remediation. This standard groups indoor environments into three qualitative conditions: Condition 1, normal fungal ecology; Condition 2, settled spores; and Condition 3, actual growth. Despite these seemingly clear categories, interpretation of data can be challenging. To address a portion of this gap, a literature review was conducted of studies evaluating fungal levels in carpet dust. The historical data were then compared to a new study that includes 131 carpet samples collected in 25 separate buildings. The sample data are categorized according to IICRC S520 Conditions 1–3 and proposed numerical guidelines are presented.
24
DETECTION OF INDOOR AIRBORNE FUNGAL CONTAMINATION THROUGH EXAMINATION OF
BUILDING HEATING, VENTILATING, AND AIR CONDITIONING (HVAC) FILTERS.
H. Perez, Drexel University, Philadelphia, PA; N. Zimmerman, Purdue University, West Lafayette, IN.
The purpose of this research was to assess viable particle quantification from building HVAC filters as a means of assessing indoor airborne fungal levels. This assessment was performed through the comparison of filter quantification results to the results of single stage viable impactor samples taken at regular intervals while test filters were in service. The filter quantification method involved the immersion of filter samples in 0.9% sterile saline, the shaking of the filter/saline combination, and the plating of aliquots of the shaking solution onto solid growth media. The inoculated media plates were incubated at room temperature for 96 hours, at which time colonies were counted. Research was conducted in three homes, an administrative office building, an academic research facility, and an outpatient health care facility. Test filters were installed in ventilation systems for periods ranging from four days to seven weeks (loading periods). Results of data collected in the outpatient facility and three homes indicated statistically significant relationships between filter quantification and air sampling results over short-term (one and two weeks) loading periods, but not over a longer term (seven weeks) loading period. The results of longer (six weeks) loading periods in the administrative and research facilities indicate the presence of a statistically significant relationship between filter quantification and air sampling results. Results also indicated that the filter quantification procedure performed on filters loaded for one week demonstrated an increased ability to distinguish between different building air concentrations when compared to single stage impactor sampling. The study outcomes suggest that the development of filter quantification as a method for the assessment of indoor airborne viable fungal levels may provide a very useful and sensitive tool for indoor air quality investigations in the future.
25
INDOOR ENVIRONMENTAL QUALITY (IEQ): A 10-YEAR CASE STUDY FOR INDUSTRY IEQ
GUIDELINES.
E. Ziegler, R. Sahay, Pure Air Control Services, Clearwater, FL.
For the last decade, sample data has been collected and analyzed from the Computer Assisted Air Management Program database (> 60,000 environmental samples from > 18,000 test sites at > 2000 buildings), which was taken at buildings and homes across the United States to assist in the identification and development of baseline IEQ levels of microbiological contaminants (both bacteria and fungi). Findings of this study suggest that < 250 CFU/m3 should be considered as normal airborne bacteria population, whereas in the case of fungi, < 350 CFU/m3. Building temperature and relative humidity besides other environmental factors influenced microbial growth during the course of this study. These baseline IEQ guidelines have been peer reviewed in legal depositions and court cases. Conclusion. Due to the absence of regulated bioaerosol contaminant levels and a more recent influx of proactive indoor environmental sampling, much has been initiated towards development of standard facility indoor environmental guidelines for microbial contaminants. The results of this study can be employed to better manage the quality of the indoor environment and be used in commercial applications.
26
A METHOD FOR INTERPRETING AIRBORNE CONCENTRATIONS OF MOLD.
J. Spurgeon, Bayshore Environmental Inc., Placentia, CA.
Hypothesis. The concentration distributions of indoor airborne spores can be used to classify site-specific exposures as low, moderate, or high. This concept has achieved general acceptance within the exposure assessment community, but limited acceptance within the IEQ community. For example, what is the significance of an airborne concentration of 2000 s/m3 of Aspergillus/Penicillium-type spores measured in an indoor environment? Are exposures low, moderate, or high? It’s difficult to even guess, because there isn’t any point of reference other than professional judgment. However, if a number of sample results are available from a broad selection of similar indoor environments (residential, commercial, school), a distribution of concentrations can be estimated for each type of space. As an example, Asp/Pen type spores were detected in 40 of 51 residential indoor samples. The GM concentration was 365 s/m3, the average concentration was 598 s/m3, and the 95th percentile concentration was 1932 s/m3. This information reveals that the Asp/Pen concentration of 2000 s/m3 exceeded 95% of all the past exposures included in the database. This might encourage the consultant to classify the site-specific exposure as “high.” The distributions of airborne concentrations for several fungal types are presented. Although based on limited sample sizes, they illustrate the utility of this approach.
A second advantage of characterizing the distribution of concentrations is that extreme concentrations are reported as well as average concentrations (although with less confidence). This is important because adverse health effects are typically associated with exposures to extreme concentrations, not average concentrations. A large-scale, multiweek investigation is discussed in which the average indoor and outdoor concentrations of Asp/Pen were similar, but the 95th percentile indoor concentration significantly exceeded the outdoor concentration. If the concentration distributions had not been constructed, then the difference between indoor and outdoor concentrations would not have been reported.
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EVALUATING AIRBORNE CULTURABLE FUNGAL CONCENTRATIONS ON WIDE-BODY COMMERCIAL
PASSENGER AIRCRAFT.
L. Taylor, CDC/NIOSH/Harvard University, Cincinnati, OH; M. Hein, K. Wallingford, CDC/NIOSH, Cincinnati, OH.
Despite the media attention that cabin air quality receives, little research has been conducted to determine the magnitude of fungal concentrations on aircraft. The primary objective of this study was to compare aircraft fungal concentrations at various in-flight times to concentrations collected inside and outside airport terminals. Sixteen flights with durations between 4.5 and 6.5 hours were evaluated on twin aisle wide-body aircraft. Using N-6 impactors and DG18 agar media, triplicate samples were collected in the front and rear of coach class during six sampling intervals throughout each flight: boarding, post-takeoff, mid-flight 1, mid-flight 2, mid-flight 3, and deplaning. Comparison samples were collected inside and outside airport terminals at the origin and destination cities. The MIXED procedure in SAS was used to model the mean and the variance-covariance matrix of the natural log-transformed fungal concentrations. Fixed effects considered included the sampling interval and the location of samples (front of coach section, rear of coach section) collected inside the aircraft. Descriptive statistics indicate that fungal concentrations on the aircraft were highest during deplaning (geometric mean (GM): 77.5 colony forming units per cubic meter (cfu/m3), geometric standard deviation (GSD): 2.8) followed by the boarding interval (GM: 65.7 cfu/m3, GSD: 3.8). The front and rear locations within the coach section of the aircraft were not significantly different (p-value > 0.2). Fungal concentrations inside the aircraft during mid-flight (GM: 9.7 cfu/m3, GSD: 2.1) were lower than concentrations observed inside the airport terminals (GM: 44.2 cfu/m3, GSD: 3.3) and appreciably lower than concentrations observed outside the airport terminals (GM: 449.4 cfu/m3, GSD: 2.4). Study results consistently demonstrate that fungal concentrations are higher outside the airport terminals than those observed in-flight on wide-body aircraft. Additional analysis regarding the specific genus and species of fungi observed should be completed to elucidate differences between the sampling environments.
28
THE EFFECT OF DISTURBING COLONIZED MOLD ON AIRBORNE SPORE CONCENTRATIONS.
S. Evans, MDE Inc., Seattle, WA.
Dust control and dust suppression are identified components of mold remediation methods in guidance documents such as the New York City Guidelines, and for class I projects, dust suppression is the only control utilized to minimize mold spore aerosolization. Dust control methods are typically specified by an industrial hygienist in mold remediation specifications. However, little data is commonly available showing the effect of movement of mold colonized materials on airborne mold concentrations after disturbance.
A study of the effect of disturbance of mold colonization on airborne spore concentrations was conducted in a building with limited air movement or other disturbance. Data was collected in a relatively small, two-room stand-alone building in the Puget Sound area that was built to research the hygrothermal performance of different building envelope assemblies. Wall assemblies consisted of insulated wood frame systems, with the interior of all test walls clay in gypsum wallboard fastened to the frame with screws. The panels remained in place for extended periods of time, and were opened only for occasional inspection, or when test wall assemblies were being removed at the end of a research phase. During the gypsum wallboard and panel removals, no formal dust suppression was utilized. Work practices, however, tended to minimize disturbance; the attachment screws were backed out of the wallboard, the wallboard was slowly and gently angled away from the wall section and supported at approximately a 45 degree angle, the air was not mechanically ventilated, and there was limited people movement.
Airborne spore concentrations were collected in the building before and after the panel removals. Visible mold colonization inside the opened wall panels was sampled to correlate to the air samples. Airborne spore concentrations became slightly elevated in at least some of the mold types found on the panel interior, as identified by cellotape samples.
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INVASIVE AND NONINVASIVE INVESTIGATION TECHNIQUES FOR MOLD INFECTED WALL
CAVITIES.
D. Regelbrugge, F. Norlock, J. Ruhl, G. Crawford, Boelter & Yates Inc., Park Ridge, IL; C. Yang, P&K Microbology Services Inc., Cherry Hill, NJ.
Air sampling for mold is often used as a noninvasive screening tool for potential hidden mold conditions in a structure. Techniques for specifically locating hidden mold in wall cavities can involve either drilling holes for insertion of a borescope probe or cutting out a wall section for direct inspection. Questions were posed as to whether culturable air sampling is a more effective technique than spore traps for screening tests and whether disturbance of walls by removal of base trim, peeling back wallpaper, and drilling and cutting wallboard have any significant impact on indoor air quality. An experiment was developed to gather information on these questions. A chamber was built to enclose wall sections that were constructed to simulate both exterior insulated and interior noninsulated walls. Water was injected to stimulate a hidden mold growth condition. Mold was allowed to grow undisturbed for 37 days with ambient air samples collected on 10 days during that time period. Air samples were also collected during a “typical” investigation of the walls to determine airborne mold levels generated from investigation activities such as trim removal and hole cutting. This presentation compares mold-in-air results from side-by-side culturable and spore trap sampling during the mold development period and during investigation activities. Conclusions were that the spore trap technique was to some extent effective in detecting hidden mold during the early stages of growth, however, high concentrations of mold spores and particles were released when holes were drilled or cut in the walls. It was also determined that mold growth was more abundant in insulated walls and walls with wallpaper. Further research is needed to evaluate air sampling as a screening tool when the hidden mold growth is more mature and when there are air pressure differentials across the test walls.
30
INTERPRETATION OF SOUTH TEXAS AIRBORNE FUNGI DATA.
S. Hays, Gobbell Hays Partners Inc., Nashville, TN; S. Kenoyer, Gobbell Hays Partners Inc., San Antonio, TX.
Air samples for fungi in Texas, primarily central southwest Texas, have been collected over a two-year period. The samples collected were analyzed microscopically and for viable fungi. The samples were collected from various structures under different conditions. In some instances the sampling was conducted due to the presence of visible fungal growth, and in others the sampling was due to non-specific concerns. In addition, some of the samples were collected as part of remediation activities. The sample results were compared outside to inside based on four criteria: the highest result per sampling event, the lowest result per sampling event, the arithmetic average per sampling event, and the frequency distribution per species. These data suggest that certain fungi are good for indicators of indoor air quality problems, while some fungi do not appear to be reliable indicators. This presentation will discuss sampling methodology, analytical results, data interpretation, and conclusions.
31
REGIONAL AND SEASONAL FUNGAL VARIABILITY IN THE CONTINENTAL U.S. FROM SPORE TRAP
ANALYSIS.
B. Cortes, EMSL Analytical Inc., Orlando, FL.
41,698 spore trap samples (32,294 indoor and 9404 outdoor) representing 8750 buildings were analyzed from July 2002 to June 2003, using standardized analysis protocols. Fungal concentrations (spores/m3) were examined across five regions of the U.S. (Northeast, Southeast, Midwest, Southwest, and West) throughout the four seasons. There was a significant difference between indoor and outdoor fungal concentrations (p < 000.1). Regardless of the heterogeneity of the outside air spora, the major indoor contaminants were Aspergillus/Penicillium (inside > outside), Cladosporium, Ascomycetes, and Basidiomycetes, representing approximately 90% of the total. Wind velocity coupled to high precipitation accounted for the highest diversity outdoors. The highest outdoor fungal concentrations for the NE and MW were in the fall and in the summer for the SE, SW, and W regions. Inside concentrations were higher during the winter in the SE and SW regions, during summer in the MW and W, and during the fall in the NE. The highest outdoor concentrations throughout the seasons were observed in the SE. There was an inverse relationship between the incidence of Aspergillus/Penicillium and that of Cladosporium although both types of spores were present at all times. The highest concentrations of Aspergillus/Penicillium were in the northern regions while the lowest concentrations were in the southern regions. Cladosporium concentrations were higher in the MW and SW regions. Ascomycete (MW > SE > W > NE > SW) and Basidiomycete (W > NE > SE > MW > SW) concentrations increased after high hygroperiods. Stachybotrys outdoor concentrations (NE > SE > SW > MW > W) represented less than 1% of the total fungal concentration although indoor amplification as high as 15% was recorded in the NE during the wintertime.
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INDOOR AIR QUALITY IN A SOUTH CENTRAL KENTUCKY SCHOOL PART I: COMFORT PARAMETERS
AND CARBON DIOXIDE.
E. Iyiegbuniwe, M. Rodriguez, Western Kentucky University, Bowling Green, KY.
In recent years, faculty and staff concerns about potential health effects resulting from indoor air pollution of offices has dramatically increased. The indoor environment is complex and often characterized by multifactors including building design, number and activities of occupants, types of furnishings, and cleaning agents. The overall objective of this study was to estimate the prevalence of reported respiratory symptoms and evaluate baseline conditions for comfort parameters and carbon dioxide (CO2) at three campus buildings. Buildings T and J are circular in shape and have central air-conditioning systems while the third (Building S) is rectangular and relies on unit ventilators located below windows. Fifty-two questionnaires completed by faculty and staff inquired about respiratory symptoms and perceived air quality at work and this formed the basis for classification of buildings included in the study (T and S as complaint and J as non-complaint). Comfort parameters and CO2 were measured indoors at 90 selected offices and day care rooms for approximately five hours each day during Summer 2004. Measurements also were made outdoors on each day for comparison of indoor samples using a direct-reading Quest AQ5001 ProTM (Quest Technologies, Oconomowoc, Wisc.). The data were analyzed for descriptive statistics and analysis of variance (ANOVA) with the Special Package for Social Sciences. Findings from the questionnaires showed differences in prevalence rates for employee-reported allergies, respiratory symptoms, and temperature extremes between buildings. Average indoor levels of comfort parameters and CO2 were within the American Society of Heating, Refrigerating and Air Conditioning Engineers’ (ASHRAE) recommended limits for both complaint buildings. Average CO2 levels at the day care in Building J exceeded the ASHRAE guideline while the average temperature levels were slightly below the recommended comfort zone. Preliminary ANOVA results showed no statistically significant difference in environmental parameters between and within buildings.
Posted May 30, 2005