A Regional Comparison of Mold Spore …

1 Journal of Occupational and Environmental hygiene , 2: 8 18. ISSN: 1545-9624 print / 1545-9632 online Copyright c 2005 JOEH, LLC. DOI: A Regional Comparison of mold Spore concentrations Outdoors and Inside Clean and mold Contaminated . Southern California Buildings Daniel M. Baxter,1 Jimmy L. Perkins,2 Charles R. McGhee,2. and James M. Seltzer3. 1. Environmental Analysis Associates Inc., and Indoor Analytical Laboratories, Inc., San Diego, California 2. University of Texas Health Science Center at Houston, School of Public Health, Regional Campus at San Antonio, San Antonio, Texas 3.

2 University of California, Irvine College of Medicine, Indoor Environmental Monitoring, Inc., San Diego, California A total of 625 buildings and outdoor locations in the San A. lthough aerobiologists studying the outdoor vari- Diego, California, area were monitored using the Allergenco ability of aeroallergens have used slit impaction Sampl-Air MK-3 impaction sampler or the Zefon Air-O-Cell slit bioaerosol cassette. Locations were classified by rigid crite- samplers for more than 20 years, it is only within ria as clean commercial, commercial with mold growth, clean the past 10 years that the use of this procedure to residential, residential with water staining, and residential evaluate bioaerosols in indoor environments, including fungal with mold growth.

3 In addition, coastal and inland outdoor ( mold ) spores, has become common practice. The most com- locations were measured. Seven categories (total spores, As- monly used devices are the Zefon Air-O-Cell (Zefon cospores/Basidiospores, Cladosporium, Smut/Myxomycetes- like, Aspergillus/Penicillium (AS/PE), Alternaria, and Uniden- International, Ocala, Fla.), Allergenco sampler (San Antonio, tified/Other) were detected frequently enough that maximum Texas), and Burkard personal sampler (Burkard Manufacturing likelihood estimate techniques could be used to determine dis- Co.)

4 , Rickmansworth, Hertfordshire, England). Slit impaction tribution parameters and, thus, treat these as continuous vari- sampling is currently the most commonly used method for ables. For total counts (no nondetectables) an analysis of vari- the collection of both nonviable and culturable airborne mold ance was used to examine differences in location means. For the other categories Land's confidence limits were generated spores. Because of size selection criteria associated with this and visually compared for differences among locations.

5 For 12 type of collection device, particles larger than m in aero- other categories (Curvularia, Dreschlera, Epicoccum, Fusa- dynamic diameter are collected with at least 50% collection rium, Mildew-like, Pithomyces, Rusts, Stachybotrys, Stemphyl- efficiency. This procedure is capable of determining the con- lium, Torula, Ulocladium, and Zygomycetes-like), detection centration of a Spore fungal grouping (morphologically sim- generally occurred in less than 10% of samples. These gen- era were treated as dichotomous (detect/nondetect) data, and ilar genus and/or species) present in the air regardless of its Chi-square analyses differentiated between locations.

6 For total viability. Although identification down to genus and species counts, values were significantly different on the order of clean is limited in some fungal groupings by this method, the ad- < outdoor < moldy. There was a large difference between vantages over viable sampling are significant. The ability to the moldy and other location classes. For AS/PE, moldy loca- provide same day analysis and the identification of nonvi- tion means were clearly higher than those for clean buildings and outdoors, although the clean and outdoor means could able spores ( , those that will not culture) are two of many not be differentiated.

7 For all other genera the results tend advantages. to indicate little or no ability to discriminate location. For The most common application of this procedure in air qual- example, there were no differences in the probabilities of de- ity investigations is to help decide whether fungal concentra- tecting Stachybotrys among the various locations. In our study tions in the indoor environment are normal or atypical . only total counts, usually driven by AS/PE concentrations , had value in determining whether a building is mold contaminated and to decide when the remediation of mold -contaminated employing our set of rigorous location classification criteria.

8 Environments has been satisfactorily completed. In spite of this procedure's widespread use, very few comparative studies Keywords mold , Comparison , airborne have been published regarding the expected range of mold spores in clean buildings, buildings with evidence of fungal Address correspondence to: Daniel M. Baxter, Environmental growth, and Regional outdoor concentrations as determined Analysis Associates, 5290 Soledad Rd., San Diego, CA 92109; by this sampling procedure. Sampling approaches, as well as e-mail: the statistical approaches used to declare a building clean or 8 Journal of Occupational and Environmental hygiene January 2005.

9 Contaminated, vary significantly among investigators. In the areas. We also evaluated plumbing utilities, including sinks, absence of standardized analysis methods, laboratory analy- showers, toilets, and furnace and air-conditioning systems for sis and data reporting procedures are also highly variable. any evidence of moisture intrusion, water leaks, or visible Investigators often rely on general comparisons of limited in- mold growth. We measured temperature, relative humidity, and door sampling with limited samples from the local outdoor air surface moisture.

10 Surface moisture measurements were col- without considering the Regional variability (geographic, mi- lected using a Delmhorst penetrating pin probe meter (Towaco, croclimatic, diurnal, and seasonal variability). Consequently, ) and/or the Tramex Moisture Encounter nonpenetrating considerable variability both in the analytical results and their moisture meter (Dublin, Ireland). Only those buildings for interpretation is common. which all inspection information was available were included. The majority of current Regional outdoor data has been This narrowed the usable number of buildings from more than obtained using the Burkard 7-day sampler and is reported 1000 to 190.