Variability of airborne fungal measurements at an office building in the eastern United States.
Park-J; Cox-Ganser-J; Rao-C; Choe-K
American Industrial Hygiene Conference and Exposition, May 8-13, 2004, Atlanta, Georgia. Fairfax, VA: American Industrial Hygiene Association, 2004 May; :91
Good sampling strategies for measuring airborne fungi require information on reproducibility as well as spatial and temporal variability. We examined variance components and reproducibility of airborne fungal measurements. We measured airborne culturable fungi (colony counts) and spore levels with single-stage multi-hole impactors loaded with malt extract agar plates and Air-O-Cell cassettes, respectively, at 30 locations in an office building with a history of water damage. Simultaneous duplicate samples were collected at 15 of those locations. We sampled at 4 time points (AM and PM on Monday and Thursday) within a week during a dry summer. Random models were used to analyze spatial and temporal variability of fungal levels and reproducibility (coefficient of variation = CV) of the duplicates. The temporal variability (within-location geometric standard deviation, GSDw = 1.44) of total colony counts was about 1.3 times higher than spatial variability (between-location GSDb = 1.11). The temporal variability (GSDw = 1.87) of total spore counts was about two-fold higher than spatial variability (GSDb<1.01). For colony counts, the temporal to spatial variance ratio was highest for Penicillium/Aspergillus (Pen/Asp) species (ratio = 1.8). For spore counts, the temporal to spatial variance ratio for basidiospores was highest (3.4), followed by Pen/Asp species (2.6), Cladosporium (2.2), and ascospores (2.1). Duplicate analyses showed that reproducibility was better for total colony counts (CV = 10%) than for total spore counts (CV = 20%). Pen/Asp species in colony counts (CV = 25%) and spore counts (CV = 40%) were the least reproducible of all identified fungal taxa. Given the high observed temporal variability of fungal measurements, a single sample at one time point provides a very limited assessment of exposure to airborne fungi in a given location within an office building. Random sampling and analytical error significantly contributed to the total variance of airborne fungal measurements, especially for Penicillium/Aspergillus species.
Airborne-particles; Sampling; Sampling-methods; Fungi; Models; Microorganisms; Aerosols
Disease and Injury: Asthma and Chronic Obstructive Pulmonary Disease
American Industrial Hygiene Conference and Exposition, May 8-13, 2004, Atlanta, Georgia