Profiles of Airborne Fungi in Buildings and Outdoor Environments in the United States

Abstract

We examined 12,026 fungal air samples (9,619 indoor samples and 2,407 outdoor samples) from 1,717 buildings located across the United States; these samples were collected during indoor air quality investigations performed from 1996 to 1998. For all buildings, both indoor and outdoor air samples were collected with an Andersen N6 sampler. The culturable airborne fungal concentrations in indoor air were lower than those in outdoor air. The fungal levels were highest in the fall and summer and lowest in the winter and spring. Geographically, the highest fungal levels were found in the Southwest, Far West, and Southeast. The most common culturable airborne fungi, both indoors and outdoors and in all seasons and regions, were Cladosporium, Penicillium, nonsporulating fungi, and Aspergillus. Stachybotrys chartarum was identified in the indoor air in 6% of the buildings studied and in the outdoor air of 1% of the buildings studied. This study provides industrial hygienists, allergists, and other public health practitioners with comparative information on common culturable airborne fungi in the United States. This is the largest study of airborne indoor and outdoor fungal species and concentrations conducted with a standardized protocol to date.

Indoor airborne fungi and wheeze in the first year of life among a cohort of infants at risk for asthma

“…Moreover, Penicillium was the only frequently occurring genus in our study showing a significant association with visible mold and somewhat weaker associations with visible water and musty/ moldy odor. Penicillium also exhibited higher indoor than outdoor levels in our study, an observation reported by others throughout the United States (Shelton et al, 2002;Chew et al, 2003;O'Connor et al, 2004). The ubiquitous nature of Penicillium sp.…”

“…Mold levels tend to be highest in the summer and fall throughout the United States (Shelton et al, 2002), and were observed in this project as well. Children born in the summer and those with fall mold collection dates, an overlapping group in our study, were at an increased risk of wheeze in unadjusted logistic regression models.…”

Culturability and concentration of indoor and outdoor airborne fungi in six single-family homes

“…In outdoor environment, the non-sporulating fungi (81.1%) was the predominant type followed by Cladosporium (70.0%), Penicillium (60.0%), Aspergillus (43.3%), Alternaria (24.4%) and Yeast (13.3%). The predominant culturable fungi reported in this study are consistent with previous studies (Ren et al, 1999;Shelton et al, 2002;Adhikari et al, 2005). Indoor and outdoor environments revealed exactly the same frequency of 81.1% of non-sporulating culturable fungi, which may be originated from Ascomycetes and Basidiomycetes.…”

“…E.g., the median levels of indoor and outdoor culturable fungi in 80 homes in Latrobe Valley, Australia were 812 and 1042 CFU m -3 , respectively (Garrett et al, 1997). The median indoor and outdoor concentrations of 1717 buildings located across the United States were 82 and 540 CFU m -3 , respectively (Shelton et al, 2002). In addition, a study conducted in Greater New Haven, Connecticut revealed higher mean levels of culturable fungi (Ren et al, 1999) than found in the present study.…”

“…As to the CFU concentrations averaged over a specific season, only the fall database showed statistically significant difference between the indoor and outdoor levels (p = 0.005). Shelton et al (2002) have shown that fungal concentration in American Midwest generally reaches the lowest level in the winter season. Increasing through the spring, it peaks during summer and fall seasons.…”