Monday, March 13, 2006

Indoor Outdoor Fungus

Indoor Air Volume 16 Page 37 - February 2006

Relationship between indoor and outdoor bioaerosols collected with a button inhalable aerosol sampler in urban homes
T. Lee1, S. A. Grinshpun1, D. Martuzevicius1,2, A. Adhikari1, C. M. Crawford1, J. Luo3, T. Reponen1

Abstract This field study investigated the relationship between indoor and outdoor concentrations of airborne actinomycetes, fungal spores, and pollen. Air samples were collected for 24 h with a button inhalable aerosol sampler inside and outside of six single-family homes located in the Cincinnati area (overall, 15 pairs of samples were taken in each home). The measurements were conducted during three seasons – spring and fall 2004, and winter 2005. The concentration of culturable actinomycetes was mostly below the detection limit. The median indoor/outdoor ratio (I/O) for actinomycetes was the highest: 2.857. The indoor of fungal and pollen concentrations followed the outdoor concentrations while indoor levels were mostly lower than the outdoor ones. The I/O ratio of total fungal spores (median = 0.345) in six homes was greater than that of pollen grains (median = 0.025). The low I/O ratios obtained for pollen during the peak ambient pollination season (spring) suggest that only a small fraction penetrated from outdoor to indoor environment. This is attributed to the larger size of pollen grains. Higher indoor concentration levels and variability in the I/O ratio observed for airborne fungi may be associated with indoor sources and/or higher outdoor-to-indoor penetration of fungal spores compared to pollen grains.

Practical Implication

This study addresses the relationship between indoor and outdoor concentrations of three different types of bioaerosols, namely actinomycetes, fungal spores, and pollen grains. The results show that actinomycetes are rare in indoor and outdoor air in Midwest, USA. Exposure to pollen occurs mainly in the outdoor air even during peak pollen season. Unexpectedly high fungal spore concentrations were measured outdoors during winter. The presented pilot database on the inhalable levels of indoor and outdoor bioaerosols can help apportion and better characterize the inhalation exposure to these bioaerosols. Furthermore, the data can be incorporated into existing models to quantify the penetration of biological particles into indoor environments from outdoors.


BrooklynDodger(s) comment: Indoor Air is a new journal on the Dodger(s) watch. Initially it looked really hot for key information; later cruising of the TOC's was less exciting.

The investigators selected homes without mold or moisture problems. Good data for a baseline and comparison to problem houses. That said, the Dodger(s) couldn't figure out what the plan was for the study, or the presentation of the data, or the conclusions.

The cleanest take home message was largely that indoor fungus concentrations were less than outdoors, and for pollen even less than that. This was observed for several types of fungus.

This observation doesn't deal with the situation where there's one particular fungus, indoors, that's creating a problem for occupants and can't be abated.