Assessment and modeling of indoor fungal and bacterial bioaerosol concentrations

In recent years, potentially harmful microorganisms such as Stachybotrys chartarum have garnered national attention when implicated with indoor air problems. However, accurate assessment of biologically contaminated indoor air has proven to be prohibitively labor, time, cost, and training intensive. The model developed in this study accurately predicts the levels of biological indoor air contaminants for the Greater Cincinnati area using a number of independent variables that can be quickly calculated without expensive, time-consuming methods. Thirty-nine single-family residences in the Greater Cincinnati area were sampled using Andersen two-stage viable microbial particle sizing sampler instruments loaded with Malt Extract Agar, Trypicase Soy Agar, Czapek's Cellulose Agar, and Corn Meal Agar. After air sampling, the Petri dishes were incubated, the number of colonies from each plate were enumerated, and the total number of viable colony forming units per cubic meter of air were calculated. Independent variables (indoor relative humidity, indoor temperature, outdoor mold, season, water damage, visible mold, damaged materials, home age, remediation factors, health questionnaire, number of occupants, and indoor pets) were then compared to the dependent variable (fungal and bacterial bioaerosol counts) by multiple linear regression using Analyze-it® for Microsoft Excel®. The final air model predicted the total number of viable colony forming units per cubic meter with 97% accuracy; the goal for this model was 90% accuracy.