K.H. Bartlett, Ph.D., S.M. Kennedy, Ph.D., M. Brauer, Sc.D., B. Dill, Ph.D., C. VanNetten, Ph.D. K.H. Bartlett, Ph.D kbartlet@interchange.ubc.ca

A two year study of elementary school classrooms was begun in 1996. Data collected included: number of occupants and patterns of occupancy, CO2 levels, temperature and percent relative humidity (%RH), total particulate, and air exchange rates using tracer gas (SF6). Indoor and outdoor bioaerosols were collected using an Andersen N-6 impactor.

The effect of measured indoor air quality parameters and building characteristics on the airborne concentrations of indoor bacteria and mesophilic fungi were evaluated using multiple linear regression. The variable with the highest predictive value for bacterial concentrations was indoor CO2 concentration, with the final equation having a R2 of 0.59. In contrast, outdoor temperature had the highest predictive value for indoor mesophilic fungi with the final equation having a R2 of 0.61.

Variables commonly measured during an indoor air quality investigation can be used to understand bioaerosol concentrations. High commensal bacterial counts are clearly related to inadequate ventilation of the occupied space. In a similar manner, the use of mechanical or natural ventilation in buildings and the concentration of fungi in the outdoor environment is related to indoor fungal counts. These data would suggest that indoor air quality investigations benefit from an integrated investigative approach.