Indoor and outdoor exposure levels of airborne bacteria and mold in various environments of Ankara, Turkey

There has been a growing concern about exposure to airborne bacteria and mold (bioaerosol) because of the related adverse health effects. In order to address the issue, this study has been performed to evaluate the bioaerosol exposure from various indoor environments of Ankara for the first time in Turkey. Bioaerosol samples were collected according to NIOSH-0800 standard method in 94 different indoor environments (houses, primary schools, kindergartens, libraries, laboratories, classrooms, offices, cafeterias, restaurants, and sport halls) and outdoor air in 2007-2008. Bacteria and mold samples were collected both during the winter and the summer to assess their seasonal variations. Air samples collected by Andersen-single stage bio-impactor on to plate count and blood agars for total bacteria count and bacteria identification, sabourod-antibiotic agar was used for mold count and identification. During the bioaerosol sampling, indoor and outdoor temperature (ºC), relative humidity (%), and concentrations (ppm) of CO2 and CO were recorded. Occupant questionnaire was filled in order to estimate sampling stations source strengths at the stations. Bacteria samples were identified as specie or at least as genera by semi-automatic instrument, VITEK32. Mold samples were identified as genera, according to their morphological structures under the light microscope. Results showed that indoor air bioaerosol levels were higher than outdoor air. Airborne bacteria and mold levels (CFU/m3) were found higher in the winter compared to those in the summer. The most prevalent bacteria genus/specie detected indoor and outdoor air were Micrococcus spp., Staphylococcus auricularis, Bacillus spp., and Staphylococcus hominis and fungal genera were Penicillium spp., Aspergillus sp., Rhizopus spp., Cladosporium spp., and Rhizomucor spp. The current bioaerosol concentrations were comparable to those in other studies, with geometric mean values between 10 and 103 CFU/m3. Several statistical tests were done to estimate the effect of environmental and occupational factors on airborne bioaerosol levels (p<0.05).