Airborne fungal profiles in office buildings in metropolitan Adelaide, South Australia: Background levels, diversity and seasonal variation

The presence of bioaerosols in indoor non-industrial workplace environments has become an increasing concern to indoor air quality assessors and Occupational Health and Safety professionals. The paucity of workplace survey information and national standards limits the comparisons that can be made when investigating suspected indoor fungal contamination. Data are needed on typical non-problem conditions, thereby providing background survey information. This study examined viable fungi in 128 air samples (89 indoor: 39 outdoor) from office buildings in Adelaide, South Australia, which has an arid Mediterranean climate. Results across four consecutive seasons show that the viable airborne fungal concentrations in indoor air were on average 75% lower than those in outdoor air. A seasonal influence was noted with higher fungal levels in autumn and summer compared with winter and spring. The most common culturable airborne fungi, across all seasons and conditions, were Penicillium, Aspergillus, Cladosporium and Alternaria. A weak correlation between fungal spore concentration in indoor air and carbon dioxide was observed (r = 0.26). No other correlations with indoor air quality parameters were noted. This study provides a profile of airborne fungal diversity and abundance in non-problem indoor environments and practical guidance to indoor air quality assessors on the interpretation of indoor fungal monitoring data.