B085 Washroom airborne bacteria

Airborne bacteria assessment in an office washroom

Brief:

Washrooms are warm and wet which provide favourable conditions for the growth of microorganisms. The health concerns of bioaerosols in washrooms have been addressed since the rapid global outbreak of severe acute respiratory symptoms (SARS) in 2003. In this study, the microbiological quality of a washroom of a typical high-rise office building in Hong Kong was investigated. A comparison of the airborne bacteria exposure levels between the high and low consumption period was made. Air (500L) were collected every 4 hours from 08:00 to 20:00 for each sampling day. The sampling periods consisted of working day on weekends (WD), Sunday and holidays (SH) and working day after holiday (AH). The results showed that average airborne bacteria count (ABC) of airborne bacteria during period WD, SH and AH were 457±136 CFU m^-3, 963 ±217 CFU m^-3, and 578±280 CFU m^-3, respectively. The indoor to outdoor (I/O) ratio during period WD, SH and AH were 7.3±3.8 CFU m^-3, 34.5±33.5 CFU m^-3, and 24.1±30.8 CFU m^-3, respectively. Significantly higher count was observed at period SH with significantly higher temperature and relative humidity as well as poor ventilation. At periods WD, ABC increased from morning to the afternoon (16:00), which was probably due to the high occupancy load thus more airborne bacteria are generated from flushing the toilet. The identified bacteria genera in air were Bacillus (with relative abundance of 12.9%), Escherichia coli (11.3%), Micrococcus (55.2%), Pseudomonas (0.02%), Staphylococcus (13.4%) and unidentified isolates (7.2%). Future investigations regarding the numerical guideline and health effects due to airborne bacteria exposure in washroom are recommended.

Further Information:

Chan WY, Mui KW, Wong LT, 2009. Airborne bacteria assessment in an office washroom, Proceedings of 2009 conference on Green Building Towards Eco-City, 11-14 October, Taipei, Taiwan, Paper E01, 1-9.