Disinfection efficiency of chlorine dioxide gas in student cafeterias in Taiwan

• Published in: Journal of the Air & Waste Management Association (1995) 2013-07, Vol.63 (7), p.796-805
• Main Authors: Hsu, Ching-Shan, Huang, Da-Ji
• Format: Article
• Language: English
• Subjects: Aerosols - analysis; Aerosols - pharmacology; Air Microbiology; Applied sciences; Atmospheric aerosols; Atmospheric pollution; Bacteria; Bacteria - isolation & purification; Cafeterias; Chlorine Compounds - analysis; Chlorine Compounds - pharmacology; Discriminant Analysis; Disinfectants - analysis; Disinfectants - pharmacology; Disinfection & disinfectants; Disinfection - methods; Environmental Monitoring; Environmental protection; Exact sciences and technology; Fungi; Fungi - isolation & purification; General processes of purification and dust removal; Indoor pollution and occupational exposure; Models, Theoretical; Oxides - analysis; Oxides - pharmacology; Pollution; Prevention and purification methods; Restaurants; Taiwan; Time Factors
• ISSN: 1096-2247; 2162-2906
• DOI: 10.1080/10962247.2012.735212

In Taiwan, the food and drink requirements of students and faculty members are met by student cafeterias. The air quality within these cafeterias should satisfy the guidelines laid down by the Taiwan Environmental Protection Agency (Taiwan EPA). Accordingly, this study performed an experimental investigation into the efficiency of two different gaseous chlorine dioxide (ClO 2 ) treatments in disinfecting a local student cafeteria, namely a single, one-off application and a twice-daily application. In both cases, the ClO 2 was applied using strategically placed aerosol devices. The air quality before and after disinfection was evaluated by measuring the bioaerosol levels of bacteria and fungi. Moreover, a stepwise discriminant analysis method was applied for predicting the residual concentrations of bacteria and fungi, as a function of the environmental parameters and the ClO 2 concentration. The experimental results showed that the average background levels of bacteria and fungi prior to ClO 2 disinfection were 972.5 ± 623.6 and 1534.1 ± 631.8 colony-forming units (CFU)/m 3 , respectively. A single ClO 2 application was found to reduce the bacterial and fungal concentration levels by as much as 65% and 30%, respectively. By contrast, a twice-daily ClO 2 application was found to reduce the bacterial and fungal concentration levels by as much as 74% and 38%, respectively. The statistical analysis results showed that the residual bacterial concentration level was determined primarily by the number of individuals present in the cafeteria, the temperature, and the ClO 2 concentration, whereas the residual fungal concentration level was determined mainly by the temperature, the total number of suspended particles, and the ClO 2 concentration. Thus, the integrated results suggest that the air quality guidelines prescribed by the Taiwan EPA for student cafeteria can best be achieved by applying ClO 2 twice daily using an appropriate deployment of aerosol devices.