Characteristics of Airborne Biocide and Its Effect on Bioaerosols

Abstract

Objective: Biocides are widely used in domestic households, industrial facilities, and living spaces. Biocidal sprays are commonly used for disinfection in indoor areas in the form of an aerosol. Biocides applied as an aerosol can be inhaled through the respiratory system into the lungs. The aim of this study was to determine the characteristics of biocide aerosol particles according to biocide solvent concentrations, and to measure changes in the bioaerosol. Methods: A biocide product with a high frequency of use was selected for use in the experiments, which were conducted in a room with a volume of 38.05 m3

the biocide was diluted with tap water at ratios of 1:200, 1:40, and 1:20. Real-time monitoring devices were used to determine the characteristics of airborne biocide particles. A scanning mobility particle sizer (SMPS), P-Trak, and an optical particle sizer (OPS) were used to measure particle size distributions and number concentrations. A DustTrak was used to measure mass concentrations. Based on consideration of previous studies, the biocide components didecyldimethylammomium chloride (DDAC), benzalkonium chloride (BAC), propiconazole (PCZ), and tebuconazole (TBZ) were selected for study. The samples were collected on glass fiber filters using a 2 L/min pump, and then analyzed by gravimetric analysis and liquid chromatography–mass spectrometry (LC-MS/MS). Bacteria and fungi were sampled on tryptic soy agar (TSA) and sabouraud dextrose agar with chloramphenicol (SDAC) plates using an Anderson one-stage viable cascade impactor, immediately before and 1 h after spraying. Bacteria were cultured for more than 48 h at 35℃ and fungi were cultured for more than 5 days at 25℃ in an incubator. After counting the number of colonies, the concentrations of microorganisms were determined. Results: (1) Biocide particle characteristics: After spraying the biocide, the number concentration of particles smaller than 100 nm increased, but the concentration did not differ significantly between the treatments with different biocide concentrations. However, the DustTrak results indicated that application of higher concentrations of biocide resulted in higher mass concentrations. Statistically significant differences in the DustTrak results were found between every biocide concentration. (2) Components of the biocide: Concentrations of BAC ranged from LOD to 25.73 g/m3 in the treatment with the high biocide concentration. (3) Microorganisms: Bacteria concentrations before and after spraying were 73.88 and 27.15 CFU/m3, respectively. The rates of decrease in biocide concentrations were 24.85% in the control, and 89.86% and 97.88% at the 1:200 and 1:40 dilutions, respectively. The highest rate of decrease was 100% at the 1:20 dilution. Concentrations of fungi were 59.60 and 23.44 CFU/m3 before and after spraying, respectively. The rate of decrease in the concentration of biocide was 40.70% in the control, and 44.47% and 71.21% at the dilutions of 1:200 and 1:40, respectively. The highest rate of decrease was 94.71% at the 1:20 dilution. Conclusions: The concentration of a biocide applied in an enclosed space can influence the characteristics of biocide aerosol in the air. The concentration of microorganisms remaining in the area where biocide was applied was dependent on the size of the biocide particles. The results of this study can be used as a reference when assessing the characteristics of biocide aerosol distributions and the concentration of microorganisms.