Study of synergistic disinfection by UVC and positive/negative air ions for aerosolized Escherichia coli, Salmonella typhimurium, and Staphylococcus epidermidis in ventilation duct flow

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Detail(s)

Original languageEnglish
Article numbere12957
Number of pages12
Journal / PublicationIndoor Air
Volume32
Issue number1
Online published19 Nov 2021
Publication statusPublished - Jan 2022

Abstract

The efficacy of the in-duct application of ultraviolet waveband C (UVC) emitting at 254 nm wavelength and air ions against aerosolized bacteria was studied in a full-scale 9-m long ventilation duct. Combined positive and negative ion polarities (bipolar ions) and combined UVC and ions were tested. The UVC was generated by a mercury-type UVC lamp and air ions were generated by positive and negative polarity ionizers. Escherichia coli (E. coli), Salmonella typhimurium (S. typhimurium), and Staphylococcus epidermidis (S. epidermidis)were tested at a concentration of 108 to 9 10 cells in 50 ml of sterilized distilled water. The case in which the positive ionizer was placed first, followed by the negative ionizer, demonstrated significantly higher disinfection efficiencies for E. coli (p = 0.007) and S. typhimurium (p < 0.001), but lower efficiency for S. epidermidis (p = 0.01) than the reversed sequence. The combination of UVC (3.71 J/m2) and air ions (1.13 × 1012 ions/m3 for positive ions and 8.00 × 1011 ions/m3 for negative ions) led to higher inactivation than individual disinfection agents operating under the same dose. A synergetic inactivation effect was observed for S. epidermidis under the combined UVC and positive ion case, while the combined UVC and negative ion case showed significant synergy effects for E. coli and S. typhimurium.

Research Area(s)

  • air ions, E. coli, Salmonella, Staphylococcus, synergistic effect, UVC

Citation Format(s)

Study of synergistic disinfection by UVC and positive/negative air ions for aerosolized Escherichia coli, Salmonella typhimurium, and Staphylococcus epidermidis in ventilation duct flow. / Nunayon, Sunday S.; Zhang, Hui H.; Chan, Vincent; Kong, Richard Y. C.; Lai, Alvin C. K.

In: Indoor Air, Vol. 32, No. 1, e12957, 01.2022.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review