Disinfection efficacy of ultraviolet germicidal irradiation on airborne bacteria in ventilation ducts

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

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Original languageEnglish
Pages (from-to)806-817
Journal / PublicationIndoor Air
Issue number6
Online published1 Sep 2018
Publication statusPublished - Nov 2018


A full-scale ventilation duct ultraviolet germicidal irradiation (in-duct UVGI) system was designed to investigate its disinfection efficacy on five airborne pathogens: Serratia marcescens, Pseudomonas alcaligenes, Escherichia coli, Salmonella enterica, and Staphylococcus epidermidis, with airflow Reynolds numbers from 4 × 104 to 8 × 104. By varying the UV intensity, the susceptibility constants (Z-values) of the bacteria were experimentally determined to be 1.2, 1.0, 0.60, 0.39, and 0.37 m2/J for S. marcescens, P. alcaligenes, E. coli, S. enterica, and S. epidermidis, respectively. The disinfection efficacy was numerically investigated on the basis of the predicted irradiance, which included emissive irradiance and diffuse refection irradiance. The results suggest that it is vital to properly evaluate the UV dose (irradiance intensity) received by airborne bacteria to determine their Z-values. In-duct UVGI inactivated nearly all of the test bacteria with Reynolds numbers of 4 × 104 (inlet velocity = 3 m/s), and the disinfection efficacy decreased as Reynolds numbers increased. The in-duct UVGI system would potentially provide a supplementary solution for improving indoor air quality (IAQ) within mechanical ventilated/air-conditioned environment.

Research Area(s)

  • air disinfection, bacteria susceptibility, in-duct UVGI, indoor air quality, irradiance, UV dose