Suitability of ultraviolet (A)-light emitting diode for air stream disinfection

Abstract

We previously developed a high powered light-emitting diode device capable of discharging germicidal ultraviolet irradiation (UVA-LED) at an approximate wavelength of 365 nm. This study examined the bactericidal activity of UVA-LED in moving air streams. Aerosols of Escherichia coli DH5α were exposed to UVA-LED irradiation using a stable current (0.5 A and 1.2 mW/cm2) or pulse current (1.0 A and 0.2 mW/cm2). Settle plate analysis was used for bioaerosol sampling, where results were expressed as Colony Forming Units. A -3 Log inactivation of the E. coli population occurred after 75 minutes of constant exposure to stable current. The pulse current produced inactivation within a similar timeframe. Our results might be significant as a basic study for further investigations about the effect of UVA-LED on airborne bacteria and its suitability for air disinfection applications.