The effectiveness of commercial household ultraviolet C germicidal devices in Thailand

Ultraviolet C (UVC), or ultraviolet germicidal irradiation, is known for its effective air, water, and surface disinfectant properties. With the rise of global awareness about public sanitation and personal hygiene due to the emergence of the current coronavirus disease 2019 pandemic, several applications of UVC were introduced to the commercial market. The present experimental study aimed to evaluate the effectiveness of commercial household ultraviolet C germicidal devices for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) inactivation. UVC dosages (mJ/cm 2 ) of 10 UVC devices were determined at the recommended settings compared to a benchmark for SARS-CoV-2 inactivated UVC dosage (3.7 mJ/cm 2 ). Of the 10 devices, 3 were handheld UVGI surface disinfection equipment, 4 were UVGI disinfection chambers, and 3 were movable UVGI air and surface purifiers. Three UVGI disinfection chambers and all movable UVGI air and surface purifiers provided sufficient UVC dosages for SARS-CoV-2 inactivation. None of the studied handheld UVGI surface disinfection equipment achieved the UVC dosage for SARS-CoV-2 inactivation. A lack of standardization in the distance and cycle duration for each UVC application was observed. Standard usage guidelines for UVC devices are required to improve the effectiveness of UVC irradiance for SARS-CoV-2 inactivation and minimize the potential side effects of UVC.