Safer school with near-UV technology: novel applications for environmental hygiene

G Messina; R Bosco; D Amodeo; N Nante; I De Palma; C Petri; G Cevenini

doi:10.1007/s40201-023-00850-5

Safer school with near-UV technology: novel applications for environmental hygiene

J Environ Health Sci Eng. 2023 Jan 26;21(1):157-165. doi: 10.1007/s40201-023-00850-5. eCollection 2023 Jun.

Authors

G Messina^{1

2}, R Bosco², D Amodeo³, N Nante^{1

2}, I De Palma³, C Petri³, G Cevenini³

Affiliations

¹ Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy.
² Post Graduate School of Public Health, Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy.
³ Department of Medical Biotechnologies, University of Siena, Siena, Italy.

Abstract

Systems capable of disinfecting air and surfaces could reduce the risk of infectious diseases transmission. Aim: to evaluate the effectiveness of near-UV LED ceiling lamps, with a wavelength of 405 nm, in improving environmental hygiene. Between November and December 2020, we conducted an experimental study having a pre-post design in a kindergarten room in Siena where 4 ceiling lamps with 405 nm LED technology were installed. Twice per day, sampling was performed before (T0) and after treatment with near-UV (T1). We used between 8 and 12 pairs of contact plates to sample at various random spots each day. Air samplings were also performed. The plates were incubated at 22 and 36 °C. Significance was set at 95% (p < 0.05). The mean level of Colony Forming Unit (CFU) at T(0) was 249 (95% CI 193.1 - 305.0) at 36 °C and 535.2 (374.3 - 696.1) at 22 °C. The reduction was significant at T(1): by 65% at 36 °C and, 72% at 22 °C. Also, for air contamination: 95.3% (98.4-92.3). A dose threshold of about 5 J/cm² was identified to have an 80% CFU abatement and remains nearly constant. The advantage of being able to use this technology in the presence of people is very important in the context of controlling environmental contamination.

Keywords: 405 nm; Environmental hygiene; Near-UV.