UV Disinfection

Ultraviolet germicidal irradiation (UVGI) inactivates pathogens by damaging genomic material. Ultraviolet Germicidal Irradiation (UVGI) is electromagnetic radiation that can destroy the ability of microorganisms to reproduce by causing photochemical changes in nucleic acids.  UVGI has been widely applied for air, water, and surface decontamination.

Recently UVGI has been identified by the Centers for Disease Control (CDC) as one of the most promising methods for N95 filtering facepiece respirator (N95 FFR) decontamination, and a workflow for UVGI-based decontamination was successfully implemented at the University of Nebraska Medical Center (UNMC), among other locations.

Pathogen inactivation depends critically on ultraviolet (UV) wavelength (peak inactivation efficacy with ~260 nm UV-C light) and dose.


References :

  • - Kowalski, W. 2009. Ultraviolet Germicidal Irradiation Handbook: UVGI for Air and Surface Disinfection. Springer

  • - N95DECON (https://www.n95decon.org/uvc)

  • - Center for Disease Control (CDC) : https://www.cdc.gov/nceh/features/uv-radiation-safety/index.html

UVGI mode of action & appropriate dosing

UVGI inactivates pathogens primarily by damaging DNA and RNA (max UV absorption at 260 nm) (Kowalski, 2009 ).

Decontamination is critically dependent on application of the appropriate UV wavelength (UV-C, with high efficacy near 260 nm ( EPA, 2006 )) and dose (≥ 1.0 J/cm² for inactivation of SARS-CoV-2 analogues in N95 FFRs)


From : Stérilisation à froid du vin e du moût par les rayons ultra violets (https://www.vignevin-occitanie.com)

References :

  • - Kowalski, W. 2009.  Ultraviolet Germicidal irradiation Handbook: UVGI for Air and Surface Disinfection.  Springer

  • - N95DECON (https://www.n95decon.org/uvc)

UVGI : decontamination and reuse of filtering facepiece respirators

From Lowe JL et al - N95 filtering facepiece respirator ultraviolet germicidal irradiation process for decontaminaton and reuse



The ongoing pandemic of SARS-CoV-2 resulting in COVID-19 has severely stressed the worldwide healthcare system and has created dangerous shortages of personal protective equipment (PPE) including N95 filtering facepiece respirators (N95 FFRs). In an effort to extend the stockpile of N95 FFRs at our institution and reduce risks associated with reuse of untreated, contaminated N95 FFRs, Lowe J et al (2020) developed a surface decontamination procedure involving the delivery of ultraviolet germicidal irradiation (UVGI) to used N95 FFRs. The evidence base supporting this program includes:


  1. 1. UVGI has been shown to effectively inactivate a wide range of human pathogens including coronaviruses and other human respiratory viruses;
  2. 2. UVGI has been demonstrated to inactivate human respiratory viruses, including coronaviruses, on various models of N95 FFRs;
  3. 3. Levels of UVGI needed to inactive human respiratory viruses are well below the level of irradiation that adversely affects the fit and filtration characteristics of N95 FFRs; and
  4. 4. UVGI can be safely administered when appropriate safeguards are in place.


Any organization considering a decontamination strategy (including UVGI, etc.) to deal with lack of supply or potential lack of N95 FFR should validate their own procedures, including desired surrogate microbial reduction and retained filter efficiency and fit.


References :

  • - Fisher, E. M., & Shaffer, R. E. (2011). A method to determine the available UV-C dose for the decontamination of filtering facepiece respirators. Journal of Applied Microbiology , 110 (1), 287–295. https://doi.org/ 10.1111/j.1365-2672.2010.04881.x

  • - Lowe JL et al - N95 filtering facepiece respirator ultraviolet germicidal irradiation process for decontaminaton and reuse (https://www.nebraskamed.com/sites/default/files/documents/covid-19/n-95-decon-process.pdf)