The Case for Ultraviolet Germicidal Irradiation (UVGI)

A summary report prepared at the request of a member of the UK parliament and a Scottish government advisor

The UK-Govt commissioned report recommends ‘Upper Room Air Irradiation’ with UVGI/UV-C in indoor spaces:

“As a means of preventing airborne transmission of SARS-CoV-2 we advocate the immediate installation of the safe and proven upper room 254nm UVGI in indoor public spaces with low air changes per hour and/or recirculated air. We further believe that if the on-going research into the new 222nm UVGI continues to demonstrate its safety and efficacy, then this technology should be adopted as it will work continuously to inactivate viruses and bacteria in the air we breathe and on surfaces we touch.”

Also:

254 nm upper-room UVGI:
Existing technology that could be implemented now and has appropriate regulation and guidance
Ultraviolet-C (UV-C) inactivates viruses and bacteria in air, on surfaces and in water (Kowalski 2009)
UV-C inactivates SARS-CoV-2, the virus responsible for Covid-19 pandemic (Heilingloh et al. 2020; Inagaki et al. 2020, Kitagawa et al. 2020, Ozog et al. 2020)
For surfaces and water, UV-C is used extensively and routinely (water treatment plants, hospitals) with excellent UK companies operating in this area (DWI 2016, SAGE 2020)
Upper-room UVGI is a beam of 254-nm UV-C that is above head height and decontaminates the air circulating through the beam
Upper-room UVGI is proven to reduce the spread of airborne viruses:
- 1957 influenza pandemic infection rates Hospital wards
  - with upper-room UVGI 1.9%
  - Without upper room UVGI 18.9% (Sabino et al. 2020)
- 1937 – 1941 measles infection rates
  - Classroom with upper-room UVGI 13.3%
  - Classrooms without upper-room UVGI 53.6% (Nardell and Nathavitharana 2019
- “Upper-room UV lights and negative air ionization each prevented most airborne TB transmission detectable by guinea pig air sampling. Provided there is adequate mixing of room air, upper-room UV light is an effective, low-cost intervention for use in TB infection control in high-risk clinical settings” conclusions from a study involving SAGE member Catherine Noakes (Escombe et al. 2009).
- Health Facilities Scotland, NHS National Services Scotland have a review for light based technologies for the decontamination of air, year of publication unknown (http://www.hfs.scot.nhs.uk/publications/1478698837Light%20Based%20Technologies%20final%20version.pdf)
Airborne transmission of SARS-CoV-2 can occur in enclosed spaces with inadequate ventilation or air handling and where there is prolonged exposure to respiratory particles, particularly when under exertion such as shouting, singing and exercising (CDC 2020)
- As of 21/10/2020 WHO state that large droplets are the primary mode of transmission. However there is a large contingent of scientists who believe aerosol transmission is the likely dominant transmission route (American Association for Aerosol Research https://youtu.be/g9CHnUMt2gY)
Therefore research indicates upper-room UVGI would be useful to reduce the spread of SARS-CoV-2
- UK academic research shows possible to achieve >90% disinfection rates with upper-room UVGI (Beggs and Avital 2020)
- Expected equivalent air changes per hour (AC/h) from upper-room UVGI = 109 AC/h
- Worst case equivalent air changes per hour (AC/h) = 11 AC/h o CDC recommends 6 – 12 AC/h for effective air disinfection
- With 10 AC/h there is 99% removal by efficiency of airborne contaminant in 28 minutes
- With 50 AC/h there is 99% removal by efficiency of airborne contaminant in 6 minutes (CDC Enivornmental Infection Control Guidelines, Appendix B. Air https://www.cdc.gov/infectioncontrol/guidelines/environmental/appendix/air.html#tableb1)
Upper-room UVGI well established technology in countries with a high TB burden, such as homeless shelters in USA and prisons in Russia. No commercial demand in UK prior to 2019 and therefore discontinued by many companies (personal communication).
Upper-room UVGI is safe as people are not irradiated with the UV-C radiation (Nardell et al. 2008). If 254 nm is incident on skin and eye it will cause an acute sunburn and keratitis (inflamed front of the eye) but it is not linked to long term effects such as skin cancer (Kowalski 2009)
Movement of air in the room and proper installation in locations that are the primary transmission route are key (Nardell and Nathavitharana 2019)
UVGI Best Practice guidelines exist (Martin et al. 2008)
Suggested next steps:
Upper-room UVGI could be installed in locations with low AC/h
Initially high-risk areas, primary transmission routes, and areas with aerosol generating procedures
Examples could include: care homes, high risk hospital clinics (e.g., dialysis units), dentist surgeries
Further roll out to businesses, e.g., hospitality, indoor sports and retail sector