AP-UVGI – Active Personnel Ultraviolet Germicidal Irradiation

Far-UVC Light: The Safe and Effective Solution for Killing Airborne Coronaviruses

Introduction

Ultraviolet (UV) light has been used for decades to kill microorganisms, including viruses and bacteria, in air and on surfaces. However, conventional germicidal UV light (UV-C) can be harmful to human health and has been linked to skin cancer and cataracts. Far-UVC light is a type of UV light that has a wavelength range of 207-222 nm and has been shown to be as effective as conventional germicidal UV light in killing microorganisms, but without the associated human health risks.

What is Far-UVC Light?

Far-UVC light is a type of UV light that has a limited penetration depth in biological materials. It is absorbed by proteins and other biomolecules, so it cannot reach living human cells in the skin or eyes. However, it can still penetrate and kill viruses and bacteria, which are typically micrometer dimensions or smaller. The approach is based on the principle that far-UVC light can penetrate and kill pathogens, but it cannot penetrate human skin or the outer tear layer on the surface of the eye.

Study Conducted by Researchers at Columbia University Irving Medical Center

A study conducted by researchers at Columbia University Irving Medical Center explored the efficacy of far-UVC light (222 nm) against two airborne human coronaviruses: alpha HCoV-229E and beta HCoV-OC43. The results showed that low doses of far-UVC light were highly efficient in inactivating these viruses when exposed in aerosol droplets similar in size to those generated during sneezing and coughing. The study found that low doses of far-UVC light at 222 nm efficiently killed airborne human coronaviruses carried by aerosols.

Efficacy of Far-UVC Light

The inactivation rate constant for the alpha coronavirus HCoV-229E was 4.1 cm2/mJ and for the beta coronavirus HCoV-OC43 was 5.9 cm2/mJ. The results also showed that exposure to far-UVC light reduced the expression of the viral spike glycoprotein, indicating a reduction in the number of infected cells. The study concluded that far-UVC light has the potential to be used in occupied public settings to prevent the airborne person-to-person transmission of pathogens such as coronaviruses.

Potential Use of Far-UVC Light

The study suggests that the use of far-UVC light may be a safe and inexpensive tool to reduce the spread of airborne-mediated viruses in public places like hospitals, transportation vehicles, restaurants, airports, and schools. The inactivation rate was estimated to be 1.2 to 1.7 mJ/cm2 of 222-nm light to inactivate 99.9% of the airborne human coronavirus tested.

Experiment Design

The far-UVC light was generated by a 12 W 222-nm KrCl excimer lamp and was directed at the UV exposure chamber, which was positioned 22 cm away from the lamp. The relative humidity, temperature, and particle size distribution were monitored throughout the experiment, and the particle size distribution was found to be 83% between 0.3 μm and 0.5 μm, 12% between 0.5 μm and 0.7 μm, and 5% >0.7 μm. The exposure intensity was measured to be approximately 90 μW/cm2, and the exposure dose to a particle was calculated to be 2 mJ/cm2.

The far-UVC dose delivered to aerosol particles was varied by inserting additional UV-transparent plastic films, resulting in three test doses of 0.5, 1.0, and 2.0 mJ/cm2. The virus infectivity was determined using the 50% tissue culture infectious dose (TCID50) assay, and the virus survival was analyzed using robust linear regression with iterated re-weighted least squares. The virus inactivation cross section, D90, which is the UV dose that inactivates 90% of the exposed virus, was calculated based on the regression results.

The study showed that far-UVC light was effective in inactivating aerosolized coronaviruses, and that the inactivation rate increased with increasing doses of far-UVC light. These results suggest that far-UVC light has the potential to be used as a safe and effective tool to reduce the spread of airborne-mediated viruses in public settings.

In conclusion, far-UVC light has shown promising results in inactivating airborne coronaviruses and has the potential to be used as a safe and effective tool to reduce the spread of airborne-mediated viruses in public settings. Further research is needed to fully understand the potential of far-UVC light in reducing the spread of viruses, including SARS-CoV-2.

 

FAQs

What is Far-UVC Light?

Far-UVC light is a type of ultraviolet (UV) light with a wavelength range of 207-222 nm. It has been shown to be as effective as conventional germicidal UV light in killing microorganisms, but without the associated human health risks.

Is Far-UVC Light Safe for Humans?

Yes, Far-UVC light is safe for humans because it has a limited penetration depth in biological materials. It is absorbed by proteins and other biomolecules, so it cannot reach living human cells in the skin or eyes.

What is the Efficacy of Far-UVC Light in Killing Airborne Coronaviruses?

A study conducted by researchers at Columbia University Irving Medical Center showed that low doses of far-UVC light (222 nm) were highly efficient in inactivating airborne human coronaviruses. The inactivation rate was estimated to be 1.2 to 1.7 mJ/cm2 of 222-nm light to inactivate 99.9% of the airborne human coronavirus tested.

What are the Potential Uses of Far-UVC Light?

The study suggests that the use of far-UVC light may be a safe and inexpensive tool to reduce the spread of airborne-mediated viruses in public places like hospitals, transportation vehicles, restaurants, airports, and schools. However, more research is needed to fully understand the potential of Far-UVC light in reducing the spread of viruses, including SARS-CoV-2.

FAQ Conclusion

Far-UVC light is a safe and effective solution for killing airborne coronaviruses. It has been shown to be as effective as conventional germicidal UV light in killing microorganisms, but without the associated human health risks. The use of Far-UVC light may be a valuable tool in reducing the spread of airborne-mediated viruses in public places, but further research is needed to fully understand its potential.