What is Coronavirus and what is Covid-19?

Coronaviruses are a large family of viruses including the common cold, MERS, SARS & H1N1 and more. Not all coronaviruses cause COVID-19, a novel (or new) coronavirus is a strain of virus that has not been previously identified in humans.

COVID-19 is the disease caused by the novel coronavirus, SARS-CoV-2 that is spreading worldwide from person to person principally through airborne contamination.


Is UVC effective against Coronavirus?

Both NIH and CDC say UVC in proper dosage is very effective in airborne and surface disinfection.

NIH “Methods: Coronavirus inactivation experiments with ultraviolet light performed in the past were evaluated to determine the UV radiation dose required for a 90% virus reduction. This analysis is based on the fact that all coronaviruses have a similar structure and similar RNA strand length.

Conclusion: Since coronaviruses do not differ structurally to any great extent, the SARS-CoV-2 virus – as well as possible future mutations – will very likely be highly UV sensitive, so that common UV disinfection procedures will inactivate the new SARS-CoV-2 virus without any further modification.”

Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7273323/

CDC “UV radiation has been employed in the disinfection of drinking water 776, air 775, titanium implants 777, and contact lenses778. Bacteria and viruses are more easily killed by UV light than are bacterial spores.  The application of UV radiation in the health-care environment (i.e., operating rooms, isolation rooms, and biologic safety cabinets) is limited to destruction of airborne organisms or inactivation of microorganisms on surfaces.”

Source: https://www.cdc.gov/infectioncontrol/guidelines/disinfection/disinfection-methods/miscellaneous.html

Yes, if the virus is directly illuminated by UV-C at the effective dose level. UV-C can play an effective role with other methods of disinfection.

Source: https://www1.fsgi.com/wp-content/uploads/IES-CR-2-20-V1-6d.pdf

This in vitro study demonstrated that irradiation with a deep ultraviolet light-emitting diode (DUV-LED) of 280 ±5 nm wavelength rapidly inactivates SARS-CoV-2 obtained from a COVID-19 patient.

Source: https://www.biorxiv.org/content/10.1101/2020.06.06.138149v1

Is UVC effective as a disinfectant for viruses and bacteria?

CDC Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008

Updated: May 2019

“The application of UV in the health-care environment (i.e., operating rooms, isolation rooms, and biologic safety cabinets) is limited to destruction of airborne organisms or inactivation of microorganisms on surfaces. “

Purelight 360 provides 300W of 254um wavelength UVC and a Sterilization Irradiation Intensity of 1500 uW/cm2. Certified Lab results show it can disinfect >99.9% of air and surfaces in a 16’ X 16’ room in 5 minutes.

Source: https://www.cdc.gov/infectioncontrol/guidelines/disinfection/index.htm

“At a viral concentration equivalent to the low-level found in settings such as hospital rooms and to the level typically found in the sputum of coronavirus disease 2019 (COVID-19) patients, a very low dose of UV-C radiation was sufficient to inactivate SARS-CoV-2 completely. At a viral input equivalent to that found in terminally ill patients, a higher dose of radiation also completely inactivated the virus.”

Source: https://www.news-medical.net/news/20200608/Irradiation-with-UV-light-kills-SARS-CoV-2.aspx

How long does it take to kill Coronavirus?

The inverse square law applies to germicidal ultraviolet as it does to light: the killing power decreases as the distance from the lamps increases.

The PureLight 360 killed more than 99.9% of PHIx-174 Virus & E. coli Bacteria in 5-20 minutes in rooms up to 24” X 24”as verified by testing at Intertek Lab USA.

Source: https://www.americanultraviolet.com/uv-germicidal-solutions/faq-germicidal.cfml

How many Coronaviruses can infect humans?

There are only 7 known coronaviruses that can infect people. 4 Common human coronaviruses are 229E (alpha coronavirus), NL63 (alpha coronavirus), OC43 (beta coronavirus), and HKU1 (beta coronavirus).

Other human coronaviruses include:

  • MERS-CoV (the beta coronavirus that causes Middle East Respiratory Syndrome, or MERS)
  • SARS-CoV (the beta coronavirus that causes severe acute respiratory syndrome, or SARS)
  • SARS-CoV-2 (the novel coronavirus that causes coronavirus disease 2019, or COVID-19)

Sometimes coronaviruses that infect animals can evolve and make people sick and become a new human coronavirus. Three recent examples of this are 2019-nCoV also called SARS-CoV-2, SARS-CoV, and MERS-CoV.

Source: https://www.cdc.gov/coronavirus/types.html

Does Coronavirus spread in the air?

From the June 2020 Proceedings of the U.S, National Academy of Sciences Identifying airborne transmission as the dominant route for the spread of COVID-19? “In this work, we show that airborne transmission, particularly via nascent aerosols from human atomization, is highly virulent and represents the dominant route for the transmission of this disease.”

Source: https://www.pnas.org/content/117/26/14857

How long can Covid-19 stay in the air?

Covid-19 can stay in the Air up to 16 hours according to researchers at Tulane University.  “We aerosolized severe acute respiratory syndrome coronavirus 2 and determined that its dynamic aerosol efficiency surpassed those of severe acute respiratory syndrome coronavirus(SARS) and Middle East respiratory syndrome(MERS). Although we performed experiment only once across several laboratories, our findings suggest retained infectivity and virion integrity for up to 16 hours in respirable-sized aerosols.”


Is UVC effective on pathogens found on materials?

Objective: This study evaluated the efficacy of UVC, a commercial quaternary ammonium compound antimicrobial spray (FAS) and UVC+FAS combined for reducing bacterial colonization on experimentally contaminated textiles.

Conclusion: UVC quickly reduced the bacterial burden on textiles to greater than 90%; UVC may be a better disinfecting agent than FAS for Gram-negative species.

Source: https://pubmed.ncbi.nlm.nih.gov/27620856/

Why are Coronaviruses easy to kill?

The susceptibility of coronavirus aerosols was 7-10 times that of the MS2 and adenovirus aerosols. Unlike bacterial aerosols, there was no significant protective effect of high RH on UV susceptibility of the tested viral aerosols. UVC is very effective on single stranded viruses such as Coronaviruses. We demonstrated that UVGI may be an effective control measure to prevent the transmission of respiratory viral diseases.

Source: https://pubs.acs.org/doi/pdf/10.1021/es070056u

Can UVC kill viruses as well as bacteria?

Yes, UV-C removes living bacteria, but viruses are technically not living organisms; thus, we should correctly say “inactivate viruses.” Individual, energetic UV-C photons photochemically interact with the RNA and DNA molecules in a virus or bacterium to render these microbes non-infectious. This all happens on the microscopic level. Viruses are less than one micrometer (μm, one-millionth of a meter) in size, and bacteria are typically 0.5 to 5 μm.

What is UV light?

Ultraviolet (UV) light is the part of the Electromagnetic Spectrum with wavelength from 10 nm (with a corresponding frequency of approximately 30 PHz) to 400 nm (750 THz), shorter than that of visible light but longer than X-rays.

Is all UV light the same?

UVC short-wavelength ultraviolet “light” (radiant energy) that has been shown to kill bacteria and spores and to inactivate viruses. Wavelengths in the photobiological ultraviolet spectral band known as the “UV-C,” from 200 to 280 nanometers (nm), have been shown to be the most effective for disinfection, although longer, less energetic UV such as UVA and UVB can also disinfect if applied in much greater doses. UV-C wavelengths comprise photons (particles of light) that are the most energetic in the optical spectrum (comprising UV, visible, and infrared) and therefore are the most photochemically active and germicidal.

Why use UVC light to disinfect?

UVC wavelengths are between 200 and 300 nanometers, making them germicidal – meaning they are capable of inactivating microorganisms, such as bacteria, viruses and protozoa.  This quality makes UVC energy an effective, environmentally-friendly and chemical-free way to prevent microorganisms from replicating in any environment. UVC does not produce odors or ozone and does not use chemicals.

What type of UV light is germicidal?

There are three UV light wavelength categories: UVA, UVB and UVC. UVC is the only wavelength known to be germicidal. UVC utilizes short-wavelength ultraviolet radiation (shorter than UVB and UVA, which are NOT germicidal) that is harmful to microorganisms.

Only short wavelength UVC produces the amount of energy necessary to kill microorganisms.

How does UVC destroy germs?

The high energy from short wavelength UVC light is absorbed in the RNA and DNA, damaging nucleic acids and preventing microorganisms from infecting and reproducing. This absorption of UVC energy forms new bonds between nucleotides, creating double bonds or “dimers.” Dimerization of molecules, particularly thymine, is the most common type of damage incurred by UVC light in microorganisms. Formation of thymine dimers in the DNA of bacteria and viruses prevents replication and ability to infect.

The most effective wavelength for inactivation, 260 nm (55), falls in the UVC range, so-named to differentiate it from near-UV found in ground-level sunlight.

Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3460660/

In 1943, Edward et al. established that vaccinia and influenza viruses are highly susceptible to UVC, with greater than 90% viral inactivation with exposure times of as little as 0.5 s for vaccinia virus (2)

Source: https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC2234659&blobtype=pdf

What is pulsed and unmeasured UVC light?

Xenon flash lamps and other unmeasured UVC lights, while they may use UVC lamps, have no way of calculating the UVC dose needed for each location to determine the positioning or time necessary to disinfect accurately, nor can they reach shadowed or hidden surfaces. As distance from the lamp increases, effectiveness against microorganisms decreases sharply – requiring multiple positioning around the room to achieve even partial disinfection.*”

*Evaluation of a Pulsed Xenon Ultraviolet Disinfection System for Reduction of Healthcare Associated Pathogens in Hospital Rooms, Michelle M. Nerandzic, BS et. al 2016

Source: https://www.cambridge.org/core/journals/infection-control-and-hospital-epidemiology/article/evaluation-of-a-pulsed-xenon-ultraviolet-disinfection-system-for-reduction-of-healthcare%20associated-pathogens-in-hospital-rooms/D946F956F78A55A5839BEC8E581CAA77

Can I use fumigation or wide-area spraying to help control Covid-19?

“EPA does not recommend use of fumigation or wide-area spraying to control COVID-19. The Centers for Disease Control and Prevention (CDC) recommends that you clean contaminated surfaces with liquid products, such as those provided on List N, to prevent the spread of disease. Read CDC’s recommendations. Fumigation and wide-area spraying are not appropriate tools for cleaning contaminated surfaces.”

Source: https://www.epa.gov/coronavirus/can-i-use-fumigation-or-wide-area-spraying-help-control-covid-19

World Health Organization (WHO) says “the applicalication of disinfectants via Spraying and fogging is not recommended”.

“In indoor spaces, routine application of disinfectants to environmental surfaces via spraying or fogging (also known as fumigation or misting) is not recommended.”

Source: https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200514-covid-19-sitrep-115.pdf?sfvrsn=3fce8d3c_6