UVC disinfection for COVID19

A lot is being discussed on effective methods of disinfection in dental clinics. With the ongoing Coronavirus pandemic, dental professionals are resorting to several ways of disinfection methods so as to protect from Covid-19 infection. UVC disinfection system is gaining importance because of ease of application. Here are some facts and valid information on UVC disinfection in dental clinic.

What is UVC ? How does it work ?

The UV spectrum is commonly divided into UVA (wavelengths of 400 nm to 315 nm), UVB (315 nm to 280 nm), and UVC (280 nm to 200 nm). UV-C comes under short wave spectrum of ultraviolet light. The germicidal effects of UVC irradiation results in cellular damage by photohydration, photosplitting, photodimerization, and photocrosslinking, thereby inhibiting cellular replication. The high energy from short wavelength UVC light is absorbed in the cellular RNA and DNA, damaging nucleic acids and preventing microorganisms from infecting and reproducing.

UVC disinfection operation

UVC can be generated from low-pressure mercury lamps that produce continuous UVC with a peak wavelength of 254 nm. The UV dose (irradiance multiplied by the exposure time in seconds) should be at least 40 mJ/cm² to inactivate viruses on perfectly flat and ideal surfaces. Studies have shown that as distance from the lamp increases, effectiveness against microorganisms decreases sharply – requiring multiple positioning around the room. In dental clinics, it would be advisable to place the lamp close to the dental chair for effective disinfection.

Are UVC disinfection systems safe ?

They can cause a severe sunburn-like reaction to skin. It is also advised to avoid direct exposure to eyes. Wavelengths below 240nm is said to be producing ozone which is harmful. Hence, using UVC disinfection of appropriate standards is important.

The UVC disinfection system must operate in unoccupied rooms, after the patient discharge and in the absence of health personnel.

Points to ponder while buying UVC device

• Does it have appropriate built-in UV safety sensors for automatic shutoff or is safe operation totally reliant on the operator?
• Does the device meet NIOSH, UL, IEEE and related safety standards?
• Is the device being used to disinfect medical devices? If so, is it compliant with US Food and Drug Administration (FDA) requirements (see FDA document 21CFR 880.6600)?
• Does the device emit/generate ozone? If so, is it compliant with NIOSH requirements. How is the ozone mitigated?

In general machine-human safety needs to be considered with all disinfection devices

Is UVC disinfection effective against Covid-19/ Coronavirus ?

UVC can be an effective measure for decontaminating surfaces that may be contaminated by the Covid-19 virus by inducing photodimers in the genomes of microorganisms. Covid-19 virus has not yet been specifically tested for its ultraviolet susceptibility but many studies related to coronaviruses, including the SARS coronavirus, have shown that they are susceptible to UVC disinfection.

Final Note

With the evolving situation of pandemic, healthcare professionals are adapting various ways of safety measures. As we are still in the path of scientific researches on effective ways to mitigate the coronavirus, solid evidences are yet to be established. But, with available resources it seems to be safer to adapt all possible and economically feasible ways of disinfection methods in dental practice.