The amazing Ultraviolet C (UVC) disinfection device has been proven to kill 99.99% of germs, and humans are known to use sunlight or UV light to kill germs. This cultural heritage has been passed down to modern times. Scientists have extended the use of high-energy UVC to public health applications, successfully eradicating the bacteria that have caused large outbreaks of SARS and MERS in the past.

 

What are germicidal UV-C lamps?

Before we define germicidal UV-C light, we need to define ultraviolet or UV light. Ultraviolet light is a naturally occurring electromagnetic radiation that is present in sunlight and actually makes up about 10% of the total light produced by the sun. Ultraviolet light is electromagnetic energy with shorter wavelengths than visible light but longer than X-rays. The wavelength of this light ranges from 10nm to 400nm and is divided into three sub-bands; UV-A, UV-B and UV-C. Ultraviolet light with wavelengths less than 290nm is considered to have "germicidal" properties. Germicidal means that light can kill (inactivate) pathogens, just like it sounds. Earth's atmosphere absorbs supermagnetic radiation with wavelengths less than 290nm, which means that most of the UV-C and UV-B produced by the sun is blocked by Earth's ozone. Germicidal UV-C light is commonly used to inactivate or kill microorganisms on surfaces, air and water. When implemented properly, UV-C lighting can kill up to 99.9% of pathogens.

 

Germicidal UV light kills pathogen cells by damaging their DNA. Exposure to certain ultraviolet wavelengths of electromagnetic radiation (light) can alter the genetic material of microorganisms and disrupt their ability to reproduce. UV energy triggers the formation of specific thymine or cysteine dimers in DNA and uracil dimers in RNA, which inactivate microorganisms by causing mutation and/or cell death and inability to reproduce. The disinfecting properties of ultraviolet light have been known for more than 140 years, ever since shorter wavelengths of sunlight were discovered to have antibacterial effects. Soon after, it was demonstrated that the ultraviolet portion of the spectrum was capable of destroying microbes.

 

After confirming that UV lighting was able to kill pathogens, the next step was to find a way to replicate UV wavelengths to disinfect surfaces, air and water. The first UV quartz lamp was invented in 1904 and gave rise to the germicidal lamp.

 

A germicidal lamp is a lamp that produces ultraviolet wavelengths (UV-C; 200nm to 280nm) with disinfecting properties, like the lamps used in this study to reuse N95 masks during the coronavirus pandemic.

 

During the COVID-19 pandemic, a 'new normal' lifestyle that requires close attention to hygiene and sanitation to avoid infectious diseases has made UVC increasingly important. UVC devices can kill bacteria in air, water, food, money, coins, banknotes, masks, etc.

 

UVC in Today's Lifestyle

UVC equipment has been used in hospitals and industry to sanitize food and ventilation systems. More recently, these devices have begun to be used in everyday life, and their use is sometimes taken for granted, such as sanitizing cafeteria cutlery or banknotes. With the COVID-19 pandemic still looming, disinfection equipment has become a popular item in everyone's daily life. As a result, more and more UVC devices are being produced and scaled down for home use so that people have them, such as UVC sterilization boxes that can be used in homes with young children, sick people, allergy sufferers. Those who need an extra clean environment. There are also portable UVC LED disinfection sticks that people can carry around to kill germs in the air, food, banknotes and other items.

Where does UVC come from?

There are several different shades and intensities of visible and invisible UV rays. UVA with wavelengths between 315-400 nanometers covers most of the atmosphere. UVB has a wavelength between 280-315 nanometers, while UVC, which has the shortest wavelength, emits the most energy between 100-280 nanometers, which can powerfully destroy particles and kill 99.99% of bacteria. UVC cannot penetrate the atmosphere and is absorbed by the ozone layer.

 

Therefore, the UV light we use for sterilization is synthesized using the familiar blue UV light bulb.

 

Effectiveness of UVC Equipment

Through the Ultraviolet Germicidal Irradiation (UVGI) process, blue ultraviolet light shines UVC rays on objects suspected of having bacteria. The energy of the rays will penetrate the DNA and RNA of the bacteria, destroying them, preventing them from multiplying and eventually dying.

 

Compared with other disinfection methods, the advantages of UVC equipment

The benefits of irradiation are that it doesn't take long, can be used as often as needed, is inexpensive, easy to use, and doesn't damage surfaces or leave any residue, which makes this method better than using alcohol or disinfectants. Also, using it on a mask does not damage the fibers of the mask, making it ideal for sterilizing items that need to be reused.

 

Precautions for using UVC irradiators

Because this type of irradiation device emits such highly destructive energy, it needs to be used with extreme care not to allow radiation to come into contact with the skin, as it poses a risk of cancer. Also, don't stare at the rays as it is harmful to the eyes and can cause cataracts. Proper radiation protection is required to use UVGI equipment.

 

Portable UVGI devices are currently not recommended as they require proper protection to prevent adverse effects. There may be better portability designs in the future.

 

Where should UVGI equipment be installed?

Areas suitable for UVGI devices are public areas that hold large numbers of people for extended periods of time, such as hospitals, classrooms, cinemas, auditoriums, sky trains, public restrooms, offices, pantries or cafeterias. For example, UVC lamps can be installed in HVAC systems. UVGI has been recommended by the U.S. Army, CDC, Federal Emergency Management Agency (FEMA) or used to isolate buildings from disease and biodefense systems, and as a method of disinfection for personal protective equipment (PPE).

 

How to choose the right and safe UVGI device

UVGI emits radiation just like in an oven, so if it's going to be used in a room, size should be taken into account to calculate the correct wattage. The room should have enough space, without corner blind spots or obstructions, to ensure effective illumination. Also, be sure to choose brands that have passed trusted product standards, such as CE, RoHS, to ensure they kill 99.9% of germs.