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Ultraviolet C (UVC) Light Kills Bacteria and Viruses

By Steven Baxter June 09, 2020

Germ & Virus Killing UVC Light

UVC lights are an excellent choice for disinfecting high-contact surfaces. We're all working from home, and despite everything, washing our hands and face is something we never mull over.

We clean high-contact surfaces in our homes and splash disinfectants to keep germs under control.

However, one super-compelling approach to sanitize and clean is to use UV light, which includes wavelengths between 200 and 280 nanometers but particularly UVC light (230 to 280 nm).

This light is naturally germicidal which means it can kill up to 99.9% of bacteria, viruses, and mold (American Ultraviolet).

Using the right UVC disinfection sanitizing light tool, you'll be ready to clean surfaces such as laptops, desktops, toilets, door handles, kitchen sinks, or things that you always carry with you, such as your smartphone.

The proper cleaning and disinfection of your laptops and cell phones is absolutely necessary, especially in these troubling times.

Your Cell Phone Can Be Dirtier than your Toilet!

Our cell phones are one of the dirtiest objects in our lives, containing almost 30,000 distinct types of bacteria and are about 7 times dirtier than your toilet.

Cleaning a smartphone with soap and water is not the only option and probably not the best option.

Cleaning your expensive smartphone with disinfectants, bleach, or alcohol is not something you want to do - especially if you want to continue to use it! These chemicals will damage your smartphone and other electronic equipment.

A safer and more convenient way is to use a UVC lamp or a specially designed UVC sanitizer case. No damaging or smelly chemicals are needed and in a matter of minutes, your smartphone is all completely sanitized. 

Indeed, a scientific study showed that a UVC sanitizer 'box' was very effective at killing pathogenic bacteria on the cell phones (mobile phones) of health-care providers (Malhotra&2020).

Can UVC Light Kill COVID-19?

Let us deal with this question now as it is probably on your mind. However, we will also say a little more about this later.

We cannot yet say if UVC light can specifically kill COVID19 as no scientific studies have tested this.

All we can say is that current scientific research shows that UVC light can kill (Walker&2007) or inactive other coronaviruses such as severe acute respiratory syndrome coronavirus (SARS-CoV) (Eickmann&2020).

The idea is that if UVC can kill other viruses, then it can probably kill COVID-19.

Please see the video below for an explanation of the physics of UVC light and its potential effect on COVID.


What is UV Light?

Ultraviolet (UV) radiation is electromagnetic radiation (EM) that has a wavelength of 100 to 400 nm. The wavelength of UV is longer than X-ray but shorter than visible light.

All electromagnetic radiation travels in waves - like waves coming into a beach or the ripples caused by a stone thrown into a still pond.

The distance between one wave and another is the wavelength. The wavelength of a ripple in a pond maybe a couple of inches, but the wavelength of EM radiation is measured in nanometers (nm).

A nanometre is very small and is one-billionth of a meter. This is about 0.0000000393 inches. This is too small for us to visualize, so here are some examples that may give you some idea of this unit.

  • A sheet of paper is about 100,000 nanometers thick
  • There are 25,400,000 nanometers in one inch
  • A human hair is approximately 80,000- 100,000 nanometers wide
  • On a comparative scale, if the diameter of a marble was one nanometer, then diameter of the Earth would be about one meter
  • One nanometer is about as long as your fingernail grows in one second

The time it takes one wavelength in a pond to pass a certain point is its frequency.

One wavelength passing a certain point in one second is 1 Hertz (Hz). This is also often stated as a ‘cycle’ because it is something that occurs again and again.

There is an inverse relationship between wavelength and frequency. This means that as the wavelength increases then the frequency decreases. Similarly, as the wavelength decreases the frequency increases.

There is also a relationship between energy, wavelength, and frequency. The energy of EM radiation increases as the wavelength gets shorter and frequency gets higher.

The energy of EM radiation decreases as the wavelength gets longer and the frequency gets lower.

Electromagnetic radiation (EM) is not just one wavelength, one frequency, or one ‘thing’. EM is composed of many different wavelengths and many different frequencies.

That is why EM radiation is often shown as a spectrum of wavelengths and frequencies. Spectrum is a word that just means ‘range’ so the spectrum is a range of wavelengths, frequencies, and energies. Please see the spectrum below.

Diagram from Wikipedia

The spectrum is typically categorized into seven regions such that as the wavelength decreases the energy and frequency increase. radio waves, microwaves, infrared (IR), light, ultraviolet (UV), X-rays, and gamma-rays are common designations.

Basically, there is EM radiation we can see, and this is visible light. Visible light has a wavelength between about 400 to 700 nm and a frequency between about 405–790 Terahertz (THz). A THz is one trillion cycles per second - very, very, fast!

Remember the rainbows in the rain you really loved as a kid? That rainbow is the visible light spectrum. The different wavelengths and frequencies of visible light give the rainbows their multiple colors.

However, not every EM radiation is visible to the human eye.

The human eye is blind to ultraviolet (UV), X-rays, and Gamma rays, because eyes don't have the biological mechanism (receptors) to detect these types of radiation. This EM radiation has shorter wavelengths (less than 400 nm) and greater frequencies (greater than 790 THz) compared with visible light.

The eye is also blind to infrared, microwaves and radio waves because of a lack of a biological detection mechanism. This type of EM radiation has longer wavelengths (longer than 700 nm) and lower frequencies (less than (405 THz) compared with visible light.

Visible and ultraviolet light (UV) originates from the sun and from man-made sources. It is responsible for summer tans, sunburns, and plant growth. An excessive level of UV radiation exposure can harm living things (plant and animal tissue).

However, there are some types (where a type is a different wavelength and frequency) of UV that are harmful to bacteria and viruses, but not so much to humans or animals.

Scientists have known for a long time that so-called broad-spectrum UV light between 200 and 400 nm is very effective at killing up to 99.9% of bacteria and viruses.

This ‘broad-spectrum’ UV light (broad-spectrum because it consists of different wavelengths and frequencies) is very often used to decontaminate surgical equipment.

The light does this by passing through the thin membranes of these microorganisms and destroying DNA and RNA. DNA is the hereditary material in cells. RNA can also act as kind of a proxy hereditary material in some viruses.

RNA also has different versions that make proteins or act as control mechanisms in the bacterial cell or virus. DNA and RNA are essential to the survival and reproduction of all cells including bacteria and viruses.

Irradiating bacteria and viruses with UV light will destroy DNA and RNA molecules. This means that the microorganisms cannot survive, cannot make more of themselves by reproduction, and die.

However, we are also made of cells and if we are exposed to UV light, then it will also damage and kill our cells.

Ultraviolet (UV) light falls between light and X-rays within the EM spectrum (100 to 400 nm). This part of the spectrum may be conveniently divided into four sub-sections or sub-types as described below.

UVA Light (315 to 400 nm)

Among UV rays, UVA rays have the least energy. These rays can cause aging of skin cells and can cause some indirect damage to the DNA of cells. UVA rays are mostly associated with long-term skin damage such as wrinkles but are also thought to play a role in certain skin cancers. UVA light is not used as a disinfectant or sanitizer. However, it is often used as a 'black light' used to visualize stains, currency watermarks, or special UV sensitive paints.

UVB Light (280 to 315 nm)

UVB rays have significantly greater energy content than UVA rays. They will directly affect the DNA in skin cells and are the key rays causing sunburns. They're also known to cause most skin cancers. UVB light can destroy bacteria and also has the following uses:
  • treats skin eruptions (e.g. eczema)
  • increase vitamin D production in humans,
  • the source of the blue light insect zappers.

However, like any other radiation, it can be dangerous if you are exposed to too much.

UVC Light (230 to 280 nm)

UVC rays have more energy than other UV ray types. This could be very damaging except that UVC light interacts with ozone in the upper atmosphere and does not touch the earth or living things in great amounts.

Consequently, UVC light does not usually pose a risk factor for skin cancer.

UVC light is 99.9% effective at killing bacteria and viruses. That is also why it is often called germicidal light.

A wavelength of about 254 nm is often used in man-made devices such as our handheld UVC light and UVC container (could also be called a box or case), so it is very effective at killing bacteria and viruses.

However, UVC light can still damage animal tissues, so you need to be careful when using man-made UVC devices. We will say more about this type of UVC light a little later.

Far UVC Light (207 to 230 nm)

Far-UVC light cannot penetrate human skin or eyes. However, it can penetrate the weaker outer membrane protection of bacteria and viruses. Far-UVC light can still alter the DNA or RNA of bacteria and viruses.

Consequently, far-UVC light will kill bacteria and viruses but without being dangerous to humans.

Scientists such as Welch and others 2018 have studied the promising effect of far-UVC light on airborne microbial diseases. Unfortunately, far-UVC devices are expensive and relatively difficult to make and are not usually available to the consumer.

Brief History of UVC Lights

As of the mid-20th century, sanitizing with UVC treatment become a common practice. In 1903 Niels Finsen was awarded the Nobel Prize in Medicine for using UV light in curing tuberculosis. Today hospitals and laboratories use UV light to maintain safe laboratories and 'clean' areas. Let's take a brief look at how UVC was used.

  • In 1908 UVC was used to disinfect Marseille, France's municipal water source.
  • Westinghouse produced the first commercial germicidal UVC lamps during the 1930s, and they were primarily used in hospitals.
  • UVC was used in hospitals, kitchens, meat storage, and processing plants, bakeries, breweries, dairies, beer manufacturing, pharmaceutical plants, and animal laboratories after World War II to disinfect air-wherever microbiological pollution was a concern.
  • UVC was introduced into air handling equipment during the 1950s and became an important weapon used to monitor and eliminate tuberculosis (TB).
  • During the 1960s, concern about microbes decreased as new medications and sterilizing cleaners were developed and increasingly available.

How Are We Exposed to UV Radiation?

Sunlight is the primary source of visible and UV radiation. The amount of UV exposure a person receives depends upon the intensity of the rays, the time the skin is exposed, and if sunscreen or antioxidant protects the skin.

The intensity of the UV rays reaching the ground depends on factors such as:

  • Time of day: UV rays are strongest between 10 am and 4 pm.
  • Season of the year: UV rays are stronger during spring and summer months. This is less of a factor near the equator.
  • Distance from the equator (latitude): UV exposure goes down as you get farther from the equator.
  • Altitude: More UV rays reach the ground at higher elevations.
  • Clouds: The effect of clouds can vary, but what’s important to know is that UV rays can get through to the ground, even on a cloudy day.
  • Reflection off surfaces: UV rays can bounce off surfaces like water, sand, snow, pavement, or even grass, leading to an increase in UV exposure.
  • Contents of the air: Ozone in the upper atmosphere, for example, filters out some UV radiation.

Man-made sources of Ultraviolet radiation

People may also be exposed to Ultraviolet rays from man-made sources. These include
  • Sunlamps and tanning beds.
  • UV handheld lamps
  • UV room lamps
  • Disinfection systems using UV radiation

The UV wavelengths used in these devices can include UVA, UVB, UVC, or a combination of these types of UV radiation (see above).

UV tanning beds often emit UVA rays and the rest is UVB. The amount and quality of ultraviolet radiation that someone is exposed to from a tanning bed (or booth) depends on the actual lamps used in the bed, how long a person remains in the bed and how many times a person uses it.

    Why Should You Use UVC light?

    We have already seen that UVC light is proven effective at killing 99.9% of bacteria and viruses.

    It does this by destroying the DNA and RNA of these microorganisms. This prevents these microorganisms from surviving and reproducing.

    In particular, UVC light can kill "superbugs," which have established antibiotic resistance. such as methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile spores (Mathew and others 2016). As we saw previously it can also kill or inactivate other viruses and coronaviruses such as SARS-CoV.

    The assumption is that if UVC light is effective at killing existing coronaviruses, then it is likely to have the same effect on COVID-19.

    UVC light can also be used to

    • disinfect water and make water drinkable
    • kill germs in laundry washers and dishwashers
    • substitute chlorine in swimming pools
    • kill airborne germs in air purifiers and HVAC systems
    • disinfect surfaces in hospitals, classrooms, kitchens, offices, and nursing homes.

    UVC lamp products are already available for large operations like industrial water purification and hospitals.

    Viruses, bacteria, mites, and molds wait for you on every surface no matter where you go. Our convenient handheld UVC lamp will effectively sanitize and disinfect any surface.

    UVC light is capable of getting into narrow spaces because it has a small wavelength. It can easily irradiate parts of telephone cases, jewelry, and other small items.

    Where can You Use Your UVC light?

    Spiffic's UVC handheld light is an ideal way to disinfect your surfaces to stay germ-free, virus-free, and healthy. This neat, handheld, compact, and foldable ultraviolet (UVC) light can disinfect and sanitize various accessible surfaces such as:
    • homewares
    • face masks
    • car keys
    • spectacles
    • goggles
    • money (notes and coins)
    • furniture
    • kitchen bench
    • equipment
    • computers
    • computer keyboards
    • cell phones
    • baby's pacifier
    • baby's bottle
    • children's toys
    • pet toys
    • pet beds
    • toilet seats
    • and more...!

      Just about any accessible surface, you can imagine can easily be disinfected and sanitized with a wave of the light!

      Great for Taxi, Uber, Bus Drivers & Delivery Drivers!

      The handheld light is useful for taxi drivers, Uber drivers, bus drivers, other people movers, or delivery drivers. The UVC light can be used to disinfect car seats, car handles, car doors, currency, paperwork, or parcels.

      If you are a people mover (taxi, Uber, or bus driver) you can keep yourself and your customers safe! 

      If your customers know you use this special UVC lamp then they are more likely to choose you and call you again.

      You also don't need to use smelly and damaging chemicals to sanitize your car, truck, or bus surfaces.

        How should I use my UVC light?

        UVC light travels in straight lines and cannot bend around corners. Consequently, you need to make sure that the surfaces you want to irradiate (e.g. benches, instruments, equipment) have a clear ‘line of sight’ to the UVC light.

        UVC light makes shadows, like visible light, when an item is in the path of the light.

        If you want to disinfect all surfaces then you need to turn the item or take the UVC lamp to the shadowed area at some stage during disinfection.

        Some UVC lamps produce ozone that could get to the shadowed areas but it is probably still a good idea to turn the item or use the UVC lamp in the shadowed area.

        The effectiveness of the UVC lamp also depends upon such things as

        • the extent of contamination on the surface (greater contamination more difficult to remove)
        • the type of surface (smooth surfaces better than rough surfaces. The surface needs to be accessible to the light)
        • the power of the UV light
        • the distance of the UV light from the surface
        • the time of irradiation (more time for the UVC light to kill bacteria and viruses)
        • the material used for the UV lamp. It must be quartz.

          Let us look at these last three points a little closer.

          UVC light needs to irradiate the surface with sufficient power, measured in watts (W), and intensity to ensure that you are killing as many bacteria and viruses as possible.

          The greater the power the greater the intensity of the UVC light. A 15 W lamp will cover about 100 square feet. A 30 W lamp will cover about 200 square feet.

          The greater the power (watts) of the UVC lamp the greater the area it can cover and the more effective it is at killing bacteria and viruses.

          The power of Spiffic’s handheld UVC lamp is 2W (UPDATE! Our new model now has more power at 3W). This means that for it to be effective you must use it over a relatively small area and at close distances.

          The area probably shouldn’t exceed the width of the lamp itself and you should hold it at a maximum of about 1 inch above the surface. 

          You should also hold the UVC lamp over the surface for up to 5 minutes for the most effective way to kill 99.99% of bacteria and viruses.

          You can use for less time but you would need to compensate for this by lowering the device to about 1 to 2 cm (0.5 inches) above the surface to be disinfected.

          You will need to hold the UVC lamp over the surface for longer times if the surface has greater contamination.

          The effectiveness of a UVC lamp varies with its distance from the surface. That is, the further away your UVC lamp is from the surface then the less effective it is at killing bacteria and viruses.

          In contrast, the closer the UVC lamp is to the surface the more effective it is at killing the microorganisms.

          A true UVC lamp is made with quartz NOT glass. Ordinary glass blocks UVC light. Quartz (also called fused quartz or quartz glass) does not block UVC light.

            Be Careful When You Use UVC lights

            You need to be very careful using UVC light because it will damage your eyes (if you look directly into the light) and will essentially cause something like severe sunburn.

            We have a warning on our handheld UVC lamp product page that notes these effects.

            You should not use a UVC lamp in any location where your hands, skin, or eyes would be exposed to the UVC light.

            You should be careful where you place your UVC lamp. If you use a non-handheld UVC lamp and fix it to a wall, then you need to ensure that the lamp is not mounted too low. If it is too low then it can enter your eyes and irradiate your skin.

            UVC light will only irradiate one side of any item (e.g. money, phone, wallet, purse) if it is in direct ‘line of sight’ of the UVC light. If you want to disinfect all ‘sides’ of an item then you need to rotate the item, move the UVC light, or hold the item in a closed container that can irradiate all surfaces.

            You can find this type of UVC closed container in our store and does not expose you or others to UVC light. In particular, it shuts off the UVC light when the lid is opened.

            If you use our portable UVC lamp then you are protected by its ability to shut off the UV lamp when turned upside down (where it would irradiate your face).

            Spiffic’s portable UVC lamp also has a safety button that requires you to hold for 3 seconds before the lamp is active. This allows you to flip open the lamp and position it over a surface without exposing yourself to the light.

            The lamp also turns itself off if you turn the lamp towards your eyes. Safety first indeed!

            Some UVC lamps product ozone. In fact, ozone also kills bacteria and viruses. However, you need to be careful if using a lamp with ozone as the ozone can affect your lungs. 

            Spiffic's handheld UVC lamp does produce a small amount of ozone but if you use in a well-ventilated area it should not be any problem.

            In any case, a UVC lamp is not a toy and you need to use it carefully as you would any other tool or instrument.

              Things to look for in a good UVC lamp

              Here are some of the things you should look for in a good portable UVC lamp
              • It is easy to hold and pack
              • It is easy to use
              • The UVC lamp is protected from damage when not being used. For example, it has a ‘flip’ case or ‘clam shell’ design.
              • It has safety features such as a 3-second button and automatic shutoff when turned upside down.
              • It has sufficient power of at least 2 W
              • The useful life of the UVC lamp is at least 6000 hours (if used properly)
              • The wavelength of the UVC lamp is between 230 and 280 nm. Usually, about 254 nm.
              • The UVC lamp is made from quartz and not ordinary glass
              • Appropriate certifications
              • Lab-tested

              How to Know if a UVC Device Works?

                Certification and Lab-Testing

                You should ensure that the UVC light you are buying has been lab-tested and has the appropriate certifications. The two main certifications you need are CE and FCC. 

                The CE is a "certification mark that indicates the product conforms with health, safety, and environmental protection standards (Wikipedia)."

                The FCC is a "certification mark employed on electronic products manufactured or sold in the United States which certifies that the electromagnetic interference from the device is under limits approved by the Federal Communications Commission (Wikipedia)." 

                Simply having someone say that the UVC lights are CE or FCC certified is NOT enough. These standards must also be assessed by an external service such as Bureau Veritas.

                Not all UVC lights are the same!

                Not all UVC lights are the same - even if they look exactly the same!

                • Some UVC lights may be low-quality copies or 'rip-offs'
                • Some UVC lights may have LED lights and not UVC tubes
                • The LED light may be small and low-powered
                • Some of the LED lights, in multiple LED light devices, may not emit any UVC light at all! They may simply be normal LED lights that help make the device look good or to just illuminate the object (so you know where the light is being used)
                • The UVC light may not have good irradiating intensity
                • Some UVC lights do not emit UVC at the correct wavelength (i.e. 253.7 nm)

                You need to check all of these issues before you buy a UVC light.

                We have done our homework and we can assure you that our UVC lamp is a high-quality product, with a quartz low-pressure Mercury lamp, that emits UVC at a wavelength of 253.7 nm, has great power for a portable device (3W), and excellent irradiating intensity.

                Please see the two videos below which test our handheld UV lights and others for both UVC intensity and the effect on bacteria.

                UVC Light Devices. Real or Fake?

                You will see that Spiffic's UVC lamp has one of the highest outputs (about 160) of UVC light compared with any other portable UVC lamp. 


                 The Effect of UVC Light on bacteria


                Once again you can see that the kind of UVC lamp that we provide here at spiffic can kill 99.9% of bacteria within 5 minutes using it about 1 inch from the surface. It is one of the quickest disinfecting handheld UVC lamps available.

                Cleaning, Disinfecting, Sanitizing, and Sterilizing - What do they mean?

                The words cleaning, disinfecting, sanitizing, and sterilizing are often misunderstood and misused. 

                Cleaning simply reduces the number of contaminants (bacteria, molds, and viruses) present on a surface. Cleaning can be done using only water or water with added soap, detergent, disinfectant, or a combination of these.

                If you use a disinfectant when you clean, then it will be more effective at killing some of the contaminants compared with using water alone or soap and water. 

                Soap and water are effective at reducing the contamination on your hands provided you wash for at least 30 seconds.

                You do not usually wash your hands with disinfectant, but you can apply disinfectant to your hands such as 70% alcohol (ethanol) or 70% isopropyl alcohol which will kill more bacteria and viruses.

                However, these chemicals can dry your skin or cause irritation. They also can't be used on open wounds - unless you want to jump through the roof in pain!

                Disinfection removes some, but not all, of the microorganisms present on a surface or skin. Disinfection can be carried out using at least three methods

              • High temperature (about water's boiling point)
              • Chemical disinfection (e.g. 70% alcohol)
              • Radiation disinfection (e.g. UVC radiation)

              • Disinfectants should never be ingested as they will burn the mouth and throat. They are also poisonous.

                Sterilization kills all microorganisms on a surface. There are three general methods of sterilization 

                1. High temperature/pressure sterilization (autoclave)
                2. Chemical sterilization (strong chemicals such as Ethylene Oxide or formaldehyde)
                3. Radiation sterilization (e.g. high dose UVC radiation). 

                As you can see the methods are similar to disinfection. However, the methods used for sterilization are usually very harsh and cannot be used on sensitive materials or skin. For example, many plastics would melt if autoclaved. These sterilization methods can remove all contaminants from surfaces, equipment, or tools. 


                  Ultraviolet light type C (UVC) light (230 to 280 nm) can protect against the spread of bacteria and viruses on most surfaces if used properly and with care.

                  Spiffic’s portable handheld UVC lamp is an excellent and convenient choice for your protection against bacteria and viruses. It is easy to carry and provides protection wherever you go.

                  Please let us know if you have any questions or comments.


                  American UltraViolet

                  Eickmann, M., Gravemann, U., Handke, W., Tolksdorf, F., Reichenberg, S., Müller, T. H., & Seltsam, A. (2020). Inactivation of three emerging viruses–severe acute respiratory syndrome coronavirus, Crimean–Congo haemorrhagic fever virus and Nipah virus–in platelet concentrates by ultraviolet C light and in plasma by methylene blue plus visible light. Vox Sanguinis, 115(3), 146-151.

                  Malhotra, S., Wlodarczyk, J., Kuo, C., Ngo, C., Glucoft, M., Sumulong, I., ... & Bender, J. M. (2020). Shining a Light on the Pathogenicity of Health Care Providers' Mobile Phones: Use of a Novel Ultraviolet-C Wave Disinfection Device. American Journal of Infection Control.

                  Mathew, J. I., Cadnum, J. L., Sankar, T., Jencson, A. L., Kundrapu, S., & Donskey, C. J. (2016). Evaluation of an enclosed ultraviolet-C radiation device for decontamination of mobile handheld devices. American journal of infection control44(6), 724-726.

                  Walker, C. M., & Ko, G. (2007). Effect of ultraviolet germicidal irradiation on viral aerosols. Environmental science & technology41(15), 5460-5465.

                  Welch, D., Buonanno, M., Grilj, V., Shuryak, I., Crickmore, C., Bigelow, A. W., ... & Brenner, D. J. (2018). Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases. Scientific Reports8(1), 1-7.


                  Please understand that the information or advice we freely offer should not be construed as professional technical, scientific, or medical advice and that you should seek the advice and guidance of qualified professionals. Please read our terms of service. Thank you!

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