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UV-C light and DNA

The Difference between UV-C Light and Far-UVC Light

UV-C light is recognized for its germicidal properties and has been used for decades to reduce the spread of bacteria and other pathogens. The COVID-19 pandemic has drawn the public’s attention to it due to that. Therefore, you can find many products online that use this band of ultraviolet light to disinfect surfaces and objects.

Yet, not all UV-C light is the same. So, it can behoove you to know the difference if you are on the lookout for disinfection devices using it. By choosing the wrong product, you risk falling victim to false advertising. As a result, you may expose yourself to germs you believed you had killed by incorrectly using devices such as cheap UV cleansers.

Two Different Kinds of UV-C Light

UV-C light falls into two categories: there’s the conventional one (also known as germicidal UV) and far-UVC light.

Both of these bands disinfect surfaces and the air. However, there’s a difference between them. In this article, we’ll explain what it is as well as the pros and cons of each band.

What Is UV-C Light?

Out of the three bands of UV light (UV-A, UV-B, and UV-C), UV-C has the shortest wavelengths, ranging from 280 nm to 100 nm. In general, the shorter the wavelength, the more damaging the radiation.

In the 1800s, scientists discovered that broad-spectrum UV-C light has the right properties to destroy 99.99% of pathogens such as viruses, fungi, and bacteria. They destroy the molecular bonds that hold their DNA and RNA together.

Since then, UV-C has been routinely deployed in:

  • Healthcare,
  • The food industry,
  • Manufacturing environments,
  • Water purification companies,
  • Fluorescent inspection, and more.

In hospitals especially, UV-C light technology has helped reduce the transmission of diseases and eliminated some of the most resistant bacteria.

With the right intensity, distance, and duration, this germicidal band can eliminate pathogens in a matter of just minutes or even seconds.

However, the biggest disadvantage of conventional germicidal light products is that you can only use them in unoccupied spaces. For safety reasons, you should only use them while wearing protective equipment because they are extremely dangerous to human health. Health hazards caused by careless exposure include burns, cataracts, and skin cancer.

What Is Far-UVC Light?

In the last decade or so, scientists started paying attention to a narrow range of UV-C wavelength known as far-UVC. While conventional germicidal light has a wavelength of around 254 nm, far-UVC light wavelength ranges between 222 and 207 nm.

Research shows that far-UVC light destroys pathogens as effectively, but without the detrimental effects on our health. There’s a catch, though.

You need a lot more time to achieve 99.99% disinfection.

Far-UVC light has a limited range and a strong absorbance in biological materials. Therefore, it cannot penetrate the outer dead-cell layer of our skin or eyes to cause tissue damage.

However, because bacteria and viruses are much smaller than human cells, far-UVC light can penetrate through their DNA and inactivate them. While this may sound like a convenient relief, the disinfection process is considerably slower.

Dose and Duration Needed to Disinfect Surfaces

While germicidal UV-C light can disinfect an unoccupied space or an area in seconds or minutes, far-UVC light is less intense. As a result, it requires a lot more time to disinfect.

For instance, a study looked at the effects of far-UVC light of 222 nm on human coronaviruses. (Not SARS-CoV-2 or COVID-19 specifically, but a range of different ones.) The aim was to provide insights on how long far-UVC light needed approximately to work in an effective way:

  • 8 minutes to destroy about 90% of coronaviruses,
  • 11 minutes to destroy about 95% of coronaviruses,
  • 16 minutes to destroy about 99% of coronaviruses,
  • 25 minutes to destroy about 99.99% of coronaviruses.

Airborne coronavirus particles can survive in the air for 3 hours or even longer in cold weather. This quality can be useful in public spaces. However, far-UVC light can be extremely inefficient in handheld devices.

After all, would you wait for up to 25 minutes to properly disinfect an area?

Final Words

Despite research claiming that far-UVC is safe for humans, some experts in the field still have doubts. Their biggest concern is that there has been limited testing on the long-term effects on humans, making it inappropriate to be labeled as ‘safe.’

As a result, there are limited products offering far-UVC technology. As scientists continue performing tests and researching safety, we are sure to see more far-UVC products on the market soon. In the meantime, UV-C products continue to be a reliable source of disinfection for many industries.

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