Optics Mag is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Read more.

What Is Ultraviolet Light (Ultraviolet Radiation)? Pros, Cons, & FAQ

Last Updated on

Plants Ultraviolet Light

Ultraviolet (UV) light is electromagnetic radiation. It has a wavelength ranging from 10 nanometers to 400 nanometers (nm). The wavelength of light refers to the distance between two wave peaks. The shorter the wavelength, the higher the energy of the radiation.

UV light has a shorter wavelength than visible light. That’s why it has more energy than visible light. Plus, it’s invisible to human eyes.

The frequency of UV light is 30 PHz (Petahertz). The frequency is the number of wave peaks that pass a given point in one second. Below, we explain the use, risks, and presence of UV light in detail.

magnifying glass 2 divider How Does It Work?

UV light works by penetrating the skin and damaging the DNA inside cells. The damage to DNA can cause cancer. The sun is the primary source of UV light, but there are artificial sources of UV light, too. These include tanning beds, welding torches, and mercury vapor lamps.

UV light can also be found in some germicidal lamps. These are used to clean surfaces or air of bacteria and viruses. As mentioned, humans cannot see UV light. It’s because we do not have the color receptors needed to see UV rays. Color receptors are found in the retina of our eyes. They help us see different colors by responding to different wavelengths of light.

Some insects and birds have an additional color receptor in their eyes that helps them see UV rays. They also have a unique structure. It transmits UV rays, allowing these species to have UV vision.

UV light
Photo Credit: Pixabay

History of UV Radiation

What is ultraviolet radiation? We only found out about it in 1801.

Johann Wilhelm Ritter, a German physicist, discovered it while experimenting with silver chloride in a leather camera case. He found that the leather blackened where it was exposed to sunlight but not where exposed to the light from a candle.

Ritter called this new kind of light (de-)oxidizing rays. Later, scientists started calling it ”chemical rays”. The name stuck throughout the 19th century.

Different researchers made attempts to identify the use and benefits of these rays. Finally, in 1878, researchers found that short-wavelength light can kill bacteria. By 1903, they discovered that 250 nm light was the most effective for sterilization. Later in 1960, scientists found how UV light affects DNA. Today, we know a lot more about ultraviolet radiation and its dangers.

What Are the Types of UV Radiation?

When most people talk about ultraviolet radiation, they are not aware of the many different types of UV radiation and how they differ from one another. UV light is categorized based on wavelength.

Plus, UV light types have different photon energies. Photon energy is a measurement of the ultraviolet light’s wavelength and frequency.

Each type of UV radiation affects humans, animals, and plant life differently. Here are the three main types of UV radiation:


UV-A has a wavelength of 315–400 nm. It has the longest wavelength of all types of UV light.

Our ozone layer does not absorb UV-A. So, it passes through the atmosphere and reaches the earth’s surface.

Photo Credit: Pixabay


UV-B has a wavelength of 280–315 nm. It is medium-wavelength radiation. The ozone layer absorbs most of UV-B. However, the rest of the UV-B radiation passes through.


UV-C radiations have a wavelength of 200–280 nm. The ozone layer absorbs them completely.

magnifying glass 1 divider Where Is It Used?

UV light has multiple applications today. For example, it helps produce Vitamin D in the human body.

Vitamin D is an essential vitamin that helps the body absorb calcium. It also regulates the immune system and neuromuscular function. However, the human body only produces Vitamin D when it is out in the Sun. Therefore, the World Health Organization recommends everyone get 5 to 15 minutes of sunlight exposure twice or thrice a week.

Besides this natural application, UV light also has many uses in the industry.

Small Summer Umbrella
Photo Credit: Pixabay

Air Sterilization

In some places, like hospitals, it’s essential to ensure high air quality. UV air sterilizers clean the air and kill bacteria, mold, and viruses.

The UV light used for this is called Germicidal UV. It is a type of UV light that is deadly to microorganisms. Besides hospitals, Germicidal UV lamps are also used in water treatment plants, food processing facilities, and laboratories.

Germicidal UV damages the DNA of bacteria, mold, and viruses. It prevents their reproduction and causes them to die.

Water Disinfection

Previously, chlorine was used to disinfect water. However, chlorine can cause harmful byproducts like trihalomethanes (THMs). These are linked to an increased risk of cancer.

Therefore, many water treatment plants today use UV light instead of chlorine. UV light can kill harmful microorganisms without causing any harmful byproducts.

UV light is used for water disinfection in the following areas:
  • Pools
  • Spas
  • Life sciences
  • Aquaculture
  • Commercial water processes
Microphotography drips of water on a leaf
Image Credit: EvgeniT, Pixabay

Sterilizing Medical Instruments

UV light also helps sterilize medical instruments. Reusable medical instruments must be sterilized before each use to prevent the spread of infection.

UV light is an effective sterilization method because it can kill bacteria. It can also penetrate the tiniest crevices of medical instruments to sterilize them completely. However, UV sterilization is not a replacement for cleaning medical instruments.

UV Spectroscopy

Spectroscopy is the study of light and other electromagnetic radiation. For example, a sample is exposed to UV light in UV spectroscopy. How the sample absorbs or reflects this UV light can describe its chemical composition.

UV spectroscopy is used in the following fields:
  • Medicine
  • Pharmaceuticals
  • Environmental science
  • Research and development
  • Cosmetics

In medicine, UV spectroscopy is used to test the purity of drugs. Meanwhile, it helps study air and water samples in environmental science.


Photographic films and papers are also sensitive to UV light. The property helps take photos for medicine and forensic investigations.

Researchers also use UV radiation to take pictures of objects in space. For example, the Hubble Space Telescope uses ultraviolet-sensitive instruments to take high-resolution images of astronomical bodies.

landscape photography using dslr
Image Credit: PhotoMIX-Company, Pixabay

Electronics Industry

Corona discharge is brought on by ionizing the air surrounding an electrically charged conductor. The conductors are usually in the form of wires or needles.

It can degrade electrical insulation. Plus, it emits ozone and nitrogen oxide. UV emissions from the electronic apparatus can help detect its corona discharge.

Thus, the electronics industry uses UV light to:
  • Detect electrical discharges
  • Find the root cause of equipment failures
  • Locate cracks in printed circuit boards

UV light is also valuable for EPROMs (Erasable Programmable Read-Only Memory). When UV light enters these modules through the quartz window on the chip, it erases the stored data.


UV light can be beneficial at a crime scene. It can help locate different fluids, such as blood, saliva, and semen.

Forensic experts use high-power sources of UV radiation to locate ejaculated bodily fluids, such as semen. They also use UV-vis microspectroscopy to analyze paint chips, textile fibers, and other trace evidence.

UV-vis microspectroscopy shows the spectral fingerprint of a substance. Therefore, it can help identify and match it to a known sample.

Hazards of UV Radiation

UV rays can be both good and bad for us. They help our bodies produce vitamin D and can cause skin cancer. Here are some hazards of UV light:

Skin Cancer

The most common notable hazard of UV light is skin cancer. When UV radiations enter the skin, they damage the DNA of the skin cells. As a result, they may cause mutations or changes in the genetic structure of the cells.

These changes can eventually lead to skin cancer. The most common types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanoma.

Skin Cancer
Image Credit: Pixabay

Premature Aging

Too much UV light exposure can also cause premature aging. As a result, fine lines, wrinkles, and age spots start to appear. The skin may also become too thin, losing its elastic property.

Eye Damage

UV rays can also damage the eyes. They can cause cataracts, macular degeneration, and pterygium.

Pterygium (a growth) forms on the white part of the eye. It can cause redness, irritation, and blurred vision. Meanwhile, macular degeneration is the deterioration of the central part of the retina. It leads to vision loss.

Immune System Weakening

Skin is a barrier that protects our body from harmful microorganisms. When the skin is damaged by UV light, it becomes less effective in doing its job. Thus, it makes us more susceptible to infections and diseases.

Woman Skin
Image Credit: Pixabay

Advantages of UV Light

Although it can harm humans, UV light can be very beneficial. Here are some advantages of UV radiation.


UV light penetrates bacterial and viral cell walls to destroy their DNA. It makes UV light a great sterilization tool.

Most applications of UV light are due to its sterilization properties. For example, hospitals use UV light to clean surgical tools and rooms.

Likewise, water treatment plants use UV light to clean water.

Cancer Treatment

UV light is used in some cancer treatments because it can damage cancer cells’ DNA and prevent them from growing and spreading.

Phototherapy is a useful therapeutic tool against skin lymphoma. It uses ultraviolet A (UVA), ultraviolet B (UVB), or a combination of the two to treat cancer.

Radiologist prepares the young woman
Image Credit: Roman Zaiets, Shutterstock


UV light can make things invisible. For example, in fluorescent lighting, UV light excites phosphors that emit visible light. It’s why fluorescent lights appear to glow. Blacklights are also a type of UV light. They make white clothes seem to glow in the dark.

Detection of Bodily Fluids

In forensics, UV light is used to detect bodily fluids. For example, blood, semen, and saliva all glow under UV light due to their unique composition. It makes UV light a valuable tool in crime scene investigation.

Disadvantages of UV Light

Besides its benefits, UV light also has many disadvantages. Here are some of them.

Cellular and Genetic Damage

UV light can cause damage to the DNA in our cells. Thus, it can lead to skin cancer and other diseases.

UV light can enter the cell because it has shorter wavelengths than visible light. Then, it damages the DNA by causing changes in the structure of the DNA strands (e.g., thymine dimers).

It can lead to errors in replication and transcription, which result in mutations. The severity of the damage depends on the dose of UV light, the length of exposure, and the cell’s repair mechanisms.

Image Credit: Pixabay

Eye Damage

UV light can also damage the eyes. It can cause cataracts, pterygium (a growth on the cornea), and other eye problems. The damage is caused by the UV light interacting with the proteins and other molecules in the eye.

The damage can be cumulative, meaning that it gets worse over time. Thus, it is essential to wear sunglasses or other eye protection outdoors.

magnifying glass 1 divider Frequently Asked Questions (FAQs)

Which Type of UV Radiation Is Most Harmful?

UV-C is the most harmful type of UV radiation. It is also the shortest wavelength and is entirely absorbed by the atmosphere, so we are not exposed to it.

Image Credit: Pixabay

How Does UV Light Affect Humans?

UV light can cause several health problems in humans, including skin cancer, eye damage, and immune system suppression.

What Are Some Ways to Reduce Exposure to UV Radiation?

You should avoid being in the sun during the peak UV hours, generally between 10 a.m. and 4 p.m. You should wear protective clothing, like pants and long-sleeved shirts. More importantly, use sunscreen when you go outside.

What Is the Source of UV Light?

There are many sources of UV light. In nature, the sun is the most common source. However, there are also man-made sources, such as tanning beds. Carbon arc lamps and mercury vapor lamps are common UV light sources in science-based settings.

Image Credit: Pixabay

Is All UV Light Harmful?

No, not all UV light is harmful. In fact, some UV light is essential for our health. For example, UV light helps our bodies produce vitamin D. However, too much exposure to UV light can be harmful.

What Are Some Indoor Sources of UV Light?

There are many sources of UV light indoors, including fluorescent light bulbs, LED lights, and some types of halogen lights. Tanning beds also emit UV light.

Image Credit: Pixabay

Can UV Light Cause Burns?

UV radiation can cause sunburns.  Symptoms of sunburn include red, painful, and blistering skin. Exposure to UV lamps can also cause burns.

Can Humans See UV Light?

Humans cannot see UV light. However, some animals, such as bees, can see UV light. The ability helps them find flowers and other sources of food.

Summer outfit
Image Credit: Pixabay

How Is UV Light Useful in Phototherapy?

Phototherapy means using light to treat a medical condition. It’s also called light therapy, heliotherapy, and photochemotherapy. UV light can help kill cancer cells that cause skin cancer. It can also help clear up psoriasis, eczema, and other skin conditions.

A Quick Reference Guide

Properties UV-A UV-B UV-C
Wavelength (nm) 315–400 280–315 200–280
Photon Energy (eV, aJ) 3.10–3.94,0.497–0.631 3.94–4.43,0.631–0.710 4.43–12.4,0.710–1.987
Ozone Absorption Not Absorbed Partially Absorbed Fully Absorbed

magnifying glass 2 divider Conclusion 

UV light falls in the 10–400 nm range, with UVC (100–280 nm) being the most harmful. The significant health effects are skin cancer, eye damage, and immune system suppression.

The most significant health hazard posed by UV radiation is skin cancer. Ultraviolet light can damage our cells’ DNA, which can lead to cancer. The risk of skin cancer increases with the amount of exposure to UV radiation.

However, the same property of UV radiation also makes it valuable. Typical applications of UV light include water purification and disinfection. UV light can also be used to detect counterfeit money and forgery.

Featured Image Credit: Helga_777, Shutterstock

About the Author Jeff Weishaupt

Jeff is a tech professional by day, writer, and amateur photographer by night. He's had the privilege of leading software teams for startups to the Fortune 100 over the past two decades. He currently works in the data privacy space. Jeff's amateur photography interests started in 2008 when he got his first DSLR camera, the Canon Rebel. Since then, he's taken tens of thousands of photos. His favorite handheld camera these days is his Google Pixel 6 XL. He loves taking photos of nature and his kids. In 2016, he bought his first drone, the Mavic Pro. Taking photos from the air is an amazing perspective, and he loves to take his drone while traveling.