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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.
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.
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.
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.
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.
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.
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.
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 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.
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.
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.
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.
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.
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:
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.
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.
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.
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.
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.
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.
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.
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.
Besides its benefits, UV light also has many disadvantages. Here are some of them.
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.
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.
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.
UV light can cause several health problems in humans, including skin cancer, eye damage, and immune system suppression.
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.
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.
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.
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.
UV radiation can cause sunburns. Symptoms of sunburn include red, painful, and blistering skin. Exposure to UV lamps can also cause burns.
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.
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.
|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|
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
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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.
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