What Are The Ultraviolet Rays? Beneficial And Harmful Effects Of UV Rays - Eye Health Nepal, Eye Care Information

What Are The Ultraviolet Rays? Beneficial And Harmful Effects Of UV Rays

What are the ultraviolet rays?

Electromagnetic Radiation has different wavelengths and frequencies. This broad range of wavelengths is known as the electromagnetic (EM) spectrum. The spectrum is divided into 7 different regions and is Radio Waves, Microwaves, Infrared (IR), Visible Light, Ultraviolet (UV), X-rays, and Gamma-rays. Thus, Ultraviolet light is electromagnetic radiation that falls in between the visible light and x-rays.


UV is also divided into 3 different bands according to the wavelength they propagate:
  • UVA, or near UV (315–400 nm)
  • UVB, or middle UV (280–315 nm)
  • UVC (100–280 nm)

Ultraviolet rays light spectrum


As sunlight passes through the atmosphere, all UVC and approximately 90% of UVB radiation are absorbed by ozone, water vapor, oxygen, and carbon dioxide. 

Effects and uses of UV Rays

UVC has Mutagenic or Carcinogenic effects on the human body. UVC is the danger of all as they have more energy than other UV rays. They can use light in the UVC wavelength for disinfecting water, sterilizing surfaces, destroying harmful micro-organisms in food products, and in air. Man-made sources of UVC include welding torches, special bacteria-killing light bulbs, and mercury lamps. UVC is responsible for Photophthalmia.

UVB also stimulates the cells to produce a thicker epidermis. Therefore, UVB is responsible both for the darkening and thickening of the outer cell layers. We know this as tanning. These reactions are the body's defence against further UV damage. A high dose of UVB causes sunburn, Cataracts in our eyes, or even skin cancer because of DNA damage. UVB tanning beds are available to purchase which provides tanning effects. Though they are considered being safe, they are not.

UVB helps our skin make Vitamin D which is good for Bones, Muscle and Immune system. UVB is used to cure many skin diseases like psoriasis sometimes called Phototherapy.

About 95 per cent of the UV rays that reach the ground are UVA rays. UVA rays pass deeper into the skin which causes premature ageing including wrinkle formation and Cancer. The energy level in UVA is lowest.

As a whole, UV rays are harmful to us and are used for UV lamps for sterilizing air and products by companies, helps the body to produce vitamin D, Phototherapies, Curing inks and paints in printing, kill bacteria and water purification, etc.


Image showing how UV rays came to earch
Photo: www.semanticscholar.org


Benefits of UV Rays:

  • Triggers Vitamin D Synthesis: About 90% of vitamin D synthesis for the human is from subcutaneous absorption of UV rays. 
  • It is used for disinfection and Sterilization purpose.  
  • Exposure to sunlight helps to increase serotonin hormone release, which is responsible for boosting mood and helps the person feel calm and focused. 
  • Other benefits such as it provide navigation for some insects, helps in some of the animal’s vision. 


List of Benefits of UV Rays:

Harmful effects of UV for Human Eyes:

Negative effects of UV rays

Excessive sun exposure can damage human eyes in the following ways.

UV rays effects on eyes like cancer, cataract, photokeratitis and pterygium



How to protect from harmful UV rays?

Three simple ways to protect yourself against exposure to harmful UV rays
  1. Wear Sunglass (Having UV protection features)
  2. Wear a hat with a broad brim
  3. Apply Sunscreen
Image showing how to protect from sun light

No comments