What is Ultraviolet

date : 11 sept 2010

author : Abang Chik

source : www.kacamatahitam.com

Introduction

Ultraviolet is an electromagnetic radiation with a wavelength is shorter than visible light but longer than x-ray, range between 10nm to 400nm. It named because the spectrum consists of electromagnetic wave with higher frequency compared with human identification.

sun's corona as seen in deep ultraviolet

Electromagnetic spectrum of ultraviolet can be divided in various types.

NAME	ABBREAVATION	WAVELENGTH (nm)
Ultraviolet A, Long wave	UVA	400-315
Near	NUV	400-300
Ultraviolet B, Medium wave	UVB	315-280
Middle	MUV	300-200
Ultraviolet C, Short wave	UVC	280-100
Far	FUC	200-122
Vacuum	VUV	200-100
Low	LUV	100-88
Super	SUV	150-10
Extreme	EUV	121-10

From the above table, generally UV can be divided into 3 major group, UVA, UVB, and UVC. We did not concern so much UVC since they will be absorb by ozone layer. However expose to UVA and UVB will be effected to vision and eye.

As shown gamma waves have the highest energy

and radio waves have the lowest energy

Radiation and your eye

There is many disadvantages of UV, it can burn your skin, skin cancer even worst for your eyes.

Extended exposure to the sun's UV ray may causes eye damage including cataracts, makular degeneration, pingueculae and pterygia and photokeratitis.

We used sunscreen to protect our body, but how about our eye? To protect our eye from the solar radiation, we can used sunglasses.

Wearing sunglasses to protect eye

A good recommendation on choosing good and quality sunglasses is very important. Its can be used when involve in outdoor activity, taking in walk, water sport and even just for relax.

To provide protection on eyes, sunglasses should be :-

• Block 99 until 100 percent of UVA and UVB
• Screen out 75 to 90 percent of visible light

You may refer article i wrote before sunglasses how should you know about them

Remember that sunglasses is not only for adult, it needs for children as well. As logically, children more spending time in the sun compared with adult. If you wearing contact lens, should bear in mind that you still need to wear sunglasses. Why? Because contact lens only covered some part of eye, the other part which exposure to sun ray (UV) might be damage you eye tissue, some more you feel more comfortable too because sunglass block the bright light.

Wearing hat with sunglasses can protect your eye

Sunglasses and UV exposure

Many misconceptions exist regarding the right sun protection for eyes, beer this in your mind :-

• Not all sunglasses block 100 UV. You may refer to optician for an evaluation. Many of eye care professional have a device called spectrophotometers that can measure that can measure the amount of visible light and UV radiation your lenses can block.
• Remember to wear sunglasses even when you are at shade. Although shade reduce UV and HEV to some degree, eye still exposure to UV ray reflected by building,roadway and other surface.
• Sunglasses important when winter, because fresh snow reflected 80 percent of UV nearly doubling overall exposure to solar UV radiation. So if you are skies or snowboarding, choosing the correct gogg lfor your activity.

Guide UV index

• Even when you have dark skin and eye, you still need to wear sunglasses. Although your dark skin may give you lower skin cancer risk, but you eye is having same risk with another fair skin when exposure to UV radiation.

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