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  5. How The Various Types Of UV Rays Affect Your Skin?

Do you love being outdoors? But, are you worried that the sun's UV rays might damage your healthy skin? Yes, as little as 15 minutes of sun exposure can affect your skin, sometimes even causing major damage.

But does this mean that you will not step outside during the day? That’s not possible! Instead, you can follow necessary steps to protect your skin’s health!

Let’s take a closer look at the different types of UV rays, how they affect your skin and what precautions you should take to minimise its adverse effects.

What is UV Radiation?

UV or ultraviolet radiations are non-ionizing, electromagnetic radiation that are a part of the whole spectrum of light that the sun sends on the earth. [1] The UV rays are neither visible to the human eye nor do they produce heat. So you may not even notice these radiations till it is too late!

Most of the UV radiations from the sun are absorbed by the ozone layer, carbon dioxide and water vapour in the atmosphere. Mostly UVA and some UVB reach us from the sunlight. [2]

While the sun is a natural source of UV rays, there are a few artificial sources of the UV rays like the tanning beds, mercury vapour lamps, some halogen, fluorescent, incandescent light sources, etc. [3]

Exposure to UV radiation may result in premature aging of your skin, appearance of wrinkles, age spots, leathery skin, etc. Overexposure to UV radiation weakens your immune system, reducing your skin’s ability to protect itself against foreign invasion.

Types of UV Radiation

Just like the visible light, the UV rays also have radiations of different wavelengths. [5] This chart compares the different types of UV radiations.

 

UVA

UVB

UVC

Wavelength[6]

315 - 400 nm (longest wavelength)

315 - 280 nm (medium wavelength)

100 - 280 nm (lowest wavelength)

Energy Content

Lowest

More than UV A

Highest

Penetration in human skin

Penetrates deepest into the skin, can reach the dermis

Can penetrate only the superficial skin layers, restricted within the epidermis

Cannot penetrate beyond the dead skin layer of the epidermis

Effects on unprotected skin

Immediate tanning effect. Contributes to skin aging and wrinkles in the long run

Short term effect causes burning and delayed tanning. Significantly contributes to cancer and increases skin aging

Redness and ulceration of skin in the short term. Prolonged exposure causes premature skin aging and skin cancer

Carcinogenic

Only in rare cases cause skin cancer

Causes of most human skin cancers

UVC from sunlight does not reach us, so not a risk factor for cancer normally

Source

Sun, tanning beds

Sun, tanning beds

UVC sanitizing lights, arc welding torches, mercury lamps

% reaching the earth’s

Almost 95% of UV radiations

Around 5% of UV radiations

Completely absorbed by the ozone layer,

surface

 

 

so does not reach us

 

mechanism of UVA and UVB radiation

SkinKraft Tip:

Your skin naturally produces vitamin D when exposed to the sun. Vitamin D is essential for the absorption of calcium into your bones which keeps them strong. So if you are avoiding the sun to protect your skin, take a vitamin D supplement in consultation with your doctor to meet your daily vitamin requirements. [4]

What is UV A Radiation?

The UVA rays have the longest wavelength in the UV spectrum. They are also our biggest cause of concern because of the high percentage of UVA rays that reaches us. UVA rays are present all year round whenever there is daylight, even if it is cloudy or foggy and you cannot see the sun. The UVA rays can even penetrate your glass window. So, you may be exposed to UVA rays in your home or car, unless your glass windows have special filters to block them out.

UVA rays are the primary culprit for skin tanning. They are also the ones used mostly in tanning beds. The UVA rays penetrate deepest into your skin and damages the proteins like collagen and elastin that lend firmness and elasticity to your skin. It can also generate free radicals. This leads to lines, wrinkles and contributes to skin aging. UVA rays also cause indirect DNA damage, thus leading to skin cancers.

UVA rays are of 2 types:

  • UVA1 - 340 to 400 nm
  • UVA2 - 320 to 340 nm

It is important to note that certain sunscreen products can block only specific wavelengths of light. You should preferably choose a sunscreen that offers protection against a broad spectrum of UV rays.

What is UV B Radiation?

A very small percentage of UVB reaches us and it is restricted only to the topmost layer of the skin. But UVB is biologically more active than UVA and causes havoc on your skin surface. UVB is responsible for intense sunburns, discoloration and other visible effects on your skin. It is also the leading cause of melanoma and other skin cancers. UVB can even damage the proteins in the lens of your eyes leading to the formation of cataract.

The intensity of UVB depends on the time of the day, season, and geographic location. UVB is more in the sunny, tropical countries especially during the warm summer months. The intensity peaks around midday. UVB is reflected by the sand, water and snow. So if you are holidaying on the beach or climbing a high mountain, make sure to use appropriate sun-protection to save your skin from detrimental effects of UVB.

Main Differences Between UVA And UVB Rays

 

UVA

UVB

Exposure

Comprises around 95% of UV rays that reach us as they are not absorbed by the ozone layer of the atmosphere

Around 5% of UV rays that reach us- a big part of the UVB rays are absorbed by the ozone layer

Erythema(rashes caused by injured or inflamed blood vessels)

Less chances of causing erythema

Higher possibility of skin burning and erythema

Tanning

Causes immediate tanning due to IPD(immediate pigment darkening and PPD(persistent pigment darkening)

Causes delayed tanning (DT) which starts 3 to 7 days post exposure and may last up to weeks

Effect on melanin(the pigment in your skin that renders its natural colour)

Tanning is caused by oxidation of melanin precursors. Does not increase melanin content

Increases melanin production in the skin by increasing the production of melanocytes. Melanin causes tanning

Photoprotection(biochemical process inside the body to cope with the damage caused by sunlight)

No photoprotection

Photoprotection by production of melanin

DNA damage

Exposure leads to formation of free radicals that cause oxidative stress, leading to indirect DNA damage

Causes DNA damage by formation of pyrimidine dimers

Vitamin D production

No Vitamin D production. Breaks down the Vitamin D bound to vitamin D receptors (VDR)

UVB converts the precursor to Vitamin D3 in skin [7]

Tips To Protect Your Skin From UV Rays

Overexposure to UV rays strongly has been strongly related to skin cancer and other forms of skin damage. Therefore you should take proper precautions before stepping out in the sun. [8]

1. Avoid The Sun

Avoid or limit going out in direct sunlight from 10am to 4pm especially if UV index is predicted to be high. UV rays can reach your skin even if you are in the shade, so do not forgo the sun-protections.

2. Sunscreen Is Your Best Friend

Use a water resistant, broad spectrum sunscreen cream or lotion with SPF 30 or higher, if you have to go out in the sun. You should apply the sunscreen at least 30 minutes before stepping out and do not forget to reuse it after a swim or if you have sweated profusely.

3. Cover It Up

Wear full sleeve clothes with denser fabrics whenever possible to hide your skin from sun exposure. Also, include wide brimmed hats and sunglasses or spectacles with UV filters to minimise UV damage to your face and eyes.

4. Ditch The Tanning Salon

Tanning beds and sun lamps can emit UVC, the harshest of the UV rays. So it is best to avoid them altogether to prevent damage to your skin and eyes.

5. Protect Your Kid

You should take special care to minimise UV exposure for young children. Children are in an ever changing growing state and environmental stress like UV exposure can cause deleterious effects on their development.

6. Choose Your Clothes Wisely

When going outdoors, choose to wear long-sleeved shirts, long skirts to protect your skin from UV rays. Also, prefer wearing dark colours as they give you more protection from the harmful rays.

Wrapping Up

The UV rays are a part of the spectrum of radiations from the sun that reaches the earth. There are several types of UV rays depending upon their wavelengths. But, UVA and UVB rays are the main two types responsible for causing damage to your skin. They have varying penetration powers and effects on your skin. While you cannot completely avoid the UV radiations coming from the sun, you can take appropriate precautions to minimize their damaging effects.

Begin By Knowing Your Skin

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