Tia cực tím, tia tử ngoại và tia UV - CLACLAC

Ultraviolet rays, ultraviolet rays and UV rays

Ultraviolet rays are also known as ultraviolet rays or UV rays ( Ultraviolet) . It is emitted by the sun with short wavelengths with high energy reaching the earth.

Did you know that ultraviolet rays are divided into 3 categories: UVA, UVB and UVC?

UVC is the part of UVB rays with the greatest energy but does not reach the earth because it is completely absorbed by the atmosphere. So in this article, we'll introduce UVA and UVB that are bad for your skin, along with UV basics.

The intensity of UV light varies by season and location

- Seasonal change:
The higher the sun rises, the stronger the ultraviolet rays. In the summer, the higher altitude of the sun shortens the distance that ultraviolet rays have to pass through the ozone layer and other layers, so they remain strong and reach the earth.
+ In contrast, in the middle of winter, the altitude of the sun is lower, so the distance through the ozone layer is longer, so the ultraviolet rays are weaker.
+ One note ultraviolet intensity remains high on cloudy days as 90% of rays can penetrate clouds.

- Change by location:
+ Latitude: the closer to the equator, the higher the UV intensity
+ Altitude: The higher the altitude, the thinner the atmosphere, so it absorbs less ultraviolet rays. For every 1,000m above sea level, UV intensity increases by 10-12%.

What is UV-A and UV-B? How do they affect your skin?

UVA is considered "ultraviolet in everyday life" because it accounts for 95% of the sun's rays, not absorbed by the ozone layer, but directly down to the earth.

UVA rays have a long wavelength and the ability to penetrate clouds and glass, so they cannot eliminate UVA rays even on cloudy days or sitting at home.

UVA rays reach the dermis, the deepest layer of your skin, and destroy collagen. The damage they cause causes the skin to lose its elasticity and firmness leading to rapid aging; The skin appears wrinkles and sags. In addition, UVA rays also stimulate the synthesis of melanin pigments, causing the skin to gradually darken and dull.

In contrast to UVA, UVB rays are called "idle ultraviolet rays" because they make up only 10% of the total UV rays, but they have a strong impact on the skin's surface.
UVB rays cause dermatitis, a rapid reddening of the skin upon exposure to it. They damage cells and cause redness like a sunburn; Melanin pigment deposition causes melasma, freckles. In addition, UVB rays also contribute to skin cancer because they can directly affect skin cells.

Dry skin due to sunburn

Repeated exposure to UV causes the skin to accumulate excess keratin, a condition called hyperkeratosis that protects the skin from external aggressors.

On the other hand, the inflammation caused by sunburn disturbs the texture of the skin, leaving it rough and rough to the touch. Damaged skin becomes dry, dull and care products or creams do not absorb well into the skin.

Dry skin also reduces the skin's natural barrier function. The inner surface of the skin is protected from external stimuli such as dirt by a sebaceous membrane that covers the surface of the skin, which is made up of sweat, sebum, and the stratum corneum. That maintains moisture in the skin. So, moisturizing thoroughly is also important for preventing sun damage.

Light-induced skin aging

What's going on while your skin is exposed to the sun?
Photoaging is a wrinkled, sagging skin condition caused by ultraviolet rays, in which UVA rays play a dominant role.

UVA rays trigger pigmentation that causes the skin to gradually darken, compared to UVB rays that cause inflammation like red burns , it seems that UVA rays have a less serious effect, but in fact, UVA rays are the main cause of skin aging.

UV-A rays with long wavelengths penetrate deep into the skin, down to the dermis. It increases enzymes that destroy collagen and elastin that maintain skin elasticity and firmness by severing collagen fibers and deforming elastin.

Refer to the following article: What is UPF50+? UPF index determines the quality of sunscreen?  


We've covered the basics of UV rays and the damage it can do to your skin.

The most effective way to prevent UV damage is to avoid UV exposure.
However, we cannot avoid 100% of UV rays in our daily life.

So wearing a wide-brimmed hat, using an umbrella, wearing UV-protective clothing, wearing sunglasses, and applying sunscreen are all ways to avoid skin problems caused by sunburn and protect yourself from UV rays.

The article is referenced at: World Health Organization

Back to blog