Which is scarier!? Ultraviolet A rays (UVA) and Ultraviolet B rays (UVB)

There are so many types of sunlight!

Have you ever heard of "infrared"? It's the technology used when exchanging phone numbers on cell phones.
So, what about "X-rays" and "gamma rays"? You may have heard of them in hospitals or elsewhere.

In addition to "visible light" that we can see, sunlight also contains "infrared rays," "ultraviolet rays," "X-rays," and "gamma rays."
Furthermore, ultraviolet light is divided into "UVA," "UVB," and "UVC" depending on its wavelength.

In the illustration above, the light rays shown on the left have shorter wavelengths, and the shorter the wavelength, the stronger its effect on the body. However, conversely, they are more easily blocked by the ozone layer surrounding the Earth. Gamma rays, X-rays, and UVC rays are blocked by the ozone layer and do not reach the ground.

Of the ultraviolet rays, only two types reach the Earth's surface: ultraviolet A rays (UVA) and ultraviolet B rays (UVB).
Now, let's look at the differences between these two types of ultraviolet light.

Ultraviolet B rays (UVB) cause skin redness.

Prolonged sun exposure can cause your skin to become bright red and develop blisters. The main cause of this type of sunburn is ultraviolet B rays (UVB).
UVB rays have high energy and can damage skin cells and cause inflammation, leading to skin cancer and age spots.
However, because of its shorter wavelength, it is blocked by the ozone layer and clouds in the upper atmosphere compared to ultraviolet A (UVA), and the amount that reaches the ground is small, only about 10% of the total amount of ultraviolet radiation.
In your daily life, you can take some precautions to avoid direct sunlight, such as using a parasol.

Ultraviolet A rays (UVA) penetrate deep into the skin.

On the other hand, ultraviolet A rays (UVA) do not cause as rapid changes to the skin as ultraviolet B rays (UVB).
While UVA rays may not cause immediate sunburn (suntan), and therefore appear to have less impact on the skin than UVB rays, recent research has revealed that UVA rays play a significant role in the development of age spots and wrinkles.
Long-wavelength ultraviolet A rays (UVA) penetrate deep into the skin, gradually causing various effects.
For example, it can denature collagen, which can lead to wrinkles and other problems. Over a long period of time, it can negatively affect the skin without you even realizing it.
Moreover, ultraviolet A rays (UVA) easily penetrate the ozone layer and constantly reach the Earth's surface at more than 20 times the rate of ultraviolet B rays (UVB).
Because it has the property of easily passing through clouds and windowpanes, countermeasures are necessary even on cloudy days or inside a sunny house.

It seems that protecting yourself from both ultraviolet B rays (UVB) and ultraviolet A rays (UVA) is very important for protecting your skin in the future.