What are UV rays? Which UV rays are harmful to the skin? How to avoid UV rays

What are UV rays?

Besides the great benefits of sunlight, there are still potential risks to human health. UV rays, also known as ultraviolet rays or ultraviolet rays, are electromagnetic waves with wavelengths shorter than visible light but longer than X-rays.

With the development of science, researchers have discovered and classified sunlight into 3 main groups based on wavelength length:

• Infrared rays
• Light that the human eye can see
• UV rays

How many types of UV rays are there?

UV rays have 3 types: UVA, UVB and UVC, in which UVA rays (wavelength 380-315 nm) are also known as long waves or black light, and UVB rays (315-280 nm wavelengths) are also known as medium waves. , UVC rays with wavelengths less than 280 nm) are also called shortwaves or sterilization waves.

UV (Ultraviolet)

UV rays bring people benefits such as helping to synthesize vitamin D in the body , in moderate doses, ultraviolet rays can stimulate all major body processes,…

However, along with the above benefits, ultraviolet rays contain many harmful agents to the skin and more seriously can cause problems related to human health.

Infrared rays

Is electromagnetic radiation with wavelengths longer than visible light. We cannot see infrared rays , but we can still feel them through the heat brought to Earth by the Sun.

Visible light

Light that can be seen by the human eye (visible light) accounts for 40% of the total solar radiation that reaches the ground, this is a natural energy source that is used quite commonly today.

How many types of UV rays are there?

The sun emits all 3 types of ultraviolet rays: UVA, UVB and UVC . However, in theory, because of the absorption of the ozone layer, 99% of the ultraviolet rays that reach the earth’s surface are in the form of UVA rays, while the ozone layer itself is produced by chemical reactions with the participation of UVC rays, UVC is absorbed by the ozone layer. Therefore, where there is sunlight, there is ultraviolet light.

• UVA rays (380 – 315 nm): not absorbed by the ozone layer, visible to birds, insects and fish.
• Ultraviolet UVB (315 – 280 nm): absorbed by the ozone layer most of the time.
• UVC (280-100 nm): completely absorbed by the ozone layer and atmosphere.

However, the ozone layer depletion is now at an alarming rate, causing UVB and UVC rays to become denser in sunlight.

Glass types, depending on quality, are generally transparent to UVA rays (UVA passes through glass) but opaque to shorter wavelengths (UVB, UVC do not penetrate glass). Silicon or quartz depending on the quality can be transparent to even UVC rays.

The degree of influence of UV rays by factors

• Geographical location

The intensity of UV rays is usually great in tropical areas, especially areas near the equator, areas further away from the equator, the risk will be less.

• Altitude above sea level

UV intensity is usually proportional to altitude above sea level.

• Time of day

UV radiation is usually highly concentrated at noon, when the sun is at a high position and shines directly, almost perpendicular to the ground (the sun on the top of the head, standing in the shadow), usually between 10 a.m. and 2 p.m. afternoon.

• Scenery and environment

UV levels are often high in large spaces, especially in highly reflective surfaces such as snow and sea sand. In fact, the level of UV rays almost doubles when UV rays are reflected from the surface of the snow.

In urban areas there is usually less UV light due to the concentration of tall buildings and the shade and trees in the city.

What UV rays affect the skin?

UVA rays

UVA rays make up 9.5% of total solar radiation and appear almost anywhere there is sunlight. This ray has the ability to penetrate clothing, glass doors , so they can affect us directly.

• With short wavelengths , UVA rays can affect the dermis layer of the skin, causing skin to darken and melasma.
• As for long wavelengths, they penetrate deep into the dermis of the skin, destroying collagen , causing the skin to quickly age.

UVB rays

UVB rays have a small wavelength and are pre-attenuated in the atmosphere, so they are mostly blocked by glass doors or common clothing . Although it seems that this ray is not as “aggressive” as UVA rays, their level of danger is not inferior.

• UVB rays are the direct agents that attack the epidermis of the skin , causing a series of damage to the skin such as: dryness, tanning, sunburn, melasma, freckles, age spots and irritation.
• Even worse, with high intensity, UVB rays will affect the basal layer of the epidermis , producing damaged cells. These cells over time will join together to form tumors and cause skin cancer .

UVC

And the number one “terminator” – UVC rays . This is the ray with the highest energy compared to the other two rays. UVC rays cause serious damage to our skin and eyes .

Fortunately, the ozone layer in the atmosphere blocks almost all of these rays from reaching the ground. However, with the gradual weakening of the ozone layer, the high-energy radiation of UVC rays can still penetrate down to the Earth’s surface, easily causing serious health problems.

How much UV is harmful?

In the alarms about the ultraviolet fraction from the Hydrometeorological Centers, the term is often used: The ultraviolet index, also known as the UV index , is an international standard measurement of the strength of ultraviolet radiation. purple from sunlight.

According to the US Environmental Protection Agency (EPA)

• UV index ranging from 0 – 2 is considered low
• UV index from 8 to 10 has a burn time of 25 minutes
• UV index of 11 or higher is considered extremely high, very dangerous , the risk of skin damage, eye burns if exposed to the sun for about 15 minutes without protection.

How to protect skin from harmful UV rays

As recommended by scientists, the best way to combat the harmful effects of UV rays is sunscreen. There are different types of sun protection, and using them correctly is also important:

Apply sunscreen

This is the most common and also the most effective. In addition to choosing a suitable sunscreen product, you should also pay attention to the sun protection factors such as SPF and PA.

SPF stands for UVB protection, the higher the number, the stronger the protection against UVB rays. PA is an indicator of sun protection.

The greater the plus number of this index, the greater the ability to protect the skin from UVA rays. You can choose products with index PA+++ to PA++++ for the best skin protection.

Whether the weather is cool or sitting in the office, you should use sunscreen to maximize your skin protection.

Use sunscreen pills

Sunscreen pills are a new and popular skin protection measure. Sunscreen pills help replenish antioxidants for the body as well as neutralize free radicals, repair damaged DNA, prevent skin cancer and effectively fight skin aging.

Some other ways to protect your skin

• Eat sensibly, supplement with antioxidants found in foods (citrus, green tea, carrots, and red bell peppers, …)
• Use specialized sunscreen clothing, equip with UV-protective sunglasses, and UV-blocking masks to prevent dangerous harmful effects from ultraviolet rays.
• Avoid exposure to the sun during peak hours (11am to 2pm)
• Limit artificial sources of radiation (light from computer screens, phones), use insulating films for glass doors in rooms or cars,…

Source: Specialist Doctor I Le Thi Thu Hang – Dermatologist – Department of Medical Examination & Internal Medicine, Vinmec Hai Phong International General Hospital

The harmful effects of UV rays are extremely powerful and all of us need knowledge and effective protection. Through this article, we hope you have a better understanding of what UV rays are, and added ways to prevent problems that damage your skin and health.

You will be interested in:

• How to use effective sunscreen for skin that doesn’t burn?
• How to choose the best sunscreen for each skin type
• What is the difference between physical sunscreen and chemical sunscreen?

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