UVA vs UVB What Causes Sunburn?

Although sunburn is one of the most common forms of skin damage many people still do not understand the difference between UVA and UVB rays and how each one effects the skin. At CHOLLEY we believe understanding ultraviolet radiation (UV) is an essential part of protecting your skin. The knowledge of UV radiation is essential for protecting your skin from both immediate damage and long-term aging concerns. Some clients ask us can you put sunscreen on sunburn. Our reply sometimes surprises them since this depends on the root causes of sunburn in the first place. Both UVA and UVB rays originate from the sun and can harm the skin but their impact on the skin is very different.

In this guide we will explain the science behind UVA and UVB radiation. In addition, we will explain how sunburn develops and why broad-spectrum sunscreen remains one of the most important tools when it comes to maintaining a healthy and youthful looking skin.

Ultraviolet (UV) radiation is a form of electromagnetic energy emitted by the sun.

This energy is invisible to the human eye. But even though it is invisible it still can penetrate the skin. Once it has penetrated the skin it can trigger a wide range of biological responses.

Scientists have classified UV radiation into three categories:

• UVA rays
• UVB rays
• UVC rays

The earth’s atmosphere thankfully is able to absorb almost all UVC radiation before it reaches the surface. So, this means the only forms of UV radiation that can affect our skin are UVA and UVB rays. Both UVA and UVB rays contribute to ski damage, but they do so by different mechanisms.

The vast majority of UV rays that reach the earth surface being around 95% are UVA rays. These rays have longer wavelengths and can penetrate deeper into the skin than UVB rays.

UVA radiation reaches the dermis. This is the deeper layer of the skin where collagen, elastin, and connective tissues are located.

Free radicals and oxidative stress are generated when UVA rays penetrate the skin. Healthy skin cells are damaged by this process and breakdown of collagen and elastin fibres are accelerated by this process.

Due to this, excessive UVA exposure is strongly linked with:

• Premature skin aging
• Fine lines and wrinkles
• Loss of elasticity
• Hyperpigmentation
• Age Spots
• Photoaging

Unlike UVB rays, UVA rays can pass through clouds and window glass. What this means is that your skin can still be exposed to a significant amount of UVA damage even on overcast days or while sitting indoors near a window.

DNA damage in skin cells has been shown to be caused by long-term exposure to UVA radiation. This cumulative damage increases the risk of developing skin cancers, including melanoma, basal cell carcinoma, and squamous cell carcinoma.

Since UVA damage is accumulated gradually overtime many people do not notice its effects until years later.

UVB rays have a shorter wavelength but significantly higher energy than UVA rays. Unlike UVA radiation, UVB rays primarily affect the epidermis, which is the outermost layer of the skin.

The DNA within the skin cells is directly damaged when UVB radiation strikes the skin. An inflammatory response is triggered by this injury when the body recognizes it.

This response produces the classic symptoms of sunburn:

• Redness
• Heat
• Tenderness
• Swelling
• Peeling
• Pain

Essentially sunburn in the body’s visible reaction to cellular damage causes by UVB radiation.  The inflammatory response will be more server the more intense the UVB radiation.

Many people see tan as a symbol of healthy skin. But tanning is a sign of skin’s attempt to protect itself from UV damage. Melanocytes produce additional melanin when they are exposed to UVB radiation. This pigment can help absorb some ultraviolet radiation and further help reduce further damage.

However, tan can only provide limited protection and does not prevent long-term skin injury.

The simple answer to this question is that UVB rays are the primary cause of sunburn. Due to their higher energy, they directly damage skin cells in the epidermis. This damage triggers redness and inflammation associated with burned skin. However, only focusing on UVB rays can be misleading.

It is true that UVB rays cause most sunburn symptoms, but UVA rays also contribute to skin injury. In fact, severe sun exposure often involves a combination of:

• UVB-induced inflammation
• UVA-induced oxidative stress
• Collagen degradation
• DNA damage

This is the reason why dermatologist emphasize providing protection against both UVA and UVB rays. A sunscreen that provides protection against UVB rays may reduce visible burning. But it is not enough since it still allows significant UVA damage to occur beneath the surface of the skin.

Most people think of a sunburn as redness that fades after a few days, but the damage actually starts much deeper within the skin.

When your skin is exposed to too much UV radiation, particularly UVB rays, the cells in the outer layer of the skin become damaged. In response, your body sends extra blood flow to the affected area, which is why sunburned skin often feels warm, looks red, and becomes tender to the touch.

Over the next few days, your skin begins its natural repair process. Some of the damaged cells are removed and replaced with new ones, which is why peeling often occurs after a moderate or severe sunburn. While peeling can be frustrating, it’s simply your body’s way of shedding injured skin and making room for healthier cells underneath.

Because sunburn weakens the skin barrier, protecting the area from further UV exposure is essential while it heals.

Since both UVB and UVA rays contribute to skin damage use and application of a broad-spectrum sunscreen is essential for comprehensive protection.

Sunscreens that have broad-spectrum formulations are designed to protect against:

• UVA-induced photoaging
• UVB-induced sunburn
• Collagen degradation
• Hyperpigmentation
• Long-term DNA damage

We have always encouraged regular daily sunscreen use at CHOLLEY. The use of regular daily sunscreen use should be done regardless of the weather conditions. It is a common mistake made by many that sunscreen is only used during beach vacations or days by the pool in summer. But this practice is not correct since UV exposure occurs throughout the year.

That is why providing consistent protection to the skin all year around is key. This strategy will help to preserve your skin and make the skin youthful looking.

At CHOLLEY, we formulate skincare products with the goal of supporting skin health before damage occurs.

When it comes to preventing sunburn, our philosophy centers on proactive protection rather than reactive treatment.

Our sunscreen formulations are designed to help shield the skin from both UVA and UVB radiation while supporting overall skin comfort and resilience. By incorporating advanced UV filters and skin-conditioning ingredients, our products help reduce the risk of excessive sun exposure that can lead to redness, inflammation, and premature aging.

For individuals with sensitive or recently sun-exposed skin, proper sunscreen selection is particularly important. Broad-spectrum protection can help minimize additional UV stress while supporting the skin’s natural recovery processes.

When combined with protective clothing, shade, hydration, and responsible sun habits, daily sunscreen use forms the foundation of an effective sun protection strategy.

For those who have wanted to know whether UVA or UVB are the cause of sunburn the answer is clear. UVB radiations is the primary cause of sunburn, inflammation and redness which are associated with sunburn.

However, we cannot ignore UVA rays. These UVA rays are able to also penetrate deep into the skin. They can contribute to conditions such as photoaging, breakdown of collagen, pigmentations issues and long-term DNA damage.

The best approach when it comes to protection is not choosing protection from one UV type and ignoring the other. The best approach is to provide a comprehensive brad-spectrum protection regularly every day.

At CHOLLEY we believe it is important to understand the difference between the UV radiations and their effect on the skin. This will enable better decision making about sun protection, skin heath, and long-term beauty. By being able to provide protection against both UVA and UVB types you can help to reduce the risks of sunburn. At the same time making sure you can preserve a healthier and more youthful looking skin for many years to come !

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