How UV Rays Damage Skin

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People diagnosed with skin cancer often ask – why did I get skin cancer, and what can I do to prevent my children from getting skin cancer? Those are excellent questions.

For you to know how to prevent skin ageing and skin cancer, you need to know about the dark side of the sun.

Today I want to share with you a deep dive into how the sun can accelerate skin ageing and also increase the risk of skin cancer.

Solar Radiation

When sunlight reaches the earth’s surface, it is made up of three main types of radiation.

Infrared radiation is what gives sunlight its warmth. Visible light helps us see. And then there’s UV light – a types of radiation that we can’t feel or see. When it comes to the damaging effects of sunlight, UV is a major culprit.

There are 2 types of UV that reach us on earth’s surface: UVA and UVB. Both types of UV can damage the skin, but in slightly different ways.


Of the two, UVB is the most damaging form of UV radiation – it causes sunburns and increases the risk of skin cancer.

The upper layer of the skin is called the epidermis. Visible light from the sun is reflected off the epidermis, but UVB penetrates into it. In the epidermis, UVB reacts with the DNA of cells and causes DNA damage. Our skin cells are able to repair DNA damage, but with time, if enough DNA damage accumulates, skin cancer can form.

In the epidermis, there are cells called melanocytes. When skin cells are damaged by UV, melanocytes release a dark pigment called melanin. Melanin is able to absorb UV light, and so the body uses melanin as a kind of UV shield. But melanin isn’t able to completely stop skin damage from UVB.

A skin tan is actually a sign that skin damage has already occurred, and the body is preparing itself for further UV exposure.

In a sunburn, UVB causes so much damage that the skin cells die and the upper layer of the skin peels off. The death of cells also triggers inflammation, making the skin red, hot and painful to touch.


UVA can also increase the risk of skin cancer but mostly it is involved in accelerating skin ageing.

UVA is able to infiltrate down to the deep layer of the skin, called the dermis. The dermis has a scaffolding of molecules such as collagen that makes your skin elastic.

When you pull on your skin, it is this scaffolding that helps your skin spring back.

UVA damages this collagen scaffolding. This makes your skin more prone to wrinkling and sagging.

The Good News

It’s not all bad news though. We know that sunlight in moderate amounts is helpful for making Vitamin D and that’s what I talked about in my last video. Also, UV light prescribed by doctors can be helpful for immune based skin conditions like psoriasis.

So in healthy doses, sunlight can be good for you, but how do you protect yourself from the damaging effects of excess UV. Well in my next video, I’m going to share with you my 4 step process to help you choose the right sunscreen for your skin.

Thanks for watching and I’ll see you in the next one!


De Gruijl FR et al 2001:

Yaar M et al. 2007:

Dermnet NZ Skin Ageing:

Video credits:

Certain illustrations adapted from


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