To answer this question, we need to first understand what the sun’s rays are made up of and how these components affect unprotected skin. While skin cancer thankfully, is not of huge concern in this part of the world, the impact of the sun is not limited to the development of skin cancer down the road.
What You Need To Know About The Sun’s Rays
We’re all familiar with visible light - the light that we can see. The sun however, also emits infrared light, UV rays, X rays and gamma rays. The infographic shows the percentage of each of these in the radiation that the sun emits. While UV light only forms around 8% of the total sunlight that hits the Earth, it causes disproportionately more damage. This is because UV light has shorter wavelengths, which means that it has more energy making each photon that hits your skin, capable of more damage. UV is also more damaging since a number of molecules in the skin are perfectly structured to be able to absorb it - fewer molecules absorb visible light and infrared radiation. UV absorption by molecules leads to chemical reactions in the skin that have negative consequences.
While over time, a body of knowledge has also begun to emerge around the impact of visible light (especially blue light since it has shorter wavelengths close to the UV range) and infrared light on our skin, for the purpose of this blog we’re going to limit ourselves to a discussion of UV radiation. The impact of UV is most harmful and has been most researched; it is also what sunscreens, at present, are designed to protect our skin from.
UV radiation refers to electromagnetic radiation with a wavelength between 100 and 400 nm and can be further subdivided into UVA, UVB and UVC. UVC radiation, while harmful for humans, is luckily unable to make it past the ozone layer. UVA and UVB are what have been most implicated in causing damage to the skin.
UV And Your Skin
After skin cancer, the sun is probably most known for its involvement in causing premature skin ageing, also called photoaging. Because UV damage happens happens deep within the skin, it can sometimes take years before this damage comes to the surface and becomes visible. UV damage happens regardless of whether or not you experience a sunburn. You can see the difference between chronological ageing and photoaging by comparing skin on an area of your body that is not exposed to the sun with an area, like your face, that is.
Exposure to UV radiation causes stress and injury to the skin. While this happens in multiple ways, one of the most studied mechanisms involves the creation of chemicals called Reactive Oxygen Species (ROS). These damage cells and cause the breakdown of collagen - a fibrous protein that gives skin strength and elasticity. The breakdown of collagen leads to the formation of wrinkles. ROS also result in DNA damage which can cause cell death and even transform healthy cells to into cancerous cells.
UV radiation also suppresses the skin’s immune system, which is essential in the skin’s defence against infections and cancers. This, along with the fact that UV results in the oxidation of sebum and an increase in the activity of melanocytes - the skin’s pigment producing factories - means that UV can worsen acne in the form of blackheads, whitehead and pimples, and can also worsen the scars and marks that are left behind once existing acne subsides. It can also lead to, and aggravate hyperpigmentation.
The interaction of UV radiation with your skin is a complex topic that I’ve tried to cover as simply as possible and I hope that I’ve succeeded. Given what you’ve just read about the impact of UV rays on your skin, do you think it’s essential to wear sunscreen to protect your skin from the effects of UV rays? I certainly do believe that sun protection is essential and it’s never too late to start practicing good sun protection to prevent future sun damage. Look for a broad-spectrum sunscreen, SPF 30 or higher, that will protect your skin from both UVA, and UVB, rays. Your skin will thank you later.