Why Sunscreen is a Life Changer?
Do you love staying in the sun? Here is a reading for you.
Ultraviolet radiation (UVR) from the sun can be divided into UVA 320–400nm, UVB 290–320nm and UVC 270–290nm. Thanks to the ozone layer that filtered the harmful UVC before it reaches us. So it leaves us with UVB and UVA that reaches the earth’ surface. UVB mostly can be blocked by glass, while UVA not.
Our skin composed of 3 layers such as epidermis (the outermost layer), dermis , and subcutaneous. Have you ever wondered why we get tanned or aged because of the sun? After skin being exposed to the UVR. The DNA of cells located in the nucleus absorbs the UV radiation and undergoes some changes. Even very small amounts of sun light on the skin can cause changes throughout the epidermis. Within hours or days, our cell will repair most of the damage, however, sometimes it causes permanent cell damage which can contribute to photo-ageing and skin cancer. Both of UVA and UVB cause damage to the skin, but they have different ways. First of all UVB is most likely the cause of our sunburn and skin cancer. I use mnemonic Burn represents B in UVB to assist me in memorising. UVB able to penetrates the epidermis layer, reaches the DNA of cells and creates DNA damage. Our cell has DNA repair mechanism but as time goes, if DNA damage accumulates, gene mutations might occur leads to skin cancer.
When the cell in the skin is damaged by the UV light, melanocytes (pigment producing cell) synthesis the pigment called melanin inside the melanosome. Melanin works as photo-protective role of the skin that acts like a shield to protect our cell by absorbing the UV light. The absorbed light energy is converted into thermal energy and will be dispersed. But, is it completely absorbed? The short answer is NO.
Furthermore, UVA also contributes to skin cancer but it is mainly the cause of skin-ageing. I used mnemonic Ageing for the A letter in UVA. It able to penetrate deeper compared to UVB down to the dermis. Dermis is composed of collagen fibre and elastic tissue that is responsible for skin strength, elasticity, and flexibility. When the UVA reaches the dermis, it can actually damage the collagen fibres and leads to the wrinkling, sagging and other sign of photo-ageing skin.
Now, let’s get into the main solution to protecting our skin from all of this. Sunscreen is the extra shield of our UVR defensive system. It prevents the transmission of UVR to the viable tissue, achieved by either scattering or absorbing UVR energy. There are some tips in choosing sunscreen such as,
- A broad-spectrum sunscreen: protects you from UVA and UVB
- Choosing SPF: SPF 15 ideal for occasional exposure. SPF 30 and higher for prolong exposure.
- Ingredients: titanium dioxide, zinc oxide(physical sunscreen) more suitable for sensitive skin. While chemical sunscreen usually contains oxybenzone, avobenzone, octisalate, octocrylene, homosalate, or octinoxate.
- Water resistant: stays effective for 40 minutes in the water. Very water resistant: stays effective for 80 minutes in the water.
How to use sunscreen correctly
- Apply sunscreen daily, even during winter or cloudy days.
- Apply sunscreen 20 minutes prior exposure, and re-applied every two hours or after sweating or swimming.
- Based on an application of 2mg/cm², apply liberally and evenly, approximately one tea spoon for each arm, leg, the front and back of the torso, and the face (including neck and ears).
- Avoid sunscreen application for babies under 6 months of age.
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