The rays from the sun make us feel good but they are highly destructive. Sun exposure causes most of the skin changes that we think of as a normal part of aging. Over time, the sun’s ultraviolet (UV) light damages the fibers in the skin called Elastin. When these fibers break down, the skin begins to sag, stretch, and lose its ability to go back into place after stretching. By damaging the skin’s cellular DNA, excessive UV radiation produces genetic mutations that can lead to skin cancer.
UV radiation is part of the electromagnetic (light) spectrum that reaches the earth from the sun. It has wavelengths shorter than visible light, making it invisible to the naked eye. These wavelengths are classified as UVA, UVB, or UVC. Most UVC is absorbed by the ozone layer and does not reach the earth (thankfully), but we have to deal with UVA and UVB rays.
Also known as Ageing Rays, emit long wave ultraviolet radiation and represent about 95% of the radiation that reaches the earth. They are present with relatively equal intensity during all daylight hours, all year long, in any climate and weather condition, and can penetrate through clouds and windows. That is why, even though they are weaker than UVB rays they actually cause more damage.
UVA, which penetrates the skin more deeply than UVB, has long been known to play a major part in skin aging and wrinkling (photoaging). Studies show that UVA damages skin cells called keratinocytes in the basal layer of the epidermis, where most skin cancers occur. UVA contributes to and may even initiate the development of skin cancers. They also decrease elastin, the substance that gives skin its structure and elasticity.
Also known as Burning Rays, cause painful skin reddening and sunburn. It tends to damage the superficial epidermal layer (thin top layer of the skin). UVB rays emit medium wave ultraviolet radiation and only about 5% of it reaches our planet. This is because part of them are absorbed by the clouds and the other part by the ozone layer. They are stronger between 10a.m and 4 p.m.
Although less numerous than UVA rays, they are more powerful and can still cause a lot of damage. Unlike UVA rays, this damage is instantly visible as it is the UVB rays that cause sunburn. In addition, they also cause abnormal cell mutations and growth pattern and can cause skin cancer.
NATURAL SPF IN DARK SKIN
Many people think “dark skin has an inbuilt SPF so sunscreen is not necessary” – It would be great if that were true, but sadly, it’s just a myth. Darker skin does have a higher natural SPF than fair skin due to increased amounts of protective melanin in it, but that doesn’t mean it isn’t prone to wrinkles, hyperpigmentation and skin cancer.
Dark skin really has an “inbuilt” SPF of between 8 and 16 (depending on how dark it is), which protects it from some of the damage caused by UV rays. The problem is that SPF 15 only filters about 92% of UVB rays. That’s a high percentage and it may seem enough to provide adequate protection, but the rays that get through the skin will, overtime, cause dark spots, premature aging, and even cancer. Dark skin is not as sun-resistant as we think it is, it can get sunburned too, but it is harder to detect because dark skin rarely turns red.
Sunscreen is a MUST when it comes to skincare. The sun’s harsh rays cause premature aging leading to wrinkles, loss of firmness and discoloration. Sunscreens protect the skin from the sun’s damaging UV radiation. There is no excuse to not use sunscreen. There are newer types with different formulations – no white cast, gel/water based, matte finish e.t.c; you just have to find what works for you.
The “Sun Protection Factor” (SPF) of a sunscreen is a clinical test measure of the effectiveness of a sunscreen product against sunburn (UVB Rays). The higher the SPF, the more sunburn protection a sunscreen offers. SPF blocks 93% of UVB Rays, SPF30 blocks 97%, SPF50 blocks 98%, SPF 100 blocks 99%. There is no sunscreen that blocks 100% of UVB rays unfortunately, you can settle for SPF50.
It is essential for your sunscreen to offer broad-spectrum protection (UVA & UVB rays). You are likely to have seen some products with “PA+++”. PA+ means your sunscreen offers some protection against UVA rays, PA++ provides moderate protection, PA++++ offers the best protection of the three.
Sunscreens effectiveness depends on: the SPF value, broad spectrum protection, level of water resistance and whether the product is used as directed. Remember to apply sunscreen at least 20minutes before heading outside and reapply every 2 to 4 hours.
There are two types of sunscreen ingredients: Chemical Blockers and Physical Blockers.
Chemical sunscreens work forming a thin, protective film on the surface of the skin and absorb the UV radiation before it penetrates the skin (E.g., Octinoxate and Oxybenzone).
Physical sunscreens are insoluble particles that form a physical shield that deflects UV rays away from the skin (E.g., Titanium Dioxide and Zinc Oxide). The physical sunscreens usually make the formulation white which gives many dark skinned people a grey/ashy look. Most sunscreens contain a mixture of chemical and physical sunscreens.
Photo Credit: Dreamstine, Dermatology, Rack & Style