Sunscreen is a topically applied product that comes in the form of creams, gels, or sprays. It contains ingredients that protect the skin by filtering out the sun's harmful ultraviolet radiation (UVR). There are three forms of UVR and these are UVC, UVB, and UVA. The two main forms of UVR which result in skin damage are UVA and UVB. Sunscreens protect the skin against UVB radiation but not UVA, unless it is clearly labeled BROAD-SPECTRUM sunscreen. Broad-spectrum sunscreens protect the skin from UVB and UVA radiation equally.

There are three types of ultraviolet radiation, these are UVC, UVB, and UVA. We only need to worry about UVA and UVB, as these are the ones that can cause skin damage.

1. UVA penetrates through the ozone layer and deep into the skin's second layer (Dermis) which contains our skin's supply of collagen and elastin. Elastin gives skin its elasticity or its ability to bounce back when stretched. Naturally, over time the skin loses its ability to bounce back and with the accumulation of UVR damage resulting in saggy skin. Collagen is what keeps our skin wrinkle-free in our youth. As we grow older the body's collagen reserve is gradually depleted resulting in the formation of wrinkles. Repeated and unprotected sun exposure causes the breakdown of collagen and speeds up the depletion of our skin's reserves. This results in deep wrinkles which are one of the many signs related to premature skin aging or photoaging.

Photoageing is characterised by the following signs:

1. • • • deep wrinkles

       • sagging skin

       • uneven skin tone

       • a leathery and thick skin texture

       • dark coloured spots (hyperpigmentation)

       • thin red facial veins (telangiectasia)

2. UVB penetrates the skin's top layer (Epidermis). The Epidermis sits above the dermis which is the skin's second and deeper layer. For more information and some visuals about the anatomy of the skin click the SKIN ANATOMY link here 🔲.

UVB does not penetrate deeply into the skin as UVA, but can still cause irreversible damage to skin cells. Overexposure to UVB without the adequate use of sun protection results in tans and sunburns. To a milder extent, frequent exposure to UVB radiation without sun protection can darken freckles and make skin conditions like melasma worse.

Intermittent and frequent sunburns also result in damage to the DNA of skin cells increasing the risk of skin cancer development. For more information about skin cancer click here 🔲.

The ozone absorbs 90% of UVB. This highlights the importance of protecting the planet from environmental pollutants that damage the ozone layer which protects us in many ways.

3. UVC is completely absorbed by the ozone layer and is therefore of no concern to the human skin.