So let’s debunk the difference between UVA and UVB rays. The sun emits both rays. And although UVB rays only make up for 5% of the rays emitted by the sun, they are very powerful. Although they may not penetrate as deeply as UVA rays, they can significantly damage the top layers of skin, causing sunburn and in worst cases, DNA mutations that can develop into melanoma and other types of cancer. UVA rays, however, penetrate the skin so deeply that they are one of the greatest culprits of premature skin ageing and other skin concerns. “UVA penetrates the dermis (the core layers of skin), causing damage to the pigment cells and collagen fibres, which can result in premature ageing,” says Dr. Gout. “ UVB rays penetrate the epidermis (the top layers of skin) and can cause pigmentation, skin roughness and give skin that typical ‘leathery’ look. SPF slows down all of the above and with daily usage and adequate quantity application, it really does preserve the health of your skin.”