Skin ages prematurely from prolonged exposure to UV radiation from the sun; UV radiation is the most important factor in skin ageing and skin disorders, accounting for about 90% of the symptoms of premature skin ageing. So sun damage and skin ageing go hand-in-hand because one leads to the other. Damage to the skin caused by excessive exposure to the sun can either be:

1. Acute, which can be caused by as little as a few hours exposure, producing the reddened, blistered skin commonly known as sunburn, or
    
2. Chronic, which is caused by the accumulated exposure of your skin to the sun throughout your life, producing photo damage or photo ageing and, in more and more cases, worrying pre-cancerous lesions and skin cancers.

• UVA radiation accounts for about 95% of all ultraviolet energy and is released throughout the daylight hours. It penetrates far into the deeper layers of the skin and can cause permanent harm to our DNA as well as to the elastin and collagen fibres that make skin supple and firm. While UVAs don't cause painful sunburn, their effects are very real and long-lasting. It's important to realize that UVAs can also pass through glass windshields and windows; they offer no protection.
   
• UVB radiation is the most harmful type of ultraviolet radiation. It is nearly 1,000 times more capable of inducing sunburn than UVA rays. UVB tends to peak in intensity between 11am and 4pm in summer. While UVBs do not penetrate deep into the skin, they can damage the DNA at the heart of skin cells and are one of the foremost causes of skin cancer. UV radiation also irradiates white blood cells, thereby suppressing the body's immunity. It takes about two weeks for your immune system to recover after sunburn (which is why people often develop cold sores after a sunburn).