Ultraviolet radiation (UV) from the sun is a high energy form of light. There are three types of UV radiation. In order of increasing energy, these are classed as UVA, UVB and UVC.
While UVC is the highest energy form of UV light, over-exposure to UVA and UVB have been linked with numerous health problems involving the skin and eyes of humans.
All three forms affect the breakdown of collagen in our skin, which can lead to premature ageing.
Sunblock is commonly used to prevent damage to the skin by preventing harmful UV radiation from being absorbed.
In the past it was thought that UVB was the most harmful. Over-exposure to UVB is known to cause skin problems including sunburn and in extreme cases, skin cancer.
More recently, UVA has been shown to contribute to skin cancer by indirectly breaking down DNA in a process that involves free radicals.