Can glass block sun rays that cause skin cancer?

People often think that glass windows protect us from sunburn and skin damage. Although most glass windows do offer some protection, they are definitely not completely sun proof and you shouldn't think of them as sun protection.

Skin cancer develops when genes in skin cells are damaged by ultraviolet radiation. This mainly comes from the sun but can be man made - for example, from sunbeds. Most skin cancers are the result of too much exposure to the sun. Ultraviolet radiation is invisible and you can't feel it on your skin. It penetrates deeply into our cells, causing changes leading to sunburn, skin ageing, eye damage and skin cancer. There are three types of ultraviolet radiation, but only two reach the earth's surface. These are UVA and UVB. UVC is filtered out by the ozone layer.

UVA causes skin ageing and research has now shown that it is also likely to cause skin cancer. UVB causes redness and sunburn and is a major risk factor for all types of skin cancer.

Most glass used for windows blocks UVB but not UVA. This means that although glass greatly reduces the risk of sunburn, it does not prevent long term damage from UVA. So, if you are driving long distances or sitting in your conservatory every day for long periods of time, you need to make sure you are using sun protection on sunny days.

Several factors can affect your risk from sun exposure. Most importantly, this is how much time you spend outdoors, but also the time of day, season, latitude, altitude and cloud cover. People with fair skin that tends to burn or freckle are at higher risk.

There is more information about the risks and causes of skin cancer in the non melanoma skin cancer section of CancerHelp UK. There is also information about protecting yourself from the sun and all types of skin cancers in the melanoma section of CancerHelp UK.