Ultraviolet radiation (UVR) is produced by the sun and by some artificial sources. The human eye cannot see it. Solar UVR which could reach the earth's surface is subdivided into two types. These are UVB and the less energetic UVA. Some people are also exposed to UVR at work, as a medical treatment or by using sunbeds.
The main source of human exposure to UVR is the sun. UVR can damage DNA in cells on the surface of the body. UVR causes the skin to burn. The skin may react to UVR exposure by tanning. It can increase the risk of developing skin cancer (melanoma, squamous cell skin cancer and basal cell cancer). Intense UVR exposure can inflame the eyes. Long-term exposure may cause cataracts. These effects can take many years to develop so overexposure now may increase risks in later life. UVR causes skin ageing and, in many people, troublesome photosensitivity rashes. It may also affect the immune system in the skin, although the consequences of this are not certain yet. The incidence of skin cancer is rising. There are now about 40,000 new cases and nearly 2,000 deaths from skin cancer in the UK each year.
Exposing the skin to UVR produces vitamin D. This benefit only needs the amount of outdoor exposure people get as part of daily life. It may be more important for health in dark-skinned people with vitamin D deficient diets. Many people 'feel better' out in the sunshine. You can keep these benefits of sunshine without increasing the health risks by following our Sunsense Guide below.
We do know that UVB is the main cause of sunburn. UVA is thought to cause skin ageing. We do not yet know enough to say which types of UVR cause cancer. The International Agency for Research on Cancer, which is part of the World Health Organization, classifies all UVR as carcinogenic (cancer-causing) to experimental animals.
Although there is limited evidence whether sunburn directly causes cancer, sunburn is a sign that the skin has been damaged. Your risk of melanoma (the main cause of death from skin cancer) is related, among other things, to the number of times you have had intense exposure to UVR. Such exposures may be particularly damaging in children, although skin cancers usually develop in adult life.
A suntan is a sign that the skin has already been exposed to UVR and is trying to protect itself from further harm. People with naturally dark or tanned skin can still suffer sunburn. A suntan only offers modest protection against further exposure.
UVR damage occurs most easily in fair-skinned people and others who burn easily in the sun. Even dark-skinned people can get sunburnt. Everyone is at risk from UVR damage to the eyes.
One-off intense exposure (as in snow blindness) can cause intense inflammation in the eye. High levels of exposure over a long time may increase your risk of a number of eye diseases including cataract.
UVR can affect the immune system. The long-term consequences of this are not known. Some people find that cold sores are reactivated after exposure to UVR.
Children have many years ahead of them. Their skin needs to be protected from damage when they are young. This may help to reduce their risks of cancer and eye disease in adult life. Children cannot be expected to take responsibility for sun protection themselves. Carers of children have a responsibility to protect the skin and eyes of their young charges.
Sunbeds emit UVR. Sunbeds cause tanning and can cause sunburn. There is no evidence to suggest that any type of sunbed is less harmful than natural sun exposure. The HPA discourages the use of sunbeds for cosmetic tanning. Sunbeds should never be used by anyone under 18 years of age. If you are over 18 years of age and wish to use a sunbed then use a facility that provides guidance to users. Limit your use of the sunbed - don't have repeated sessions to build up a quick tan before a summer holiday.
The first line of defence is to know your skin type and keep alert for weather reports predicting that the global solar UV index will be 3 or more which can damage sensitive skin. This will let you plan adequate protection to be out and about on days when sunlight could damage your skin or eyes. A solar index of 6 or more is considered high.
|Global solar UV index||Approximate time for sunburn to begin in skin type a|
|8 or more||less than 20 minutes|
The next line of defence is to protect the skin and eyes by seeking shade or wearing clothing, wide brimmed hats and wrap-around sunglasses. The best clothing is loose fitting with a close weave. The third line of defence is sunblock or broad-band sunscreen (at least SPF 15). It should be used generously and applied frequently to areas that cannot be shaded from the sun with clothing. If used correctly, sunscreens will prevent sunburn. However, if you use them in order to stay out longer in the sun, you may partially or entirely lose the benefits in terms of protection from UVR exposure.
The final line of defence is early detection of skin cancer. Remember the signs of early melanoma and check yourself and your family.
This advice is based on a report by the National Radiological Protection Board (NRPB) expert Advisory Group on Non-Ionising Radiation (AGNIR). NRPB was an independent body that was set up by the Government in 1970 to provide advice on protection from radiation. In April 2005 NRPB merged with the Health Protection Agency (HPA) and now forms the Radiation Protection Division of the HPA. The AGNIR consists of UK experts who have reviewed all the science. The report, Health Effects from Ultraviolet Radiation, considers what is known about the health effects of UVR and how you can protect against them.
The Sun Protection Factor (SPF) is the ratio of the UVR exposure to produce minimal reddening of the skin on a site protected by sunscreen to the UVR exposure to produce a comparable reddening on unprotected skin. An SPF of 10 would reduce exposure to 10% of that of unprotected skin.
March 2004,(revised May 2006)
Last reviewed: 21 October 2009