DEPARTMENT OF DERMATOLOGY:YORK AND SCARBOROUGH ENJOYING THE SUN SAFELY Everyone enjoys sunny days and outdoor activities. Sunlight can be harmful, however, even in Britain, so it is essential to know how to enjoy it safely. The harmful part of sunlight is ultraviolet of which the lower energy rays are called type A (UVA) and the higher energy rays type B (UVB). Problems which affect all light-skinned people (and especially the fair skinned) are: UVA : Ageing - this builds up gradually over the years depending on the total amount of sunlight you get. UVB : Burning - if you get too much sunlight at one time. We now know that sun exposure increases the risk of skin cancer, this is due mainly to UVB but also partly to UVA. Some people get inflammatory itchy skin conditions from sunlight - photosensitivity or "sun allergy"; this is due mainly to UVA but UVB is often important too. General aspects of sun protection. The nearer to the equator, the nearer to midsummer, and the nearer to midday, the stronger and more dangerous are the sun's rays. The strongest sunlight occurs between two hours before and two hours after true midday (i.e. 11 am to 3 pm British Summer Time). Remember that the sun's rays can be just as harmful whatever you are doing, for example working out of doors, gardening, walking, or playing sports, even if you are not deliberately sunbathing. There can be a lot of ultraviolet about on a cloudy bright day, and some is reflected into shady places. Remember that snow, sand, water and concrete reflect the ultraviolet and increase its effect. UVA gets through glass but UVB does not. If you are sitting out, try to avoid the midday sun or sit in a shady place. Hats or caps with brims, and sunglasses, help to shade the face. Keep reasonably clothed - the protection depends on the density of the fabric, not its colour. Summer cotton clothes of medium weight give good protection, but burning can occur through thin fabrics. Nylon tights give no significant protection. Skin which is not well protected by clothing should be treated with a sunscreen. Sunscreens These are creams or lotions which reduce the amount of the sun's rays getting through to the skin; the effectiveness or a sunscreen in doing this for UVB is called its sun protection factor (SPF). A cream which in proper use lets through, for example, a tenth of the UVB is called factor 10 or SPF 10; the higher the number, the more effective the sunscreen. A protection factor of this type is sometimes given for UVA, but mostly a 1 to 4 star rating is used to indicate the UVA protection relative to the UVB protection (thus 4 stars means the cream is as good for UVA as for UVB). Most sunscreens contain invisible substances which chemically absorb the rays, especially UVB. However, for very high protection, especially for UVA a fine white powder is used which physically reflects the rays away from the skin. The resulting whitish layer on the skin may be unacceptable for general use, but worth tolerating in special circumstances. Remember to follow closely the manufacturer's directions especially with regard to the frequency of application, and to treat all exposed areas. Do not miss the skin of the ears, next to the hairline, around eyes and mouth, and the lips: lipstick keeps out the sun's rays, and invisible sunscreening lip salves are available. Choosing a sunscreen General use for every white skinned person, but especially the fair-skinned and children: prevention of burning, and long term prevention of cancer, require mainly UVB protection, but UVA protection is also advised. There are many sunscreens with UVB sun protection factors around 15 or 20 which include a helpful degree of UVA protection (usually three stars), and which are pleasant to use, Choose one whose look, feel and smell you are happy with, and if there are a few of these, then the higher the factor the better. There is little point in deliberately choosing anything weaker than these. Higher factor sunscreens may be advisable if you are in strong sunlight for long periods. Sun-allergic people should generally choose products with UVB protection of factor 20 or more, with 4 stars for UVA. To reduce the ageing effects of sunlight, use products with high UVA and UVB protection. Some cosmetics include sunscreen agents, but you should check that the protection is adequate. Sunglasses which keep out both UVA and UVB also help. Some people dislike the feeling of cream on the skin, and may feel reluctant to use sunscreens. Some of the sunscreens mentioned above for general use are thinner fluids, sometimes called lotions or milks rather than creams, and leave very little greasiness on the skin. Another possibility is an alcohol-based solution of a sunscreening agent called PABA (e.g. "Spectraban 25", but note that other Spectraban products are different). This dries into the skin and is non-greasy. Once absorbed, it gives day-long: protection against UVB. However, it has no UVA protection, and can leave a yellowish stain on fabrics. If you anticipate swimming or heavy sweating, use a water-resistant sunscreen. Like any other skin product, sunscreens can occasionally cause allergic rashes. If this seems to happen, consult your doctor or pharmacist. If you require advice on any aspect of selection of a sunscreen, a pharmacist will be able to help. Some shops may have samples of different sunscreens available to help you check that the look, the feel and the smell are acceptable.

My thanks to Dr Highet of York and to Trevor Rimmer for bringing this information to the group's attention.

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