How do sun tan creams work

A.� Either by blocking or absorbing ultraviolet (UV) light. Sunlight comes in three forms: infrared (heat), visible light and ultraviolet. Ultraviolet light also comes in three forms: UVA, UVB and UVC. UVA causes tanning, UVB causes sunburn while UVC is filtered out by the Earth's atmosphere

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Q.� How does the cream absorb UV light

A.� By using chemicals. PABA, para-aminobenzoic acid, which absorbs UVB, is the first and most common absorption chemical used in sun skin care products.

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Q.� What are SPFs

A.� SPF stands for sun protection factor found in sun tan creams. The SPF works as a multiplying factor. For example if you can spend�five minutes in the sun before burning and you use a cream with a SPF of 10, then you should be able to�safely spend 50 minutes in the sun.

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Q.� How does my skin tan

A.� When you get a tan your skin produces pigment in reaction to ultraviolet light in sunlight. The pigment absorbs the UV radiation in sunlight, protecting the cells from UV damage. The pigment takes some time to be produced, which is why a tan needs to be built up slowly over a period of days, until the pigment builds up in your cells to a level that is protective.

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Q.� What causes sunburn

A.� If you are Caucasian and you don't have a tan, then your skin isn't protected from the sun's ultraviolet radiation. By exposing your skin to the sun, and therefore UVB light, your skin's cells become damaged, your body responds to this by increasing the blood flow to the skin, which causes the redness associated with sunburn.

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Q.� Is it true that I can't get sunburnt in a greenhouse

A.� UV light can be absorbed or amplified by different surfaces. Glass is a very good absorber of UV light, so yes, you're less likely to suffer sunburn in a glass greenhouse. Sunscreen ingredients are partly based on the UV absorbing properties of glass.

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Q.� How do people skiing tan

A.� Tanning is caused by light, not heat. As explained earlier, different surfaces reflect or absorb light to different degrees, snow can reflect up to 90% of UV light, which explains why skiers have to protect exposed skin as much as someone sitting on a hot sunny beach.

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by Lisa Cardy