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4 Take a look at the title of the text and say what it is about. Then read the text to check your guesses.

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UK scientists have developed UV-sensitive indicators that change colour when there is a danger of sunburn.

Over 70 000 people in the UK are diagnosed with skin cancer each year and sunburn is a contributing factor. The signs of sunburn can take four to eight hours to develop, by which time the skin is already damaged. While there are several UV dosimeters on the market, most are unable to distinguish between different skin types. Also, they show a gradual colour change in response to sun exposure, which makes identifying the sunburn risk difficult. Andrew Mills and colleagues from the University of Strathclyde, Glasgow, have created what they claim is a 'simple, inexpensive, unambiguous sunburn indicator ' that can be tuned to different skin types.

Mills' indicator uses a UV-driven acid-release agent coupled to a pH-indicating dye. Sunlight decomposes the acid-release agent leading to protonation of the dye, which causes a striking colour change. The length of time before the colour changes can be altered by using different acid-release agents or dyes, explains Mills, meaning that the indicator could be varied for use on all skin types.

As an alternative to this indicator, Mills has also made a blue indicator based on a tin oxide photocatalyst, which reduces a dye and becomes colourless on exposure to sunlight. 'The inorganic pigment materials match the way the skin absorbs UV radiation,' says Mills.

It is the simplicity of the chemistry, and its ability to work on all skin types, that makes this research so effective,' comments Peter Robertson, an expert in photocatalysis at the Robert Gordon University, Aberdeen, UK. He adds how 'gratifying it is to see academic science coming up with a solution that is going to have an impact on society'.

Mills says he is optimistic that these indicators will become commercially available but adds that the greatest challenge will be getting our sun-loving society to accept them.

Nicola Wise

http://www.rsc.org/chemicaltechnology