As part of the Government's Health of the Nation target to reduce the incidence of skin cancer, clothing protection factors - or CPF numbers - will be introduced, comparable to the numbers on suntan creams.
Yesterday, health promoters issued a new set of guidelines, based on Australian research, on the safest colours and types of material to wear in the sun.
The general rule now, in addition to covering up, is to wear dark-coloured clothes because they transmit less ultraviolet radiation to the skin; to pick tightly woven fabrics so that less ultraviolet radiation can pass through and to wear loose clothes for comfort in hot weather.
The experts warned against cheesecloth, baseball hats which offer no neck protection; the colour white which can scatter ultraviolet rays and direct them to exposed skin; and any mesh fabric.
Alastair McKinlay, of the National Radiological Protection Board (NRPB), which is leading the research into a clothes- labelling system, said people should also be aware that being wet reduced the protective qualities of fabric.
In Australia, a clothes-labelling system is beginning and this summer 600,000 tags went on to clothes. One British company, Raw Clothing, has agreed to pilot a CPF symbol in this country. Triangular labels will show numbers, for example '30' would indicate high protection and '5' low protection.
The Health Education Authority, the NRPB, representatives of the clothing industry and the Department of Health are working together on the fabric-labelling scheme which Dr Jackie Chambers, of the HEA, said should be seen in about 18 months.
More than 40,000 people in the UK are diagnosed with skin cancer every year. About 4,500 of these are malignant melanoma - the most dangerous form - which kills 1,300 people in Britain a year. Incidence has increased by 50 per cent in 10 years. Non- melanoma cancers, also associated with ultraviolet radiation, rose from 19,000 cases in 1974 to 36,000 in 1988. These cancers rarely kill but necessary surgery can be disfiguring.