Skiers at higher risk of ultraviolet exposure

People heading for the ski slopes this spring are being warned to use sunscreen and sunglasses after a New Zealand study found ultraviolet rates were up to 30 per cent greater at high altitudes.

Scientists from the National Institute of Water and Atmospheric Research and Canterbury University wore specially designed monitoring badges to measure how much ultraviolet radiation they were exposed to on the Mt Hutt skifield in September and October last year.

They compared that to levels during the same time in the sea-level Christchurch suburb of Riccarton.

Dr Richard McKenzie, one of the researchers, said the study replicated similar findings overseas. Not only were ultraviolet levels higher at greater altitudes but the intensity of the ultraviolet rays on snow-covered surfaces was even greater because of the reflection.

The peak ultraviolet levels on the skifield at an altitude of 2.1km were 20 to 30 per cent greater than those measured on the same day in the city.

Dr McKenzie said the increase in ultraviolet levels at high altitudes was due to the combined effects of less air to scatter the radiation, the reflection of snow, and less atmosphere above to cut down ultraviolet levels.

Cancer Society SunSmart spokeswoman Wendy Billingsley said the New Zealand study reinforced warnings by the World Health Organisation that the thinner atmosphere of high altitudes absorbed less radiation.

In Europe ultraviolet levels jumped 10 to 12 per cent for every kilometre but in New Zealand the increase was 5 to 10 per cent because of the cleaner air.

Ms Billingsley said it was vital people used sunscreen and good-quality sunglasses in the snow.

"And they should not forget either that the reflected ultraviolet is directed at skin which does not usually have sun shining on it, for example, the under side of the nose and chin which is even more vulnerable."

The New Zealand study was published in May in the European journal of Photochemical and Photobiological Sciences.