New gauge of sun risk 'safer'

Supporters of the ultraviolet index (UVI) have rejected weather expert Augie Auger's criticism of the new method for telling people how long they can stay in the sun.

The UVI, developed by the World Health Organisation, has been introduced to replace "burn time".

The Cancer Society, the Health Sponsorship Council's SunSmart brand, the National Institute of Water and Atmospheric Research, the MetService and academic institutions have backed the move.

But Mr Auer, a former MetService chief forecaster, has accused the groups of jumping on the bandwagon by supporting what he calls a "confusing" index being pushed by the WHO.

Cancer Society spokeswoman Wendy Billingsley responded that the index was a safer and more scientific indicator than burn time.

She said it was an absolute measure and was applicable to everyone.

"It tells you how much ultraviolet radiation there is in the atmosphere," she said.

"It's the same for everybody, and everybody can use that information to judge the behaviour they should take individually for that particular level of radiation."

She said burn time gave people the message that they could stay out safely in the sun for a certain length of time.

"Try putting an 18-month-old, fair-skinned baby in the sun alongside a 40-year-old, weatherbeaten bloke for the same length of burn time and see who ends up with blisters."

UVI uses a fan shape with coloured, numbered bands to indicate levels of risk from low (1) to extreme (11).

Ms Billingsley said the WHO recommendation was adopted after research in New Zealand.

A Cancer Society and SunSmart website had UVI information for individuals according to skin type and age, she said.

Mr Auer said the only difference between the two methods was that burn time was easier to understand.

"Burn time is based on UVI - it doesn't come out of left field," he said.

"It's a matter of communication."

Understanding UVI required doing some sums - dividing 144 by the UVI rating to get the burn time, said Mr Auer. A UVI rating of eight gave a burn time of 18 minutes.

- NZPA