Beef up UV warnings, cancer expert urges Observatory

Doctor wants index to show more types of dangerous rays

A cancer expert has urged the Observatory to improve its UV index to include more harmful types of ultraviolet rays, amid fears that the incidence of some types of skin cancer is set to soar.

Anthony Ying Chi-ho suggested that as well as measuring ultraviolet B (UVB) rays, the index should also include UVA rays, which had a shorter wavelength and could penetrate deeper into the skin.

In making the suggestion Dr Ying, chairman of the cancer detection and prevention subcommittee of the Hong Kong Anti-Cancer Society, acknowledged this was not the international norm and could require more advanced equipment.

The Observatory said it had no plans to measure UVA radiation, which was only a tiny fraction of the total UV radiation and were not included in World Health Organisation guidelines.

Dr Ying's call was made against a background of projections that the number of new cases of non-melanoma skin cancer, far more common than melanoma skin cancer, would increase 23 per cent in the next two years to more than 700 cases from 569 in 2005, the most recent year for which the Hong Kong Cancer Registry provides statistics.

Dr Ying said that was double the incidence of 1990, when there were 346 new cases.

Part of the reason was the ageing population - with skin cancer more common among the elderly - and the tendency for people to spend more time outdoors.

The popularity of tanning beds was also a factor.

'If more people use tanning beds, we cannot exclude the possibility that the incidence rate of skin cancer will increase among young people and the middle-aged,' he said, referring to non-melanoma skin cancer.

The Observatory should also provide advice on what to do - avoid the outdoors or apply more sunscreen, for example - when levels of ultraviolet rays were high or extremely high, Dr Ying said.

The Observatory was considering posting such advice, but did not plan to measure UVA, senior scientific officer Chan Chik-cheung said.

'It is not just a matter of getting better technology,' he said.

The Observatory followed the World Health Organisation's guidelines, which did not require reporting of UVA levels on UV indexes.

'UVB has a lot more influence,' he said. 'Only a hundredth to a thousandth of UV rays are UVA, so we look only at UVB.'

UV levels had fluctuated, but not risen or dropped dramatically from 2000 to last year. It was unclear whether they would rise in coming years. The Observatory had not analysed data for UV levels before and therefore could not extrapolate for predictions, Mr Chan said.

Dr Ying is speaking with schools about how to prevent overexposure to UV rays.

He advised people to avoid going outdoors at times of high UV exposure, especially at noon, and to use sunscreen of SPF 15 or above with PA++ or PA+++ sun protection.