People worried about the ravages of the sun on their faces will have more help from the city's weather scientists this summer.
The Observatory, which has been issuing only a general ultra-violet (UV) index, will now offer a separate alert for the longest wavelength UVA radiation.
Weather scientists say the more specific index will warn those who not only want to avoid sunburn, but also want to keep their skin pale, wrinkle-free and younger-looking. Instant readings of the UVA index will be on a five-level scale ranging from 0 to 54.
Ultra-violet radiation is catagorised into different wavelengths - A, the medium-length B waves and the shorter C. The earth's ozone layer prevents most of the radiation penetrating through the atmosphere. Type C is almost non-existent, while the intensity of B is lower than A when it reaches the atmosphere.
But the Observatory said the general and A indexes corresponded closely to one another and it was unlikely that one index would be high while the other was low. Observatory director Dr Lee Boon-ying said yesterday that UVA had been neglected in the past but more studies indicated that these rays also could damage health.'The impact is also great in terms of making skin age faster with more wrinkles and might lead to the development of skin cancer, too,' he said.
Lee said the public should refer to the UVA index in their choice of sun block lotion. As well as the level of sun protection factor (SPF) on the bottle, people are advised to use lotion that also lists the protection grade for UVA, which may also be shown as PA (a grade in which the more + signs indicate a higher protection level).
