HK warns on UV radiation danger With Hong Kong experiencing some of the most intense ultraviolet radiation in the world, the Observatory will next week begin issuing hourly public alerts when they reach extreme levels. Health experts warn prolonged exposure to such high levels of UV rays from the Sun can cause severe eye damage. Excessive exposure to sunlight is to blame for 80 per cent of skin cancer cases around the world, the World Health Organisation also says. Hong Kong is the first place in the world at its latitude - 22 15 North - to issue such warnings, Observatory senior scientific officer Chan Chik-cheung said. The WHO considers a UV index reading of 11 or above to be extreme. Yesterday - when high temperatures and strong sunlight prompted the year's first very hot weather warning - the UV index reached 12. Health officials warned of the risk of heatstroke and sunburn. The index is expected to be the same today. Latitude, altitude and the amount of ozone in the atmosphere affect the intensity of UV rays. They also vary according to the time of day. The Observatory began measuring UV levels in 1999. The highest level recorded was 15, in July 2003. Records show the UV index reaches extreme levels an average of 59 days a year. Most occur between May and August. Mr Chan said health concerns had prompted the Observatory to step up its warnings about the dangers of UV exposure. It currently issues warnings when extreme UV levels are expected. In future, when extreme levels are detected it will issue precautionary announcements and include advice 'to avoid prolonged exposure to the sun so as to protect skin and eyes' in its hourly bulletins for the media. Doctors say that when the UV index is high (6 or above), people should consider wearing long-sleeved clothing made from close-woven fabric and a wide-brimmed hat, or use an umbrella; seek shade; wear sunglasses that block UV rays; and apply sunscreen with a protection factor of 15 or above. As the index rises, these precautions should be reinforced, they say. Earlier this month, a University of Hong Kong study found that people were not nearly as aware of the damage excessive exposure to high UV levels can do to the eyes as they were of the risks of skin damage. Rufina Chan Tin-yan, president of the Hong Kong Society of Professional Optometrists, said people must wear dark sunglasses and a hat and carry an umbrella to fully protect the eyes. Contact lens wearers should ensure their lenses have UV protection.