Nepalis are being exposed to Ultraviolet radiation rated as "very high" to "extreme" by the World Health Organization, according to a first-of-its-kind study carried out in the Himalayan region.

According to Monday's The Himalayan Times daily, Ultraviolet radiation emitted by the sun is known to cause skin cancer, photokeratitis - a burn of the cornea - and cataract.

Researchers from Pulchowk Engineering Campus, in collaboration with the Norwegian University of Science and Technology regularly recorded radiation data for three years in stations in Kathmandu, Pokhara, Biratnagar and Lukla to come up with the conclusion.

"The data from the four stations showed that the WHO-formulated UV index for the areas falls on the 'very high' and 'extreme' category," said Bal Krishna Sapkota, professor at the campus and coordinator of the research project.

According to the WHO, the UVI is a measure of the level of UV radiation. The values of the index range from zero upward -- the higher the UVI, the greater the potential for damage to the skin and eye, and the less time it takes for harm to occur. UV radiation that scores 8-10 on the index is categorized as 'very high' and those above 11 are categorized as 'extreme'.

As the altitude increases, the UV radiation index also registers a steady rise. Snowy surfaces are better reflectors of UV, said the report.