WHO launches Solar Alert8217; on eclipse

The TSE this month is the last of this millennium and the first in the last forty years to be visible in Europe. During direct viewing of the sun, for even a few seconds, light entering the eye is concentrated at a point called retina to the extent that it can burn retina cells which may result in blindness, who said in a release.

Direct viewing can even damage the fovea, another eye part, due to which people cannot view fine details, particularly under low-light conditions.

Appropriate and certified filters should be used to view the TSE, WHO says. A safe solar filter should reduce the amount of sunlight reaching the eye by a factor of much more than 1000. It should also effectively reduce infrared and ultraviolet rays invisible to humans.

Such a filter looks totally black, or, if made of reflective material, like a mirror. Viewing a normal scene with such a filter is not possible, WHO says.

For example, if an ordinary lamp is viewed using such filters, the brightest part of the lamp can be barely discerned. However, details of an eclipse as it progresses can be clearly discerned using such standard filters.

Dark filters used in welding are suitable and probably the best. These are marked with numbers indicating their darkness. Filters with numbers greater than ten are sufficiently protective and above 12 are comfortable. Those with numbers more than 14 might be too dark to be useful, according to WHO.

Mylar 8211; a trademark polyester film widely used for insulating purpose 8212; can be coated with sufficient amount of aluminium to make it almost totally reflective.

The film can then be suitably laminated and made wrinkle-free by a protective holder like a pair of eyeglasses to view the eclipse. The film with the holder can adequately protect the eyes.

The safest way to view an eclipse, however, is to use a pinhole camera, WHO says.

Over-exposure to sunlight could pose serious health problems for skin and the immune system too. Solar radiation is associated with many chronic skin conditions including skin cancers of which melanoma is the most life-threatening.

More than two million cases of non-melanoma skin cancers and 200,000 malignant melanomas occur annually worldwide, according to the United Nations Environment Programme.