UV index

From ArticleWorld

The UV index is an internationally-recognized, standardized measurement of the strength of the sun’s UV radiation at a specific time and location. The purpose of the UV index is to help those that are out in the sun find out what the strength of the sun is in order to protect themselves on high-risk days.

History

The UV index was developed in 1992 by three scientists in Canada. The UV index used by the US was put in place in 1994. Several other countries developed their own method of calculating the UV index until the World Health Organization intervened and established an international calculation method. This was put into place in the US in 2004. Some countries, including the US and Australia, have developed standards for a UV alert, similar to a smog alert, that tells residents when the danger is especially elevated.

Description

The UV index ranges from 1 (a very weak sun) to 11 (a very strong sun). Public health officials recommend that some sort of sun protection be used when the index reaches 3 or higher. Sun protection can be as simple wearing a hat or can involve the use of high-strength sunblocks. The numbers relate to a measurement of the strength of the sun divided by the surface of an area of the earth.

The strength of the sun is predicted by what the sun’s strength will be during the 4 hours around noon and factors in things like altitude and clouds. The calculations also factor in the type of rays that are most likely to affect the skin. This UV index is then used to predict what the sun’s intensity will be like on the same or the subsequent day.

Using the index

Regardless of the UV index, health officials recommend wearing sunglasses outdoors, especially in the snow. At levels at or greater than 3, the use of sunscreen and a hat is recommended. At a level of 6 or greater, a sunscreen with a strength of SPF 15 is recommended along with the reduction of time spent in the sun to avoid peak times. A level of 8-10 is very high, meaning that significant care in the sun should be taken. At the highest level of 11, all protection, including the wearing of long pants and shirts with long-sleeves, should be used along with avoidance of sun exposure at peak times.