The UV Index

How to use it to protect your skin from sun damage.

The UV Index is a forecast of the probable intensity of skin damaging ultraviolet radiation reaching the surface during the solar noon hour: 11:30-12:30 Local Standard Time, or 12:30-13:30 Local Daylight Time. The greater the UV Index is the greater the amount of skin damaging UV radiation. How much UV radiation is needed to actually damage one's skin is dependent on several factors. In general, the darker one's skin is — that is, the more melanin one has in his/her skin — the longer (or the more UV radiation) it takes to cause erythema (skin reddening).

UV Graph

The figure above shows a look-up chart where you may cross check your propensity to burn versus the UV Index. For those who always burn and never tan, the times to burn are relatively short compared to those who almost always tan.

The EPA has devised general guidelines as far as what to do to protect oneself from overexposure to UV radiation. These are shown in the table below.

Exposure Category UV Index Protective Actions
Very Low 0, 1, 2 Apply skin protection factor (SPF) 15 sunscreen.
Low 3, 4 SPF 15 & protective clothing and hat.
Moderate 5, 6 SPF 15, protective clothing, and UV-A&B sunglasses.
High 7, 8, 9 SPF 15, protective clothing, sunglasses and make attempts to avoid the sun between 10am to 4pm.
Very High 10+ SPF 15, protective clothing, sunglasses and avoid being in the sun between 10am to 4pm.