How to Protect Your Skin from the Sun's Harmful Ultraviolet Rays

With the Memorial Day weekend underway, so is the unofficial start to the summer season. As more and more people head outside to enjoy the warm temperatures and ample sunshine, 'tis also the season for sunburns. Understanding the UV Index scale will help you make more informed decisions so that you can protect your skin. Here is what you need to know heading into sunburn season.

Specifics of the UV Index

This is the time of the year to begin paying attention to the UV Index when you check your local weather report. The UV Index (UVI) is a number that indicates the strength of the sun's ultraviolet rays at any given time.

While these rays are invisible, they can cause significant amounts of damage to the skin and eyes. Too much sun exposure can lead to painful sunburns, premature skin aging, eye damage, and deadly skin cancer.

The UV Index was first used in the early 1990s by Environment Canada, the agency in Canada that is most comparable to the U.S. National Oceanic and Atmospheric Administration (NOAA). The index was tweaked through a joint effort between the World Health Organization (WHO) and the World Meteorological Organization (WMO). The scale is now used worldwide, providing an easily recognizable device to understand the present dangers from the sun when spending time outside.

There are a number of factors that go into determining the UV Index. The time of the day is a key element. UV rays are naturally the strongest when the sun is the highest in the sky, generally between the hours of 10 am and 4 pm.

The time of the year also greatly influences the UV Index. The intensity of the sun's rays is the highest during the spring and summer seasons. Locations closest to the equator typically experience stronger UV rays. Similarly, locations with higher elevations also see more UV exposure.

A pervasive ozone layer also works to block UV rays. This means that thin ozone layers translate to higher UV numbers. In this same vein, cloud cover also blocks UV rays from filtering down to ground level with as much intensity.

Agencies such as the National Weather Service (NWS) rely on a standardized set of data to determine the UV Index for each day. These indices frequently change throughout the day, making it important to keep tabs on the number periodically when spending time outside.

How to Interpret the UV Index Number