The UV Index: What Is It And How Does It Affect Your Skin?

Summertime is often associated with beautiful, healthy-looking, tanned skin. Warmer destinations, especially those with beaches, are preferred vacation spots because of the extra sun exposure. However, this extra exposure comes with additional problems in the form of negative effects from ultraviolet (UV) rays on the skin. Sun damage may be partially reversible, but it is best to avoid it altogether.


According to data published by the American Academy of Dermatology Association, one in five Americans will develop skin cancer over the course of their life. This shockingly high rate is due to our penchant for being outdoors and soaking up the sun without any protection. Fortunately, the easiest way to address this problem is by being aware of the UV Index, which indicates the degree to which the sun emits its UV rays at any given point in time. Knowing this, along with the aging and potential skin cancer risks posed by exposure to UV rays, allows you to take adequate precautions that correspond to the level shown on the UV Index.

What is the UV Index?

The World Health Organization (WHO) defines the UV Index as a measure of the level of UV radiation present in the sun's rays. This number starts at zero, and the higher it climbs, the more dangerous the effects of UV radiation are on the skin and eyes, especially in fair-skinned people. Higher numbers also cause damage more quickly. The UV Index is, therefore, an important tool that allows people to prepare for sun exposure.


WebMD explains that the UV Index was created in 1994 by the National Weather Service and the Environmental Protection Agency (EPA) as a means for Americans to plan their skin protection for the day. It was made so that people could plan for sun exposure in the same way they plan for rain or snow by checking the weather forecast beforehand. The National Weather Service calculates the UV Index in America each day.

Recognizing its importance, the WHO adopted the UV Index and implemented it on a larger scale with access in other countries. This means that you can check the UV Index when you travel to other parts of the world.

How is the UV Index measured?

The UV index measures the strength of the sun's UV rays in a specific location on a given day. The higher the number, the greater the potential harm to your health. WHO lists three ranges in this regard. The first is 0-2, which is safe for outdoor activities. The second is 3-7, which is moderately dangerous. If the index falls in this range, stay in shady areas and cover your skin with clothing, a hat, and sunscreen. If the number is 8 or above, it is best to avoid outdoor activities altogether. If you must be outside, cover yourself with sunscreen, clothing, sunglasses, and a hat, and stay in shady areas.


Note that the index values change throughout the day. According to the EPA, the time between 10 a.m. and 4 p.m. is the riskiest, depending on the geographical location and whether daylight savings time is in effect.

How the UV Index affects your skin

While it's important to understand what numbers on the UV Index are dangerous for you, it's equally crucial to comprehend the extent of the effects that harmful UV rays can have on your skin and eyes. Lisa Hageman, manager of the Preventive Medicine Initiative at Backus Hospital, told Hartford Healthcare, "Amazingly, the sun's UV rays can damage unprotected skin in as few as 15 minutes and it can take as long as 12 hours for skin to show the full effect of sun exposure ... It's important to recognize that any change in your skin's color after you've been outside indicates damage from UV rays. Tanned skin is damaged skin."


In addition to changes in skin color, sun damage can also cause symptoms such as hot skin, swelling, tenderness or pain, and pus-filled blisters (via Mayo Clinic). Severe sunburn can even lead to headaches, fever, nausea, and fatigue. According to Yale Medicine, you may not see any symptoms of sun damage at all, but could still have suffered underlying damage that could eventually lead to premature aging with signs like wrinkles, fine lines, dark spots, and hyperpigmentation.

How to care for your skin in high UV Index areas

Knowledge is power. By knowing the daily UV Index number you will be exposed to, you can prepare yourself by wearing the right clothing and sunscreen with a high SPF factor and avoiding outings as much as possible. The care of your skin is in your hands, and with a little bit of knowledge, you can stay ahead of the game.


However, no amount of exposure to direct sunlight is good for you, and you should follow basic sun care protection steps whenever you step out of the house. This includes wearing high-quality sunscreen every day and having it with you when you are out and about, in case you need to reapply it later. Plan your day to avoid being outdoors between 10 a.m. and 4 p.m. Perhaps do indoor errands during that time and leave outdoor activities for the morning or evening. Additionally, use a self-tanner to get the perfect bronze instead of relying on direct exposure to the sun.