Understanding the UV Index

Mar, 16

Understanding the UV Index

Ultraviolet radiation, commonly referred to as UV radiation, is emitted constantly from the sun. It has an overall wavelength range between 100 and 400 nanometers (nm) which is divided into three sections: UVA (315-400 nm), UVB (280-215 nm), and UVC (100-180 nm). The earths surrounding atmosphere absorbs approximately all UVC radiation and about 90% of UVB radiation. The UV radiation that reaches the earths surface is composed of mostly UVA radiation with small measurements of UVB. Over the years, extensive research done by scientists and medical experts has shown the detrimental effects of ultraviolet radiation (UV) on the skin. This harmful light can instigate side effects varying from mild sunburns to deadly skin cancer. In order to expand the publics knowledge of ultraviolet radiation as a potential health hazard, the Environmental Protection Agency and National Weather Service developed the UV Index. This index is published daily and consists of an estimation of the UV radiations maximum risk factor for the following day. When reading the UV Index it is important to keep the following factors in mind:

  • Exposure categories are conservative and based off the effects of UV radiation on fair skin.
  • The index contains a description of the effect of cloud cover.
  • The UV radiation risk may fluctuate depending on the distance from the UV Index origin.
  • The UV intensity in the continental United States is reduced to about half its usual intensity approximately 3 hours before and 3 hours after noon.
The following is a table depicting the UV Index and its categories according to rate of exposure. This table also includes possible solutions developed by the Environmental Protection Agency to aide in reducing UVA and UVB exposure:

Exposure Category

UV Index

General Recommended Action (All Skin Types)

Maximum 0,1,2 Apply SPF 15+ sunscreen
Moderate 3,4 Apply SPF 15+ sunscreen and wear protective clothing including a hat
High 7,8,9 Apply SPF 15+ sunscreen, wear protective clothing including a hat and protective sunglasses
Very High 10+ Apply SPF 15+ sunscreen, wear protective clothing including a hat and protective sunglasses, avoid the sun between 10 am and 4 pm.

UVA/UVB radiation levels are at their highest on cloudless days, but can still maintain dangerous levels despite cloud coverage due to the scattering of radiation by water molecules and other atmospheric particles. UVA/UVB radiation also has the ability to penetrate through glass and most fabrics. It then penetrates the epidermis and dermis (outer and inner layers of skin) and increases the chance of sunburn and skin-cancer. This is one of the many reasons why it is a crucial to the healthy maintenance of skin to maintain an awareness of the dangers of UV radiation as well as knowledge of how to prevent the serious damage it can cause. Aside from the general recommended action provided in the above table, here are a few additional suggestions to protect your skin from UVA/UVB radiation damage:

  • Avoid sun tanning as well as tanning beds-UV radiation from tanning beds can cause premature wrinkles as well as skin cancer.
  • Be cautious of water, snow, and sand-They reflect the damaging light from the sun which can increase chances of sunburn.
  • Some experts suggest safely consume vitamin D - Instead of sunbathing, eat vitamin supplements and vitamin D fortified foods.
  • Watch the UV Index - It provides information that can help daily activities be planned in a way to prevent overexposure to UV radiation.

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1 comment

kristian kirkin

January 11, 2018

This does not aid in understanding the inner workings so to speak, just the dangers and action to prevent them.


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How To Determine Your Hat Size

Many companies provide unique sizing charts for each of their hats. We try to have as many of these charts across all our sun hats. Despite that, we decided to take this a step further and offer the closest thing to a universal metrics system that caters to both men and women. That said, and without further ado, please find below the sizing charts along with instructions on how to measure your head circumference.

In order to determine your head size, please size your head circumference by measuring above the ears and across your eyebrows (in centimeters, if possible). Please stick your finger under the tape and there you have head circumference! If you fall between measurements go for the next hat size up. If a hat for any reason runs small or large, we will indicate that in the product description*.

* Please note, One Size Fits Most Hats indicates Size Medium (or 57cm)

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