Why Should I Stay Out of the Sun Between 10:00 a.m. and 4:00 p.m.?

We've heard all of the sun safety tips. But, do you know the 'why' behind some of these tips? Learn as we begin our series on sun safety guidelines. First up, Why are we advised to stay out of the sun between 10:00 a.m. and 4:00 p.m.?
2021-05-20
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Answering the “Why’s” of Sun Safety Tips, Part One

We’ve heard all of the sun safety tips. I hope that many of us can repeat them effortlessly to our children. But, do you know the ‘why’ behind some of these tips? Over the next few weeks, we’ll discuss the “why” to these various safety tips. Honestly, they are pretty interesting and make the importance of sun safety easy to understand.

So, why should you stay out of the sun between 10:00 a.m. and 4:00 p.m.? Before answering this question, it is crucial to help you understand (at a high level) what ultraviolet radiation is and how it affects our skin.

Ultraviolet Radiation 101

Ultraviolet radiation is energy naturally produced by the sun. UV rays (UVA and UVB) wavelengths are shorter than visible light, making them impossible to see with just our eyes. According to the Skin Cancer Foundation, while UVA and UVB rays differ in how they affect the skin, they both cause damage.

UVB radiation causes damage when the light waves penetrate the outermost layers of the skin. The ‘B’ in UVB refers to burning. While this type of light does help our bodies with vitamin D production, too much exposure causes damage to the skin, resulting in skin cancer, sunburns, and can cause cataracts.

UVA radiation contains wavelengths that can penetrate deeper into the skin and affect the DNA of the skin cells. The ‘A’ in UVA refers to its effects on aging. They attack the cell membranes and change the proteins that make up collagen and elastin. We talk about the importance of collagen and elastin in many of our blogs because they are what keeps our skin firm and smooth. When the collagen and elastin are damaged, our skin begins to wrinkle and sag.

The Strength of UV Rays Differ Throughout the Year and Day

Depending on what hemisphere you live in, the strength of the ultraviolet rays intensifies throughout the year. The shorter the path that the UV rays have to travel, the greater the potential for damage. At various times of the year, the earth’s tilt points more towards the sun, exposing those areas to more UV rays. Those living near the equator have to be more diligent due to the extended exposure beyond the seasonal changes received by the rest of the world.

The intensity of UV radiation also changes based upon the time of day. When the sun is highest in the sky, the distance it has to travel is shorter, making the hours between 10:00 a.m. and 4:00 p.m. the strongest for UV radiation.

How does UV Radiation Lead to Skin Cancer?

As discussed earlier, UV radiation is energy from the sun. Exposure to UV rays radiation damages the chromosomes of our cells and mutates the DNA. According to SciTable by Nature Education, the chromosome that suppresses tumor growth is heavily damaged and is no longer effective at regulating the cell cycle resulting in uncontrolled cell division. Another DNA mutation caused by UV radiation results in the alteration of nucleotide base pairs. It can also result in an uncontrolled rapid division of the cell. As these cells replicate, so does the mutation, and a mass of cells, or a tumor, can form. One mutated cell is rarely the cause of cancer development. Cancer usually develops due to an accumulation of gene mutations. 

So, back to the original question, “Why should I stay out of the sun between 10:00 and 4:00?”  

Staying out of the sun between the hours of 10:00 and 4:00 limits your exposure to the sun’s most intense UltraViolet radiation. This radiation can lead to overexposure which can lead to damaged skin and possibly skin cancer. 

Don’t Skip Your Annual Skin Exam!

The effects of sunburns from our younger years can take decades to show. Be diligent and schedule your annual skin exams with one of our board-certified providers. Early detection is key to winning the battle against skin cancer. You can easily schedule online here or by calling our office at (704) 228-8287. 

(Coming soon, understanding the ‘why’ behind the guidelines of selecting and using SPF)