Sun Protection 101

This post addresses how sunburns happen, why it’s important to protect yourself from too much exposure, what causes sun tans, and what are the ways a backpacker can avoid sun damage. As the title implies, humans are susceptible to damage from sun exposure. Not some humans- all humans. Most mammals have thick fur to help protect themselves from the elements, such as sunlight. Human fur is sparse in all but a few places on their bodies, so they have had to develop other ways to protect themselves. 

Travellers can minimize sun damage using the following means: 

  • Clothing and Accessories
    • Dark colors
    • UPF fabrics
    • Hats, Scarves, and Buffs
    • Sunglasses
  • Sunscreen
  • Avoidance

But why do we need to protect our skin in the first place? If you’re not interested in the science, skip ahead to Sunburns, but know that you are lame.

What is Sunlight Radiation?

What humans perceive as visible light is only a tiny portion of a type of radiation called electromagnetic (EM) radiation. That’s right, the human eye is a radiation detector! Think of radiation as a form of energy that travels in waves or as particles. Other EM radiation types include radio waves, microwaves, and x-rays. At high enough levels, any type of EM energy will damage living cells.

Luckily for us, our sun emits mostly visible light and infrared radiation- which is why sunlight feels warm. But it also emits another type of EM energy, called ultraviolet radiation, or UV light. 99% of the sun’s EM emissions are visible light, infrared, and UV radiation. UV energy is formed from nuclear reactions in the sun’s core and travels an average of 93 million miles just to reach earth and give you a sunburn. Roughly 5% of people can see it.  

What does UVA, UVB, and UVC mean?

There are three categories of UV radiation, distinguished by their wavelength in nanometers: 


  • 315-400 nm
  • Can penetrate glass.
  • Can penetrate past the epidermis and into the dermis. 
  • Least energetic category of UV radiation.  And therefore the least harmful per unit. 
  • 95% of all UV radiation that reaches earth’s surface. There are a lot of UVA units. 
  • Causes immediate tanning, and sometimes sunburn. 
  • Causes wrinkles, premature agings, some skin cancers.



  • 280-315nm
  • Can not penetrate glass.
  • Penetrates the top layers of skin.
  • 5% of all UV radiation that reaches earth’s surface.
  • Causes sunburn and blistering, and delayed tanning. 
  • Causes skin cancer and premature aging. 



  • 180-280nm
  • Blocked by the earth’s atmosphere.
  • Most energetic UV radiation

UV levels increase with altitude: every 1000 foot gain in altitude means a UV level increase of roughly 4%. The atmosphere at high altitudes is thinner, meaning there is less of it to get in the way of UV photons. So more damage can happen faster the higher above sea level you get.

Sunburns: What are they really?

Mammals, such as elephants, pigs, and humans lack fur which protects them from harmful radiation. As a result, they can be damaged when exposed to high levels of UV radiation. The term sunburn, however, is somewhat misleading, because the problem is not heat damage. “Sun-deterioration” might be a more appropriate name, but doesn’t roll off the tongue as easily.

UV photons have enough energy to break chemical bonds, which is a bad thing for us. UV energy penetrates into cells at light speed, damaging their DNA or other important substances at the atomic level. It also deteriorates folate (aka folic acid/Vitamin B), which is necessary for cell division and aids in DNA synthesis and repair. Again, this is a bad thing for us: Sunburns hurt because the tissue is damaged.

After humans are damaged by sun exposure, their body automatically floods the affected area with blood to aid in cellular regeneration, making the sunburned area appear red. Inflammation may occur as an immune system response to further aid in repair. Negative effects build up over time as the body fails to repair everything.

Sometimes, cells whose DNA has been altered by the bombardment of UV photons, start reproducing that mutated DNA and become cancerous. Skin cancer is the most common type of cancer in the US. 

Fun Fact

Scientists hypothesize that UV radiation is what influenced primordial amino acid groups to form RNA and eventually DNA. UV radiation may have caused all life as we know it.

Suntants: How do people get them?

When skin darkens after sun exposure, it’s because of a pigment called melanin. Melanin is resistant to UV damage: it can absorb UV photons without deteriorating and disperse the energy as heat. It is believed that pigmentation started to appear around 1.2 million years ago, in conjunction with the reduction of human body fur. The body’s ability to produce melanin varies by individual.

There is no evidence that a sun tan has health benefits beyond aiding in UV protection. Sun tans do not appear without the presence of UV radiation. 

Sun Protection Options

Clothing and Accessories

Visible light and UV rays have a tough time travelling through dense matter. That is why things, like trees and your own body, cast shadows. Clothing does a pretty good job of UV protection because it creates a physical barrier of comparatively dense matter that either absorbs or scatters incoming UV rays. The thicker the fabric, the better protection it offers. 

Dark colors absorb more EM energy than light colors. Absorbing infrared energy is what makes dark clothing feel warm in sunlight. That same ability to absorb EM energy is what protects you from UV radiation. 

“Color” is the indirect result of photon absorption; objects do not possess color, but rather: reflect it (it being radiation/photons within the visible light spectrum). Visible color is actually that which the object is NOT able to absorb: some wavelengths get absorbed and are therefore “invisible”, some wavelengths bounce off and are “visible” when they are perceived by the eye. When something looks dark, that is because it is doing a good job of absorbing light, and other radiation. What the eye perceives as blackness is actually the lack of EM radiation (light): there is no energy to register → there is no “color” → blackness. 

Since white light is all colors mixed together, that means white objects reflect all visible light. Light colored clothing is good at reflecting other wavelengths of EM radiation too, such as infrared, but are less likely to block UV radiation. 

A fabric’s ability to block UV light is reported as UPF, which stands for Ultraviolet Protection Factor. A higher number means more UV is blocked. 

For example: UPF 50

1/50 = 2% of UV will penetrate


(50-1)/50 = 98% of UV is blocked

The rating number (inversely) indicates how much UV energy is blocked.

Often, the parts of the body that get the most direct sun are the head, neck, and shoulders. In addition to the clothing you wear, several accessories can provide targeted sun protection.

  • Hats: Especially in warm climates, a wide-brimmed hat is a great way to limit exposure. Make sure you get one that allows airflow, which will help keep you head cooler. 
  • Scarves are the most versatile way to keep the sun off you. They can be wrapped around your head and neck or draped over your shoulders. Choose a lightweight scarf in hot climates, which will reduce its effectiveness but won’t roast you alive. In colder climates, a heavier scarf does double duty, protecting you from the sun and keeping you warm. 
  • Buffs are stretchy tubes of fabric that can be worn in a variety of ways. Regarding sun protection, they are particularly useful for shielding the neck. Buffs are usually made of synthetic fabrics, which unfortunately can get hot and stuffy. 
  • Sunglasses stop some, but not all UV radiation from reaching your eyes. While the lenses can stop all direct UV rays, 14-45% of ambient light still gets around the front of most glasses. That’s better than nothing, though. The best glasses block out more, but charge you for it. Always get polarized lenses when you can. 

Each one of these items make great souvenirs and are easy to find. Many backpackers don’t bring one from home, but rather buy one (or several) as they travel.


Humans are not the only animals to use sunscreen, but we are the only to manufacture it for mass distribution. There are two ways sunscreen can stop UV radiation: by scattering the UV rays or by absorbing them. 

  • Physical sunscreen scatters UV photons.
  • Chemical sunscreen absorbs UV photons.

Physical sunscreens
work by creating a material barrier on top of your skin that scatters and deflects incoming UV rays away from your skin. Because of the nature of how they work, they are also called “blockers.” Physical sunscreens are usually mineral based, containing materials such as titanium dioxide and zinc oxide. They are effective as soon as they are applied. 

Chemical sunscreens absorb UV rays and turn them into heat. Your body’s melanin is a natural example. Manufactured chemical sunscreens may contain compounds, such as oxybenzone, octinoxate, octisalate,and avobenzone. Chemical sunscreens require 20-30 minutes to work: it takes time for the excess moisture to evaporate and the protective layer to form onto your skin.


Sun protection factor, SPF, indicates a sunscreen’s effectiveness at blocking UV radiation. Higher numerical values, like 50-70, are better at blocking out UV rays than lower ratings. 

For example: UPF 30 vs 70

1/30 = 3% of UV will penetrate vs 1/70 = 1% of UV will penetrate

(30-1)/30 = 97% of UV is blocked (70-1)/70 = 99% of UV is blocked

A high SPF is especially important near the equator, at high elevations, or during any beach vacations.

Fun Fact

Some animals use sunscreen! If you’ve ever seen a documentary of an elephant or pig rolling in the mud, they are applying physical sunscreen.


UV levels correspond to those of visible light. They are at their highest when their source (the sun) is closest to your position, which is to say: directly overhead, at midday. During morning and evening the light lessens because it has more atmosphere to travel through. 

Those most sensitive to sunburns could benefit from staying inside during the sunniest times of day, from 11am-3pm. Those hours also tend to be the warmest. It might be a good idea to plan a long lunch or museum visit. However, being able to plan every minute of every day is an unrealistic expectation for a backpacker. So it helps to have other ways to avoid the sun.

In the hottest, sunniest climates or at high altitudes, consider travelling with an umbrella. Not for when it rains, but for use against the sun. An umbrella is a portable, personal shade maker. Getting a little shade can help you feel 10-15 degrees cooler by blocking solar radiation. There is a reason they are so popular at beaches! No one says you can’t use one whenever and wherever you want.

How to protect yourself from the sun as a backpacker

You can’t always stay out of the sun. And sometimes, you don’t want to. But that doesn’t mean you have to face it unprepared. 

When you are going to be in the sun, wear the right clothing. Cover up as much as you can without overheating. And have the right gear, whether it’s a hat, scarf, or umbrella.

Protect your skin where it is exposed by using sunscreen. Healthcare professionals recommend that sun protection is always worn. By everyone. For day to day activities, SPF 15 is recommended. A variety of skin creams and moisturizers are available and are marketed for both men and women. During direct and extended exposure, opt for the highest SPF rated sunscreen you can find. It’s worth spending a few extra dollars to avoid days of discomfort later.

And always protect your eyes from UV radiation by wearing sunglasses.

Don’t worry about having the perfect sun solution before you go: it’s okay to try out different combinations to find what works best for you.

Disclosure: This post may contain affiliate links, meaning at no additional cost to you, I will earn a commission or compensation if you click through and/or make a purchase. The opinions and recommendations expressed here are my own. 

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Adventure may hurt you but monotony will kill you.

― Unknown

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