Do All Hats Block UV Rays?

After seeing how skin cancer ravages its victims, it is surprising that more people don’t pay more attention to how they protect their skin against UV rays. While it is essential that the whole body is protected, wearing a hat for protection should be non-negotiable for anyone spending regular time in the sun.

All hats Block the sun’s UV rays; however, the hat’s color, construction, UPF rating, size, and fit contribute to its ability to block UV rays. A white hat made from denim with a broad brim, a rating of UOF100, and fits well with a securing string is best.

While research has shown that people with a thick full head of hair have a measure of inbuilt protection against UV rays, their face, shoulders, and upper torso are not protected.

All Hats Block UV Rays, But Some Are More Effective

All hats are not created equal, and while most will block UV rays, five factors need to be considered when assessing how effective they are.

  • The hat’s color
  • The hat’s construction
  • Ultraviolet Protection Factor (UPF) rating
  • The size of the hat
  • The fit of the hat

The Hat’s Color

The reason why lighter colors reflect UVA light is a little involved.

The wavelengths of UVA light range between 315 to 400 nanometers.

Visible light rays range between 400 to 750 nanometers. All visible light colors fall within this band.

The color white combines all light colors, whereas black is the absence of visible color.

The human eye interprets the light colors reflected from the object that absorbs all the wavelengths but the color your brain perceives. White objects appear white because they don’t absorb any color and reflect all the colors. The human brain interprets this as “white.”

Similarly, a black object appears that way because all colors have been absorbed, and none have been reflected back. The brain interprets this absence of color as “black.”

It is for this reason that white reflects the band of Ultraviolet light called UVA.

To cut a long story short, the lighter the hat, the more UV light is reflected. Similarly, a black hat absorbs UV rays and therefore offers lower protection.

The Hat’s Construction

The type of material, the weave, and the hat’s texture affect how well it reflects the UVA rays.

Hats made from Synthetic and semisynthetic fibers (polyester or rayon) have the best barrier-type properties against UVA rays.

Heavy, dense materials such as denim, wool, and corduroy provide the best protection against UVA rays.

Tightly woven fabrics are another category that provides good protection against UVA rays.

Lightweight (natural materials) fabrics are generally thinner and, as such, allow more UVA rays to pass through.

Ultraviolet Protection Factor (UPF) Rating

Some hats are sold specifically as being UV resistant and will state the Ultraviolet Protection Factor (UPF) rating on the label.

The UPF rating is a number and shows what fraction of the sun’s UV rays are able to pass through the hat.

  • A rating of UPF50 allows 1/50th of the sun’s UV rays to pass through.
  • A rating of UP100 only allows 1/100th of the sun’s UV rays to pass through, which means it provides twice the protection of a UPF50  hat.

The Hat Size Affects How Much UV Protection Is Provided

The wider the hat’s brim, the greater the level of protection.

A wide-brimmed “hunter’s” hat provides more protection than a baseball cap.

How The Hat Fits Affects How Much UV Protection Is Provided

A loose hat that regularly flies off the wearer’s head will provide only intermittent protection, while a tightly fitting hat (even one with a restraining string) will be more secure and therefore provide more protection.

Because of this, it is important to choose the hat you will wear based on the activity.

If you are on a speed boat traveling over the waves, you need a tight-fitting, possibly restrained hat.

If you are taking a gentle stroll through the countryside and the weather is calm, a loose-fitting hat provides sufficient protection.

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What Are UV Rays?

Solar radiation is the group name for all the energy that arrives from the sun.

Solar radiation is categorized by the respective wavelengths, as listed below.

Waves On The Electromagnetic spectrumWavelength
Radio Waves10 billion nanometers
Infrared700 nanometers
Visible Light400 to 750 nanometers
Ultraviolet Light100 to 400 nanometers
X-Rays2 nanometers
Microwaves0.01 to 10 nanometers
Gamma Rays< 0.01 nanometers

Most of the energy from the sun falls into the infrared wavelength, visible light wavelength, and ultraviolet wavelengths.

The longest wavelengths are radio is much lower.

The  short-wavelength X-rays are produced by the hottest and most active parts of the sun’s outer atmosphere (the corona.)

How Do UV Rays Affect The Body?

UV rays are split into three bands.

Bands of UVWavelength
UVA315 to 399 nm nanometers
UVB280 to 314 nm nanometers
UVC100 to 279 nm nanometers

UVC Rays Don’t Reach The Earth

The short wavelength UVC is the most dangerous band of IV radiation; however, it cannot penetrate the earth’s atmosphere.

UVB Rays Damage The Skin

UVB rays are partially absorbed by the ozone layer (O3); however, some reach the earth.

This is the most biologically active band of UV light. The shorter the wavelength, the more active the UV ray, and the greater the damage to the human body.

It is thought that UVB rays are primarily responsible for the following conditions.

  1. UVB rays are responsible for delayed tanning.
  2. They are responsible for burning.
  3. They speed up skin aging.
  4. It is a primary cause of the development of skin cancer.
  5. UVB rays can also weaken the immune system.
  6. can also cause eye problems.
  7. UVB rays are suspected of causing a reduction in the formation of new neurons (neurogenesis.)
  8. UVB rays are suspected of causing a reduction in synaptic protein.

A reduction in neurogenesis is considered partially responsible for learning and memory impairments and depression.

Synaptic protein neurotransmitters are responsible for releasing and participating in the early development of neurons.

UVA Rays Cause That Tan

Almost 95% of UVA rays reach the earth.

UVA rays can penetrate human skin and cause the following effects.

  • They are responsible for the immediate tanning of the skin.
  • UVA rays are responsible for wrinkles forming in the skin
  • UVA rays cause leathery skin, liver spots, actinic keratosis, and solar elastosis (the skin loses its elastic quality.)
  • Recent studies have found that UVA rays may also be responsible for skin cancers.


A broad-brimmed hat, which fits well, has a high UOF rating, is made from a thick, closely wound fabric, and is colored white, providing the best protection against the sun’s EV rays.