Clearly, our heads can get the first and most intense exposure to UV when outdoors. Read more...
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Does hair offer any UV protection?
The hair itself can be considered a natural barrier for the scalp to UV exposure. How much protection it offers can vary widely, however. The three factors that influence the ability of hair to effectively protect against UV exposure include:
Not surprisingly, one of the only studies I came across reviewing the UV protection offered by hair found that the higher the density, thickness, and darker color, the more UV protection offered. This study by De Galvez et al found approximately 300 brown, blond, and/or red hairs per square centimeter or about 400 white hairs per square centimeter are needed to achieve an SPF of 0 to 10. A study by Birnbaum et al found that Americans of Hispanic descent had about 169 to 178 hairs per square centimeter, 148 to 160 hairs per square centimeter in people of African descent, and about 214 to 230 hairs per square centimeter in Caucasian individuals. All of these values are significantly lower than the needed 300 hairs per square centimeter to achieve an SPF of 0 to 10.
The only other factor I would include in this is hairstyle. In practice, the location of the hair part and hair whorl clearly influence the susceptibility of the scalp, forehead, ears, and neck to sun damage.
Can sunscreen be applied to the scalp?
The ability to apply sunscreen to the scalp and evenly distribute the product in such a way that reliable UV protection can be achieved is based on several factors. These factors include:
Quality and density of hair
Form of sunscreen
If the hair is thick and coarse, the ability to evenly distribute a sunscreen product can be challenging. Applying the product to the hair part and hair whorl is essential, however, the general application of sunscreen throughout the scalp would be challenging.
There are numerous forms of sunscreen. The FDA proposes the following forms of sunscreen as GRASE, generally recognized as safe and effective.
To apply any of these products to the scalp will likely leave a noticeable residue on the hair to impact its appearance.
What about sunscreen sprays and powders?
The FDA has proposed that sunscreen sprays may require more testing and labeling requirements before being considered GRASE. Sunscreen powders have also been deemed in need of further testing before being determined to be generally recognized as safe and effective by the FDA.
Sunscreen sprays are thinner, lightweight, and often clear when applied. They are a common choice for people to use on the scalp either by spraying directly or by applying to their hands and then applying. Until further testing and labeling details are made available, it is difficult to say how effective these are for the scalp. Most sunscreen powders tend to be mineral powders containing zinc or titanium. Several contain nanoparticles as well.
What is the best way to protect the scalp from UV exposure?
The best protection we can get for our scalps is by using UPF hats. Remember that the hat should be rated for UPF to verify the amount of UVA and UVB protection offered by the hat. Although any added UV protection you can get from sunscreen products is helpful, it is difficult to say how effective these are.