Do UV cut products really work?

By Koharu Kameda

I have done an interesting experiment during the summer break in 2021.

Have you ever wondered if sunscreen or any products that are supposed to block UV light really work or not?

Well, this time I have carried out a simple experiment to test this.

The method is really easy.

Step 1: prepare special beads that change its colour when it is hit by UV light. I got them from amazon. These plastic beads contain a fluorescent material. When exposed to ultraviolet light, the electron energy state of the fluorescent material becomes an excited state, but immediately returns to the ground state. This state change continues repeatedly while exposed to ultraviolet rays, but when the excited state returns to the ground state, light of a colour peculiar to the fluorescent material comes out. If you stop exposing it to ultraviolet rays, the state will not change and it will not emit light.

Step 2: prepare the products that you want to test. This time I have prepared two different sunscreens, one is non-chemical and another is normal sunscreen from a Japanese pharmacy. I used a transparent plastic board and spread sunscreen all over it. Also, I tested UNIQLO UV cut arm covers, jeans(non-uv cut),uv-cut umbrella, and a hiking hat.

Step 3: Place the beads underneath the products prepared in step 2, leave it outside (exposed to sunlight) for 1 minute and observe the colour of the beads.

For your information, non-chemical sunscreen (sometimes called physical sunscreen) does not contain UV absorbers which are ingredients such as oxybenzone, homosalate, octinoxate, and octocrylene that may cause health issues like hormone disruption to you and or to your fetus (if you are pregnant). Instead, they contain natural minerals as an alternative active ingredient such as zinc oxide or titanium dioxide which sits on top of your skin and blocks the UV light from getting to it.

There are three different types of UV rays: UV-A, UV-B, and UV-C. UV-C is absorbed by the ozone layer so it does not reach us. UV-B mainly affects the surface of your skin (epidermis), while UV-A affects the dermis which is a deeper part of your skin.

Both UV-A and UV-B cause ageing, wrinkles, spots, and inflammation but only UV-A causes skin to tan. The way skin tanning works is that when UV-A rays reach the dermis, the skin will release melanin, a pigment that protects the skin, from melanocytes.

SPF stands for sun protection factor, a relative measurement for the amount of time the sunscreen will protect you from ultraviolet (UV) rays. PA is the protection grade for UVA established by the Japanese. It basically informs users of the level of protection towards UVA rays. PA+ means the sunscreen provides some protection against UVA rays, PA++ indicates moderate protection while PA+++ shows very good protective abilities against UVA rays.

Here are the results with pictures:

In conclusion, UV cut products really do cut UV rays.

Even if clothes do not say UV-cut, it still has an ability to cut some UV light.

However, both sunscreens seem as though they don’t cut as much UV light as clothes do. One of the research papers I have read said that you have to apply sunscreen at least 3 layers at once because even if sunscreen itself has high SPFs and PAs, when you spread them out on your skin, there will be unevenness and therefore, not the whole area can be protected. Additionally, it will be much better if you use makeup sponge to apply sunscreen to reduce the unevenness and also to remove the excess which helps the makeup you apply on top to stay longer.

Bibliography:

https://www.draliabadi.com/womens-health-blog/potentially-bad-ingredients-in-sunscreen/

https://www.cdc.gov/nceh/features/uv-radiation-safety/index.html

https://www.madaboutscience.com.au/shop/colour-change-uv-beads.html

https://www.pinkparlour.asia/id/stories/what-do-sunscreen-numbers-mean-does-spf-100-gives-double-the-coverage-of-spf-50/