Search

Testing Sunscreens Against "Long UVA" and How to Protect Yourself

かずのすけ · ▶ 22:44 · 3 min read
EnglishespañolIndonesia日本語한국어português繁體中文

Translated from 日本語

Open on YouTube ↗
Overview

In recent years, "long UVA" (long-wavelength UVA: 380–400 nm) has drawn attention for reaching deep into the skin and contributing to photoaging. This video presents an experiment testing how well 15 popular commercially available sunscreens block it, along with countermeasures and tips for choosing products.

3 min read
0:06

The Basics of UV Rays and Long UVA

  • Types of UV rays:
    • UVB: High in energy, it causes acute sunburn such as redness and inflammation (measured by SPF).
    • UVA: Making up about 95% of the UV rays that reach the earth's surface, it penetrates deep into the skin and causes long-term photoaging such as dark spots and wrinkles (measured by PA).
  • What is long UVA?:
    • It refers to the longer-wavelength portion of UVA, from 380 to 400 nm, and accounts for about 80% of the UVA reaching the earth's surface.
    • Because it is close to visible light and relatively low in energy, it doesn't cause sudden inflammation, but it is highly penetrating and reaches the deep layers of the skin.
8:37

Testing 15 Sunscreens for Long UVA Protection

Using a light capable of emitting 395 nm UV rays and a UV meter, the experiment tested how well films coated with sunscreen blocked the light.

  • Most products showed strong blocking performance:
    • Many products, including La Roche-Posay, Astalift (D-UV Guard), Orbis, Muji, Chacott, and Ceraneige, blocked nearly 100% of long UVA.
    • Even most sunscreens that don't explicitly claim "long UVA protection" turned out to provide solid protection.
  • Products that let some light through:
    • Slight transmission was observed with Anessa (Gold) and Curél's UV serum.
    • Skin Aqua (Hyaluronic UV Serum) only reduced the reading by about half, showing significant transmission.
15:49

Why Do Some Block It and Others Don't?

  • Whether UV scattering agents (powders) are present:
    • Because long UVA is close to visible light, it's highly likely that physical scattering and blocking by "powders (scattering agents)" such as titanium dioxide and zinc oxide is what works effectively.
    • The products with noticeable transmission were fully transparent gel formulas without powders, while non-chemical sunscreens made only with scattering agents blocked the light well.
18:09

Precautions and How to Choose for Long UVA Protection

  • Trade-offs with texture and skin irritation:
    • Adding more scattering agents tends to cause a white cast, a squeaky feel, and a powdery texture.
    • When relying on UV absorbers to strongly block long UVA, formulas may contain ingredients prone to irritation, such as avobenzone, or many different absorbers, which can be a burden on sensitive skin.
  • Conclusions and advice:
    • There's no need to be swayed by extreme fear-based messaging like "If it isn't long UVA–compatible, your skin will age."
    • In many cases, even regular sunscreens provide sufficient long UVA protection as long as they contain powders like titanium dioxide or zinc oxide.
    • The recommendation is to choose a sunscreen that suits your skin type and that you can comfortably keep using.

Article published