Why the Sun Feels Hotter but UV Is the Real Threat
Heat and UV aren't the same thing — and confusing them burns people.
The UV Index scale runs from 1-2 (low) to 11+ (extreme); protection is advised above 3.
Roughly 95% of the UV reaching Earth's surface is longer-wavelength UVA.
Questions we get a lot
Is visible light bad for skin?
Visible light makes up about 45% of sunlight. Research shows high-energy visible (blue) light can worsen pigmentation and melasma, especially in medium-to-deep skin tones. Tinted sunscreens containing iron oxides help shield against it, which clear sunscreens generally do not.
How does sunscreen actually work?
Sunscreens use UV filters in two groups. Organic ('chemical') filters such as avobenzone absorb UV and release it as a small amount of heat. Mineral ('physical') filters — zinc oxide and titanium dioxide — mainly absorb UV and also scatter some. Both cut how much UV reaches living skin cells.
What is the difference between UVA and UVB rays?
UVB rays have shorter wavelengths and cause sunburn, affecting mainly the skin's surface; UVA rays penetrate deeper and drive premature aging, wrinkles and pigmentation. About 95% of the UV reaching the ground is UVA. Both damage DNA and contribute to skin cancer, which is why 'broad-spectrum' protection against both matters.
r/AsianBeauty: 'Why do K-beauty sunscreens talk about UVA so much more than US ones?'