The UV Index Will Peak Soon — Here's What That Means
Late spring is when UV starts climbing toward its summer high.
UV intensity rises roughly 4-5% for every 1,000 feet of elevation gain.
UC San Diego's Dr. Y. Linda Liou advises sun protection whenever the UV index is 3 or higher.
Frequently asked questions
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 does the UV index mean and when should I protect my skin?
The UV Index, from the EPA and WHO, rates the strength of midday UV on a scale from 1–2 (low) to 11+ (extreme). Dermatologists generally advise sun protection whenever it reaches 3 or higher. It appears in most weather apps and rises with sun elevation, altitude and proximity to the equator.
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.
r/SkincareScience: 'Can someone explain UVA vs UVB like I'm five?'
Sources & citations
- Sklar LR et al., 'Effects of ultraviolet and visible radiation on the skin,' Photochem Photobiol Sci, 2013
- skincancer.org ↗