Why UVA Is Called the 'Aging Ray'
A deep look at the wavelength behind your wrinkles and dark spots.
About 95% of the UV radiation reaching the ground is UVA, and unlike UVB it passes largely unblocked through clouds and ordinary window glass.
Dermatologists summarize the divide simply: UVB causes the burn, while UVA quietly drives the long-term aging — penetrating deeper to damage collagen and elastin.
Questions we get a lot
Why is UVA called the 'aging ray'?
UVA has a longer wavelength than UVB, so it penetrates deeper into the dermis where collagen and elastin live. There it generates free radicals that degrade those support proteins over time, producing wrinkles, sagging and uneven pigmentation. Because the damage accumulates silently for years, daily UVA protection is what slows visible photoaging.
Does UVA come through windows and on cloudy days?
Yes. UVA passes through clouds and ordinary window glass that block most UVB, so you accumulate aging exposure even indoors near a window or while driving. That is a key reason dermatologists recommend broad-spectrum sunscreen every day, not just on sunny days outdoors.
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/SkincareAddiction: 'Does UVA actually come through car windows and age my skin?'