Why Sun Damage Is 90% of Visible Aging
The wrinkles you blame on age are mostly the sun.
Up to 80% of UV rays can penetrate cloud cover on an overcast day.
Visible light makes up about 45% of sunlight and can worsen pigmentation in deeper skin tones.
Frequently asked questions
What is photoaging?
Photoaging is skin aging caused by ultraviolet exposure rather than the passage of time. UVA breaks down collagen and elastin and triggers pigment changes, causing wrinkles, sagging, rough texture and dark spots. Much of what people consider normal facial aging is actually cumulative sun damage that sunscreen helps prevent.
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.
Does UV come through windows and clouds?
Largely, yes. Standard glass blocks most UVB but lets UVA through, so windows at home, in the office, or a car's side windows still expose skin to aging rays (laminated windshields block most UVA). Clouds stop only a fraction of UV, so protect skin near windows and on overcast days.
r/SkincareAddiction: 'Does UV actually come through car windows?'
Sources & citations
- WHO, 'Global Solar UV Index: A Practical Guide' (World Health Organization, 2002)
- today.ucsd.edu ↗