N=1 Sunlight, Even Through Glass (UVA), Severely Ages Skin




This man received hours of left-side-of-face sunlight a day for years, driving his delivery truck. This is probably why the left side of his face (right in the picture, obviously) now looks many years older. He’s 69, though.

Sunlight has UVA (higher frequency, deeper penetrating) and UVB rays. UVB is completely blocked by thin glass (your car window).

It’s possible that he had his window rolled up most of the time, and that this demonstrates that UVA alone can age skin.

UVA is already known to cause skin cancer (including melanoma), even though it’s primarily UVB that causes sunburn (and long term tanning). UVA causes a different short term tanning response and is used in tanning beds.

Wikipedia on sunscreen:

A set of final U.S. FDA rules going into effect for summer 2012 defines the phrase “broad spectrum” as having a UVA SPF at least as high as the UVB SPF.

Before you go crazy with sunscreen, be aware that you need Vitamin D to avoid depression and other harms. I recommend 4000 IU/day in the morning (well in excess of the RDA), although ideally you should have your blood levels tested, as too much and too little are both bad (but too little is worse).