Sun damage through cycling clothing?

[Globalti]

After years of ignoring the warnings I'm paying the price; my forearms are covered in solar keratoses and I have a couple on my head, which are itchy and irritating. I've had some frozen off but they have reappeared so now I'm having to put a cream on them every day, which is like a local chemo treatment. In daytime now I only ever wear long-sleeved jerseys. I've got a Specialized sunblock jersey that's SPF30 and is just a thin but very dense white fabric.

 

[fatjel]

I’ve always burned easy and never much liked the sun
My muddy fox tights and long sleeve shirts ensure I remain sun burn free
Never needed anti sun wear
Only place I ever get tanned is an inch wide strip between gloves and shirt sleeves