Cecil wrote:
“Check out sunscreens containing zinc oxide, titanium dioxide, or avobenzone. Though not easy to come by, these
are among the few commercially available ingredients known to protect against UV-A.”
Zinc oxide is the white pigment in poor-quality white paint.
Titanium dioxide is the white pigment in good-quality white paint.
Both of them are solids, in the form of tiny particles. So unless you put enough of them on that you look completely white, you haven’t been thorough enough.
If I recall correctly, zinc oxide is in that solid (blue tinted?) stuff lifeguards use on their noses.
Welcome to the SDMB, and thank you for posting your comment.
Please include a link to Cecil’s column if it’s on the straight dope web site.
To include a link, it can be as simple as including the web page location in your post (make sure there is a space before and after the text of the URL).
Cecil’s column can be found on-line at this link:
Are sunscreens effective in preventing skin cancer?
I just wanted to do this once. Hee,hee
ChiefWahoo, your posting style is strangely familiar. 
As they say, imitation is the sincerest form of flattery. I don’t say it, but I’ve heard them. 