Reply #9: Dr Eric Madrid's response to the same mindless comment (April 28):

[tiptoe]

 

actually, Mexico city has high air pollution/ozone which filters UVB...not so far fetched.

http://vitamind-prescription.com/2009/04/26/swine-flu-prevention-and-treatment-can-vitamin-d-help/#comment-205

Mexico City — an example of a city with "lots of sun" and, yet, one whose denizens are vulnerable to Vitamin D Deficiency (...and rickets...and influenza infections, etc.)

Los Angeles ? "severe" ozone [O₃] problem, too. (see the news)

"It was...pointed out that ozone [O₃] absorbs UVB rays used in the synthesis of vitamin D.  Dr. Specker said cases of rickets appear to be increasing in Mexico City, perhaps as a result of the high concentration of ozone in the city."

http://209.85.173.132/search?q=cache:SIjL3S17BsgJ:www.cdc.gov/nccdphp/dnpa/nutrition/pdf/Vitamin_D_Expert_Panel_Meeting.pdf+%2B%22Ozone%22+%2B%22Vitamin+D+Deficiency%22+%2B%22Mexico+City%22&cd=1&hl=en&ct=clnk&gl=us&client=firefox-a