Last Updated: Feb 01, 2017 Views: 1954
According to several sources I've seen, standard automotive glass does not block all UV rays.
This is quoted from a safety publication produced by Ohio State University:
Most people believe they are safe from the sun’s ultraviolet rays when they ride in a car or truck. However, motor vehicles provide inadequate protection from both UV-A and UV-B types of rays.
UV-A rays penetrate the skin deeply and are constant throughout the year. UV-B rays damage the top layers of the skin and are most intense during the summer. A vehicle’s windshield and side windows somewhat reduce exposure to solar UV-B. But only the windshield
comes partially treated against UV-A. Other vehicle windows block
little or no sun. According to Sun and Skin News, a publication of the Skin Cancer Foundation, studies have shown that photo-damage is greater on the left side of the body in American drivers and on
the right side of the body in Australian drivers, whose steering wheels are on the right side of the car. When older people who have driven frequently are examined clinically, the skin that has been next to the driver’s window is rougher, has developed more pigment, and has
sustained overall sun-induced damage.
Passengers are also vulnerable to UV-A. Children are especially at risk because they already spend more time than adults in the sun and because they frequently sit in the back seat of a vehicle, where none of the glass offers UV-A protection. Babies are at greatest risk since their skin cannot properly protect itself from sun damage. Melanin, the natural pigment that provides a small amount of sun protection, is not fully developed in babies.
There are other websites that have the same info:
Alfred University's library has more technical holdings on glass, so you might want to contact them for further information. Pat Lacourse answers technical reference questions (email:firstname.lastname@example.org). Their reference desk number is: 607-871-2951. Their library catalog is available for searching on the web: http://scholes.alfred.edu.