Using PVC is a very bad idea. Why? Because phalates can be picked up with the gases.
"What are phthalates? How are they used?
Phthalates are a class of widely used industrial compounds known technically as dialkyl or alkyl aryl esters of 1,2-benzenedicarboxylic acid. There are many phthalates with many uses, and just as many toxicological properties.
Phthalates crept into widespread use over the last several decades because of their many beneficial chemical properties. Now they are ubiquitous, not just in the products in which they are intentionally used, but also as contaminants in just about anything. About a billion pounds per year are produced worldwide.
Intentional uses of phthalates include softeners of plastics, oily substances in perfumes, additives to hairsprays, lubricants and wood finishers. That new car smell, which becomes especially pungent after the car has been sitting in the sun for a few hours, is partly the pungent odor of phthalates volatilizing from a hot plastic dashboard. In the evening's cool they then condense out of the inside air of the car to form an oily coating on the inside of the windshield.
What are the health concerns?
Much of the existing literature on phthalates' toxicological properties focuses on the old approach to toxicology: high level exposure for cancer endpoints, and occupational exposure leading to adult infertility. In the past several years, however, particularly led by Earl Gray's laboratory at the US Environmental Protection Agency, attention has turned to low-dose toxicity of phthalates during crucial windows of fetal development. As these studies have advanced, they have fundamentally changed our perception of potential health risks of phthalates.
http://www.ourstolenfuture.org/newscience/oncompounds/phthalates/phthalates.htm
