This Brooklyn Green Team member was surprised recently by the smell of chemicals wafting up from her new yoga mat while in downward facing dog. Some brief googling revealed that most traditional yoga mats are made from PVC!
PVC (polyvinyl chloride) is the third most commonly used thermoplastic polymer and is used in construction, toys, clothing, and upholstery, just to name a the few of the products we are in nearly constant contact with every day. Needless to say, PVC is an environmental toxin and considered to be the most toxic plastic.
It's ironic that this harmful substance has even worked it's way into yoga practice, but fear not. There are eco-friendly mat alternatives, such as those made from plant fibers or natural rubber. A quick google search for eco mats will bring up a lot of info. Do your research and see what feels comfortable for you.
Read an article about PVC mats.