This is the first polypropylene rug that I have purchased, and I probably will not purchase one again.  The rug itself appears to be well made (we've had it for about 3 months now), and I like the way that it looks - but it is still out-gassing.  The odor of the rug was very strong for the first two weeks after purchase and it still has mild odor (by the way, I do not have a particularly sensitive sense of smell).  If you purchase this rug, I would recommend airing it out for at least 2 weeks (a month if you can) in a well ventilated space that you don't use frequently. Or better yet - go with another material!