I read the reviews before I purchased this, and some said there is no odor to the topper after removing from the sealed bag.  Mine had a very strong odor upon removal from the bag, but I placed it under the fan and opened the window for 2 days and I no longer smell it.  By the way, the instructions do mention that the topper needs to be placed in a well-ventilated room.  It puffed up to the full size of the mattress after a few hours, and feels wonderfully soft!