Do these mats off-gas much? Will my basement end up smelling like rubber? Sensitive to odors, so this could be a show stopper.

Our 1/2" Premium Mega Mats do have an odor to them, which does dissipate over time. If you are sensitive, we recommend mopping these mats with a mild soap and water solution. Once mopped, you will want these mats to air dry in a well-ventilated area. Repeat these steps as many times as necessary to get the smell to a tolerable level.