I was so ignorant--I ordered a plastic mat to go under my chair and suffered with it for three days before deciding the headaches would not stop.

 I was stupid enough to think the toxic chemicals would dissipate. Enough! I put it outside. I see another mat with this advertisement: 

• Includes rectangular mat made of clear polycarbonate; free of phthalates, tin, lead, and cadmium; no emissions or odor

I should have looked for such a statement.