This is an important article to read. There is a regulation that requires car seats to meet the same flammability standards as the rest of the car interior. To accomplish this, manufacturers add fire retardant chemicals to the polyurethane foam that pads the seats. This article states its unnecessary and scientists agree that fire retardants can harm our health and there are safer ways to meet flammability standards.
Britax and Clek were rated as the car seats that exposed children to the lowest concentrations of chemicals. I am super happy I have Britax!!