![](https://metrodomedreamscapes.com/wp-content/uploads/2017/01/DSC01431-350x262.jpg)
The dome’s roof was covered with teflon. A chemical used in the manufacture of teflon called PFOA doesn’t naturally break down, and because of this, by 2003 the average concentration of PFOA in the blood of an adult American was four to five parts per billion. Toxicologists recommend a safety limit of 0.2 parts per billion. In other words, there’s a little bit of the Metrodome in all of us.