Where are you getting the DOT thing from? DOT incident response is the group responsible for urgent public health announcements from transit related accidents. They may have been coordinating with the EPA, but even from the article the other user cited talks about what I’m saying happened here:

The head of the National Transportation Safety Board said recently that her agency’s investigation showed that the vent and burn of the vinyl chloride was unnecessary because the company that produced that chemical was sure no dangerous chemical reaction was happening inside the tank cars. But the officials who made the decision have said they were never told that.

I’m just so lost about where this is coming from.