She's not talking about acid rain. She's talking about vinyl chloride getting into the ground water. The threat of acid rain is gone.

https://innotechtoday.com/chemicals-from-ohio-train-derailment-spark-concerns-of-acid-rain/

>Acid rain could have formed after the controlled release and burn of chemicals on Feb. 6,” Kevin Crist, professor of chemical and biomolecular engineering and the director of the Air Quality Center at Ohio University, said. “If it did form and fall, it would have most likely occurred downwind of East Palestine.

>“There would maybe be localized problems, but once that plume is gone, it’s gone. Unless it’s sticking to a residue.”

And the expert you cite is saying the same thing. These chemicals are short lived in the atmosphere.