Soon after the derailment of a Norfolk Southern train in East Palestine, Ohio, a team of researchers began roving the small town in a Nissan van…

But a new study from the team behind the research van — a group of scientists at Carnegie Mellon and Texas A&M universities — raises a flag about a different substance.

According to the study, levels of a chemical irritant called acrolein detected near the derailment site on Feb. 20 and 21 were up to six times higher than normal levels recorded before the disaster. But local and federal officials had told residents it was safe to return home on Feb. 8…

“The acrolein was a little bit surprising,” said Albert Presto, an associate research professor in mechanical engineering at Carnegie Mellon, who conducted the research.