Chemicals released during the East Palestine train wreck fires in February 2023 in Ohio spread across 16 U.S. states, according to research of federal precipitation and pollution data partially funded by the U.S. Department of Agriculture—National Institute of Food and Agriculture.

The Guardian reports that a paper in IOPScience, published by the U.K.’s Institute of Physics showed that analysis of rain and snow samples collected from northern Wisconsin to Maine to North Carolina in the weeks following the crash found the highest levels recorded over the last ten years of pH and some dangerous compounds. That includes chloride, which researchers say was largely released during a controversial controlled burn of highly toxic vinyl chloride carried by the train.

The authors of the paper, “Widespread impacts to precipitation of the East Palestine Ohio train accident” said they expected to find some evidence of the burn 50 miles from the site, but the vast range that it was spread was “very surprising.” 

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“We saw the chemical signal from this fire at a lot of sites and far away,” said David Gay, a University of Wisconsin researcher and lead author. “There was more than we ever would have guessed.”

Chloride and pH levels were highest in northern Pennsylvania just east of the wreck, and along the U.S.-Canada border. Though data for Canada was not available to researchers, Gay said he is certain its precipitation was also contaminated.