https://phys.org/news/2018-07-aims-deaths-gypsum-laced-manure-emissions.html

"In agricultural production, gases near manure storages can pose severe health problems and even be lethal due to toxicity or displacing oxygen," said Eileen Fabian, professor of agricultural engineering. "Tragically, the potential for gypsum bedding to have lethal consequences was not known until it was too late."

Fabian and Michael Hile, a postdoctoral scholar in agricultural and biological engineering, were among a team of investigators—which included experts from Penn State Extension's agricultural safety program, manure haulers, farmers and industry professionals—that collected data linking gypsum-laced manure and toxic hydrogen sulfide gas levels during manure agitation in the wake of several human and cattle deaths in 2012.