What is H2S? Dairy expert explains toxic gas that likely killed six Northern Colorado farm workers

Preliminary investigations into the deaths of six people at a Northern Colorado dairy farm point toward the dairy farm workers being exposed to the toxic gas known as hydrogen sulfide, or “H2S.” The workers, who include a boy who was still in high school, were killed while working on a dairy farm in Keensburg, a town in southeastern Weld County.

“This has, unfortunately, happened on dairy farms across the country,” said David Douphrate, a dairy farm safety expert and Associate Director of the High Plains and Intermountain Center for Agriculture and Safety, an entity headquartered at Colorado State University.

While Douphrate has heard of tragic fatalities related to H2S, he said this is the first time he has seen so many killed in one location at one time by the gas.

“I have never heard of six people in this type of incident,” Douphrate said.

He explained that H2S is a toxic gas that is created by the manure in which cows at dairy farms output.

“Hydrogen sulfide is very toxic to humans; when inhaled, it can be lethal,” Douphrate said. “That is one of the hazards on a dairy farm that can present a very dangerous environment for workers.”

Douphrate does not know the specifics of the deaths in Keensburg, however, based on the investigation’s information that has been released, he said it is likely the men were working around piping in a confined space that was transferring the gas away from the manure before it would be used for compost or more.

“Manure decomposes, and as it decomposes, it releases toxic gases. One of those is hydrogen sulfide,” Douphrate said.

He explained it doesn’t take long for those gases to impact someone. “It can be pretty quick. If the concentration is high enough, then someone who is in that environment, with a few breaths, they can succumb to the effects of hydrogen sulfide.”

Of the six people who died at the farm, many were related. Alejandro Espinoza Cruz and his sons, Oscar Espinoza Leos and Carlos Espinoza Prado, were among the deceased. The other three deceased included Jorge Sanchez Pena, Ricardo Gomez Galvan, and Noe Montanez Casanas.

The victims ranged in age from 50 years old to as young as 17 years old.

Dispatch information from 911 obtained by CBS News Colorado suggested one person was initially reported as passed out and entrapped in a confined space. As the call continued to emergency officials, more people were slowly added to the number impacted.

While not informed of any specifics of the investigation, Douphrate said it is possible that the number continued to rise as the men tried to help each other.

“Usually, unfortunately, what you see is one person goes down and another person goes in to save them, and they are affected, and they succumb to the gas,” Douphrate speculated. “It is just dangerous work, and we try to control those hazards to the best of our ability. It is just very tragic and very unfortunate.”