Two employees of the Staker Parson cement plant were working under a silo containing cement powder when the automatic control valve malfunctioned and caused the silo to remain in the open position, according to the Arizona Daily Star.
Capt. Adam Goldberg, a Northwest fire spokesman, stated that when crews from the fire department arrived their first priority was to decontaminate the employees by washing the cement powder off them using hoses.
Both men had respiratory complaints and one man had eye irritation, said Goldberg. They were both taken to the hospital for further treatment.
Two other employees worked for about an hour to plug the silo to keep the cement powder from continuing to leak out. They wore basic protective clothing, but also had to be decontaminated. They were also taken to the hospital for further evaluation.
All of the men were released from the hospital shortly after the incident.