Madison, WI – Officials with Meriter Hospital in Madison say three of their employees were treated for elevated carbon monoxide levels Tuesday night.

Meriter’s Senior Communications Strategist Leah Huibregtse said the employees were working in the lobby area of the Emergency Room and began to feel ill. They were later treated with oxygen. All responded well.

Huibregtse tells 27 News Madison Fire was called to assist, and they believe the cause of the carbon monoxide levels was a car left running near the entrance of the ER.

No patients were impacted and carbon monoxide levels in the patient care areas were not elevated.

Huibregtse said Meriter is installing additional carbon monoxide monitoring equipment in the ER out of an abundance of caution.