Mysterious noxious fumes were detected recently near an operating room at Sparrow Hospital in Lansing, Mich., according to a report from Lansing State Journal.
Hospital officials have since reported that the fumes came from concrete sealing work that was being done behind the hospital.
While the hospital maintains patients weren't exposed to anything considered hazardous or toxic, "a number of individuals" who were affected by the fumes were treated for symptoms.
The Lansing State Journal reports the fumes have been eliminated and air quality has been restored, but all hospital rooms affected by the fumes are expected to be cleaned and have air quality verified before they are re-opened for patients.