The call came into Philadelphia firefighters at 7:48 a.m. Tuesday.
Crews responded to the Wistar Institute at 3601 Spruce Street and evacuated number of people.
There were reports of people with irritation to their eyes.
HAZMAT personnel entered the building and nothing registered on their meters. Air samples showed that there was a steam leak in the basement.
One man was transported to the Hospital of the University of Pennsylvania for evaluation.
Images from Chopper 6 HD over the scene showed several fire trucks on the scene and several people standing out on the sidewalk in front of the building.
Authorities are continuing the investigation.