Reports of a chemical spill on campus sent emergency responders to Chevron Science Center this… Updated: 5:46 p.m. One experiment brought a pair of emergency calls for gas leaks to Pitt’s campus today. Emergency responders did not find any leaks, although they did find an unusual situation.

City fire battalion Chief Keith Bradley,who responded to the afternoon alarm, said a young graduate student was conducting an experiment with chemicals added to natural gas, which is usually odorless. The smell worked its way into the building, and the chemicals were harmless.

“She wasn’t doing anything wrong,” Bradley said of the student, whose name he did not release. “There’s just something wrong with the system.”

Bradley said that the fume hood system in the building worked properly, but the powerful odor, even diluted to “one or two parts per million,” could drift up out of sinks on other floors.

Sinks without water in the U-bend, which prevents odors from drifting out of most household sinks, allowed the smell to drift up, he said.

Bradley said that there wasn’t any danger from the odor, but the student was working to keep it from happening again.

In the morning, Bob Farrow, battalion chief for the county’s Hazardous Materials team, said the crew did not find anything out of the ordinary. The first time officials responded to the building, about 10:30 a.m., it was for a report of a hydrogen sulfide leak on the ninth floor of the building.

Pitt spokesman John Fedele said that someone on the ninth floor smelled gas and pulled the fire alarm, causing the entire building to evacuate, including construction crews.

Just after 10:30 a.m. several police units and fire engines responded to Parkman Avenue in front of Chevron. Most students and staff stood across Parkman Avenue, under either awnings or umbrellas to stay out of the rain.

Pitt student John Mcelhattan stood under the awning of the Twentieth Century Club along with the rest of his class. They had evacuated a few minutes before and several students around him wondered if their lab might be canceled.

“Originally we thought it was a fire alarm,” he said after the first alarm. “Maybe something to do with the construction. We haven’t been told what was going on.”

A city policeman restricted traffic on Parkman Avenue at the intersection of Bigelow Boulevard. Work continued on the pavement of Parkman Avenue. By then, four fire engines, one city paramedic truck and six police units sat on either Parkman or University Drive A, next to Chevron.

At about 10:40 a.m., the first Hazardous Materials engine arrived, followed shortly by a second. Less than five minutes later a group of about a half dozen firefighters entered Chevron.

A Hazardous Materials crew sent to the ninth floor could not determine the source of a sulfur smell, Farrow said.

He said the smell had dissipated and responders allowed people back in the building just after 11 a.m.

Fedele said that workers from Pitt’s Office of Environmental Health and Safety did not find a leak or spill, and could not determine the source of the smell.

Two students, Farrow said, initially reported eye irritation but it faded and the students refused treatment from city paramedics.

Then, just after 4 p.m., police received a call about natural gas odor in Chevron. Someone smelled the odor of natural gas on the third floor. Just after 4:20 p.m. police activated the fire alarm and evacuated the building.

Several additional Pitt police units responded, a pair of fire engines pulled up and city police restricted traffic on Parkman.

About half a dozen firefighters entered Chevron for a few minutes, then exited at about 4:30 p.m. Shortly after, students re-entered the building to — most likely — continue class.