Saturday was the second night in a row the smell of rotten eggs permeated the air in parts of Meadville for several hours.

The odor may have dissipated, but the mystery surrounding its cause still lingers.

The stench of hydrogen

sulfide came out of Meadville’s sanitary sewer system for several hours Saturday night in an area bounded by Baldwin, Terrace, Spring streets and Glenwood Avenue. The same thing had happened in the same area Friday night.

“We have no clue,” Lt. Ryan Carlson of Meadville Central Fire Department said Saturday night following the evening’s incident.

“We still don’t know what caused it,” Capt. Evan Hasko of Meadville Central Fire Department said of Friday’s incident. “We’re lucky it’s staying within the sewer system and not going into people’s homes.”

“We’re going to have to regroup Monday and see what we have,” said Joe Chriest, Meadville’s city manager, who was called to the scene Saturday.

One person was taken to Meadville Medical Center for evaluation during Saturday night’s incident and still was undergoing treatment for a respiratory ailment as of press time.

No other injuries were reported in either incident and no one was transported to the hospital from Friday’s incident.

Hydrogen sulfide has the odor of rotting eggs and can be lethal in concentrated doses.

Emergency personnel were called the scene just after 6 p.m. Saturday after residents along Glenwood Avenue noticed the odor. Sanitary sewers were flushed with water until the hydrogen sulfide levels dropped back to zero around 9:15 p.m. Saturday.

On Friday, emergency personnel had been called to the same area around 7:30 p.m. and stayed until 11:16 p.m. before levels of hydrogen sulfide finally had dropped back to zero after flushing the sanitary sewers in the area with water.

Friday and Saturday were the third and fourth times the odor has been noticed in the same area of the city within the past year. It was noticed both in June 2007 and August 2007.

The 2007 incidents were so bad some homes were evacuated and a few residents were hospitalized.

On both Friday and Saturday emergency personnel went door-to-door urging residents to leave the area. Hasko estimated between 50 and 75 homes and apartments were in the area.