A janitor mistakenly mixed chlorine and sulfuric acid Tuesday morning in a high-rise that houses the St. Paul Athletic Club and a hotel, sending off fumes that sickened him, forced the building’s evacuation and closed part of the skyway system and a block of Cedar Street below, authorities said.

The incident began about 7:30 a.m., when the janitor set off fumes on the seventh floor, Fire Marshal Steve Zaccard said. There is a swimming pool on the eighth floor, he added.

Assistant Fire Chief Jim Smith said the building was ventilated and the area was back to normal about noon.

The janitor was treated at the scene for difficulty breathing and taken to Regions Hospital, Zaccard said. He added that he didn’t know of anyone else who had gotten sick.

Along with the connecting skyways being blocked off, Cedar Street was closed through most of the morning to vehicles and pedestrians, Zaccard said.

A hazardous materials team entered the building about 8:45 a.m., took readings and found that no chemicals had escaped from the room where the incident occurred, according to the fire marshal.

A waste-handling company was called in to dispose of the chemicals.

Floors 10, 11 and 12 contain rooms for Hotel 340. Along with the athletic club, the College of St. Scholastica and the Global Language Institute also operate out of the 96-year-old building.

Paul Walsh, Nicole Norfleet