Updated 02/06/12 – 2 p.m.

CHICAGO (CBS) – U.S. Sen. Dick Durbin said Monday he hopes the owner of the Old Post Office building is going to make good on his word to help vent harmful exhaust fumes from Union Station, located just below the building.

WBBM Newsradio Political Editor Craig Dellimore reports Amtrak and the senator were threatening legal action to force the issue.

To cut down on harmful fumes around the southbound tracks at Union Station, Amtrak and Metra have been using filters, cleaner-burning fuels and shorter idling times.

But Durbin said officials haven’t gotten the cooperation of British developer Bill Davies, who owns the shuttered Old Chicago Main Post Office building above those tracks.

According to the Chicago Tribune, testing by Amtrak has found ventilation fans at the Old Post Office building repeatedly malfunction and, at times, operate at only 53 percent of design capacity.

LISTEN: WBBM Newsradio Political Editor Craig Dellimore reports

One reason tests show the air quality is so low for commuters in Union Station’s south concourses is the ventilation system in the old, mostly-unused Old Post Office building above isn’t fully operational.

Amtrak, which owns Union Station, has threatened legal action to force Davies to fix the problem.

A statement from the property manager – issued while Durbin was holding a news conference about the issue – said Davies is fixing it.

“Well, he hasn’t taken care of it yet,” Durbin said. “I don’t know where he is, but I would just say that our report is about 53 percent of their ventilation fans … are currently working. We want 100 percent.”

But Durbin cautiously welcomed the news that property managers will be making the necessary repairs.

“I don’t want to win a lawsuit, I want to clean up the air in this building. If they’re prepared to do this – if that’s what they’re saying – then we’ll have a press conference and thank them,” Durbin said.

Amtrak and Metra also are taking steps to make their trains run cleaner and greener.

Last year, Metra placed new, more efficient filters in all of its cars. The filters can reduce the amount of diesel soot inside train cars by 75 percent during outbound trips. It also switched to cleaner diesel fuel to reduce soot emissions, according to the Tribune.

Metra also obtained federal funding to install technology that can down train engines automatically when they idle longer than 10 minutes, the newspaper reported.