Thousands of commuters continue to breathe high levels of lung-damaging diesel exhaust at Chicago's Union Station, in part because of nagging maintenance problems at the Old Post Office that straddles the southbound tracks.



Testing by Amtrak has determined that ventilation fans at the shuttered post office building repeatedly malfunction. At times, the system of 11 ducts and fans has operated at just 53 percent of its design capacity, according to a letter to U.S. Sen. Dick Durbin from Joseph Boardman, Amtrak's president and chief executive.



After months of negotiations, Amtrak officials are filing a lawsuit in federal court seeking to force Bill Davies, the British developer who bought the former post office building in 2009, to follow through on promises to fix the problem.



City officials already have cited Davies' International Property Developers with two violations of Chicago building codes related to the ventilation system.



"This owner's failure to remedy the situation shows a disregard for the air quality in the station area and for the people who use the station," Boardman wrote in a letter obtained by the Tribune.



Targeting Davies is the latest response to a 2010 Tribune investigation that revealed high levels of noxious diesel soot inside Metra passenger cars. The newspaper's testing and a follow-up study by Metra found the worst pollution problems are on trains leaving the south platform at Union Station.



For most people, exposure to diesel pollution occurs during their daily commutes. The exhaust is a complex mix of toxic substances such as benzene, arsenic and formaldehyde, many of which can cause cancer. It also is filled with tiny particles, commonly called soot, that can inflame the lungs, trigger asthma attacks and cause premature death.



Legal agreements require the owners of skyscrapers built above the Union Station tracks to maintain ventilation ducts and fans that suck diesel fumes out of cramped tunnels shared by Amtrak and Metra trains. But commuters and employee unions have complained for years about thick blue clouds of locomotive exhaust that linger above the tracks.



Davies, a Liverpool-based developer who last year proposed turning the post office building into an office tower and shopping mall, is represented locally by Daley & George, the law firm of former Mayor Richard Daley's brother Michael.



In an email response to questions Sunday, Martin Mulryan, Davies' project manager, said the firm is "committed to improving the ventilation and maintenance systems, with the goal of making the building a model for environmental standards."



Amtrak, Metra and city officials have singled out the building as a significant hurdle in their efforts to improve air quality for train passengers.



In response to the Tribune investigation, Metra upgraded air filters on each of its passenger cars to reduce diesel pollution. The rail service also switched to cleaner fuel to curb the amount of soot emitted by its locomotives.



With help from Durbin, Metra obtained federal funds to install equipment on some of its locomotives that automatically shuts down the engines if they idle longer than 10 minutes. It also is rebuilding two of its aging locomotives to substantially reduce harmful emissions.



Amtrak, meanwhile, is planning to replace all of its locomotives with cleaner models starting in 2015. The upgrades depend on federal funding that has been targeted for congressional budget cuts.



mhawthorne@tribune.com



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