The company has built one new battery of coke ovens and is building two new quench towers to reduce pollution at the plant's other two batteries, about 10 miles south of Pittsburgh.
The new coke battery has been running since November, but the Pittsburgh Post-Gazette ( http://bit.ly/16gjnGR) reports the steelmaker recently got an extension until July 31 to meet certain emission requirements from the Allegheny County Health Department.
A health department official says coal dust and other pollutants are still leaking when coal is loaded into the ovens for baking.
U.S. Steel has until August 2015 to meet federal air standards.
Information from: Pittsburgh Post-Gazette, http://www.post-gazette.com