CEMEX Construction Materials Atlantic (formally Southdown Cement Company) operates a Portland cement kiln plant in Xenia, Ohio. In the late 1990's, the facility commenced construction on a major modification which increased levels of sulfur dioxide (SO2) and nitrogen oxides (NOx) above the Prevention of Significant Deterioration (PSD) thresholds in 40 CFR 52.21. The company failed to apply for a PSD permit at the time, which would have applied Best Available Control Technology (BACT) at the facility. In response to these violations, CEMEX has agreed to install a Lime Spray Absorber (LSA) system to control SO2, and a Selective Non-Catalytic Reduction (SNCR) system to control NOx. The U.S. EPA expects the LSA to reduce SO2 emissions by 627,600 pounds per year; and the SNCR to reduce NOx emissions by 4,716,000 pounds per year. These emission reductions will lower ground-level ozone (smog), fine particulate and acid rain levels in surrounding areas. CEMEX has also agreed to pay a total penalty of $1,400,000 to the U.S. Government, the State of Ohio and the Dayton, Ohio-based Regional Air Pollution Control Agency.