Oxy’s oil and gas, chemical and midstream operations generate air emissions, including sulfur oxides (SOx), nitrogen oxides (NOx) and carbon monoxide (CO), among other substances. These air emissions are generated from boilers, heaters, engines, flares and turbines, and from other process sources. Emissions of SOx and CO from facilities operated by Oxy decreased by 4.5 percent to 4,200 metric tons and 21 percent to 10,300 metric tons, respectively, from 2006 to 2007, while emissions of NOx increased by 21.5 percent to 17,500 metric tons during the same period. The reduction in CO emissions was due to reduced flare volumes at operations in the Middle East, while SOx emissions decreased as a result of lower flare volumes at U.S. operations, which were partially offset by higher sulfur concentrations in certain gas streams used for fuel in the Middle East. The increase in NOx emissions reflects significant acquisitions of oil and gas and midstream assets in 2006 and 2007, as well as activities associated with increased oil and gas production.