The same group of air pollutant emissions from outer continental shelf (OCS) operations are subject to different regulatory programs, depending on the location of the operation. The Department of the Interior (DOI) has jurisdiction over OCS sources in federal waters in the western Gulf of Mexico and most of the central Gulf. The Consolidated Appropriations Act, 2012 ( P.L. 112-74 ), transferred air emission authority in the OCS off Alaska's north coast from the Environmental Protection Agency (EPA) to DOI. EPA has jurisdiction over sources in all other federal waters. Congress established the programs through different statutes, and the two agencies implement the programs through separate regulations. Pursuant to the underlying statutes, the regulations have different scopes, emission thresholds for eligibility, and compliance obligations. Therefore, two identical operations, located in separate jurisdictions, could face considerably different requirements and procedural time frames. Some may criticize this arrangement for its inconsistent treatment of air emissions. Others may point out that the differences create inconsistent opportunities for oil and gas development. For much of the past 30 years, these differences received little attention, primarily because most of the federal oil and gas resources in EPA's jurisdiction have been subject to moratoria. Moreover, the level of activities in the regions open to development has varied dramatically. According to DOI data from 2010, there were 3,409 production wells in the Gulf of Mexico and 23 in the Pacific. Figure 1 illustrates the divided jurisdiction in the Gulf of Mexico. Although active leases are located in EPA's jurisdiction, none of the Gulf of Mexico platforms are in EPA's jurisdiction. In 2008, moratoria provisions expired, allowing many of the areas in EPA's jurisdiction to potentially open for oil and gas leasing activity. In addition, estimates of oil and gas resources have spurred interest in areas other than the Gulf ( Table 1 ). For example, OCS areas off the Atlantic coast have also received attention in recent years. In 2007, the Minerals Management Service (MMS) proposed a lease sale in an area offshore of Virginia. The lease sale was set to take place in 2011. In the aftermath of the 2010 Deepwater Horizon oil spill, the Obama Administration canceled the sale (May 27, 2010). In addition, in DOI's most recent five-year plan for OCS leasing, DOI decided not to include the Mid- and South Atlantic planning areas. Many Members of the 112 th Congress have sought to expand OCS oil and gas development. The House has passed several bills that would direct DOI to hold lease sales in particular areas, including the formerly proposed Virginia lease sale and areas of Southern California. In addition, areas of the U.S. Arctic region, which were not subject to the moratoria, have generated recent congressional interest as industry has sought to establish a greater presence in the area. A primary driver for the activity in this region is the shrinking Arctic ice cap, or conversely, the growing amount of ice-free ocean in the summertime. As interest in developing OCS resources in EPA's jurisdiction has increased, the EPA OCS air program has received increased scrutiny from some Members. In particular, Members have focused on the permit activity of Shell in the Chukchi Sea, part of the federal waters off Alaska's north coast. This interest led to the enactment of the Consolidated Appropriations Act, 2012 ( P.L. 112-74 ) on December 23, 2011, which transferred air emission authority in the OCS off Alaska's north coast from the Environmental Protection Agency (EPA) to DOI. This report will provide an overview and brief history of the separate regulatory programs, examine and compare the requirements of the programs, and highlight potential implications of the differences. Although OCS sources can involve other industry sectors (e.g., deepwater ports or offshore wind projects), the focus of this report is air emissions from the OCS oil and gas exploration, development, and production operations. OCS sources of air emissions can vary considerably, depending on the specifics of the operation. Offshore oil and gas sector operations, in particular, may include evolving technologies and take place in different settings, making it difficult to generalize air emission potentials. For example, mobile offshore drilling units involved in deepwater drilling in the Gulf of Mexico may emit considerably more emissions than a rig anchored to the sea floor in shallow water. Operations in the Arctic region may involve icebreaker vessels, which may generate considerably more emissions than other support vessels. A Senate Report from the 1990 Clean Air Act (CAA) amendments stated: "The construction and operation of OCS facilities emit a significant amount of air pollution which adversely impacts coastal air quality in the United States. Operational emissions from an OCS platform and associated marine vessels can routinely exceed 500 tons of nitrogen (NO x ) and one hundred tons of reactive hydrocarbons annually." Based on a review of EPA OCS permit documents, the 1990 Senate Report estimate is still valid, particularly for nitrogen oxide (NO x ) emissions. Table 2 identifies emission ranges of selected air pollutants from seven OCS oil/gas operations seeking, or recently receiving, air permits in EPA's jurisdiction. In some cases, the ranges cover a wide spectrum. For each source, NO x emissions account for the majority of the operations' regulated pollutants. Four of the pollutants in Table 2 are considered "criteria" pollutants and have a National Ambient Air Quality Standard (NAAQS). Both NO x and volatile organic carbon (VOC) emissions lead to ozone (O 3 ) formation (sometimes described as smog), which is also a criteria pollutant. According to congressional testimony from EPA Administrator Jackson, "a single exploratory drilling operation could emit approximately as much air pollution on a daily basis as a large state-of-the-art oil refinery." A brief history of federal OCS air emission governance may be instructive to policymakers. First, its history may help explain the rationale for the current framework. Second, some of the arguments made during its development may apply to current issues. Passed as separate statutes in 1953, the Submerged Lands Act and the Outer Continental Shelf Lands Act (OCSLA) established federal jurisdiction and governance, respectively, for oil and gas resources on the OCS. The 1953 OCSLA did not specifically mention air emissions, but provided the Secretary of the Department of the Interior with general authority, stating: "The Secretary may at any time prescribe and amend such rules and regulations as he determines to be necessary and proper in order to provide for the prevention of waste and conservation of the natural resources of the outer Continental Shelf." The Nixon Administration established the Environmental Protection Agency (EPA) in 1970 under an executive branch reorganization plan. Although federal legislation addressing air pollution was first passed in 1955, the CAA Amendments of 1970 established the foundation of the federal air emissions program that exists today. For example, the 1970 law (among other provisions) set national standards for air quality, created a program to require the best available control technology at major new sources of air pollution, and established a program to regulate air toxics. In 1977, Congress made further amendments to the CAA, establishing (among other provisions) the prevention of significant deterioration (PSD) program. Tension arose between the CAA provisions of the 1970s and the 1953 OCSLA. The 1953 OCSLA did not specifically mention which federal agency would have jurisdiction over the air quality effects of OCS development, resulting in uncertainty over what jurisdiction, if any, the newly created Environmental Protection Agency (EPA) had for air quality control in the OCS. The jurisdictional uncertainty led EPA to assert its authority to regulate air emissions from OCS sources in April 1978. In September 1978, Congress passed the Outer Continental Shelf Lands Act of 1978 ( P.L. 95-372 ), providing the Department of the Interior (DOI) with authority to regulate the national offshore oil and gas program including the regulation of air emissions from offshore oil and gas operations. A federal appeals court affirmed DOI's authority (versus EPA authority) in 1979, in a case brought by the State of California against DOI. DOI issued regulations in 1980. Some stakeholders in California continued to voice concerns regarding the level of control for OCS source air emissions. A 1992 report from the National Research Council stated: Offshore air pollution is a problem in California that is not present in other oil-producing regions in the country (with the possible exception of the West Coast of Florida). Atmospheric conditions peculiar to coastal California involve a combination of the amount of sunlight, the mixture of pollutants already present, the direction of prevailing winds, and the presence of coastal mountain ranges—all of which work to trap smog along the coastal strip. A major problem here has been that air quality standards for air above federal waters were not as stringent as those for state waters. Congress made substantial amendments to the CAA in 1990. A newly added Section 328 authorized EPA to implement certain air quality provisions of the act at offshore facilities, except for those west of 87.5 degrees longitude (i.e., Western and Central areas of the Gulf of Mexico). Offshore facilities not under EPA jurisdiction remain under DOI jurisdiction. EPA promulgated regulations for OCS sources in 1992. In addition, Section 328(b) required the Secretary of the Interior to prepare a study assessing impacts of OCS sources in nonattainment areas that fail to meet NAAQS for ozone or nitrogen dioxide. Based on the results, the Secretary shall consult with the EPA Administrator to determine if additional actions are necessary. MMS published this study in 1995, which concluded that "the contribution of [OCS petroleum development] emission sources on onshore ozone concentrations is small." The MMS regulations remained largely unchanged (discussed below). Decades long moratoria of oil and gas development for much of the OCS have influenced the level of interest regarding OCS air emission issues.