Thus, there is continuing pressure to tighten air quality standards: a tightening of the standard for fine particles was finalized September 21, 2006. With this background in mind, the bulk of this report provides an overview of seven prominent air issues of interest in the 109 th Congress: revision of the particulate standards; multi-pollutant (or Clear Skies) legislation for electric power plants; mercury from power plants; New Source Review; the gasoline additives MTBE and ethanol; ozone nonattainment area deadlines; and the "conformity" of transportation and clean air planning. EPA's professional staff and the Clean Air Scientific Advisory Committee (CASAC), a group established by the Clean Air Act to provide independent scientific advice to the Administrator, had recommended stronger standards. CASAC's Views

The Administrator's decisions represent the first time in CASAC's nearly 30-year history that the promulgated standards fall outside of the range of the scientific panel's recommendations. It is the CASAC ' s consensus scientific opinion that the decision to retain without change the annual PM 2.5 standard does not provide an ' adequate margin of safety ... requisite to protect the public health ' (as required by the Clean Air Act) .... "
With regard to PM 10 , the letter stated that CASAC was "completely surprised" at the decision to revert to the use of PM 10 as the indicator for coarse particles, noting that the option of retaining the existing daily PM 10 standard was not discussed during the advisory process and that CASAC views this decision as "highly problematic." Clear Skies/Multi-Pollutant Legislation

A major focus of congressional attention in the first session of the 109 th Congress was whether to take action on the Clear Skies Act, a bill that would regulate multiple pollutants from coal-fired electric power plants. The bill would have significantly amended the Clean Air Act to establish a cap-and-trade system for emissions from electric power plants and other sources of air pollution, while eliminating or deferring numerous existing regulations affecting those sources. Under the Clean Air Act, they are not necessarily subject to stringent requirements. The key questions have been how stringent the caps should be, and whether carbon dioxide (CO 2 ) will be among the emissions subject to a cap. Although stalled for the previous three years, Clear Skies was set for early consideration in the 109 th Congress by the Senate Environment and Public Works Committee; but the opposing sides were not able to reach a consensus and the bill failed on a tie vote on March 9, 2005. Immediately following the vote, on March 10, 2005, EPA announced that it would promulgate final regulations for utility emissions of SO 2 and NOx in 28 eastern states and the District of Columbia through its Clean Air Interstate Rule (CAIR). In addition to the arguments over technology availability and cost, it is unclear whether EPA has legislative authority to establish a cap-and-trade program for mercury: many argue that the agency is required by the statute to impose MACT standards on each individual plant once it has decided to control mercury emissions. On September 13, however, the Senate rejected S.J.Res. 20 , 51-47, thus allowing the EPA rule to go forward. The New Source Review debate has occurred largely in the courts. MTBE and Ethanol

Congress acted on several Clean Air Act issues in H.R. 6 , the comprehensive energy bill that it passed and sent to the President July 29, 2005. The most significant of these issues dealt with ethanol and reformulated gasoline (RFG). 109-58 and H.R. Ozone Nonattainment Area Deadlines

Another Clean Air Act provision that was in the House-passed version of H.R. 6 dealt with the deadlines for attaining air quality standards. As enacted, the Energy Policy Act of 2005 does establish a demonstration project, however, to address the issue of upwind pollution. 3 ( P.L. 109-59 ), the transportation bill that the President signed August 10, 2005.
The courts and the executive branch have faced major decisions on clean air issues in 2006, with Congress playing a limited role. One focus has been the EPA Administrator's September 21, 2006 decision regarding air quality standards for fine particles. According to EPA and the consensus of the scientific community, current concentrations of fine particles cause tens of thousands of premature deaths annually. The Administrator's September 21 decision will strengthen the standards; according to the agency, it will reduce premature mortality by 1,200 - 13,000 persons annually. However, many are unhappy that the new standard will not be more stringent—for the first time ever, it falls outside of a range recommended by the Clean Air Scientific Advisory Committee (CASAC), an independent body established by the Clean Air Act to provide expert scientific advice. On September 29, the seven members of CASAC stated that the Administrator's decision does not provide an adequate margin of safety requisite to protect the public health.
In 2005, Congress acted on several Clean Air Act (CAA) issues in legislation that it passed and sent to the President. The most significant of these issues, dealing with ethanol and reformulated gasoline (RFG), were addressed in the Energy Policy Act of 2005, H.R. 6 (P.L. 109-58). Congress also amended the Clean Air Act in H.R. 3 (P.L. 109-59), the transportation bill that the President signed August 10, 2005. H.R. 3 modified the requirement that state and local transportation planners demonstrate conformity between their transportation plans and the timely achievement of air quality standards.
Other Clean Air Act amendments have stalled. A bill that would have established a cap-and-trade program for emissions of sulfur dioxide (SO2), nitrogen oxides (NOx), and mercury from coal-fired electric power plants (S. 131) was among the first items on the agenda of the 109th Congress: entitled the Clear Skies Act, the bill was scheduled for markup by the Senate Environment and Public Works Committee March 9, 2005. But the committee failed to approve it on a 9-9 tie vote, in large part because of complaints that the bill would weaken existing Clean Air Act requirements. Another issue in the debate was whether to cap emissions of the greenhouse gas carbon dioxide (CO2) in addition to the other three pollutants. With Clear Skies stalled, EPA finalized the Clean Air Interstate Rule (CAIR), which will cap emissions of SO2 and NOx from power plants in 28 eastern states and the District of Columbia and establish a cap-and-trade system through regulation.
A deadline for mercury regulations helped drive the Clear Skies debate: EPA faced a judicial deadline of March 15, 2005, to promulgate standards for power plant mercury emissions. The agency met this deadline, but the specific regulations have been widely criticized. A resolution to "disapprove" (overturn) the regulations under the Congressional Review Act (S.J.Res. 20) was defeated on a vote of 51-47, September 13, 2005, but the courts have yet to rule on challenges filed by 15 states and other groups. Whether to modify other requirements of the Clean Air Act (New Source Review, deadlines for nonattainment areas, and provisions dealing with interstate air pollution) have also been contentious issues.