Clean Air Act

This paper surveys recent and historical publications on automotive powertrain control. Controloriented models of gasoline and diesel engines and their aftertreatment systems are reviewed, and challenging control problems for conventional engines, hybrid vehicles and fuel cell powertrains are discussed. Fundamentals are revisited and advancements are highlighted. A comprehensive list of references is provided.

This article reports on the data collected on one of the most ambitious government-sponsored environmental data acquisition projects of all time, the Risk Management Plan (RMP) data collected under section 112(r) of the Clean Air Act Amendments of 1990. This RMP Rule 112(r) was triggered by the Bhopal accident in 1984 and led to the requirement that each qualifying facility develop and file with the U.S. Environmental Protection Agency a Risk Management Plan (RMP) as well as accident history data for the five-year period preceding the filing of the RMP. These data were collected in 1999-2001 on more than 15,000 facilities in the United States that store or use listed toxic or flammable chemicals believed to be a hazard to the environment or to human health of facility employees or off-site residents of host communities. The resulting database, RMP*Info, has become a key resource for regulators and researchers concerned with the frequency and severity of accidents, and the underlying facility-specific factors that are statistically associated with accident and injury rates. This article analyzes which facilities actually filed under the Rule and presents results on accident frequencies and severities available from the RMP*Info database. This article also presents summaries of related results from RMP*Info on Offsite Consequence Analysis (OCA), an analytical estimate of the potential consequences of hypothetical worst-case and alternative accidental releases on the public and environment around the facility. The OCA data have become a key input in the evaluation of site security assessment and mitigation policies for both government planners as well as facility managers and their insurers. Following the survey of the RMP*Info data, we discuss the rich set of policy decisions that may be informed by research based on these data.

Environmental laws such as the Clean Air Act are administered largely at the state level, with more or less enthusiasm, depending on the state. Here we examine the spatial distributions of four indicators of environmentalism: organizational membership, public opinion, Congressional representation and state-level environmental policy. Public support for environmental protection is strongest in the nation's northeast quadrant and the West Coast. The Dakotas, the intermountain West and the Deep South have the least concern. Level of environmentalism is largely explained by state levels of electricity consumption and education and inversely by political conservatism. Cultural traditions also apparently explain some of the variation across regions. #

Regenerative braking systems (RBS) are an effective method of recovering the energy released and at the same time reducing the exhaust and brake emissions of vehicles. This method is based on the principle of converting the kinetic energy created by the mechanical energy of the motor into electrical energy. The converted electrical energy is stored in the battery for later use. This braking system must meet maximum energy recovery criteria by performing its function safely within the shortest braking distance. This study was conducted to provide comprehensive information about regenerative energy systems. These systems provide economic benefits via fuel savings and prevention of material loss. Their use also contributes to a clean environment and renewable energy sources, which are among the most important issues on the global agenda. It is clear that more comprehensive studies should be carried out in this area.

Anyone who has traveled through the coal producing areas of northern Appalachia during the past five years has probably noticed the appearance of billboards and yard signs with colorful slogans decrying the “War on Coal.” In 2012, both the Obama and Romney campaigns paid particular attention to the Upper Ohio Valley, a blue-collar region that often voted Democratic, but where many residents had developed a strong sense of resentment against policies portrayed as harmful to the local high sulfur coal industry. In October 2015, local mining giant Murray Energy joined Ohio, West Virginia and twenty-two other states in suing the U.S. Environmental Protection Agency over its new “Clean Power Plan,” designed to limit greenhouse gas emissions using provisions of the Clean Air Act. In a December editorial, CEO Robert Murray declared his intention “to aggressively fight back against the Obama regime's political power grab [on behalf of] good Americans [who] only want to work in honor and dignity.” “It is a blatantly illegal effort by the Executive Branch,” he continued, “to use the Clean Air Act of 1971 in a way never intended by Congress to promulgate carbon dioxide emission reductions across America, which will radically and destructively transform our electric power system.”

The current debate over the Clean Power Plan is the latest in a series of political, cultural and economic battles that have been fought since the passage of the Clean Air Act during the height of the postwar environmental movement.  These tensions were especially apparent in the periods around significant amendments to the law in 1977 and 1990. Despite the ongoing significance of the Clean Air Act, however it has yet received surprisingly little attention by historians.  Journalists and legal scholars who have examined conflict between the coal industry and environmental regulators largely focused on the formal arena of Congressional politics, leaving a critical gap in our understanding of how broader issues played out on the local and state levels.

This paper focuses on the Upper Ohio Valley before, during and after the Clean Air Act Amendments of 1977 as mining companies and their political allies mobilized the region’s residents to attend hearings, travel to rallies, and vote against candidates seen as allied with pro-environmental platforms. Ohio’s Republican governor, James Rhodes, proved particularly adept at tapping into this anti-environmental sentiment and repeatedly clashed with EPA officials over regulating the state’s coal-burning power plants. These local and state frictions also manifested on the federal level, where Ohio Senator Howard Metzenbaum found himself at odds with his Democratic colleague and equally powerful Senator Edmund Muskie, whose native Maine was on the receiving end of devastating acid rain pollution. Understanding the economic and cultural as well as political history of these dynamics is particularly important in contextualizing not only the contemporary debate over global warming but also the broader shift of conservatives and the Republican Party away from the tenuous environmentalist consensus of the early 1970s.

Voluntary environmental programs are codes of progressive environmental conduct that firms pledge to adopt. This paper investigates whether ISO 14001, a voluntary program with a weak sword—a weak monitoring and sanctioning mechanism—can mitigate shirking and improve participants' environmental performance. Sponsored by the International Organization for Standardization (ISO), ISO 14001 is the most widely adopted voluntary environmental program in the world. Our analysis of over 3,000 facilities regulated as ...

Mount Washington, NH in the White Mountain National Forest, is flanked to the north-northeast and south by two Class I Wilderness areas, the Great Gulf and Presidential Range-Dry River Wildernesses, respectively. The Clean Air Act protects Class I Area natural resource values from air pollution. Aerosol sulfate, a fine particulate component that is often transported long distances, is a known contributor to visibility degradation and acidic deposition. We examined summertime fine particulate aerosol mass and sulfate, strong acidity and ammonium concentrations from 1988 to 2007 on Mount Washington at two elevations, 452 and 1540 m (msl). The former site is often within, and the latter at the interface of, the planetary boundary layer. Comparisons of sampling interval durations (10 and 24 h) and site vs. site are made. We also examine the extent to which aerosol sulfate is neutralized. Ten hour (daytime) compared to 24 h samples have higher mass and aerosol sulfate concentrations, however paired samples are well correlated. Fine mass concentrations compared between the 452 m and 1540 m sites (standard temperature and pressure corrected) show a weak positive linear relationship with the later being approximately 32% lower. We attribute the lack of a strong correlation to the facts that the 1540 m site is commonly at the interface of and even above the regional planetary boundary layer in summer and that it can intercept different air masses relative to the 452 m site. Sulfate is w18% lower at the higher elevation site, but comprises a greater percentage of total fine mass; 42% compared to 37% for the high and low elevation site, respectively. Aerosol strong acidity was found to increase with increasing sulfate concentrations at both sites. Further the ratio of hydrogen to sulfate ion was greater in 24 h than 10 h samples at the higher elevation site likely due to overnight transport of fresh acidic aerosols.

Title IV of the 1990 Clean Air Act instituted a nationwide system of tradeable pollution permits for sulfur dioxide emitted by electric power plants.This paper provides new estimates of the cost savings from allowance trading, utilizing an econometric model of abatement choices made by electric utilities under various policy regimes My baseline estimate of abatement cost under the allowance market is $747 million during each year of Phase I, which lasted from 1995 to 1999. I estimate that annual abatement costs would have been $150 million to $180 million greater under performance standards, holding aggregate abatement constant. These figures correspond to cost savings from trading of 17

This research develops and applies a new structure for the transportation planning model that includes feedback between demand, assignment, and traffic control. New methods, combined with a renewed interest in transportation planning models prompted by the Clean Air Act of 1990 and the Intermodal Surface Transportation Efficiency Act of 1991, warrant a reconsideration of the traditional "four-step" transportation planning model. This paper presents an algorithm for feedback which results in consistent travel times as input to travel demand and output from route assignment. The model, including six stages of Trip Generation, Destination Choice, Mode Choice, Departure Time Choice, Route Assignment and Intersection Control is briefly outlined. This is followed by an application comparing a base year 1990 application with a forecast year of 2010. The 2010 forecast is solved both with and without feedback for comparison purposes. Incorporation of feedback gives significantly different results than the standard model. David Levinson and Ajay Kumar Integrating Feedback into the Transportation Planning Model: Structure and Application2 ________________________________________________________________________ Recently, some literature has appeared on combining demand, assignment, and intersection control into a single modeling framework ,( 3 ). This paper reviews the theory and develops a procedure with feedback between assignment, demand, and intersection control. The procedure is applied to the Baltimore-Washington metropolitan region. The results suggest that introducing feedback between congested travel times and demand and between link flows and intersection control provides a more realistic representation of travel patterns and traffic flows. The procedure is especially relevant in the context of long-term forecasting when we have even less understanding of the possible interrelationship between travel demand and emerging metropolitan structure.

This research develops and applies a new structure for the transportation planning model that includes feedback between demand, assignment, and traffic control. New methods, combined with a renewed interest in transportation planning models prompted by the Clean Air Act of 1990 and the Intermodal Surface Transportation Efficiency Act of 1991, warrant a reconsideration of the traditional "four-step" transportation planning model. This paper presents an algorithm for feedback which results in consistent travel times as input to travel demand and output from route assignment. The model, including six stages of Trip Generation, Destination Choice, Mode Choice, Departure Time Choice, Route Assignment and Intersection Control is briefly outlined. This is followed by an application comparing a base year 1990 application with a forecast year of 2010. The 2010 forecast is solved both with and without feedback for comparison purposes. Incorporation of feedback gives significantly different results than the standard model. David Levinson and Ajay Kumar Integrating Feedback into the Transportation Planning Model: Structure and Application2 ________________________________________________________________________ Recently, some literature has appeared on combining demand, assignment, and intersection control into a single modeling framework ,( 3 ). This paper reviews the theory and develops a procedure with feedback between assignment, demand, and intersection control. The procedure is applied to the Baltimore-Washington metropolitan region. The results suggest that introducing feedback between congested travel times and demand and between link flows and intersection control provides a more realistic representation of travel patterns and traffic flows. The procedure is especially relevant in the context of long-term forecasting when we have even less understanding of the possible interrelationship between travel demand and emerging metropolitan structure.

This research develops and applies a new structure for the transportation planning model that includes feedback between demand, assignment, and traffic control. New methods, combined with a renewed interest in transportation planning models prompted by the Clean Air Act of 1990 and the Intermodal Surface Transportation Efficiency Act of 1991, warrant a reconsideration of the traditional "four-step" transportation planning model.

We examine the effects of the 1990 Clean Air Act Amendments (CAAAs) on ambient concentrations of PM 10 in the United States between 1990 and 2005. We find that non-attainment designation has no effect on the 'average monitor' in non-attainment counties, after controlling for weather and socioeconomic characteristics at the county level. In sharp contrast, if we allow for heterogeneous treatment by type of monitor and county, we do find that the 1990 CAAAs produced substantial effects. Our best estimate suggests that PM 10 concentrations at monitors with concentrations above the national annual standard dropped by between 7µg/m 3 and 9µg/m 3 , which is roughly equivalent to a 11-14% drop. We also show that monitors which were in violation of the daily standard experience two fewer days in violation of the daily standard the following year. Empirical results suggest that this treatment effect is independent of whether the EPA has finalized the non-attainment designation.

In order to improve public health in areas with air quality problems, the U.S. Clean Air Act imposes a variety of federal regulations on gasoline, which have led to a proliferation of fuel blends known as "boutique fuels." More than 45 fuel blends are sold nationwide. We examine the effects of this program on wholesale gasoline prices. The methodological innovation in this study is the use of a regulatory distance measure as a proxy for measuring market power that arises from product differentiation. We find that Clean Air regulation increases gasoline prices by increasing the cost of refining, but more importantly, by creating regulatory "islands," it segments the market and increases the market power of firms. Our estimation controls for the potential endogeneity of the regulatory variables. We find that OLS techniques systematically underestimate the effect of regulation on gasoline prices. ; Nauges and Thomas: LERNA-INRA, University of Toulouse, 21 Allée de Brienne, 31000 Toulouse France, cnauges@toulouse.inra.fr and thomas@toulouse.inra.fr, respectively. Correspondence: Chakravorty, 407 823 4728, fax: 407 823 3269. J u l -9 6 J a n -9 7 J u l -9 7 J a n -9 8 J u l -9 8 J a n -9 9 J u l -9 9 J a n -0 0 J u l -0 0 J a n -0 1 J u l -0 1 J a n -0 2 J u l -0 2 1995 real wholesale and crude oil prices (cents/gallon)

1,3-Butadiene, classi"ed as hazardous in the 1990 Clean Air Act Amendments, is an important ambient air pollutant. Understanding its atmospheric transformation is useful for its own sake, and is also helpful for eliciting isoprene's fate in the atmosphere (isoprene dominates the biogenic emissions in US). In this paper, samples from both hydroxyl-and ozone-initiated photooxidation of 1,3-butadiene were analyzed by derivatization with O-(2,3,4,5,6-penta#uorobenzyl)hydroxylamine followed by separation and detection by gas chromatography/ion trap mass spectrometry to detect and identify carbonyl compounds. The following carbonyls were observed: formaldehyde, acrolein, glycolaldehyde, glycidaldehyde, 3-hydroxy-propanaldehyde, hydroxy acetone, and malonaldehyde, which can be classi"ed into three categories: epoxy carbonyls, hydroxyl carbonyls, and di-carbonyls. Three non-carbonyls, furan, 1,3-buatdiene monoxide, and 1,3-butadiene diepoxide, were also found. To con"rm their identities, both commercially available and synthesized standards were used. To investigate the mechanism of 1,3-butadiene, separate batch reactor experiments for acrolein and 1,3-butadiene monoxide were carried out. Time series samples for several products were also taken. When necessary, computational chemistry methods were also employed. Based on these results, various schemes for the reaction mechanism are proposed.

The 1977 and 1990 Amendments to the Clean Air Act call for visibility and atmospheric deposition monitoring throughout the United States. We compare sulfate and nitrate particle mass concentrations measured by two regional air quality networks, the Interagency Monitoring of PROtected Visual Environments (IMPROVE) network and the Clean Air Status and Trends Network (CASTNet), or CASTNet Deposition Network (CDN). The intent of this comparison is to quantify bias that may be introduced from di!erences in the respective network's sampling protocols. A number of sampling protocol di!erences exist between the two networks that may lead to sampling bias, particularly for particle NO\ . Observed di!erences between particle SO\ mass concentrations reported by the two monitoring networks are generally small, yet statistically signi"cant at many comparison sites. Di!erences between particle NO\ mass concentrations are substantial, statistically signi"cant at nearly all comparison sites, and the bias magnitude varies by geographic region. Di!erences in particle NO\ , based on data from monitoring sites selected for this comparison, are 40% in the west, 56% in the interior desert/mountain region, and !9% in the east, expressed as the IMPROVE mean subtracted from the CDN mean, as a percent of the IMPROVE mean. Comparisons are made using data from 23 locations where monitoring sites from IMPROVE and CDN are within approximately 50 km.

The purpose of this research was to evaluate five transportation planning processes used in Florida to determine how greenhouse gas (GHG) emissions considerations can be incorporated into the processes. These included the federal metropolitan planning organization long range transportation planning process (MPO LRTP) and transportation improvement programming (TIP) with application of federal Clean Air Act (CAA) air quality conformity analysis;

Air pollution emissions from older fossil-fueled power plants are often much greater than emissions from newer facilities, in part because older plants are exempt from modern emission standards required of new plants under the Clean Air Act. To quantify potential health benefits of emission reductions, there is a need to apply atmospheric dispersion models that can estimate the incremental contributions of power plants to ambient concentrations with reasonable accuracy over long distances. We apply the CALPUFF atmospheric dispersion model with meteorological data derived from NOAA's Rapid Update Cycle model to a set of nine power plants in Illinois to evaluate primary and secondary particulate matter impacts across a grid in the Midwest. In total, the population-weighted annual average concentration increments associated with current emissions are estimated to be 0.04 mg m À3 of primary fine particulate matter (PM 2.5 ), 0.13 mg m À3 of secondary sulfate particles, and 0.10 mg m À3 of secondary nitrate particles (maximum impacts of 0.3, 0.2, and 0.2 mg m À3 , respectively). The aggregate impact estimates are moderately insensitive to parametric assumptions about chemical mechanism, wet/dry deposition, background ammonia concentrations, and size of the receptor region, with the largest uncertainties related to nitrate particles and long-range transport issues. Additional uncertainties may be associated with inherent limitations of CALPUFF, but it appears likely that the degree of uncertainty in atmospheric modeling will not dominate the total uncertainty associated with health impact or benefit estimation. Although the annual average concentration increments from a limited number of sources are relatively small, the large population affected by long-range transport and the number of power plant sources around the US imply potentially significant public health impacts using standard epidemiological assumptions. Our analysis demonstrates an approach that is applicable in any setting where source controls are being evaluated from a public health or benefit-cost perspective. r

This research develops and applies a new structure for the transportation planning model that includes feedback between demand, assignment, and traffic control. New methods, combined with a renewed interest in transportation planning models prompted by the Clean Air Act of 1990 and the Intermodal Surface Transportation Efficiency Act of 1991, warrant a reconsideration of the traditional "four-step" transportation planning model. This paper presents an algorithm for feedback which results in consistent travel times as input to travel demand and output from route assignment. The model, including six stages of Trip Generation, Destination Choice, Mode Choice, Departure Time Choice, Route Assignment and Intersection Control is briefly outlined. This is followed by an application comparing a base year 1990 application with a forecast year of 2010. The 2010 forecast is solved both with and without feedback for comparison purposes. Incorporation of feedback gives significantly different results than the standard model. David Levinson and Ajay Kumar Integrating Feedback into the Transportation Planning Model: Structure and Application2 ________________________________________________________________________ Recently, some literature has appeared on combining demand, assignment, and intersection control into a single modeling framework ,( 3 ). This paper reviews the theory and develops a procedure with feedback between assignment, demand, and intersection control. The procedure is applied to the Baltimore-Washington metropolitan region. The results suggest that introducing feedback between congested travel times and demand and between link flows and intersection control provides a more realistic representation of travel patterns and traffic flows. The procedure is especially relevant in the context of long-term forecasting when we have even less understanding of the possible interrelationship between travel demand and emerging metropolitan structure.

The Clean Air Act mandates that the US Environmental Protection Agency (EPA) develop National Ambient Air Quality Standards for criteria air pollutants and conduct periodic reviews of the standards based on new scientific evidence. In recent reviews, evidence from epidemiologic studies has played a key role. Epidemiologic studies often provide evidence for effects of several air pollutants. Determining whether there are independent effects of the separate pollutants is a challenge. Among the many issues confronting the interpretation of epidemiologic studies of multi-pollutant exposures and health effects are those specifically related to statistical modeling. The EPA convened a workshop on 13 and 14 December 2006 in Chapel Hill, North Carolina, USA, to discuss these and other issues; Session Three of the workshop was devoted specifically to statistical modeling. Prominent statistical modeling issues in epidemiologic studies of air pollution include (1) measurement error across the co-pollutants; (2) correlation and multi-collinearity among the co-pollutants; (3) the timing of the concentration-response function; (4) confounding; and (5) spatial analyses.

Title IV of the 1990 Clean Air Act Amendments introduced a cap-and-trade system for sulfur dioxide emissions from electric power plants in the United States. This paper analyzes the effects of that regulatory change on the prices charged by the two railroads that hauled low-sulfur coal east from Wyoming.

This study examines the optimum automotive emission control levels within a marginal benefit-cost framework. We assume that benefits consist of market and nonmarket components. Cost of control is estimated from historical and projected data ft9 published in the literature. The results of the analyses indicate that even with a high estimate of benefits, the economically optimal vehicle emission levels are strikingly less severe than those required by the 1970 Clean Air Act.

The Air Toxics Health Effects Database (ATHED) is currently used by the EPA's Office of Air Quality Planning and Standards (OAQPS) to support risk assessments for the Residual Risk Program. An assessment of the residual risk is required to be performed at a specified time (typically 8years) following the promulgation of a technology-based Maximum Achievable Control Technologies (MACT) standard. The goal of the Residual Risk Program is to assure that the risk that remains after MACT standards are implemented (i.e., the "residual risk") is acceptable, and if not, to propose additional regulations to mitigate those risks. ATHED maintains all available reference values for each chemical as separate data records, and includes values for all exposure durations (acute, short-term, subchronic and chronic). These values are used as benchmarks to determine acceptable exposure levels to the hazardous air pollutants (HAPs) listed in Section 112 of the Clean Air Act. ATHED also provides useful background information on the uncertainty and/or modifying factors that were applied in the derivation of each reference value, as well as the point of departure and the critical study/studies. To facilitate comparisons across durations for a specific chemical, ATHED data can be graphically presented.

The Clean Air Act mandates that the US Environmental Protection Agency (EPA) develop National Ambient Air Quality Standards for criteria air pollutants and conduct periodic reviews of the standards based on new scientific evidence. In recent reviews, evidence from epidemiologic studies has played a key role. Epidemiologic studies often provide evidence for effects of several air pollutants. Determining whether there are independent effects of the separate pollutants is a challenge. Among the many issues confronting the interpretation of epidemiologic studies of multi-pollutant exposures and health effects are those specifically related to statistical modeling. The EPA convened a workshop on 13 and 14 December 2006 in Chapel Hill, North Carolina, USA, to discuss these and other issues; Session Three of the workshop was devoted specifically to statistical modeling. Prominent statistical modeling issues in epidemiologic studies of air pollution include (1) measurement error across the co-pollutants; (2) correlation and multi-collinearity among the co-pollutants; (3) the timing of the concentration-response function; (4) confounding; and (5) spatial analyses.

Mount Washington, NH in the White Mountain National Forest, is flanked to the north-northeast and south by two Class I Wilderness areas, the Great Gulf and Presidential Range-Dry River Wildernesses, respectively. The Clean Air Act protects Class I Area natural resource values from air pollution. Aerosol sulfate, a fine particulate component that is often transported long distances, is a known contributor to visibility degradation and acidic deposition. We examined summertime fine particulate aerosol mass and sulfate, strong acidity and ammonium concentrations from 1988 to 2007 on Mount Washington at two elevations, 452 and 1540 m (msl). The former site is often within, and the latter at the interface of, the planetary boundary layer. Comparisons of sampling interval durations (10 and 24 h) and site vs. site are made. We also examine the extent to which aerosol sulfate is neutralized. Ten hour (daytime) compared to 24 h samples have higher mass and aerosol sulfate concentrations, however paired samples are well correlated. Fine mass concentrations compared between the 452 m and 1540 m sites (standard temperature and pressure corrected) show a weak positive linear relationship with the later being approximately 32% lower. We attribute the lack of a strong correlation to the facts that the 1540 m site is commonly at the interface of and even above the regional planetary boundary layer in summer and that it can intercept different air masses relative to the 452 m site. Sulfate is w18% lower at the higher elevation site, but comprises a greater percentage of total fine mass; 42% compared to 37% for the high and low elevation site, respectively. Aerosol strong acidity was found to increase with increasing sulfate concentrations at both sites. Further the ratio of hydrogen to sulfate ion was greater in 24 h than 10 h samples at the higher elevation site likely due to overnight transport of fresh acidic aerosols.

The original US Clean Air Act (CAA), implemented by the Environmental Protection Agency in 1971, and the amendments to the act in 1977 and 1990 have required a considerable evolution of the quality of coal burned by utilities and in the type pollution control equipment needed to reduce SO 2 and NO x emissions. Any change in coal quality or emission's control implies a change in the amount, type, and quality of coal combustion by-products (CCB). CCB is a collective term for fly ash, bottom ash and boiler slag, and flue-gas desulfurization (FGD) or fluidized-bed combustion produced in coal burning.

The grandfathering of existing sources of pollution is a common feature of the regulatory state. Sources in operation at the time of the enactment of new regulatory requirements are typically exempted from these requirements because of the high cost of retrofitting their operations. Grandfathering regimes give existing sources a significant advantage relative to new sources and therefore give them an

The integrated biogeochemical model, PnET-BGC, was used to simulate the response of soil and surface water at the reference watershed (W6) at the Hubbard Brook Experimental Forest, New Hampshire, to changes in atmospheric deposition. The performance of the model was assessed using two objective statistical criteria, the normalized mean absolute error, and the efficiency, in order to compare simulated results with observed values between 1980 and 1998. Model results showed good agreement with measured concentrations of stream Ca 2+ , and SO 4 2À , while stream NO 3 À and Al concentrations and soil solution Ca/Al ratios were over predicted after 1990. Model simulations showed that there was some improvement in soil and stream chemistry in response to the 1990 Amendments to the Clean Air Act (CAAA) compared to conditions without this legislation. However, the 1990 CAAA will not result in substantial changes in critical indicators (e.g. soil base saturation, soil solution Ca/Al, stream pH, acid neutralizing capacity (ANC) and Al concentrations). The slow recovery rates suggest that additional reduction in strong acid inputs will be required to significantly alleviate ecosystem stress from acidic deposition. Simulation of the impact of equivalent reductions in SO 4 2À and NO 3 À deposition indicated slightly greater recovery under the SO 4 2À reductions compared with NO 3

This paper studies fiscal federalism when voter information varies across regions. We develop a model of political agency with heterogeneously informed voters. Rent-seeking politicians provide public goods to win the votes of the informed. As a result, rent extraction is lower in regions with higher information. In equilibrium, electoral discipline has decreasing returns. Thus, political centralization efficiently reduces aggregate rent

The aim of the present paper is to offer an exploratory contribution to the general debate on sustainable transport, in particular from the perspective of impact assessment of sustainable transport policy. Specifically, starting from data available from different public sources in the United States, two different types of analyses are conducted: (1) comparison of the declared short term results of

Methanogenic flowthrough aquifer columns were used to investigate the potential of bioaugmentation to enhance anaerobic benzene-toluene-ethylbenzene-xylene (BTEX) degradation in groundwater contaminated with ethanol-blended gasoline. Two different methanogenic consortia (enriched with benzene or toluene and o-xylene) were used as inocula. Toluene was the only hydrocarbon degraded within 3 years in columns that were not bioaugmented, although anaerobic toluene degradation was observed after only 2 years of acclimation. Significant benzene biodegradation (up to 88%) was observed only in a column bioaugmented with the benzene-enriched methanogenic consortium, and this removal efficiency was sustained for 1 year with no significant decrease in permeability due to bioaugmentation. Benzene removal was hindered by the presence of toluene, which is a more labile substrate under anaerobic conditions. Real-time quantitative PCR analysis showed that the highest numbers of bssA gene copies (coding for benzylsuccinate synthase) occurred in aquifer samples exhibiting the highest rate of toluene degradation, which suggests that this gene could be a useful biomarker for environmental forensic analysis of anaerobic toluene bioremediation potential. bssA continued to be detected in the columns 1 year after column feeding ceased, indicating the robustness of the added catabolic potential. Overall, these results suggest that anaerobic bioaugmentation might enhance the natural attenuation of BTEX in groundwater contaminated with ethanol-blended gasoline, although field trials would be needed to demonstrate its feasibility. This approach may be especially attractive for removing benzene, which is the most toxic and commonly the most persistent BTEX compound under anaerobic conditions. on October 16, 2015 by guest http://aem.asm.org/ Downloaded from FIG. 5. Persistence of the bssA gene in soil samples from the column bioaugmented with toluene-and o-xylene-enriched methanogenic consortium. Open bars, 1 year after inoculation; filled bars, 1 year after exposure to BTEX and ethanol (EtOH) ceased.

Relatively little is known about the spectrum of health effects, and the scope and level of ambient air concentrations of those pollutants regulated under the Clean Air Act as "hazardous air pollutants." The U.S. Environmental Protection Agency's (USEPA) Cumulative Exposure Project uses currently available emissions inventories, from a variety of source types, and an atmospheric dispersion model to provide estimates of ambient concentrations for 148 hazardous air pollutants (HAPs) in over 60,000 census tracts for the year 1990. This paper uses currently available hazard information for those pollutants and provides a database of potential regulatory threshold concentrations

This article seeks to briefly evaluate the context behind the development of regulations related to chromium pollution control in metal finishing industries. The available evidence suggests the possibility of elevation of the issue to the agenda for agency rule-making, and subsequent implementation can occur even in the absence of focusing events. Based on historical evidence, this article illustrates that gradual accumulation of knowledge of harmful effects of chromium over the period of decades has been instrumental in the formulation and implementation of standards and guidelines to regulate chromium in the environment under major statutes such as the Clean Air Act, the Clean Water Act, the Safe Drinking Water Act, and so on. The implementation of command and control regulations has resulted in appreciable reduction of chromium released into the environment, thereby minimizing the impact on human health and the environment. However, achieving full compliance from metal finishing industries is still an illusion. There are examples of violations committed by industries. In response to this realization, policy evolution in the chromium pollution control domain has occurred in two directions: (1) gradual replacement of existing standards with more stringent standards and guidelines and (2) emphasis on multimedia, voluntary, and participatory approaches to improve compliance. But the results from the latter are not as dramatic as previously envisioned. Borrowing from the experience of the Common Sense Initiative (CSI), this article argues that consensus-based, multistakeholder collaboration can be a policy development tool.

The US Acid Rain Program (Title IV of the 1990 Clean Air Act Amendments) has achieved substantial reductions in emissions of sulfur dioxide (SO 2 ) and nitrogen oxides (NO x ) from power plants in the United States. We compare new estimates of the benefits and costs of Title IV to those made in 1990. Important changes in our understanding of and ability to quantify the benefits of Title IV have occurred. Benefits to human health now take a much higher profile because the contribution of SO 2 and NO x emissions to the formation of fine particulate (PM 2.5 ) is substantial, and evidence of the harmful human health effects of PM 2.5 has emerged in the last 15 years. New estimates of the health benefits of PM 2.5 reductions are the largest category of quantified health and environmental benefits and total over US$100 billion annually for 2010 when the program is expected to be fully implemented. Although important uncertainties exist in any specific estimate of the benefits, even if the estimates were calculated using more limiting assumptions and interpretations of the literature they would still substantially exceed the costs. Estimates of annualized costs for 2010 are about US$3 billion, which is less than half of what was estimated in 1990. Research since 1990 also suggests that environmental problems associated with acid deposition and nitrogen deposition are more challenging to resolve than originally thought and will require larger reductions in emissions to reverse. The greater than expected benefits to human health, the greater vulnerability of natural resources and ecosystems, and the lower than expected costs all point to the conclusion that further reductions in SO 2 and NO x emissions from power plants beyond those currently required by Title IV are warranted. q