Unleaded Gasoline Shortages and Fuel Switching

The use of leaded gasoline in automobiles equipped with catalytic converters causes deactivation of the converters and leads to significant increases in emissions of reactive hydrocarbons, a precursor of ozone. Such fuel switching may be a contributing factor to the increase in photochemical smog levels recently observed in the South Coast Air Basin (SOCAB).     

Assessment of Arsenic Losses during Ashing: A Comparison of Two Methods Applied to Atmospheric Participates

A comparison was made of over 300 pairs of arsenic results from instrumental neutron activation and flameless atomic absorption analyses of atmospheric particulates collected on glass fiber filters. Atomic absorption analyses involved low temperature ashing of filters at high power levels. No matrix modification chemicals were added to the acid extract which was analyzed. Neutron activation results are on the average 9% higher than those obtained by atomic absorption and the difference is statistically significant. This small difference is probably due to the analytical techniques or acid extraction and not in any important way to losses during low temperature ashing. This conclusion is in sharp contrast to other recently reported situations where low temperature ashing losses in analyzing atmospheric particulate were sizable. Although the atmospheres sampled differed somewhat between these situations the most obvious difference was in the combustibility of the filters used in sampling.     

Uncertainty requirements of the European Union’s Industrial Emissions Directive for monitoring sulfur dioxide emissions: Implications from a blind comparison of sulfate measurements by accredited laboratories

When annual average PM_2.5 (fine particulate matter sized 2.5 microns and less) data for 2005 became available in April 2006 and the 3-yr average PM_2.5 concentration in an area just north of the Houston Ship Channel reached 15.0 µg/m³, the Texas Commission on Environmental Quality (TCEQ) initiated daily collection of quartz fiber as well as Teflon PM_2.5 filter samples for chemical speciation analysis. The purpose of the chemical speciation analysis was to use the speciation data, together with meteorological data and hourly TEOM (tapered element oscillating microbalance) PM_2.5 mass data, to identify the causes of the high PM_2.5 concentrations affecting the monitoring site and the neighborhood. The ultimate purpose was to target emission reduction efforts to sources contributing to the high measured PM_2.5 concentrations. After a year of data collection, it was recognized that a specific source, unpaved driveways and loading areas along the Ship Channel and dirt tracked onto Clinton Drive, the main artery running east-west north of the Ship Channel, were the primary cause for the Clinton Drive site's measuring PM_2.5 concentrations significantly higher than other sites in Houston. The source characterization and remediation steps that have led to sustained reduced concentrations are described in this paper.

Implications: With PM_2.5 exceedances it can be essential to have or develop chemical speciation data as part of the process of identifying the source types causing exceedances of an annual standard. Positive matrix factorization (PMF) analysis proved to be a powerful tool that identified the two locally emitted species contributing to exceedances, which did not occur at other sites in the region. They were calcium sulfate (gypsum), an industrial by-product, and soil minerals. Other data analysis approaches were necessary to distinguish North African dust events, which PMF failed to identify.     

Statistical Assumptions Matter in Data Analysis for Texas Ozone Nonattainment Sites

Strategies for control of ozone aim at regulation of its chemical precursors, non-methane organic compounds (NMOC) and nitrogen oxides (NOx). It is therefore important to analyze how these precursors vary temporally and geographically. This study finds significant and important differences among four Texas ozone nonattainment sites, Dallas, Ft. Worth, El Paso, and Houston, for 1984, 1985, and 1986 for NMOC, NOx, and their ratio NNR. These differences were detected through nonparametric analysis of variance and Student-New-man-Keuls’s test for multiple comparisons on rank-transformed data. A noteworthy feature of the data analysis is its attention to the assumptions underlying the statistical methods. Classical models based on normal or lognormal theory had to be abandoned for lack of realism. It is demonstrated how alternative models may be applied to yield appropriate, rather than inappropriate, conclusions.     

The Impact of Increased Recycle Rates on Markets in Florida

The State of Florida passed The Florida Solid Waste Management Act of 1988 mandating that county recycling programs be initiated by July 1, 1989. The legislation further expressed the goal that, at a minimum, recycling efforts reduce the amount of solid waste requiring final disposal or resource recovery by 30 percent by the end of 1994. This study was performed to determine the impact on recycle markets when the amounts of materials recycled from the municipal solid waste stream are increased by 30 percent in Florida.

The composition of the municipal waste stream was quantified in terms of the amounts of paper, plastic, metals, glass, and rubber. The effect of a 30 percent increase in the recycle rate of each class of material was calculated and compared to existing recycle rates in the State of Florida. It was determined that there are few capacity constraints on the increase in recycle rates for aluminum, steel (i.e., tin cans), and color separated glass. There are, however, serious constraints on increasing recycle rates for paper, plastics and rubber tires.     

Mercury Measurement and Its Control: What We Know,Have Learned,and Need to Further Investigate

ABSTRACT

Based on the available evidence of health effects, the U.S. Environmental Protection Agency (EPA) has been evaluating the need to regulate mercury releases to the environment. In response to the congressional mandates in The 1990 Clean Air Act Amendments (CAAA), the EPA has issued the Mercury Study Report and the Study of Hazardous Air Pollutant Emissions from Electric Utility Steam Generating Units Report. In spite of the enormous effort represented by these reports, as well as the efforts of both the U.S. Department of Energy (DOE) and the Electric Power Research Institute (EPRI), in conducting the field measurement programs that form the basis for these reports, a definitive answer on the need for mercury regulation has not been found. However, the EPA, as well as other regulatory agencies and health researchers, have suggested a “plausible link” between anthropogenic sources emitting mercury and the methylation, bioaccumulation in the food chain, and adverse health effects in humans and wildlife.

Policy-makers have recognized that regulations must be based on good science and that a number of issues still remain. These issues can generally be grouped into four main categories: emissions inventory, control technology, fate of releases, and health effects. This paper will discuss recent, ongoing, and planned studies to address the remaining issues regarding the presence of mercury in the environment, with an emphasis on those studies that are directly related to the DOE/Federal Energy Technology Center’s (FETC) programmatic effort.     

The Effects of Repairs on Tailpipe Emissions for On-Board Diagnostics II-Equipped Vehicles with the Malfunction Indicator Light Illuminated

Abstract

A total of 77 On-Board Diagnostics II (OBDII)-equipped vehicles with illuminated malfunction indicator lights (MILs) and non-evaporative codes were tested before and after repair. The test cycles included the Federal Test Procedure (FTP), IM240, and steady-state cycles. A total of 17 vehicles were found with emissions greater than 1.5 times their respective FTP emissions standards. Repair of these vehicles resulted in dramatic reductions in overall emissions for all the cycles. A majority of the remaining vehicles were found to have emissions below the certification standard for the FTP both before and after repair. Repairs for the vehicles with emissions <1.5 times the standard resulted in some smaller but quantifiable emission reductions over the FTP and IM240 but larger reductions over the steady-state driving tests. Misfires, bad oxygen sensors, and exhaust gas recirculation (EGR) problems were the most common non-evaporative causes for triggering the MIL. The results show some fundamental differences between identifying malfunctioning vehicles using OBDII as opposed to more traditional dynamometer tests. In particular, for many systems, OBDII identifies components that are operating outside their design specification rather than for a specific emissions threshold.     

Air Quality Modeling and Decisions for Ozone Reduction Strategies

Abstract

Despite the widespread application of photochemical air quality models (AQMs) in U.S. state implementation planning (SIP) for attainment of the ambient ozone standard, documentation for the reliability of projections has remained highly subjective. An “idealized” evaluation framework is proposed that provides a means for assessing reliability. Applied to 18 cases of regulatory modeling in the early 1990s in North America, a comparative review of these applications is reported. The intercomparisons suggest that more than two thirds of these AQM applications suffered from having inadequate air quality and meteorological databases. Emissions representations often were unreliable; uncertainties were too high. More than two thirds of the performance evaluation efforts were judged to be substandard compared with idealized goals. Meteorological conditions chosen according regulatory guidelines were limited to one or two cases and tended to be similar, thus limiting the extent to which public policy makers could be confident that the emission controls adopted would yield attainment for a broad range of adverse atmospheric conditions. More than half of the studies reviewed did not give sufficient attention to addressing the potential for compensating errors. Corroborative analyses were conducted in only one of the 18 studies reviewed. Insufficient attention was given to the estimation of model and/or input database errors, uncertainties, or variability in all of the cases examined. However, recent SIP and policy‐related regional modeling provides evidence of substantial improvements in the underlying science and available modeling systems used for regulatory decision making. Nevertheless, the availability of suitable databases to support increasingly sophisticated modeling continues to be a concern for many locations. Thus, AQM results may still be subject to significant uncertainties. The evaluative process used here provides a framework for modelers and public policy makers to assess the adequacy of contemporary and future modeling work.