An evaluation of the tapered element oscillating microbalance method for measuring diesel particulate emissions

We determined the usefulness of tapered element oscillating microbalances (TEOMs) for researchers and engineers involved with measuring diesel particulate mass. Two different test facilities were used for generating diesel particulates and comparing the TEOM to the commonly used U.S. Environmental Protection Agency (EPA) manual filter method. The EPA method is very labor-intensive and requires long periods of time to complete. The TEOM is an attractive approach because it has the potential to reduce the amount of time and labor required in diesel testing, as well as to provide real-time particulate-mass data that are not obtainable with the EPA method. It was found that the TEOM was a precise and easy-to-operate instrument that could measure the mass concentration (MC) of diesel particulate emissions in real time. Although the TEOM diesel particulate MC measurements were highly correlated with the manual filter measurements, the two techniques were not equivalent because the TEOM consistently reported MC results that were 20-25% lower than those obtained using the manual filter technique. In conclusion, the TEOM can be used to increase test-cell throughput and to measure transient values of diesel particulate emissions at sites performing diesel-engine testing. However, unless EPA is able to certify the TEOM as an equivalent method, it cannot replace the manual filter method for diesel certification work.     

An Evaluation of the Tapered Element Oscillating Microbalance Method for Measuring Diesel Particulate Emissions

Abstract

We determined the usefulness of tapered element oscillating microbalances (TEOMs) for researchers and engineers involved with measuring diesel particulate mass. Two different test facilities were used for generating diesel particulates and comparing the TEOM to the commonly used U.S. Environmental Protection Agency (EPA) manual filter method. The EPA method is very labor-intensive and requires long periods of time to complete. The TEOM is an attractive approach because it has the potential to reduce the amount of time and labor required in diesel testing, as well as to provide real-time particulate-mass data that are not obtainable with the EPA method. It was found that the TEOM was a precise and easy-to-operate instrument that could measure the mass concentration (MC) of diesel particulate emissions in real time. Although the TEOM diesel particulate MC measurements were highly correlated with the manual filter measurements, the two techniques were not equivalent because the TEOM consistently reported MC results that were 20–25% lower than those obtained using the manual filter technique. In conclusion, the TEOM can be used to increase test-cell throughput and to measure transient values of diesel par-ticulate emissions at sites performing diesel-engine testing. However, unless EPA is able to certify the TEOM as an equivalent method, it cannot replace the manual filter method for diesel certification work.     

Effects of Fuel Variables on Diesel Emissions

The body of information presented in this paper is directed towards engineers in the field of environmental sciences involved in measuring and/or evaluating the emissions from a variety of diesel engines or vehicles. This paper summarizes recent data obtained by EPA on identification and quantification of different emissions (i.e. characterization) from a variety of diesel engines.

Extensive work has been done comparing emissions from some light duty diesel and gasoline passenger cars. The work on the diesel vehicles was expanded to include tests with five different diesel fuels to determine how fuel composition affects emissions. This work showed that use of a poorer quality fuel frequently made emissions worse. The investigation of fuel composition continued with a project in which specific fuel parameters were systematically varied to determine their effect on emissions. EPA is presently testing a variety of fuels derived from coal and oil shale to determine their effects on emissions.

EPA has also tested a heavy duty Volvo diesel bus engine designed to run on methanol and diesel fuel, each injected through its own injection system. The use of the dual fuel resulted in a reduction in particulates and NO _x but an increase in HC and CO compared to a baseline Volvo diesel engine running on pure diesel fuel.

Finally, some Ames bioassay tests have been performed on samples from the diesel passenger cars operated on various fuels and blends. An increase in Ames test response (mutagenicity) was seen when the higher aromatic blend was used and also when a commercial cetane improver was used. Samples from the Volvo diesel bus engine fueled with methanol and diesel fuel showed that use of a catalyst increased the Ames response.     

Multiple-year black carbon measurements and source apportionment using delta-C in Rochester, New York

Black carbon (BC), an important component ofthe atmospheric aerosol, has climatic, environmental, and human health significance. In this study, BC was continuously measured using a two-wavelength aethalometer (370 nm and 880 nm) in Rochester; New York, from January 2007 to December 2010. The monitoring site is adjacent to two major urban highways (I-490 and I-590), where 14% to 21% of the total traffic was heavy-duty diesel vehicles. The annual average BC concentrations were 0.76 microg/m3, 0.67 microg/m3, 0.60 microg/m3, and 0.52 microg/m3 in 2007, 2008, 2009, and 2010, respectively. Positive matrix factorization (PMF) modeling was performed using PM2.5 elements, sulfate, nitrate, ammonia, elemental carbon (EC), and organic carbon (OC) data from the US. Environmental Protection Agency (EPA) speciation network and Delta-C (UVBC370nm-BC880nm) data. Delta-C has been previously shown to be a tracer of wood combustion factor It was used as an input variable in source apportionment models for the first time in this study and was found to play an important role in separating traffic (especially diesel) emissions from wood combustion emissions. The result showed the annual average PM2.5 concentrations apportioned to diesel emissions in 2007, 2008, 2009, and 2010 were 1.34 microg/m3, 1.25 microg/m3, 1.13 microg/m3, and 0.97 microg/m3, respectively. The BC conditional probability function (CPF) plots show a large contribution from the highway diesel traffic to elevated BC concentrations. The measurements and modeling results suggest an impact of the US Environmental Protection Agency (EPA) 2007 Heavy-Duty Highway Rule on the decrease ofBC and PM2.5 concentrations during the study period.     

Review of Federally Sponsored Research on Diesel Exhaust Odors

The information presented in this paper is directed to persons concerned with control of exhaust odors from diesel-engine-powered vehicles. This paper summarizes projects sponsored by the Environmental Protection Agency (EPA) over the past years in the field of diesel-exhaust odor. These investigations have concentrated on developing measurement methods for quantifying different odor levels, evaluating various odor control methods, and evaluating public opinions of such odors.

A human panel method using odor reference standards has been found suitable to measure these odor levels. In addition to this technique, chemical characterization work has been sponsored under a project jointly sponsored by the Coordinating Research Council and the EPA to isolate and identify those species responsible for the odor.

Knowledge of these odorous compounds and the techniques necessary to isolate them should lead to development of a chemical method to measure this type of odor, in place of human panelists. Such basic information would also lead to developing control techniques to minimize this odor.

Several control techniques were evaluated for diesel exhaust odor. To date, the most effective method is an improved needle injector for use in the Detroit Diesel type E 6V-71 engine commonly used in buses.

Finally, public reaction to diesel-engine-exhaust odor has been measured. It has been found that a systematic relationship exists between increasing public objections and increasing diesel odor intensity.     

Multiple-year black carbon measurements and source apportionment using Delta-C in Rochester,New York

Black carbon (BC), an important component of the atmospheric aerosol, has climatic, environmental, and human health significance. In this study, BC was continuously measured using a two-wavelength aethalometer (370 nm and 880 nm) in Rochester, New York, from January 2007 to December 2010. The monitoring site is adjacent to two major urban highways (I-490 and I-590), where 14% to 21% of the total traffic was heavy-duty diesel vehicles. The annual average BC concentrations were 0.76 μg/m³, 0.67 μg/m³, 0.60 μg/m³, and 0.52 μg/m³ in 2007, 2008, 2009, and 2010, respectively. Positive matrix factorization (PMF) modeling was performed using PM_2.5 elements, sulfate, nitrate, ammonia, elemental carbon (EC), and organic carbon (OC) data from the U.S. Environmental Protection Agency (EPA) speciation network and Delta-C (UVBC_370nm – BC_880nm) data. Delta-C has been previously shown to be a tracer of wood combustion factor. It was used as an input variable in source apportionment models for the first time in this study and was found to play an important role in separating traffic (especially diesel) emissions from wood combustion emissions. The result showed the annual average PM_2.5 concentrations apportioned to diesel emissions in 2007, 2008, 2009, and 2010 were 1.34 μg/m³, 1.25 μg/m³, 1.13 μg/m³, and 0.97 μg/m³, respectively. The BC conditional probability function (CPF) plots show a large contribution from the highway diesel traffic to elevated BC concentrations. The measurements and modeling results suggest an impact of the U.S Environmental Protection Agency (EPA) 2007 Heavy-Duty Highway Rule on the decrease of BC and PM_2.5 concentrations during the study period.

Implications: This study suggests that there was an observable impact of the U.S EPA 2007 Heavy-Duty Highway Rule on the ambient black carbon concentrations in Rochester, New York. Aethalometer Delta-C was used as an input variable in source apportionment models and it allowed the separation of traffic (especially diesel) emissions from wood combustion emissions.     

Particulate Matter in New Technology Diesel Exhaust (NTDE) is Quantitatively and Qualitatively Very Different from that Found in Traditional Diesel Exhaust (TDE)

ABSTRACT

Diesel exhaust (DE) characteristic of pre-1988 engines is classified as a “probable” human carcinogen (Group 2A) by the International Agency for Research on Cancer (IARC), and the U.S. Environmental Protection Agency has classified DE as “likely to be carcinogenic to humans.” These classifications were based on the large body of health effect studies conducted on DE over the past 30 or so years. However, increasingly stringent U.S. emissions standards (1988–2010) for particulate matter (PM) and nitrogen oxides (NO_x) in diesel exhaust have helped stimulate major technological advances in diesel engine technology and diesel fuel/lubricant composition, resulting in the emergence of what has been termed New Technology Diesel Exhaust, or NTDE. NTDE is defined as DE from post-2006 and older retrofit diesel engines that incorporate a variety of technological advancements, including electronic controls, ultra-low-sulfur diesel fuel, oxidation catalysts, and wall-flow diesel particulate filters (DPFs). As discussed in a prior review (T. W. Hesterberg et al.; Environ. Sci. Technol. 2008, 42, 6437-6445), numerous emissions characterization studies have demonstrated marked differences in regulated and unregulated emissions between NTDE and “traditional diesel exhaust” (TDE) from pre-1988 diesel engines. Now there exist even more data demonstrating significant chemical and physical distinctions between the diesel exhaust particulate (DEP) in NTDE versus DEP from pre-2007 diesel technology, and its greater resemblance to particulate emissions from compressed natural gas (CNG) or gasoline engines. Furthermore, preliminary toxicological data suggest that the changes to the physical and chemical composition of NTDE lead to differences in biological responses between NTDE versus TDE exposure. Ongoing studies are expected to address some of the remaining data gaps in the understanding of possible NTDE health effects, but there is now sufficient evidence to conclude that health effects studies of pre-2007 DE likely have little relevance in assessing the potential health risks of NTDE exposures.

IMPLICATIONS Based on the distinct physical and chemical properties of New Technology Diesel Exhaust (NTDE), it has become clear that findings from the health effects studies conducted on traditional DE (TDE) over the last 30 years have little relevance to NTDE, which is more similar to the exhaust from compressed natural gas (CNG) or gasoline engine emissions than to traditional TDE. Once sufficient health effects data are available for NTDE, it will thus be necessary to conduct new hazard and risk assessments for NTDE that are independent of the DE toxicological database acquired on emissions from pre–2007 diesel technology.     

Particulate matter in new technology diesel exhaust (NTDE) is quantitatively and qualitatively very different from that found in traditional diesel exhaust (TDE)

Diesel exhaust (DE) characteristic of pre-1988 engines is classified as a "probable" human carcinogen (Group 2A) by the International Agency for Research on Cancer (IARC), and the U.S. Environmental Protection Agency has classified DE as "likely to be carcinogenic to humans." These classifications were based on the large body of health effect studies conducted on DE over the past 30 or so years. However, increasingly stringent U.S. emissions standards (1988-2010) for particulate matter (PM) and nitrogen oxides (NOx) in diesel exhaust have helped stimulate major technological advances in diesel engine technology and diesel fuel/lubricant composition, resulting in the emergence of what has been termed New Technology Diesel Exhaust, or NTDE. NTDE is defined as DE from post-2006 and older retrofit diesel engines that incorporate a variety of technological advancements, including electronic controls, ultra-low-sulfur diesel fuel, oxidation catalysts, and wall-flow diesel particulate filters (DPFs). As discussed in a prior review (T. W. Hesterberg et al.; Environ. Sci. Technol. 2008, 42, 6437-6445), numerous emissions characterization studies have demonstrated marked differences in regulated and unregulated emissions between NTDE and "traditional diesel exhaust" (TDE) from pre-1988 diesel engines. Now there exist even more data demonstrating significant chemical and physical distinctions between the diesel exhaust particulate (DEP) in NTDE versus DEP from pre-2007 diesel technology, and its greater resemblance to particulate emissions from compressed natural gas (CNG) or gasoline engines. Furthermore, preliminary toxicological data suggest that the changes to the physical and chemical composition of NTDE lead to differences in biological responses between NTDE versus TDE exposure. Ongoing studies are expected to address some of the remaining data gaps in the understanding of possible NTDE health effects, but there is now sufficient evidence to conclude that health effects studies of pre-2007 DE likely have little relevance in assessing the potential health risks of NTDE exposures.     

Unregulated greenhouse gas and ammonia emissions from current technology heavy-duty vehicles

The study presents the measurement of carbonyl, BTEX (benzene, toluene, ethyl benzene, and xylene), ammonia, elemental/organic carbon (EC/OC), and greenhouse gas emissions from modern heavy-duty diesel and natural gas vehicles. Vehicles from different vocations that included goods movement, refuse trucks, and transit buses were tested on driving cycles representative of their duty cycle. The natural gas vehicle technologies included the stoichiometric engine platform equipped with a three-way catalyst and a diesel-like dual-fuel high-pressure direct-injection technology equipped with a diesel particulate filter (DPF) and a selective catalytic reduction (SCR). The diesel vehicles were equipped with a DPF and SCR. Results of the study show that the BTEX emissions were below detection limits for both diesel and natural gas vehicles, while carbonyl emissions were observed during cold start and low-temperature operations of the natural gas vehicles. Ammonia emissions of about 1 g/mile were observed from the stoichiometric natural gas vehicles equipped with TWC over all the driving cycles. The tailpipe GWP of the stoichiometric natural gas goods movement application was 7% lower than DPF and SCR equipped diesel. In the case of a refuse truck application the stoichiometric natural gas engine exhibited 22% lower GWP than a diesel vehicle. Tailpipe methane emissions contribute to less than 6% of the total GHG emissions.

Implications: Modern heavy-duty diesel and natural gas engines are equipped with multiple after-treatment systems and complex control strategies aimed at meeting both the performance standards for the end user and meeting stringent U.S. Environmental Protection Agency (EPA) emissions regulation. Compared to older technology diesel and natural gas engines, modern engines and after-treatment technology have reduced unregulated emissions to levels close to detection limits. However, brief periods of inefficiencies related to low exhaust thermal energy have been shown to increase both carbonyl and nitrous oxide emissions.     

Determination of acute exposure guideline levels in a dispersion model

The U.S. Environmental Protection Agency (EPA) is in the process of establishing acute exposure guideline levels (AEGLs) for a number of toxic chemicals. These guidelines represent predictable human consequences from measured exposures of selected toxic chemicals over time. They are intended for emergency planning and regulatory purposes. This paper presents a method that can be used by atmospheric dispersion models to compute AEGL values and graphically display the regions exposed to each guideline level on area maps. EPA currently defines three levels of AEGLs corresponding to increasingly severe symptoms, ranging from notable discomfort (AEGL-1) to serious adverse health effects (AEGL-2) to life-threatening effects or death (AEGL-3). For each chemical's three AEGL levels, guideline concentrations are defined for five exposure durations: 10 min, 30 min, 1 hr, 4 hr, and 8 hr. Dispersion models can compute a chemical dosage (time-integrated concentration) and a peak concentration throughout the area exposed to the plume. The AEGL then can be computed by finding the effective duration of the plume at each location, computing the AEGL-equivalent dosages for these durations, and comparing the dosage at each point with the AEGL-equivalent dosages. AEGL contours then can be plotted and readily interpreted in terms of expected toxicity levels for each level of health impact.     

Federal Regulations for New Source Performance Standards

Section 111 of the Clean Air Act Amendments of 1970 authorizes the U.S. Environmental Protection Agency (EPA) to impose emission standards (NSPS) on those stationary sources that are determined to be significant contributors to air pollution and that consequently endanger the public health or welfare. In five years EPA promulgated 19 final and 1 proposed NSPS for stationary sources. Section 112 of the Act authorizes EPA to promulgate national emission standards for hazardous air pollutants (NESHAPS). EPA promulgated three final and 1 proposed regulation under Section 112. In addition, EPA promulgated NSPS for three "designated" pollutants from specific sources under Section Hid. EPA’s use of Section 111 and 112 authority provides for a quick response emission control program compared to the relatively slow process of establishing additional ambient air quality standards and having the states adopt implementation plans (Section 109). Three court cases, argued in the U.S. Court of Appeals for the District of Columbia, established basic guidelines for future promulgation of NSPS although certain legal actions are still pending. Proposed amendments to the Clean Air Act would further broaden and strengthen EPA’s direct regulatory authority.     

柴油机排放颗粒物净化技术研究进展

柴油机被认为是城市大气微粒的主要污染源。柴油机颗粒物组成复杂并且颗粒粒径甚小,大都属于亚微米级粒子和纳米级粒子。因而柴油机颗粒物对人类健康和大气环境的影响受到世人的广泛关注。本文主要对柴油机排放颗粒物的生成机理、化学组成及危害、物理性质、检测方法和净化技术等方面进行综述与探讨。     

Regulated and unregulated emissions from modern 2010 emissions-compliant heavy-duty on-highway diesel engines

The U.S. Environmental Protection Agency (EPA) established strict regulations for highway diesel engine exhaust emissions of particulate matter (PM) and nitrogen oxides (NO_x) to aid in meeting the National Ambient Air Quality Standards. The emission standards were phased in with stringent standards for 2007 model year (MY) heavy-duty engines (HDEs), and even more stringent NO_X standards for 2010 and later model years. The Health Effects Institute, in cooperation with the Coordinating Research Council, funded by government and the private sector, designed and conducted a research program, the Advanced Collaborative Emission Study (ACES), with multiple objectives, including detailed characterization of the emissions from both 2007- and 2010-compliant engines. The results from emission testing of 2007-compliant engines have already been reported in a previous publication. This paper reports the emissions testing results for three heavy-duty 2010-compliant engines intended for on-highway use. These engines were equipped with an exhaust diesel oxidation catalyst (DOC), high-efficiency catalyzed diesel particle filter (DPF), urea-based selective catalytic reduction catalyst (SCR), and ammonia slip catalyst (AMOX), and were fueled with ultra-low-sulfur diesel fuel (~6.5 ppm sulfur). Average regulated and unregulated emissions of more than 780 chemical species were characterized in engine exhaust under transient engine operation using the Federal Test Procedure cycle and a 16-hr duty cycle representing a wide dynamic range of real-world engine operation. The 2010 engines’ regulated emissions of PM, NO_X, nonmethane hydrocarbons, and carbon monoxide were all well below the EPA 2010 emission standards. Moreover, the unregulated emissions of polycyclic aromatic hydrocarbons (PAHs), nitroPAHs, hopanes and steranes, alcohols and organic acids, alkanes, carbonyls, dioxins and furans, inorganic ions, metals and elements, elemental carbon, and particle number were substantially (90 to >99%) lower than pre-2007-technology engine emissions, and also substantially (46 to >99%) lower than the 2007-technology engine emissions characterized in the previous study.

Implications:?Heavy-duty on-highway diesel engines equipped with DOC/DPF/SCR/AMOX and fueled with ultra-low-sulfur diesel fuel produced lower emissions than the stringent 2010 emission standards established by the U.S. Environmental Protection Agency. They also resulted in significant reductions in a wide range of unregulated toxic emission compounds relative to older technology engines. The increased use of newer technology (2010+) diesel engines in the on-highway sector and the adaptation of such technology by other sectors such as nonroad, displacing older, higher emissions engines, will have a positive impact on ambient levels of PM, NOx, and volatile organic compounds, in addition to many other toxic compounds.     

C5–C12 volatile organic compounds at roadside,residential, and background locations in Ankara,Turkey: Temporal and spatial variations and sources

Abstract

Particle emissions of modern diesel engines are of a particular interest because of their negative health effects. The special interest is in nanosized solid particles. The effect of an open channel filter on particle emissions of a modern heavy-duty diesel engine (MAN D2066 LF31, model year 2006) was studied. Here, the authors show that the open channel filter made from metal screen efficiently reduced the number of the smallest particles and, notably, the number and mass concentration of soot particles. The filter used in this study reached 78% particle mass reduction over the European Steady Cycle. Considering the size-segregated number concentration reduction, the collection efficiency was over 95% for particles smaller than 10 nm. The diffusion is the dominant collection mechanism in small particle sizes, thus the collection efficiency decreased as particle size increased, attaining 50% at 100 nm. The overall particle number reduction was 66–99%, and for accumulation-mode particles the number concentration reduction was 62–69%, both depending on the engine load.     

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.     

Determination of PAHs in diesel particulate matter using thermal extraction and solid phase micro-extraction

Determination of polycyclic aromatic hydrocarbons (PAHs) from chemical analysis of the diesel particulate matter (DPM) requires considerable sampling expertise and is often time-consuming because sample preparation demands strict extraction procedures due to the complex nature of the DPM matrix. In this study, a method to measure the emissions of the 16-U.S. Environmental Protection Agency (EPA) priority PAHs adsorbed in diesel particles has been developed. This method involves the capture of the DPM in glass microfibre filters, thermal extraction of the compounds from the particulate matrix in a thermogravimetric analyzer (TGA), determination of the concentration by means of a solid phase micro-extraction (SPME) fibre and subsequent analysis using a gas chromatograph coupled to a mass spectrometer (GC/MS). Analyses of a fully characterised DPM prepared by the National Institute of Standards and Technology, NIST (SRM 1650b), were performed and calculated errors showed that the method is capable of giving reliable quantitative data. Additionally, DPM collected from a diesel engine was analyzed and the results showed the high method sensitivity to the engine operating conditions.     

The "Least Favored Method"—A Primer on the RCRA Land Disposal Regulations

In May of 1990 the U.S. Environmental Protection Agency (EPA) completed a four year long series of rulemakings on land disposal of over. 450 hazardous wastes regulated under the Resource Conservation and Recovery Act (RCRA). The new regulations stipulate that hazardous wastes may not be disposed of on land—if at all—unless they are first treated in a prescribed manner. The Land Disposal Regulations (LDRs) will change disposal requirements for approximately 41 million tons of hazardous waste annually, at a cost to the regulated community of over a billion dollars. Despite EPA’s efforts to educate industry, the LDRs remain a source of confusion for many. This article is intended to clear up at least some of the confusion by providing an overview of the regulations and the decision-making processes which occurred during the four years of EPA rulemakings and, more recently, in the courts.     

Oxidant generation and toxicity enhancement of aged-diesel exhaust

Diesel exhaust related airborne Particulate Matter (PM) has been linked to a myriad of adverse health outcomes, ranging from cancer to cardiopulmonary disease. The underlying toxicological mechanisms are of great scientific interest. A hypothesis under investigation is that many of the adverse health effects may derive from oxidative stress, initiated by the formation of reactive oxygen species (ROS) within affected cells. In this study, the main objective was to determine whether aged-diesel exhaust PM has a higher oxidant generation and toxicity than fresh diesel exhaust PM. The diesel exhaust PM was generated from a 1980 Mercedes-Benz model 300SD, and a dual 270 m³ Teflon film chamber was utilized to generate two test atmospheres. One side of the chamber is used to produce ozone–diesel exhaust PM system, and another side of the chamber was used to produce diesel exhaust PM only system. A newly optimized dithiothreitol (DTT) method was used to assess their oxidant generation and toxicity. The results of this study showed: (1) both fresh and aged-diesel exhaust PM had high oxidant generation and toxicity; (2) ozone–diesel exhaust PM had a higher toxicity response than diesel exhaust PM only; (3) the diesel exhaust PM toxicity increased with time; (4) the optimized DTT method could be used as a good quantitative chemical assay for oxidant generation and toxicity measurement.     

Review of light-duty diesel and heavy-duty diesel gasoline inspection programs

Emissions from diesel vehicles and gas-powered heavy-duty vehicles are becoming a new focus of many inspection and maintenance (I/M) programs. Diesel particulate matter (PM) is increasingly becoming more recognized as an important health concern, while at the same time, the public awareness of diesel PM emissions because of their visibility have combined to increase the focus on diesel emissions in the United States. This has resulted in an increased interest by some states in including heavy-duty vehicle testing in their I/M program. This paper provides an overview of existing I/M programs focused on testing light-duty diesel vehicles, heavy-duty diesel vehicles, and heavy-duty gasoline vehicles (HDGVs). Information on 39 I/M programs in 27 different states in the United States plus 9 international inspection programs is included. Information on the status of diesel emissions technology and current test procedures is also presented. The goal is to provide useful information for air quality managers as they work to decide whether such I/M programs would be worth pursuing in their respective areas and in evaluating the emissions measurement technology to be used in the program. Testing of HDGVs is generally limited to idle testing, because dynamometer testing of these vehicles is not practical, and most were not certified on a chassis basis. Testing of diesel vehicles has mostly been limited to SAE J1667 "snap-idle" opacity testing. Cost-effective technology for measuring diesel emissions currently does not exist, and, therefore, opacity-type measurements, although not effective at reducing the pollutants of most significant health concern, will continue to be used.     

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.