Hazardous air pollutant emissions from gas-fired combustion sources: emissions and the effects of design and fuel type

Air emissions from gas-fired combustion devices such as boilers, process heaters, gas turbines and stationary reciprocating engines contain hazardous air pollutants (HAPs) subjected to consideration under the federal clean air act (CAA). This work presents a recently completed major research project to develop an understanding of HAP emissions from gas-fired boilers and process heaters and new HAP emission factors based on field emission tests of gas-fired external combustion devices used in the petroleum industry. The effect of combustion system design and operating parameters on HAP emissions determined by both field and research tests are discussed. Data from field tests of gas-fired petroleum industry boilers and heaters generally show very low emission levels of organic HAPs. A comparison of the emission data for boilers and process heaters, including units with and without various forms of NOx emission controls, showed no significant difference in organic HAP emission characteristics due to process or burner design. This conclusion is also supported by the results of research tests with different burner designs. Based on field tests of units fired with natural gas and various petroleum industry process gases and research tests in which gas composition was intentionally varied, organic HAP emissions were not determined to be significantly affected by the gas composition. Research data indicate that elevated organic HAP emission levels are found only under extreme operating conditions (starved air or high excess air combustion) associated with poor combustion.     

U. S. EPA Views as “Unwarranted” Federal Regulatory Involvement in Odor Control

ABSTRACT

Although there have been several studies examining emissions of criteria pollutants from in-use alternative fuel vehicles (AFVs), little is known about emissions of hazardous air pollutants (HAPs) from these vehicles. This paper explores HAP tailpipe emissions from a variety of AFVs operating in the federal government fleet and compares these emissions to emissions from identical vehicles operating on reformulated gasoline. Emissions estimates are presented for a variety of fuel/model combinations and on four HAPs (acetaldehyde, 1,3-butadi-ene, benzene, and formaldehyde). The results indicate that all AFVs tested offer reduced emissions of HAPs, with the following exceptions: ethanol fueled vehicles emit more acetaldehyde than RFG vehicles, and ethanol- and methanol-fueled vehicles emit more formaldehyde than RFG vehicles. The results from this paper can lead to more accurate emissions factors for HAPs, thus improving HAP inventory and associated risk estimates for both AFVs and conventional vehicles.     

National estimates of outdoor air toxics concentrations

The Clean Air Act identifies 189 hazardous air pollutants (HAPs), or "air toxics," associated with a wide range of adverse human health effects. The U.S. Environmental Protection Agency has conducted a modeling study with the Assessment System for Population Exposure Nationwide (ASPEN) to gain a greater understanding of the spatial distribution of concentrations of these HAPs resulting from contributions of multiple emission sources. The study estimates year 1990 long-term outdoor concentrations of 148 air toxics for each census tract in the continental United States, utilizing a Gaussian air dispersion modeling approach. Ratios of median national modeled concentrations to estimated emissions indicate that emission totals without consideration of emission source type can be a misleading indicator of air quality. The results also indicate priorities for improvements in modeling methodology and emissions identification. Model performance evaluation suggests a tendency for underprediction of observed concentrations, which is likely due, at least in part, to a number of limitations of the Gaussian modeling formulation. Emissions estimates for HAPs have a high degree of uncertainty and contribute to discrepancies between modeled and monitored concentration estimates. The model's ranking of concentrations among monitoring sites is reasonably good for most of the gaseous HAPs evaluated, with ranking accuracy ranging from 66 to 100%.     

National review of ambient air toxics observations

Ambient air observations of hazardous air pollutant (HAPs), also known as air toxics, derived from routine monitoring networks operated by states, local agencies, and tribes (SLTs), are analyzed to characterize national concentrations and risk across the nation for a representative subset of the 187 designated HAPs. Observations from the National Air Toxics Trend Sites (NATTS) network of 27 stations located in most major urban areas of the contiguous United States have provided a consistent record of HAPs that have been identified as posing the greatest risk since 2003 and have also captured similar concentration patterns of nearly 300 sites operated by SLTs. Relatively high concentration volatile organic compounds (VOCs) such as benzene, formaldehyde, and toluene exhibit the highest annual average concentration levels, typically ranging from 1 to 5 µg/m³. Halogenated (except for methylene chloride) and semivolatile organic compounds (SVOCs) and metals exhibit concentrations typically 2–3 orders of magnitude lower. Formaldehyde is the highest national risk driver based on estimated cancer risk and, nationally, has not exhibited significant changes in concentration, likely associated with the large pool of natural isoprene and formaldehyde emissions. Benzene, toluene, ethylbenzene, and 1,3-butadiene are ubiquitous VOC HAPs with large mobile source contributions that continue to exhibit declining concentrations over the last decade. Common chlorinated organic compounds such as ethylene dichloride and methylene chloride exhibit increasing concentrations. The variety of physical and chemical attributes and measurement technologies across 187 HAPs result in a broad range of method detection limits (MDLs) and cancer risk thresholds that challenge confidence in risk results for low concentration HAPs with MDLs near or greater than risk thresholds. From a national monitoring network perspective, the ability of the HAPs observational database to characterize the multiple pollutant and spatial scale patterns influencing exposure is severely limited and positioned to benefit by leveraging a variety of emerging measurement technologies.

Implications:?Ambient air toxics observation networks have limited ability to characterize the broad suite of hazardous air pollutants (HAPs) that affect exposures across multiple spatial scales. While our networks are best suited to capture major urban-scale signals of ubiquitous volatile organic compound HAPs, incorporation of sensing technologies that address regional and local-scale exposures should be pursued to address major gaps in spatial resolution. Caution should be exercised in interpreting HAPs observations based on data proximity to minimum detection limit and risk thresholds.     

Formation and Removal Reactions of Hazardous Air Pollutants

Current regulatory policies for hazardous air pollutants (HAPs) target the sources of direct emissions. In addition to direct emissions, some of the aromatic, nitrogenated, and oxygenated HAPs can be formed in the atmosphere. Formaldehyde and acetaldehyde, in particular, are produced by almost every hydrocarbon photooxidation reaction. Estimates have been made that, in some urban areas, in situ formation contributes as much as 85 percent of the ambient levels of formaldehyde and 95 percent for acetaldehyde. Over 40 percent of the HAPs being regulated under Title III of the 1990 Clean Air Act Amendments have atmospheric lifetimes of less than one day. The transformation products of these HAPs with low atmospheric persistence are important for assessing risks to human health, especially for cases where the transformation products are more toxic than the HAP itself.     

Emission factors of air toxics from semiconductor manufacturing in Korea

The development of local, accurate emission factors is very important for the estimation of reliable national emissions and air quality management. For that, this study is performed for pollutants released to the atmosphere with source-specific emission tests from the semiconductor manufacturing industry. The semiconductor manufacturing industry is one of the major sources of air toxics or hazardous air pollutants (HAPs); thus, understanding the emission characteristics of the emission source is a very important factor in the development of a control strategy. However, in Korea, there is a general lack of information available on air emissions from the semiconductor industry. The major emission sources of air toxics examined from the semiconductor manufacturing industry were wet chemical stations, coating applications, gaseous operations, photolithography, and miscellaneous devices in the wafer fabrication and semiconductor packaging processes. In this study, analyses of emission characteristics, and the estimations of emission data and factors for air toxics, such as acids, bases, heavy metals, and volatile organic compounds from the semiconductor manufacturing process have been performed. The concentration of hydrogen chloride from the packaging process was the highest among all of the processes. In addition, the emission factor of total volatile organic compounds (TVOCs) for the packaging process was higher than that of the wafer fabrication process. Emission factors estimated in this study were compared with those of Taiwan for evaluation, and they were found to be of similar level in the case of TVOCs and fluorine compounds.     

Volatile organic compound emissions from municipal solid waste disposal sites: a case study of Mumbai, India

Improper solid waste management leads to aesthetic and environmental problems. Emission ofvolatile organic compounds (VOCs) is one of the problems from uncontrolled dumpsite. VOCs are well known to be hazardous to human health and many of them are known or potential carcinogens. They also contribute to ozone formation at ground level and climate change as well. The qualitative and quantitative analysis of VOCs emitting from two municipal waste (MSW) disposal sites in Mumbai, India, namely Deonar and Malad, are presented in this paper. Air at dumpsites was sampled and analyzed on gas chromatography-mass spectrometry (GC-MS) in accordance with U.S. Environmental Protection Agency (EPA) TO-17 compendium method for analysis of toxic compounds. As many as 64 VOCs were qualitatively identified, among which 13 are listed under hazardous air pollutants (HAPs). Study of environmental distribution of a few major VOCs indicates that although air is the principal compartment of residence, they also get considerably partitioned in soil and vegetation. The CO2 equivalent of target VOCs from the landfills in Malad and Deonar shows that the total yearly emissions are 7.89E+03 and 8.08E+02 kg, respectively. The total per hour ozone production from major VOCs was found to be 5.34E-01 ppb in Deonar and 9.55E-02 ppb in Malad. The total carcinogenic risk for the workers in the dumpsite considering all target HAPs are calculated to be 275 persons in 1 million in Deonar and 139 persons in 1 million in Malad.     

Emission Factors of Air Toxics from Semiconductor Manufacturing in Korea

Abstract

The development of local, accurate emission factors is very important for the estimation of reliable national emissions and air quality management. For that, this study is performed for pollutants released to the atmosphere with source-specific emission tests from the semiconductor manufacturing industry. The semiconductor manufacturing industry is one of the major sources of air toxics or hazardous air pollutants (HAPs); thus, understanding the emission characteristics of the emission source is a very important factor in the development of a control strategy. However, in Korea, there is a general lack of information available on air emissions from the semiconductor industry. The major emission sources of air toxics examined from the semiconductor manufacturing industry were wet chemical stations, coating applications, gaseous operations, photolithography, and miscellaneous devices in the wafer fabrication and semiconductor packaging processes. In this study, analyses of emission characteristics, and the estimations of emission data and factors for air toxics, such as acids, bases, heavy metals, and volatile organic compounds from the semiconductor manufacturing process have been performed. The concentration of hydrogen chloride from the packaging process was the highest among all of the processes. In addition, the emission factor of total volatile organic compounds (TVOCs) for the packaging process was higher than that of the wafer fabrication process. Emission factors estimated in this study were compared with those of Taiwan for evaluation, and they were found to be of similar level in the case of TVOCs and fluorine compounds.     

Concentrations of mobile source air pollutants in urban microenvironments

Human exposures to criteria and hazardous air pollutants (HAPs) in urban areas vary greatly due to temporal-spatial variations in emissions, changing meteorology, varying proximity to sources, as well as due to building, vehicle, and other environmental characteristics that influence the amounts of ambient pollutants that penetrate or infiltrate into these microenvironments. Consequently, the exposure estimates derived from central-site ambient measurements are uncertain and tend to underestimate actual exposures. The Exposure Classification Project (ECP) was conducted to measure pollutant concentrations for common urban microenvironments (MEs) for use in evaluating the results of regulatory human exposure models. Nearly 500 sets of measurements were made in three Los Angeles County communities during fall 2008, winter 2009, and summer 2009. MEs included in-vehicle, near-road, outdoor, and indoor locations accessible to the general public. Contemporaneous 1- to 15-min average personal breathing zone concentrations of carbon monoxide (CO), carbon dioxide (CO₂), volatile organic compounds (VOCs), nitric oxide (NO), nitrogen oxides (NO_x), particulate matter (<2.5 μm diameter; PM_2.5) mass, ultrafine particle (UFP; <100 nm diameter) number, black carbon (BC), speciated HAPs (e.g., benzene, toluene, ethylbenzene, xylenes [BTEX], 1,3-butadiene), and ozone (O₃) were measured continuously. In-vehicle and inside/outside measurements were made in various passenger vehicle types and in public buildings to estimate penetration or infiltration factors. A large fraction of the observed pollutant concentrations for on-road MEs, especially near diesel trucks, was unrelated to ambient measurements at nearby monitors. Comparisons of ME concentrations estimated using the median ME/ambient ratio versus regression slopes and intercepts indicate that the regression approach may be more accurate for on-road MEs. Ranges in the ME/ambient ratios among ME categories were generally greater than differences among the three communities for the same ME category, suggesting that the ME proximity factors may be more broadly applicable to urban MEs.

Implications:Estimates of population exposure to air pollutants extrapolated from ambient measurements at ambient fixed site monitors or exposure surrogates are prone to uncertainty. This study measured concentrations of mobile source air toxics (MSAT) and related criteria pollutants within in-vehicle, outdoor near-road, and indoor urban MEs to provide multipollutant ME measurements that can be used to calibrate regulatory exposure models.     

A Comparison of Organic Emissions from Hazardous Waste Incinerators Versus the 1990 Toxics Release Inventory Air Releases

Incineration is often the preferred technology for disposing of hazardous waste and remediating Superfund sites. The effective implementation of this technology is frequently impeded by strong public opposition to hazardous waste incineration (HWI). One of the reasons cited for this opposition is the perception that the emission of organics pose an unreasonable threat to human health. While numerous risk assessments for these facilities have demonstrated that the risks from the inhalation of HWI emissions are very low, this has not totally allayed some of the concerns. In order to put organic emissions in perspective, the mass of these emissions from the incineration of hazardous waste on a national scale has been estimated using “reasonable worst-case” assumptions and compared to the 1990 Toxics Release Inventory (TRI) air releases. Comparisons were made for 15 carcinogenic organic compounds and 17 non-carcinogenic organic compounds. Ratios for all but one of these compound-specific HWI emissions to their corresponding TRI air releases ranged from 0.0003 to 0.678 percent. The total mass emissions (110.5 tons) of all 32 specific organics from HWIs was less than 0.03 percent of the corresponding 1990 TRI air releases (431,586 tons).     

Assessment of volatile organic compound and hazardous air pollutant emissions from oil and natural gas well pads using mobile remote and on-site direct measurements

Emissions of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) from oil and natural gas production were investigated using direct measurements of component-level emissions on pads in the Denver-Julesburg (DJ) Basin and remote measurements of production pad-level emissions in the Barnett, DJ, and Pinedale basins. Results from the 2011 DJ on-site study indicate that emissions from condensate storage tanks are highly variable and can be an important source of VOCs and HAPs, even when control measures are present. Comparison of the measured condensate tank emissions with potentially emitted concentrations modeled using E&P TANKS (American Petroleum Institute [API] Publication 4697) suggested that some of the tanks were likely effectively controlled (emissions less than 95% of potential), whereas others were not. Results also indicate that the use of a commercial high-volume sampler (HVS) without corresponding canister measurements may result in severe underestimates of emissions from condensate tanks. Instantaneous VOC and HAP emissions measured on-site on controlled systems in the DJ Basin were significantly higher than VOC and HAP emission results from the study conducted by Eastern Research Group (ERG) for the City of Fort Worth (2011) using the same method in the Barnett on pads with low or no condensate production. The measured VOC emissions were either lower or not significantly different from the results of studies of uncontrolled emissions from condensate tanks measured by routing all emissions through a single port monitored by a flow measurement device for 24 hr. VOC and HAP concentrations measured remotely using the U.S. Environmental Protection Agency (EPA) Other Test Method (OTM) 33A in the DJ Basin were not significantly different from the on-site measurements, although significant differences between basins were observed.

Implications: VOC and HAP emissions from upstream production operations are important due to their potential impact on regional ozone levels and proximate populations. This study provides information on the sources and variability of VOC and HAP emissions from production pads as well as a comparison between different measurement techniques and laboratory analysis protocols. On-site and remote measurements of VOC and HAP emissions from oil and gas production pads indicate that measurable emissions can occur despite the presence of control measures, often as a result of leaking thief hatch seals on condensate tanks. Furthermore, results from the remote measurement method OTM 33A indicate that it can be used effectively as an inspection technique for identifying oil and gas well pads with large fugitive emissions.     

Advances in science and applications of air pollution monitoring: A case study on oil sands monitoring targeting ecosystem protection

The potential environmental impact of air pollutants emitted from the oil sands industry in Alberta, Canada, has received considerable attention. The mining and processing of bitumen to produce synthetic crude oil, and the waste products associated with this activity, lead to significant emissions of gaseous and particle air pollutants. Deposition of pollutants occurs locally (i.e., near the sources) and also potentially at distances downwind, depending upon each pollutant’s chemical and physical properties and meteorological conditions. The Joint Oil Sands Monitoring Program (JOSM) was initiated in 2012 by the Government of Canada and the Province of Alberta to enhance or improve monitoring of pollutants and their potential impacts. In support of JOSM, Environment and Climate Change Canada (ECCC) undertook a significant research effort via three components: the Air, Water, and Wildlife components, which were implemented to better estimate baseline conditions related to levels of pollutants in the air and water, amounts of deposition, and exposures experienced by the biota. The criteria air contaminants (e.g., nitrogen oxides [NO_x], sulfur dioxide [SO₂], volatile organic compounds [VOCs], particulate matter with an aerodynamic diameter <2.5 μm [PM_2.5]) and their secondary atmospheric products were of interest, as well as toxic compounds, particularly polycyclic aromatic compounds (PACs), trace metals, and mercury (Hg). This critical review discusses the challenges of assessing ecosystem impacts and summarizes the major results of these efforts through approximately 2018. Focus is on the emissions to the air and the findings from the Air Component of the ECCC research and linkages to observations of contaminant levels in the surface waters in the region, in aquatic species, as well as in terrestrial and avian species. The existing evidence of impact on these species is briefly discussed, as is the potential for some of them to serve as sentinel species for the ongoing monitoring needed to better understand potential effects, their potential causes, and to detect future changes. Quantification of the atmospheric emissions of multiple pollutants needs to be improved, as does an understanding of the processes influencing fugitive emissions and local and regional deposition patterns. The influence of multiple stressors on biota exposure and response, from natural bitumen and forest fires to climate change, complicates the current ability to attribute effects to air emissions from the industry. However, there is growing evidence of the impact of current levels of PACs on some species, pointing to the need to improve the ability to predict PAC exposures and the key emission source involved. Although this critical review attempts to integrate some of the findings across the components, in terms of ECCC activities, increased coordination or integration of air, water, and wildlife research would enhance deeper scientific understanding. Improved understanding is needed in order to guide the development of long-term monitoring strategies that could most efficiently inform a future adaptive management approach to oil sands environmental monitoring and prevention of impacts.

Implications: Quantification of atmospheric emissions for multiple pollutants needs to be improved, and reporting mechanisms and standards could be adapted to facilitate such improvements, including periodic validation, particularly where uncertainties are the largest. Understanding of baseline conditions in the air, water and biota has improved significantly; ongoing enhanced monitoring, building on this progress, will help improve ecosystem protection measures in the oil sands region. Sentinel species have been identified that could be used to identify and characterize potential impacts of wildlife exposure, both locally and regionally. Polycyclic aromatic compounds are identified as having an impact on aquatic and terrestrial wildlife at current concentration levels although the significance of these impacts and attribution to emissions from oil sands development requires further assessment. Given the improvement in high resolution air quality prediction models, these should be a valuable tool to future environmental assessments and cumulative environment impact assessments.     

Transfer of methyl chloroform, trichloroethylene and tetrachloroethylene to milk, tissues and expired air following intraruminal or oral administration in lactating goats and milk-fed kids

The distribution of methyl chloroform was determined (MCF), trichloroethylene (TRI) and tetrachloroethylene (PCE) in milk, tissues and expired air by intraruminally administering 0.625 ml kg(-0.75) of an equal-volume mixture of the three compounds to lactating goats. The milk secreted during 24 h after the intraruminal administration contained 1.42 mg of MCF, 1.87 mg of TRI, 6.43 mg of PCE and 0.33 mg of trichloroethanol (TCE). MCF, TRI and PCE appeared in the blood less than 30 min after administration. Oral administration of these chemicals to milk-fed kids showed that at 3.5 h post-administration, the liver contained these chemicals in greatest abundance. The adaptation of milk-fed kids to 3 weeks administration of small amounts of propylene glycol stimulated the metabolic conversion of TRI to TCE. There were linear relationships between the blood concentrations of these chemicals and the expiration rates after oral administration of 0.4 ml kg(-1) of each chemical to milk-fed kids. The expiration rates of MCF, TRI and PCE were 605, 122 and 46 microg min(-1) kg(-1) at 2 microg ml(-1) blood concentrations of MCF, TRI and PCE, respectively. These results suggested that MCF is little metabolized, being most readily exhaled in expired air, while PCE demonstrates the greatest tissue-partitioning, being largely secreted into the milk or retained in the liver. TRI can be extensively metabolized to other compounds such as TCE in milk-fed kids.     

Releases and transfers from petroleum and chemical manufacturing industries in Korea

Considerable effort and expense have been devoted to the estimation and acquisition of Toxics Release Inventory (TRI) data. To reduce the effort required and the number of reporting mistakes in the calculation of emissions, we developed an estimation program named TRIWIN after standardization of emission estimation techniques. The program was distributed to 6 petroleum and 150 chemical manufacturing companies, and emission data for 62 chemicals were collected and analyzed. From the TRIWIN-based results obtained, it was found that more than 90% of releases from petroleum and chemical manufacturing industries in Korea were emitted to atmosphere in 1999. Volatile organic compounds are major aerial contaminants and are released primarily via fugitive emission sources such as valves, pumps, or flanges. In addition, the effect of the application of point-source management was noticeable on the emission quantities. Consequently, TRIWIN not only helped reporters to implement TRI easily and accurately, but also identified emission sources, major pollutants in facilities, and provided a standard method of assessing the environmental impact of facilities.     

Relationship between chlorine consumption and chlorination by-products formation for model compounds

The objective of this research is to investigate the relationship between chlorine decay and the formations of disinfection by-products (DBP), including trichloromethane (TCM) and chloroacetic acid (CAA) in the presence of four model compounds, i.e., resorcinol, phloroglucinol, p-hydroxybenzoic acid, and m-hydroxybenzoic acid. The chlorine degradation in model compounds with OH and/or COOH functional groups were rapid after chlorination. The TCM yields of carboxylic group substituted compounds (3-hydroxybenzoic acid [3-HBA], 4-hydroxybenzoic acid [4-HBA]) were found to be lower than that of the m-dihydroxy substituted compounds. Phloroglucinol, with one more OH substitution group than resorcinol, tends to form significant amounts of CAA after chlorination. However, it was observed that with the COOH substitution of 3-HBA and 4-HBA tend to exhibit more CAA formation potential than resorcinol. The developed parallel second and first-order reaction model for chlorine demand has been successfully utilized for TCM, CAA and DBP formation modeling. A high correlation between CAA and TCM was observed for the model compounds.     

Assessment of the emissions and air quality impacts of biomass and biogas use in California

It is estimated that there is sufficient in-state “technically” recoverable biomass to support nearly 4000 MW of bioelectricity generation capacity. This study assesses the emissions of greenhouse gases and air pollutants and resulting air quality impacts of new and existing bioenergy capacity throughout the state of California, focusing on feedstocks and advanced technologies utilizing biomass resources predominant in each region. The options for bioresources include the production of bioelectricity and renewable natural gas (NG). Emissions of criteria pollutants and greenhouse gases are quantified for a set of scenarios that span the emission factors for power generation and the use of renewable natural gas for vehicle fueling. Emissions are input to the Community Multiscale Air Quality (CMAQ) model to predict regional and statewide temporal air quality impacts from the biopower scenarios. With current technology and at the emission levels of current installations, maximum bioelectricity production could increase nitrogen oxide (NO_x) emissions by 10% in 2020, which would cause increases in ozone and particulate matter concentrations in large areas of California. Technology upgrades would achieve the lowest criteria pollutant emissions. Conversion of biomass to compressed NG (CNG) for vehicles would achieve comparable emission reductions of criteria pollutants and minimize emissions of greenhouse gases (GHG). Air quality modeling of biomass scenarios suggest that applying technological changes and emission controls would minimize the air quality impacts of bioelectricity generation. And a shift from bioelectricity production to CNG production for vehicles would reduce air quality impacts further. From a co-benefits standpoint, CNG production for vehicles appears to provide the best benefits in terms of GHG emissions and air quality.

Implications:?This investigation provides a consistent analysis of air quality impacts and greenhouse gas emissions for scenarios examining increased biomass use. Further work involving economic assessment, seasonal or annual emissions and air quality modeling, and potential exposure analysis would help inform policy makers and industry with respect to further development and direction of biomass policy and bioenergy technology alternatives needed to meet energy and environmental goals in California.     

Use of Bioassay Methods to Evaluate Mutagenicity of Ambient Air Collected Near a Municipal Waste Combustor

An ambient air sampling study was conducted around a municipal waste combustor; a primary goal was to develop procedures and methods to evaluate the emissions of organic mutagens resulting from incomplete combustion of municipal waste. The products of Incomplete combustion from incineration include complex mixtures of organics, particularly polycycllc aromatic compounds, which are present after atmospheric dilution and cooling In emissions as semi-volatile or particle bound organic compounds. Combustion emissions are generally recognized as a potential cancer risk since they contain many carcinogenic and mutagenlc polycyclic aromatic hydrocarbons. Analyzing such a complex mixture for the presence of even a few selected chemicals is difficult and provides risk information on only a fraction of the chemicals present. Bioassay methods, however, may be directly applied to evaluate the mutagenic and potential carcinogenic activity of the complex organics from combustion emissions. The Salmonella (Ames) assay was used to determine the mutagenicity associated with particles from ambient air collected near a municipal waste combustor. Dose-response data was generated, and mutagenicity concentrations were calculated to demonstrate the utility of bioassay In assessing the potential Impact of emissions from municipal waste combustion. This phase of study quantified mutagenicity concentrations In ambient air but did not detect organic mutagens that could be attributed to Incinerator emissions.     

Transport and chemical composition of the summer aerosol in the Norwegian Arctic

The chemical composition and transfer routes of the Arctic aerosol during summer have been studied at Ny-Alesund, Bjørnøya, Hopen and Jan Mayen in the period August/September 1983. Samples were also collected on mainland Norway to assess the origin of aerosols transported to the Norwegian Arctic. The concentrations of Si, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Pb, Zn and Cu were measured in samples from a six-stage cascade impactor of Battelle design by particle-induced X-ray emissions (PIXE). The concentrations of Cd, Ni, Pb and Zn were also measured in samples from high-volume samplers by atomic absorption spectrophotometry (AAS).Three interesting periods were identified from the element concentrations. At the beginning of the measurement campaign, the air pollutants measured at Ny-Alesund and Hopen most likely originated in northern America and Greenland. A few days later, very high concentrations of Cd and Zn at Ny-Alesund seemed to be due to air mass transfer from the Soviet Union. During the last episode, observed at Ny-Alesund and Hopen in September, elevated concentrations of several anthropogenic pollutants appeared to be due to emissions in Europe.The results show that anthropogenic emissions from sources in western Europe, Eurasia and northern America may pollute the Arctic air not only in winter but in summer as well. Present levels of air pollutants in the Norwegian Arctic in summer are within the range of levels observed in other remote regions, but are one order of magnitude higher than in Antarctica.     

Impact of three interactive Texas state regulatory programs to decrease ambient air toxic levels

The Federal Clean Air Act (FCAA) framework envisions a federal-state partnership whereby the development of regulations may be at the federal level or state level with federal oversight. The U.S. Environmental Protection Agency (EPA) establishes National Ambient Air Quality Standards to describe “safe” ambient levels of criteria pollutants. For air toxics, the EPA establishes control technology standards for the 187 listed hazardous air pollutants (HAPs) but does not establish ambient standards for HAPs or other air toxics. Thus, states must ensure that ambient concentrations are not at harmful levels. The Texas Clean Air Act authorizes the Texas Commission on Environmental Quality (TCEQ), the Texas state environmental agency, to control air pollution and protect public health and welfare. The TCEQ employs three interactive programs to ensure that concentrations of air toxics do not exceed levels of potential health concern (LOCs): air permitting, ambient air monitoring, and the Air Pollutant Watch List (APWL). Comprehensive air permit reviews involve the application of best available control technology for new and modified equipment and ensure that permits protect public health and welfare. Protectiveness may be demonstrated by a number of means, including a demonstration that the predicted ground-level concentrations for the permitted emissions, evaluated on a case-by-case and chemical-by-chemical basis, do not cause or contribute to a LOC. The TCEQ's ambient air monitoring program is extensive and provides data to help assess the potential for adverse effects from all operational equipment in an area. If air toxics are persistently monitored at a LOC, an APWL area is established. The purpose of the APWL is to reduce ambient air toxic concentrations below LOCs by focusing TCEQ resources and heightening awareness. This paper will discuss examples of decreases in air toxic levels in Houston and Corpus Christi, Texas, resulting from the interactive nature of these programs.

Implications: Texas recognized through the collection of ambient monitoring data that additional measures beyond federal regulations must be taken to ensure that public health is protected. Texas integrates comprehensive air permitting, extensive ambient air monitoring, and the Air Pollutant Watch List (APWL) to protect the public from hazardous air toxics. Texas issues air permits that are protective of public health and also assesses ambient air to verify that concentrations remain below levels of concern in heavily industrialized areas. Texas developed the APWL to improve air quality in those areas where monitoring indicates a potential concern. This paper illustrates how Texas engaged its three interactive programs to successfully address elevated air toxic levels in Houston and Corpus Christi.