Previous analysis of historical air quality data for the southern Arizona region (Linak and Peter... more Previous analysis of historical air quality data for the southern Arizona region (Linak and Peterson, 1981 Atmospheric Enoironment 15, 2421-2432) suggested that sulfur containing aerosol species have a significant impact on local visibility. A field monitoring program was therefore undertaken to further characterize the particle size and chemical distribution of atmospheric aerosols in the area. Measurements of various gaseous pollutants, meteorological conditions and light-scattering coefficient were also included. Separate studies during winter and summer months were made to discern seasonal changes in aerosol behavior. In addition to detailed analysis ofdata for selected days, statistical analysis of the entire data set was performed. It was found that, while localized visibility correlated best with large-particle aerosol volume, regional haze was most affected by small-particle (sub pm) aerosol volume.
When "containerized" liquid wastes, bound on sorbents. are introduced i... more When "containerized" liquid wastes, bound on sorbents. are introduced into a rotary kiln in a batch mode, transient phenomena in-volving heat transfer into, and waste mass transfer out of, the sorbent can oromote the raoid release of waste vaoor into the kiln environment. This raoid vaoor release can cause depletion and displacement of the excess oxygen from the primary flame, and formation ofa "puff," which can result in a temporary Failure orthe incinerator system. Parametric studies on a specially designed rotary kiln incinerator simulator showed that puffs are easily generated even with very small quantities of surrogate wastes and at excess air values exceeding 100 percent. Furthermore, their magnitudes and intensities increase with increasing kiln temperature and kiln rotation speed. A theoretical model describing simultaneous heat and mass transfer through a sorbent aggregate, coupled with vapor pressure driven waste vaporization within the sorbent aggregate, was combined with a fragmcntauon model and was able qualitatively to predict experimentally observed effects relating to puff duration, kiln rotation speed, kiln temperature. and stoichiometric oxygen requirement of the surrogate waste. Extrapolation of the model to conditions beyond the experimental test matrix indicated very strong influences of waste boiling point (and consequently latent heat), and of sorbent parameters such as overall void fraction in the container and the sorption characteristics of the individual sorbent particles. The theoretical results support the experimental data from the rotary kiln incinerator simulator and suggest that the experimentally observed trends have general practical validity. The model constitutes a first step in being able to rank wastes and sorbents with respect to their propensity to produce puffs.
Studies during the past 50 years have characterized the carcinogenicity and mutagenicity of extra... more Studies during the past 50 years have characterized the carcinogenicity and mutagenicity of extractable organic material (EOM) of particulate matter (PM) in ambient air and from combustion emissions. We have summarized conclusions from these studies and present data supporting those conclusions for 50 combustion emissions, including carcinogenic potencies on mouse skin (papillomas/mouse/mg EOM), mutagenic potencies (revertants/μg EOM) in the Salmonella (Ames) mutagenicity assay, and mutagenicity emission factors (revertants/kg fuel or revertants/MJthermal) in Salmonella. Mutagenic potencies of EOM from PM in ambient air and combustion emissions span 1–2 orders of magnitude, respectively. In contrast, the revertants/m3 span >5 orders of magnitude due to variable PM concentrations in ambient air. Carcinogenic potencies of EOM from combustion emissions on mouse skin and EOM‐associated human lung cancer risk from those emissions both span ~3 orders of magnitude and are highly associa...
Journal of the Air & Waste Management Association, 2022
ABSTRACT A combustion model, originally developed to simulate the destruction of chemical warfare... more ABSTRACT A combustion model, originally developed to simulate the destruction of chemical warfare agents, was modified to include C1-C3 fluorinated organic reactions and kinetics compiled by the National Institute of Standards and Technology (NIST). A simplified plug flow reactor version of this model was used to predict the destruction efficiency (DE) and formation of products of incomplete combustion (PICs) for three C1 and C2 per- and poly-fluorinated alkyl substances (PFAS) (CF4, CHF3, and C2F6) and compare predicted values to Fourier Transform Infrared spectroscopy (FTIR)-based measurements made from a pilot-scale EPA research combustor (40–64 kW, natural gas-fired, 20% excess air). PFAS were introduced through the flame, and at post-flame locations along a time-temperature profile allowing for simulation of direct flame and non-flame injection, and examination of the sensitivity of PFAS destruction on temperature and free radical flame chemistry. Results indicate that CF4 is particularly difficult to destroy with DEs ranging from ~60 to 95% when introduced through the flame at increasing furnace loads. Due to the presence of lower energy C-H and C-C bonds to initiate molecular dissociation reactions, CHF3 and C2F6 were easier to destroy, exhibiting DEs >99% even when introduced post-flame. However, these lower bond energies may also lead to the formation of CF2 and CF3 radicals at thermal conditions unable to fully de-fluorinate these species and formation of fluorinated PICs. DEs determined by the model agreed well with the measurements for CHF3 and C2F6 but overpredicted DEs at high temperatures and underpredicted DEs at low temperatures for CF4. However, high DEs do not necessarily mean absence of PICs, with both model predictions and limited FTIR measurements indicating the presence of similar fluorinated PICs in the combustion emissions. The FTIR was able to provide real-time emission measurements and additional model development may improve prediction of PFAS destruction and PIC formation. Implications: The widespread use of PFAS for over 70 years has led to their presence in multiple environmental matrixes including human tissues. While the chemical and thermal stability of PFAS are related to their desirable properties, this stability means that PFAS are very slow to degrade naturally and potentially difficult to destroy completely through thermal treatment processes often used for organic waste destruction. In this applied combustion study, model PFAS compounds were introduced to a pilot-scale EPA research furnace. Real-time FTIR measurements were performed of the injected compound and trace products of incomplete combustion (PICs) at operationally relevant conditions, and the results were successfully compared to kinetic model predictions of those same PFAS destruction efficiencies and trace gas-phase PIC constituents. This study represents a significant potential enhancement in available tools to support effective management of PFAS-containing wastes.
This item was digitized from a paper original and/or a microfilm copy. If you need higher-resolut... more This item was digitized from a paper original and/or a microfilm copy. If you need higher-resolution images for any content in this item, please contact us at [email protected]
Given the extent to which per- and polyfluoroalkyl substances (PFAS) are used in commercial and i... more Given the extent to which per- and polyfluoroalkyl substances (PFAS) are used in commercial and industrial applications, the need to evaluate treatment options that reduce environmental emissions and human and ecological exposures of PFAS is becoming more necessary. One specific chemical class of PFAS, fluorotelomer alcohols (FTOHs), have vapor pressures such that a significant fraction is expected to be present in the gas-phase even at ambient temperatures. FTOHs are used in a variety of PFAS applications, including synthesis and material coatings. Using two complementary mass spectrometric methods, the use of calcium oxide (CaO) was examined as a low temperature and potentially low-cost thermal treatment media for removal and destruction of four gas-phase FTOHs of varying molecular weights. This was accomplished by assessing the removal/destruction efficiency of the FTOHs and the formation of fluorinated byproducts as a function of treatment temperature (200 - 800 °C) in the presence of CaO compared to thermal-only destruction. During the treatment process, there is evidence that other PFAS compounds are produced at low temperatures (200 - 600 °C) as the primary FTOH partially degrades. At temperatures above 600 °C, thermal treatment with CaO prevented the formation or removed nearly all these secondary products.
Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 2019
Highlights • Biodiesels are sometimes made of either canola, soy, or waste vegetable oil (WVO). •... more Highlights • Biodiesels are sometimes made of either canola, soy, or waste vegetable oil (WVO). • Comparative mutagenicity of their emissions under the same conditions is needed. • We determined mutagenicity emission factors, revertants/megajoulethermal (rev/MJth). • The rev/MJth in Salmonella TA98 +S9 ranked: petroleum > canola > WVO > soy. • The rev/MJth of biodiesels were generally 50-80% lower than that of petroleum diesel.
Pulverized bituminous coal was burned in a 10W externally heated entrained flow furnace under air... more Pulverized bituminous coal was burned in a 10W externally heated entrained flow furnace under air-combustion and three oxy-combustion inlet oxygen conditions (28, 32, and 36%). Experiments were designed to produce flames with practically relevant stoichiometric ratios (SR=1.2-1.4) and constant residence times (2.3s). Size-classified fly ash samples were collected, and measurements focused on the soot, elemental carbon (EC), and organic carbon (OC) composition of the total and ultrafine (<0.6μm) fly ash. Results indicate that although the total fly ash carbon, as measured by loss on ignition, was always acceptably low (<2%) with all three oxycombustion conditions lower than air-combustion, the ultrafine fly ash for both air-fired and oxy-fired combustion conditions consists primarily of carbonaceous material (50-95%). Carbonaceous components on particles <0.6μm measured by a thermal optical method showed that large fractions (52-93%) consisted of OC rather than EC, as expected. This observation was supported by thermogravimetric analysis indicating that for the air, 28% oxy, and 32% oxy conditions, 14-71% of this material may be OC volatilizing between 100 and 550°C with the remaining 29-86% being EC/soot. However, for the 36% oxy condition, OC may comprise over 90% of the ultrafine carbon with a much smaller EC/ soot contribution. These data were interpreted by considering the effects of oxy-combustion on flame attachment, ignition delay, and soot oxidation of a bituminous coal, and the effects of these processes on OC and EC emissions. Flame aerodynamics and inlet oxidant composition may influence emissions of organic hazardous air pollutants (HAPs) from a bituminous coal. During
Abstract A multivariate statistical analysis of the pollutant and meteorological data collected i... more Abstract A multivariate statistical analysis of the pollutant and meteorological data collected in and near Tucson, Arizona during the period 1974–1978 is presented. These data are analyzed for trends and correlations between visibility (as reported by National Weather Service), light scattering coefficient (from the integrating nephelometer), and atmospheric loadings of various pollutants. Significant findings include (1) evidence of regional sulfate loading, uniformly distributed in urban and nonurban areas and (2) significant correlation of sulfate to light scattering coefficient, but little correlation to NWS visibility. As a result of this analysis, a field study of size and chemical distribution of atmospheric aerosols in this region was undertaken.
Previous analysis of historical air quality data for the southern Arizona region (Linak and Peter... more Previous analysis of historical air quality data for the southern Arizona region (Linak and Peterson, 1981 Atmospheric Enoironment 15, 2421-2432) suggested that sulfur containing aerosol species have a significant impact on local visibility. A field monitoring program was therefore undertaken to further characterize the particle size and chemical distribution of atmospheric aerosols in the area. Measurements of various gaseous pollutants, meteorological conditions and light-scattering coefficient were also included. Separate studies during winter and summer months were made to discern seasonal changes in aerosol behavior. In addition to detailed analysis ofdata for selected days, statistical analysis of the entire data set was performed. It was found that, while localized visibility correlated best with large-particle aerosol volume, regional haze was most affected by small-particle (sub pm) aerosol volume.
This paper summarizes information and results presented at the 1989 Symposium on Stationary Combu... more This paper summarizes information and results presented at the 1989 Symposium on Stationary Combustion NOX Control, held March 6-9, 1989 in San Francisco. Cosponsored by the Electric Power Research Institute (EPRI) and the U.S. Environmental Protection Agency, (EPA) the symposium was the fifth in a biennial series.
There is increasing evidence that exposure to air pollutants during pregnancy can result in a num... more There is increasing evidence that exposure to air pollutants during pregnancy can result in a number of deleterious effects including low birth weight and the incidence of allergic asthma. To investigate the in utero effects of DE exposure, timed pregnant BALB/c mice were exposed to 0, 0.8 or 3.1 mg/m 3 of DE during gestation days (GD) 9 to GD 18. The number of successful pregnancies was 15/20 in the air controls and 10/20 in each of the diesel exposures. Immune function in the 6-week-old offspring as determined by development of delayed type hypersensitivity (DTH) reactions to bovine serum albumin (BSA), antibody titers to injected sheep red blood cells (SRBC), splenic T cells expressing CD45 + CD3 + CD8 + and CD3 + CD25 + , and mRNA expression of TNF-␣, TLR2, SPA , TGF- and Foxp3 in the lung were not affected by prenatal DE exposure. On the other hand, lung TLR4 mRNA expression, the number of neutrophils in the bronchoalveolar lavage fluid (BALF) and splenic T cells expressing CD45 + CD3 + CD4 + and CD4 + CD25 + were differentially affected depending on the DE concentration and gender. When additional groups of mice were sensitized and challenged via the respiratory tract with ovalbumin to induce allergic airway inflammation, female mice had higher protein levels in the BALF compared to males and this was reduced by prenatal exposure to either concentration of DE. No other changes in allergen-induced immunity, lung function or severity of inflammation were noted. Collectively, the results show that in utero exposure to DE altered some baseline inflammatory indices in the lung in a gender-specific manner, but had no effect on development of specific immune responses to experimental antigens, or the severity of allergic lung inflammation.
Exposure to diesel exhaust particles (DEP) induces inflammatory signaling characterized by MAP ki... more Exposure to diesel exhaust particles (DEP) induces inflammatory signaling characterized by MAP kinase-mediated activation of NFkB and AP-1 in vitro and in bronchial biopsies obtained from human subjects exposed to DEP. NFkB and AP-1 activation results in the upregulation of genes involved in promoting inflammation in airway epithelial cells, a principal target of inhaled DEP. IL-8 is a proinflammatory chemokine expressed by the airway epithelium in response to environmental pollutants. The mechanism by which DEP exposure induces IL-8 expression is not well understood. In the current study, we sought to determine whether DEP with varying organic content induces IL-8 expression in lung epithelial cells, as well as, to develop a method to rapidly evaluate the upstream mechanism(s) by which DEP induces IL-8 expression. Exposure to DEP with varying organic content differentially induced IL-8 expression and IL-8 promoter activity human airway epithelial cells. Mutational analysis of the IL-8 promoter was also performed using recombinant human cell lines expressing reporters linked to the mutated promoters. Treatment with a low organic-containing DEP stimulated IL-8 expression by a mechanism that is predominantly NFkB-dependent. In contrast, exposure to high organic-containing DEP induced IL-8 expression independently of NFkB through a mechanism that requires AP-1 activity. Our study reveals that exposure to DEP of varying organic content induces proinflammatory gene expression through multiple specific mechanisms in human airway epithelial cells. The approaches used in the present study demonstrate the utility of a promoter-reporter assay ensemble for identifying transcriptional pathways activated by pollutant exposure.
Ash particle size distributions and ash chemical composition were measured from the convection se... more Ash particle size distributions and ash chemical composition were measured from the convection section of a laboratory-scale pulverized coal combustor for a wide range of staged and unstaged combustion stoichiometries. Samples of bituminous coal and lignites from the western United States were combusted. It was determined that staged combustion tends to increase the final submicron aerosol mass loading for the lignites considered, although the extent of increase depended on the relative composition of volatile ash species. Chemical analysis indicated enrichment of the more volatile species (such as Na and K) both in the smaller particle sizes and on the surfaces of particles.
Substantial research and regulatory efforts have focused on ambient air concentrations of particu... more Substantial research and regulatory efforts have focused on ambient air concentrations of particulate matter (PM) due to epidemiological evidence which links ambient exposures with adverse health effects. More recently, black carbon (BC), a ...
American Journal of Physiology-Lung Cellular and Molecular Physiology, 2006
In vivo exposure to diesel exhaust particles (DEP) elicits acute inflammatory responses in the lu... more In vivo exposure to diesel exhaust particles (DEP) elicits acute inflammatory responses in the lung characterized by inflammatory cell influx and elevated expression of mediators such as cytokines and chemokines. Signal transducers and activators of transcription (STAT) proteins are a family of cytoplasmic transcription factors that are key transducers of signaling in response to cytokine and growth factor stimulation. One member of the STAT family, Stat3, has been implicated as a regulator of inflammation but has not been studied in regard to DEP exposure. The results of this study show that DEP induces Stat3 phosphorylation as early as 1 h following stimulation and that phosphorylated Stat3 translocates into the nucleus. Inhibition of epidermal growth factor receptor (EGFR) and Src activities by the inhibitors PD-153035 and PP2, respectively, abolished the activation of Stat3 by DEP, suggesting that Stat3 activation by DEP requires EGFR and Src kinase activation. The present study...
Previous analysis of historical air quality data for the southern Arizona region (Linak and Peter... more Previous analysis of historical air quality data for the southern Arizona region (Linak and Peterson, 1981 Atmospheric Enoironment 15, 2421-2432) suggested that sulfur containing aerosol species have a significant impact on local visibility. A field monitoring program was therefore undertaken to further characterize the particle size and chemical distribution of atmospheric aerosols in the area. Measurements of various gaseous pollutants, meteorological conditions and light-scattering coefficient were also included. Separate studies during winter and summer months were made to discern seasonal changes in aerosol behavior. In addition to detailed analysis ofdata for selected days, statistical analysis of the entire data set was performed. It was found that, while localized visibility correlated best with large-particle aerosol volume, regional haze was most affected by small-particle (sub pm) aerosol volume.
When &amp;quot;containerized&amp;quot; liquid wastes, bound on sorbents. are introduced i... more When &amp;quot;containerized&amp;quot; liquid wastes, bound on sorbents. are introduced into a rotary kiln in a batch mode, transient phenomena in-volving heat transfer into, and waste mass transfer out of, the sorbent can oromote the raoid release of waste vaoor into the kiln environment. This raoid vaoor release can cause depletion and displacement of the excess oxygen from the primary flame, and formation ofa &amp;quot;puff,&amp;quot; which can result in a temporary Failure orthe incinerator system. Parametric studies on a specially designed rotary kiln incinerator simulator showed that puffs are easily generated even with very small quantities of surrogate wastes and at excess air values exceeding 100 percent. Furthermore, their magnitudes and intensities increase with increasing kiln temperature and kiln rotation speed. A theoretical model describing simultaneous heat and mass transfer through a sorbent aggregate, coupled with vapor pressure driven waste vaporization within the sorbent aggregate, was combined with a fragmcntauon model and was able qualitatively to predict experimentally observed effects relating to puff duration, kiln rotation speed, kiln temperature. and stoichiometric oxygen requirement of the surrogate waste. Extrapolation of the model to conditions beyond the experimental test matrix indicated very strong influences of waste boiling point (and consequently latent heat), and of sorbent parameters such as overall void fraction in the container and the sorption characteristics of the individual sorbent particles. The theoretical results support the experimental data from the rotary kiln incinerator simulator and suggest that the experimentally observed trends have general practical validity. The model constitutes a first step in being able to rank wastes and sorbents with respect to their propensity to produce puffs.
Studies during the past 50 years have characterized the carcinogenicity and mutagenicity of extra... more Studies during the past 50 years have characterized the carcinogenicity and mutagenicity of extractable organic material (EOM) of particulate matter (PM) in ambient air and from combustion emissions. We have summarized conclusions from these studies and present data supporting those conclusions for 50 combustion emissions, including carcinogenic potencies on mouse skin (papillomas/mouse/mg EOM), mutagenic potencies (revertants/μg EOM) in the Salmonella (Ames) mutagenicity assay, and mutagenicity emission factors (revertants/kg fuel or revertants/MJthermal) in Salmonella. Mutagenic potencies of EOM from PM in ambient air and combustion emissions span 1–2 orders of magnitude, respectively. In contrast, the revertants/m3 span >5 orders of magnitude due to variable PM concentrations in ambient air. Carcinogenic potencies of EOM from combustion emissions on mouse skin and EOM‐associated human lung cancer risk from those emissions both span ~3 orders of magnitude and are highly associa...
Journal of the Air & Waste Management Association, 2022
ABSTRACT A combustion model, originally developed to simulate the destruction of chemical warfare... more ABSTRACT A combustion model, originally developed to simulate the destruction of chemical warfare agents, was modified to include C1-C3 fluorinated organic reactions and kinetics compiled by the National Institute of Standards and Technology (NIST). A simplified plug flow reactor version of this model was used to predict the destruction efficiency (DE) and formation of products of incomplete combustion (PICs) for three C1 and C2 per- and poly-fluorinated alkyl substances (PFAS) (CF4, CHF3, and C2F6) and compare predicted values to Fourier Transform Infrared spectroscopy (FTIR)-based measurements made from a pilot-scale EPA research combustor (40–64 kW, natural gas-fired, 20% excess air). PFAS were introduced through the flame, and at post-flame locations along a time-temperature profile allowing for simulation of direct flame and non-flame injection, and examination of the sensitivity of PFAS destruction on temperature and free radical flame chemistry. Results indicate that CF4 is particularly difficult to destroy with DEs ranging from ~60 to 95% when introduced through the flame at increasing furnace loads. Due to the presence of lower energy C-H and C-C bonds to initiate molecular dissociation reactions, CHF3 and C2F6 were easier to destroy, exhibiting DEs >99% even when introduced post-flame. However, these lower bond energies may also lead to the formation of CF2 and CF3 radicals at thermal conditions unable to fully de-fluorinate these species and formation of fluorinated PICs. DEs determined by the model agreed well with the measurements for CHF3 and C2F6 but overpredicted DEs at high temperatures and underpredicted DEs at low temperatures for CF4. However, high DEs do not necessarily mean absence of PICs, with both model predictions and limited FTIR measurements indicating the presence of similar fluorinated PICs in the combustion emissions. The FTIR was able to provide real-time emission measurements and additional model development may improve prediction of PFAS destruction and PIC formation. Implications: The widespread use of PFAS for over 70 years has led to their presence in multiple environmental matrixes including human tissues. While the chemical and thermal stability of PFAS are related to their desirable properties, this stability means that PFAS are very slow to degrade naturally and potentially difficult to destroy completely through thermal treatment processes often used for organic waste destruction. In this applied combustion study, model PFAS compounds were introduced to a pilot-scale EPA research furnace. Real-time FTIR measurements were performed of the injected compound and trace products of incomplete combustion (PICs) at operationally relevant conditions, and the results were successfully compared to kinetic model predictions of those same PFAS destruction efficiencies and trace gas-phase PIC constituents. This study represents a significant potential enhancement in available tools to support effective management of PFAS-containing wastes.
This item was digitized from a paper original and/or a microfilm copy. If you need higher-resolut... more This item was digitized from a paper original and/or a microfilm copy. If you need higher-resolution images for any content in this item, please contact us at [email protected]
Given the extent to which per- and polyfluoroalkyl substances (PFAS) are used in commercial and i... more Given the extent to which per- and polyfluoroalkyl substances (PFAS) are used in commercial and industrial applications, the need to evaluate treatment options that reduce environmental emissions and human and ecological exposures of PFAS is becoming more necessary. One specific chemical class of PFAS, fluorotelomer alcohols (FTOHs), have vapor pressures such that a significant fraction is expected to be present in the gas-phase even at ambient temperatures. FTOHs are used in a variety of PFAS applications, including synthesis and material coatings. Using two complementary mass spectrometric methods, the use of calcium oxide (CaO) was examined as a low temperature and potentially low-cost thermal treatment media for removal and destruction of four gas-phase FTOHs of varying molecular weights. This was accomplished by assessing the removal/destruction efficiency of the FTOHs and the formation of fluorinated byproducts as a function of treatment temperature (200 - 800 °C) in the presence of CaO compared to thermal-only destruction. During the treatment process, there is evidence that other PFAS compounds are produced at low temperatures (200 - 600 °C) as the primary FTOH partially degrades. At temperatures above 600 °C, thermal treatment with CaO prevented the formation or removed nearly all these secondary products.
Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 2019
Highlights • Biodiesels are sometimes made of either canola, soy, or waste vegetable oil (WVO). •... more Highlights • Biodiesels are sometimes made of either canola, soy, or waste vegetable oil (WVO). • Comparative mutagenicity of their emissions under the same conditions is needed. • We determined mutagenicity emission factors, revertants/megajoulethermal (rev/MJth). • The rev/MJth in Salmonella TA98 +S9 ranked: petroleum > canola > WVO > soy. • The rev/MJth of biodiesels were generally 50-80% lower than that of petroleum diesel.
Pulverized bituminous coal was burned in a 10W externally heated entrained flow furnace under air... more Pulverized bituminous coal was burned in a 10W externally heated entrained flow furnace under air-combustion and three oxy-combustion inlet oxygen conditions (28, 32, and 36%). Experiments were designed to produce flames with practically relevant stoichiometric ratios (SR=1.2-1.4) and constant residence times (2.3s). Size-classified fly ash samples were collected, and measurements focused on the soot, elemental carbon (EC), and organic carbon (OC) composition of the total and ultrafine (<0.6μm) fly ash. Results indicate that although the total fly ash carbon, as measured by loss on ignition, was always acceptably low (<2%) with all three oxycombustion conditions lower than air-combustion, the ultrafine fly ash for both air-fired and oxy-fired combustion conditions consists primarily of carbonaceous material (50-95%). Carbonaceous components on particles <0.6μm measured by a thermal optical method showed that large fractions (52-93%) consisted of OC rather than EC, as expected. This observation was supported by thermogravimetric analysis indicating that for the air, 28% oxy, and 32% oxy conditions, 14-71% of this material may be OC volatilizing between 100 and 550°C with the remaining 29-86% being EC/soot. However, for the 36% oxy condition, OC may comprise over 90% of the ultrafine carbon with a much smaller EC/ soot contribution. These data were interpreted by considering the effects of oxy-combustion on flame attachment, ignition delay, and soot oxidation of a bituminous coal, and the effects of these processes on OC and EC emissions. Flame aerodynamics and inlet oxidant composition may influence emissions of organic hazardous air pollutants (HAPs) from a bituminous coal. During
Abstract A multivariate statistical analysis of the pollutant and meteorological data collected i... more Abstract A multivariate statistical analysis of the pollutant and meteorological data collected in and near Tucson, Arizona during the period 1974–1978 is presented. These data are analyzed for trends and correlations between visibility (as reported by National Weather Service), light scattering coefficient (from the integrating nephelometer), and atmospheric loadings of various pollutants. Significant findings include (1) evidence of regional sulfate loading, uniformly distributed in urban and nonurban areas and (2) significant correlation of sulfate to light scattering coefficient, but little correlation to NWS visibility. As a result of this analysis, a field study of size and chemical distribution of atmospheric aerosols in this region was undertaken.
Previous analysis of historical air quality data for the southern Arizona region (Linak and Peter... more Previous analysis of historical air quality data for the southern Arizona region (Linak and Peterson, 1981 Atmospheric Enoironment 15, 2421-2432) suggested that sulfur containing aerosol species have a significant impact on local visibility. A field monitoring program was therefore undertaken to further characterize the particle size and chemical distribution of atmospheric aerosols in the area. Measurements of various gaseous pollutants, meteorological conditions and light-scattering coefficient were also included. Separate studies during winter and summer months were made to discern seasonal changes in aerosol behavior. In addition to detailed analysis ofdata for selected days, statistical analysis of the entire data set was performed. It was found that, while localized visibility correlated best with large-particle aerosol volume, regional haze was most affected by small-particle (sub pm) aerosol volume.
This paper summarizes information and results presented at the 1989 Symposium on Stationary Combu... more This paper summarizes information and results presented at the 1989 Symposium on Stationary Combustion NOX Control, held March 6-9, 1989 in San Francisco. Cosponsored by the Electric Power Research Institute (EPRI) and the U.S. Environmental Protection Agency, (EPA) the symposium was the fifth in a biennial series.
There is increasing evidence that exposure to air pollutants during pregnancy can result in a num... more There is increasing evidence that exposure to air pollutants during pregnancy can result in a number of deleterious effects including low birth weight and the incidence of allergic asthma. To investigate the in utero effects of DE exposure, timed pregnant BALB/c mice were exposed to 0, 0.8 or 3.1 mg/m 3 of DE during gestation days (GD) 9 to GD 18. The number of successful pregnancies was 15/20 in the air controls and 10/20 in each of the diesel exposures. Immune function in the 6-week-old offspring as determined by development of delayed type hypersensitivity (DTH) reactions to bovine serum albumin (BSA), antibody titers to injected sheep red blood cells (SRBC), splenic T cells expressing CD45 + CD3 + CD8 + and CD3 + CD25 + , and mRNA expression of TNF-␣, TLR2, SPA , TGF- and Foxp3 in the lung were not affected by prenatal DE exposure. On the other hand, lung TLR4 mRNA expression, the number of neutrophils in the bronchoalveolar lavage fluid (BALF) and splenic T cells expressing CD45 + CD3 + CD4 + and CD4 + CD25 + were differentially affected depending on the DE concentration and gender. When additional groups of mice were sensitized and challenged via the respiratory tract with ovalbumin to induce allergic airway inflammation, female mice had higher protein levels in the BALF compared to males and this was reduced by prenatal exposure to either concentration of DE. No other changes in allergen-induced immunity, lung function or severity of inflammation were noted. Collectively, the results show that in utero exposure to DE altered some baseline inflammatory indices in the lung in a gender-specific manner, but had no effect on development of specific immune responses to experimental antigens, or the severity of allergic lung inflammation.
Exposure to diesel exhaust particles (DEP) induces inflammatory signaling characterized by MAP ki... more Exposure to diesel exhaust particles (DEP) induces inflammatory signaling characterized by MAP kinase-mediated activation of NFkB and AP-1 in vitro and in bronchial biopsies obtained from human subjects exposed to DEP. NFkB and AP-1 activation results in the upregulation of genes involved in promoting inflammation in airway epithelial cells, a principal target of inhaled DEP. IL-8 is a proinflammatory chemokine expressed by the airway epithelium in response to environmental pollutants. The mechanism by which DEP exposure induces IL-8 expression is not well understood. In the current study, we sought to determine whether DEP with varying organic content induces IL-8 expression in lung epithelial cells, as well as, to develop a method to rapidly evaluate the upstream mechanism(s) by which DEP induces IL-8 expression. Exposure to DEP with varying organic content differentially induced IL-8 expression and IL-8 promoter activity human airway epithelial cells. Mutational analysis of the IL-8 promoter was also performed using recombinant human cell lines expressing reporters linked to the mutated promoters. Treatment with a low organic-containing DEP stimulated IL-8 expression by a mechanism that is predominantly NFkB-dependent. In contrast, exposure to high organic-containing DEP induced IL-8 expression independently of NFkB through a mechanism that requires AP-1 activity. Our study reveals that exposure to DEP of varying organic content induces proinflammatory gene expression through multiple specific mechanisms in human airway epithelial cells. The approaches used in the present study demonstrate the utility of a promoter-reporter assay ensemble for identifying transcriptional pathways activated by pollutant exposure.
Ash particle size distributions and ash chemical composition were measured from the convection se... more Ash particle size distributions and ash chemical composition were measured from the convection section of a laboratory-scale pulverized coal combustor for a wide range of staged and unstaged combustion stoichiometries. Samples of bituminous coal and lignites from the western United States were combusted. It was determined that staged combustion tends to increase the final submicron aerosol mass loading for the lignites considered, although the extent of increase depended on the relative composition of volatile ash species. Chemical analysis indicated enrichment of the more volatile species (such as Na and K) both in the smaller particle sizes and on the surfaces of particles.
Substantial research and regulatory efforts have focused on ambient air concentrations of particu... more Substantial research and regulatory efforts have focused on ambient air concentrations of particulate matter (PM) due to epidemiological evidence which links ambient exposures with adverse health effects. More recently, black carbon (BC), a ...
American Journal of Physiology-Lung Cellular and Molecular Physiology, 2006
In vivo exposure to diesel exhaust particles (DEP) elicits acute inflammatory responses in the lu... more In vivo exposure to diesel exhaust particles (DEP) elicits acute inflammatory responses in the lung characterized by inflammatory cell influx and elevated expression of mediators such as cytokines and chemokines. Signal transducers and activators of transcription (STAT) proteins are a family of cytoplasmic transcription factors that are key transducers of signaling in response to cytokine and growth factor stimulation. One member of the STAT family, Stat3, has been implicated as a regulator of inflammation but has not been studied in regard to DEP exposure. The results of this study show that DEP induces Stat3 phosphorylation as early as 1 h following stimulation and that phosphorylated Stat3 translocates into the nucleus. Inhibition of epidermal growth factor receptor (EGFR) and Src activities by the inhibitors PD-153035 and PP2, respectively, abolished the activation of Stat3 by DEP, suggesting that Stat3 activation by DEP requires EGFR and Src kinase activation. The present study...
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Papers by William Linak