Browsing by Author "Volckens, John, advisor"
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Item Open Access A low-cost monitor for simultaneous measurement of fine particulate matter and aerosol optical depth(Colorado State University. Libraries, 2018) Wendt, Eric, author; Volckens, John, advisor; Jathar, Shantanu, committee member; Yalin, Azer, committee member; Pierce, Jeffrey, committee memberExposure to airborne particulate matter with diameters less than 2.5 µm (PM2.5) is a leading cause of death and disease globally. In addition to affecting health, PM2.5 affects climate and atmospheric visibility. NASA currently uses satellite imaging technology to measure particulate matter air pollution across the world. Satellite image data are used to derive aerosol optical depth (AOD), which is the extinction of light in the atmospheric column. Although AOD data are often used to estimate surface PM2.5 concentration, there is considerable uncertainty associated with the relationship between satellite-derived AOD and ground-level PM2.5. Instruments known as Sun photometers can measure AOD from the Earth's surface and are often used for validation and calibration of satellite data. Reference-grade Sun photometers generally do not have co-located PM2.5 measurements and are too expensive to deploy in large numbers. The objective of this work was to develop an inexpensive and compact integrated PM2.5 mass and AOD sampler known as the Solar-Powered Aerosol Reference Calibrator (SPARC). PM2.5 is sampled using an ultrasonic pumping system, a size-selective cyclone separator, and a filter. Filter measurements can be used to correct the output from a low-cost direct-reading PM2.5 sensor housed within the SPARC. AOD is measured using optically filtered photodiodes at four discrete wavelengths. A suite of integrated sensors enable time-resolved measurement of key metadata including location, altitude, temperature, barometric pressure, relative humidity, solar incidence angle and spatial orientation. The AOD sensors were calibrated relative to a reference monitor in the Aerosol Robotics Network (AERONET). Field validation studies revealed close agreement for AOD values measured between co-located SPARC and AERONET monitors and for PM2.5 mass measured between co-located SPARC and EPA Federal Reference Method (FRM) monitors. These field validation results for this novel monitor demonstrate that AOD and PM2.5 can be accurately measured for the evaluation of AOD:PM2.5 ratios.Item Open Access A personal thermophoretic sampler for airborne nanoparticles(Colorado State University. Libraries, 2010) Thayer, Daniel Lee, author; Marchese, Anthony, advisor; Volckens, John, advisor; Popat, Ketul, committee member; Prieto, Amy, committee memberEngineered nanoparticles are materials with at least one dimension measuring less than 100 nm that are designed on the molecular scale to produce unique or enhanced properties that differ from the bulk material. However, the same properties that make engineered nanoparticles attractive to industry also may present potential health risks to the workers who manufacture them. Very little human exposure data exist for these particles, although they are known enter the body through a number of routes (e.g., respiration, dermal penetrations, and ingestion). Nanoparticles that enter the body can also translocate from one organ to another by virtue of their small size. A cost-effective personal sampler is necessary to evaluate levels of worker exposure to these materials to determine the relative levels of individual risk. Such a sampler must be capable of collecting nanoparticles with high efficiency for subsequent analysis of size, surface chemistry, morphology, and other properties. In addition, the sampler must be able to differentiate between incidental nanoparticles, which are nanoparticles that are naturally present in the environment, and engineered nanoparticles. As detailed in this thesis, a small thermal precipitator was designed to measure breathing-zone concentrations of airborne nanoparticles. The thermal precipitator samples aerosol by producing a 1000 °C cm ' temperature gradient between two aluminum plates (0.1 cm separation distance) using a resistive heater, a thermoelectric cooler, a temperature controller, and two thermistor sensors. The collection efficiency was evaluated for 15, 51, 100, and 240 nm particles at flow rates of 5 and 20 mL/min. Tests were also performed with a zero temperature gradient to determine losses in the device for measurement correction. The homogeneity of particle collection across the collection surface was evaluated using electron microscopy and imaging software. The results indicate that thermal precipitation is a feasible approach for personal monitoring of airborne nanoparticle concentrations in the workplace.Item Open Access Cookstove startup material characterization and quantification and acute cardiopulmonary effects from controlled exposure to cookstove air pollution(Colorado State University. Libraries, 2018) Fedak, Kristen M., author; Peel, Jennifer L., advisor; Volckens, John, advisor; Clark, Maggie, committee member; Nelson, Tracy, committee member; Wilson, Ander, committee memberTo view the abstract, please see the full text of the document.Item Open Access Design of an inhalable aerosol size spectrometer(Colorado State University. Libraries, 2015) Ndonga, Mwangi, author; Volckens, John, advisor; Reynolds, Stephen, committee member; Kreidenweis, Sonia, committee memberIndustrial hygienists lack the proper instruments to measure size distributions of inhalable particulate matter (0-100 μm) as defined by ACGIH/ISO/CEN. The Portable Inhalable Particle Spectrometer (PIPS) was designed to size-segregate IPM in calm-air environments – which constitute a majority of workplaces. The PIPS uses an upward air velocity to restrict particle aspiration into the device to diameters above a specified cut-size. A vertical test chamber was also designed to facilitate aerosol dispersion and experimental evaluation of the PIPS. Two PIPS tubes were tested (1.5 cm and 5 cm) at four face velocities (0.6, 1.35, 2.5 and 3.5 cm·s⁻¹) that correspond to cut-sizes of 20, 30, 40 and 50 μm in aerodynamic diameter, respectively. The observed performance of the PIPS deviated from model estimates as face velocity or tube diameter was increased. The fluid regime present inside the chamber, due to the operating PIPS, likely influenced the measured sampling efficiency of the PIPS.Item Open Access Development and application of an improved in vitro model for aerosol toxicology(Colorado State University. Libraries, 2014) Hawley, Brie, author; Volckens, John, advisor; Dow, Steven, committee member; Ryan, Elizabeth, committee member; Reynolds, Stephen, committee memberIn vitro cellular studies offer an economical and rapid screening tool for assessing aerosol toxicity. Traditional submerged in vitro cell models and exposure techniques are often criticized for their inability to (1) simulate in vivo cellular morphology (2) maintain the chemical and physical characteristics of sampled aerosol and (3) estimate 'delivered' exposure levels. Further, the exposure levels applied in traditional submerged in vitro systems are often orders of magnitude above inhalational exposures that occur in vivo. Improved airway cell culture models and direct air-to-cell exposure systems have been developed over the last few decades; these improvements offer greater 'real-world' significance to in vitro aerosol toxicology. Air-liquid interfaced airway cell cultures offer greater physiological relevance than previous, submerged cell cultures. Further, direct air-to-cell exposure systems offer the ability to (1) better maintain the chemical and physical characteristics of test aerosols and (2) more closely control and approximate exposure levels. Presented here, are two improved direct air-to-cell aerosol exposure systems that rely upon electrostatic deposition or gravitational settling to directly expose well-differentiated airway cell cultures to three different aerosols of interest, with regard to occupational and environmental health. The first and second study presented here used electrostatic deposition to expose well-differentiated normal human bronchial epithelial cells to diesel particulate matter and complete diesel exhaust. Cells were exposed to either (1) diesel particulate matter or (2) complete diesel exhaust from an engine run on either petro- or biodiesel, and with and without a diesel particulate filter. Cellular response was assessed by measuring transcripts associated with inflammation, oxidative stress, aromatic hydrocarbon response and overall cellular dysfunction at 1, 3, 6, 9, and 24 hours after exposure to diesel particulate matter. Cellular response to complete diesel exhaust was assessed by measuring transcripts associated with oxidative stress and aromatic hydrocarbon response at two hours after exposure. The main aims of these two studies were to (1) characterize the time course of the proinflammatory response of normal human bronchial epithelial cells after exposure to diesel particulate matter and (2) screen for the effects of exposure to petro- and biodiesel exhaust, with and without a diesel particulate filter. The third study presented here used gravitational settling to expose well-differentiated human bronchial or nasal epithelial cells to two different particle size fractions from inhalable dust collected at a local dairy parlor. Cellular response was assessed by measuring transcripts associated with inflammation at two hours after exposure. Cell compromise was also measured in all three studies by measuring percent lactate dehydrogenase release. Significant airway cellular responses were observed in all three studies, at levels of exposure far lower than reported in previous traditional in vitro studies. Results from the work presented here strongly support the use of improved airway cell models and direct air-to-cell exposure systems in future in vitro studies in aerosol toxicology.Item Open Access Development and validation of an outdoor low-cost smoke monitor(Colorado State University. Libraries, 2017) Kelleher, Scott, author; Volckens, John, advisor; Jathar, Shantanu, committee member; Anderson, Georgiana Brooke, committee member; Pierce, Jeffrey, committee memberWildfires and prescribed fires produce emissions that are harmful to human health. These health effects, however, are difficult to quantify, likely in part due to sparse data on exposure. The ability to measure fire emissions as they reach sensitive areas is critical to ensuring the protection of public health. Ground level quantification of smoke from wildfires and prescribed fires has proven to be a difficult task. The state of the art for monitoring outdoor air quality has long relied upon expensive, cumbersome equipment that generally requires line power. Few ground-based measurements are typically made during fire events, which limits our ability to quantify and assess the impact of smoke from fire events. The objective of this work was to develop and validate a new type of outdoor air quality monitor, the Outdoor Aerosol Sampler (OAS). The OAS is an active, filter-based air sampler that has been miniaturized and weatherproofed. The OAS represents and attempt to address the technical limitations of field sampling with a device that is relatively inexpensive and independently powered. Prototype development of the OAS was made possible through low-cost electronics, open-source programming platforms, and in house fabrication methods. An online PM2.5 sensor was selected and integrated with the OAS. A Monte Carlo simulation aided in the selection of battery and solar power necessary to independently power the OAS, while keeping cost and size to a minimum. Cellular communications established via Short Message Service (SMS) technology were utilized in transmitting online sensor readings and controlling the OAS remotely. Numerous OAS were deployed to monitor smoke concentrations downwind from a large prescribed fire. Mass concentrations sampled from the burn were interpolated to depict smoke concentration gradients downwind of the fire. Field tests found OAS solar charging efficiency (6.7%) to be slightly less than model input efficiency (7.5%). Outdoor urban testing of the OAS demonstrates moderate agreement with equivalent federal reference method samplers for gravimetric analysis of PM2.5.Item Open Access Development of paper-based analytical devices for particulate metals in welding fume(Colorado State University. Libraries, 2015) Cate, David M., author; Henry, Charles S., advisor; Volckens, John, advisor; Dandy, David, committee member; Peel, Jennifer, committee member; Lear, Kevin, committee memberExposure to metal-containing particulate matter places a tremendous burden on human health. Studies show that exposures lead to cardiovascular disease, asthma, flu-like illnesses, other respiratory disorders, and to increased morbidity. Individuals who work in occupations such as metalworking, construction, transportation, and mining are especially susceptible to unsafe exposures because of their proximity to the source of particle generation. Despite the risk to worker health, relatively few are routinely monitored for their exposure due to the time-intensive and cost-prohibitive analytical methods currently employed. The current paradigm for chemical speciation of workplace pollution is outdated and inefficient. Paper-based microfluidic devices, a new type of sensor technology, are poised to overcome issues associated with chemical analysis of particulate matter, specifically the cost and timeliness of exposure assessment. Paper sensors are designed to manipulate microliter liquid volumes and because flow is passively driven by capillary action, analysis costs are very low. The objective of this work was to develop new technology for rapidly measuring Ni, Cu, Fe, and Cr in welding fume using easy-to-use paper devices. This dissertation covers the development of two techniques for quantifying metal concentration: spot integration and distance-based detection. Metal concentrations as low as 0.02 ppm are reported. A method for controlling reagent deposition as well as a new interface for multiplexed detection of metals, is discussed.Item Open Access Effects of fuel moisture content on pollutant emissions from a rocket-elbow cookstove(Colorado State University. Libraries, 2018) van Zyl, Lizette, author; Volckens, John, advisor; Jathar, Shantanu, committee member; Anderson, Georgiana Brooke, committee memberCookstoves have been studied in recent decades for their health- and environment-relevant emissions. Many pollutants, stoves, and burning parameters have been investigated across these studies, including fuel moisture content, which is believed to have substantial impact on stove emissions. Yet, the effects of fuel moisture content on emissions remain poorly characterized. To address this gap in knowledge, this study characterized particle and gas-phase pollutant emissions during a laboratory experiment exploring three levels of fuel moisture from a single tree sample. Moisture levels tested here varied from 5% to 30% water content, by weight. A novel technique for re-moisturizing the fuel samples was developed and employed to expedite the experimental duration and to ensure consistency across tests. Results from the study demonstrate strong trends in emissions related to changes in moisture content. Results also suggest there are benefits to drying wood to below 10% moisture content as compared to burning wood that is slightly above the 20% level recommended by the U.S. Environmental Protection Agency. When wood was dried to 5% instead of 25%, modified combustion efficiency improved and average mass-based emissions factors decreased for all pollutant species (formaldehyde, acetaldehyde, benzene, toluene, ethylbenzene, m+p-xylenes, o-xylenes, PM2.5, methane, carbon monoxide, and organic carbon) save black carbon. Dry fuel generated less smoke and higher temperatures than wet fuel. Wet fuel was also difficult to keep lit and burned much slower than dry fuel. Efficiency, burn rate, and stove temperature all affect the way people use their stoves for heating or cooking. Since moisture content impacted efficiency, burn rate, and temperature during this study, as well as multiple gas and particle-phase pollutants, moisture content should be accounted for in future stoves studies, both in the lab and in the field.Item Open Access Filtration efficiency and breathability of fabric masks and their dependence on fabric characteristics(Colorado State University. Libraries, 2022) Fontenot, Jacob, author; Volckens, John, advisor; Carter, Ellison, committee member; Jathar, Shantanu, committee memberThroughout the COVID-19 pandemic, the demand for face coverings offering two-way protection significantly increased, which resulted in widespread use of masks made from common fabrics (e.g., wool, cotton, and synthetic materials). However, the effectiveness of these fabric masks, which vary in material and design, is not well understood. This work investigates the performance of fabric masks, namely filtration efficiency and breathability, and their dependence on fabric characteristics. Filtration efficiency (FE) and flow resistance – a measure of mask breathability – were evaluated for 50 fabric masks, followed by individual layer testing (n = 70 total layers). The characteristics of the fabric layers, namely yarn diameter, fiber diameter, thread count, air permeability, porosity, cloth cover factor, infra-red (IR) attenuation, and fabric thickness were quantified in a laboratory setting. Fabric mask FEs were relatively low (i.e., < 50%) for submicron particles but increased with particle diameter. Approximately half of the masks achieved a FE meeting the Level 1 barrier standard specified in ASTM F3502-21. The FE and flow resistance of the component fabric layers was found to accurately predict the FE and flow resistance of the entire mask; therefore, we find that fabric masks can generally be treated as filters in series. FE exhibited the strongest relationship with cloth cover factor, IR attenuation, air permeability, and the number of fabric layers; in contrast, we found little to no relationship between FE and yarn diameter, fiber diameter, thread count, porosity, fabric thickness, and fabric material (e.g., natural vs. synthetic). Results of this work should help inform the design of more effective fabric masks, which could prove especially useful for airborne infectious disease response efforts in resource limited environments (i.e., where N95 technologies are not available) around the planet.Item Open Access Inflammatory effects of cook stove emissions on cultured human bronchial epithelial cells(Colorado State University. Libraries, 2010) Hawley, Brie, author; Volckens, John, advisor; Willson, Bryan, committee member; Reynolds, Stephen J., committee memberApproximately half the world's population uses biomass as a fuel for cooking and heating. This form of combustion is typically achieved by burning wood in a primitive indoor cook stove. Human exposure to combustion byproducts emitted from these 'traditional' stoves is an important global health concern. Such exposures cause an estimated two million premature deaths each year and have been associated with increased incidence of pulmonary disease, eyesight degradation, cancer, and adverse pregnancy outcomes. Many types of 'improved cook stoves' have been developed over the past few decades to address this concern. The aim of this research was to compare the effects of traditional and improved cook stove emissions on normal human bronchial epithelial cells exposed to a single biomass combustion event. We used a direct, aerosolto-cell deposition system to expose cell cultures to cook stove emissions. We then quantified the relative expression of three different mRNA transcripts associated with a cellular inflammation at 1 and 24 hours following exposure. We hypothesized that cultured human bronchial epithelial cells exposed to wood smoke from an improved cook stove would produce lower levels of inflammatory transcripts as compared to cells exposed to emissions from a traditional stove. Wood smoke was generated from three stove types: an energy efficient model designed and distributed by Envirofit International, an energy efficient model designed and distributed by Philips Inc., and a traditional three stone fire. The emissions from each cook stove were substantially different, with the three stone fire having the highest emissions of particle number, particle size, and particle mass. Cellular expression of inflammatory genes was also significantly higher in exposed vs. control cells, with the three stone fire having the greatest effect. These results provide preliminary evidence that improved cook stoves have the potential to improve human health.Item Open Access Laboratory evaluation of a microfluidic electrochemical sensor for aerosol oxidative load(Colorado State University. Libraries, 2012) Shapiro, Jeffrey, author; Volckens, John, advisor; Henry, Charles, committee member; Peel, Jennifer, committee memberHuman exposure to particulate matter (PM) air pollution is associated with both human morbidity and mortality. The mechanisms by which PM impacts human health are yet unresolved, but evidence suggests that PM intake leads to cellular oxidative stress through the generation of reactive oxygen species (ROS). Therefore, reliable tools are needed for estimating the oxidant generating capacity, or oxidative load, of PM. The most widely reported method for assessing PM oxidative load is the dithiothreitol (DTT) assay. The traditional DTT assay utilizes filter-based PM collection in conjunction with laboratory analysis. However, the traditional DTT assay suffers from poor time resolution, loss of reactive species during sampling, and high limit of detection. Recently, a new DTT assay was developed by coupling a Particle Into Liquid Sampler with microfluidic-electrochemical detection. This 'on-line' system allows continuous monitoring of PM reactivity (~three minute measurement resolution) from substantially reduced sample masses (nanograms). This study reports on a laboratory evaluation of the on-line DTT approach. A standard urban dust sample was aerosolized in a laboratory test chamber at three atmospherically-relevant concentrations allowing comparison of the on-line and traditional DTT methods. The on-line system gave a stronger correlation between DTT consumption rate and PM mass (R2 = 0.93) than the traditional method (R2 = 0.29). The on-line system also reported ~1.4 times greater relative reactivity for a given PM sample compared to the traditional method (p = 0.022) indicating improved efficiency for the capture and detection of redox-active species. These results suggest that on-line methods for PM sampling and reactivity analysis may improve our ability to study impacts of PM exposure on human health.Item Open Access Low-cost devices for occupational and environmental exposure assessment(Colorado State University. Libraries, 2018) Quinn, Casey, author; Volckens, John, advisor; Henry, Charles, advisor; Magzamen, Sheryl, committee member; Anderson, Georgiana Brooke, committee member; Reynolds, Stephen, committee memberThe measurement of chemical and physical stressors in occupational and environmental settings traditionally requires sophisticated equipment, trained professionals, and laboratory-based analyses. These requirements are cost and time prohibitive and, thus, limit the quantity and frequency of exposure monitoring. This dissertation focuses on the development of low-cost monitoring tools for evaluation of air and water quality. Water Quality Assessment Metal contamination of natural and drinking water systems poses hazards to public and environmental health. Quantifying metal concentrations in water typically requires sample collection in the field followed by expensive laboratory analysis that can take days to weeks to obtain results. The first portion of this was to develop a low-cost, field-deployable method to quantify trace levels of copper in drinking water by coupling solid-phase extraction/preconcentration with a microfluidic paper-based analytical device. This method has the advantages of being hand-powered (instrument-free) and using a simple 'read by eye' quantification motif (based on color distance). Tap water samples collected across Fort Collins, CO were tested with this method and validated against ICP-MS. We demonstrate the ability to quantify the copper content of tap-water within 30% of a reference technique at levels ranging from 20 to 500,000 ppb. The application of this technology, which should be sufficient as a rapid screening tool, can lead to faster, more cost-effective detection of soluble metals in water systems. Air Quality Assessment Personal monitors for air quality are expensive and cumbersome, which hinders epidemiologic and occupational exposure assessments. The Automated Microenvironmental Aerosol Sampler (AMAS) is a low-cost, wearable device containing four filter-pump assemblies designed to measure personal exposure particulate matter air pollution. This novel device collects size-selective samples of particulate matter from within distinct personal microenvironments (i.e. at home, at work, and in transit). The AMAS uses on-board sensors (GPS, light intensity, temperature, pressure, and acceleration) coupled with an algorithm (developed and described in to this work) to determine when an individual enters a given microenvironment and then initiates sampling through one of three filter assemblies. Low-cost devices capable of in-field quantification of pollutant hazards can allow researchers to afford more monitoring and analysis equipment and increase the size of epidemiology and industrial hygiene cohorts.Item Open Access Low-cost embedded systems for community-driven ambient air quality monitoring(Colorado State University. Libraries, 2022) Wendt, Eric, author; Volckens, John, advisor; Pierce, Jeffrey, committee member; Jathar, Shantanu, committee member; Pasricha, Sudeep, committee memberFine particulate matter (PM2.5) air pollution is a leading cause of death, disease and environmental degradation worldwide. Existing PM2.5 measurement infrastructure provides broad PM2.5 sampling coverage, but due to high costs (>10,000 USD), these instruments are rarely broadly distributed at community-level scales. Low-cost sensors can be more practically deployed in spatial and temporal configurations that can fill the gaps left by more expensive monitors. Crowdsourcing low-cost sensors is a promising deployment strategy in which sensors are operated by interested community members. Prior work has demonstrated the potential of crowdsourced networks, but low-cost sensor technology remains ripe for improvement. Here we describe a body of work aimed toward bolstering the future of community-driven air quality monitoring through technological innovation. We first detail the development of the Aerosol Mass and Optical Depth (AMODv2) sampler, a low-cost monitor capable of unsupervised measurement of PM2.5 mass concentration and Aerosol Optical Depth (AOD), a measure of light extinction in the full atmospheric column due to airborne particles. We highlight key design features of the AMODv2 and demonstrate that its measurements are accurate relative to standard reference monitors. Second we describe a national crowdsourced network of AMODv2s, in which we leveraged the measurement capabilities of the AMODv2 in a network of university students to analyze the relationship between PM2.5 and AOD in the presence of wildfire smoke in the United States. Finally, we propose a cloud screening algorithm for AOD measurements using all-sky images and deep transfer learning. We found that our algorithm correctly screens over 95% of all-sky images for cloud contamination from a custom all-sky image data set. Taken as a whole, our work supports community-driven air pollution monitoring by advancing the tools and strategies communities need to better understand the air they breathe.Item Open Access Personal, spatiotemporal exposure assessment: method development and application(Colorado State University. Libraries, 2013) Adams, Colby D., author; Volckens, John, advisor; Reynolds, Stephen, committee member; Peel, Jennifer, committee member; Brazile, William, committee member; Laituri, Melinda, committee memberTo view the abstract, please see the full text of the document.Item Open Access Quantifying commuter exposures to volatile organic compounds(Colorado State University. Libraries, 2014) Kayne, Ashleigh, author; Volckens, John, advisor; Peel, Jennifer, committee member; Collett, Jeffrey L., committee memberMotor-vehicles can be a predominant source of air pollution in cities. Traffic-related air pollution is often unavoidable for people who live in populous areas. Commuters may have high exposures to traffic-related air pollution as they are close to vehicle tailpipes. Volatile organic compounds (VOCs) are one class of air pollutants of concern because exposure to VOCs carries risk for adverse health effects. Specific VOCs of interest for this work include benzene, toluene, ethylbenzene, and xylenes (BTEX), which are often found in gasoline and combustion products. Although methods exist to measure time-integrated personal exposures to BTEX, there are few practical methods to measure a commuter's time-resolved BTEX exposure which could identify peak exposures that could be concealed with a time-integrated measurement. This study evaluated the ability of a photoionization detector (PID) to measure commuters' exposure to BTEX using Tenax TA samples as a reference and quantified the difference in BTEX exposure between cyclists and drivers with windows open and closed. To determine the suitability of two measurement methods (PID and Tenax TA) for use in this study, the precision, linearity, and limits of detection (LODs) for both the PID and Tenax TA measurement methods were determined in the laboratory with standard BTEX calibration gases. Volunteers commuted from their homes to their work places by cycling or driving while wearing a personal exposure backpack containing a collocated PID and Tenax TA sampler. Volunteers completed a survey and indicated if the windows in their vehicle were open or closed. Comparing pairs of exposure data from the Tenax TA and PID sampling methods determined the suitability of the PID to measure the BTEX exposures of commuters. The difference between BTEX exposures of cyclists and drivers with windows open and closed in Fort Collins was determined. Both the PID and Tenax TA measurement methods were precise and linear when evaluated in the laboratory using standard BTEX gases. The LODs for the Tenax TA sampling tubes (determined with a sample volume of 1,000 standard cubic centimeters which is close to the approximate commuter sample volumes collected) were orders of magnitude lower (0.04 to 0.7 parts per billion (ppb) for individual compounds of BTEX) compared to the PIDs' LODs (9.3 to 15 ppb of a BTEX mixture), which makes the Tenax TA sampling method more suitable to measure BTEX concentrations in the sub-parts per billion (ppb) range. PID and Tenax TA data for commuter exposures were inversely related. The concentrations of VOCs measured by the PID were substantially higher than BTEX concentrations measured by collocated Tenax TA samplers. The inverse trend and the large difference in magnitude between PID responses and Tenax TA BTEX measurements indicates the two methods may have been measuring different air pollutants that are negatively correlated. Drivers in Fort Collins, Colorado with closed windows experienced greater time-weighted average BTEX exposures than cyclists (p: 0.04). Commuter BTEX exposures measured in Fort Collins were lower than commuter exposures measured in prior studies that occurred in larger cities (Boston and Copenhagen). Although route and intake may affect a commuter's BTEX dose, these variables are outside of the scope of this study. Within the limitations of this study (including: small sample size, small representative area of Fort Collins, and respiration rates not taken into account), it appears health risks associated with traffic-induced BTEX exposures may be reduced by commuting via cycling instead of driving with windows closed and living in a less populous area that has less vehicle traffic. Although the PID did not reliably measure low-level commuter BTEX exposures, the Tenax TA sampling method did. The PID measured BTEX concentrations reliably in a controlled environment, at high concentrations (300-800 ppb), and in the absence of other air pollutants. In environments where there could be multiple chemicals present that may produce a PID signal (such as nitrogen dioxide), Tenax TA samplers may be a better choice for measuring BTEX. Tenax TA measurements were the only suitable method within this study to measure commuter's BTEX exposure in Fort Collins, Colorado.Item Open Access Residential cookstove emissions: measurement and modeling from the lab and field(Colorado State University. Libraries, 2018) Bilsback, Kelsey, author; Volckens, John, advisor; Barnes, Elizabeth, committee member; Jathar, Shantanu, committee member; Marchese, Anthony, committee member; Pierce, Jeffrey, committee memberEmissions from solid-fuel cookstoves, which result from poorly controlled combustion, have been linked to indoor and outdoor air pollution, climate forcing, and human disease. The adverse effects of cookstoves have motivated commitment of substantial time and resources towards development of "improved" cookstoves that operate more efficiently and reduce emissions of harmful air pollutants. However, once disseminated to cookstove users, improved cookstoves often do not ameliorate air quality to a level that substantially reduces health risks or negative environmental impacts. Several critical knowledge gaps related to the emissions and performance of "improved" cookstoves exist; attempting to address these gaps is the subject of this dissertation. Widely-used laboratory testing protocols overestimate the ability of improved stoves to lower emissions. In this work, we develop and validated a novel laboratory test protocol entitled the Firepower Sweep Test. We find that the Firepower Sweep Test reproduces the range of PM2.5 and CO emissions observed in the field, including high emissions events not typically observed under current laboratory protocols. We also find that firepower is modestly correlated with emissions, although this relationship depends on stove-fuel combination. Our results justify incorporating multiple-firepower testing into laboratory-based protocols, but demonstrate that firepower alone cannot explain the observed variability in cookstove emissions. Cookstoves emit many pollutants; however, most studies only measure fine particulate matter (PM2.5) and carbon monoxide (CO). In this work, we present an extensive inventory of air pollutants emitted from wood, charcoal, kerosene, and liquefied petroleum gas (LPG) cookstoves. One-hundred and twenty pollutants, including PM2.5, CO, organic matter, elemental carbon, inorganic ions, carbohydrates, ultrafine particles, volatile organic compounds, carbonyls, and polycyclic aromatic hydrocarbons, are included in this inventory. Our results demonstrate that, while most improved stoves tend to reduce PM2.5 and/or CO emissions, reductions PM2.5 and/or CO emissions do not always correspond to reductions of other harmful pollutants. These findings highlight the need to characterize the full emissions profile of "improved" cookstove designs before they are disseminated to users. Accurate emissions data are critical inputs for models that aim to quantify the impacts of cookstoves on climate and health. Currently, model inputs are primarily derived from laboratory experiments that do not represent in-home use. In this work, we present a relatively inexpensive technique that uses a temperature measurement made at the combustion chamber outlet to estimate firepower. These firepower estimations have the potential to provide valuable information about the range of firepowers over which cookstoves are operated at during real-world use. We also demonstrate that in-use firepower measurements from "improved" cookstoves can be combined with laboratory emissions data from the Firepower Sweep Test to estimate in-use emissions using linear regression models. We find that the model predictions are accurate enough to determine which International Standards Organization emissions tier a given "improved" stove is likely to fall under.