Aerosol Science And Technology[JOURNAL]
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138 papers
Dihydroxyacetone levels in electronic cigarettes: Wick temperature and toxin formation.
Vreeke S, Korzun T, Luo W … +3 more , Jensen RP, Peyton DH, Strongin RM
Aerosol Sci Technol · 2018 · PMID 30686853 · Full text
Recently, we reported the presence of dihydroxyacetone (DHA), the active ingredient in sunless tanners, in the aerosol of an electronic cigarette. DHA has been shown to react with DNA . The FDA restricts the use of DHA t...
Recently, we reported the presence of dihydroxyacetone (DHA), the active ingredient in sunless tanners, in the aerosol of an electronic cigarette. DHA has been shown to react with DNA . The FDA restricts the use of DHA to external application only. It states that it should not be inhaled, ingested, or come into contact with any areas containing mucous membranes, due to unknown risk. Herein, the quantification of DHA in the aerosols of three brands of e-cigarettes has been carried out. These included two devices with horizontal heating coil configurations as well as one with a sub-ohm resistance vertical heating coil. In order to understand and begin to address the origin of DHA and related aerosol products, the wicking properties of the three e-cigarettes were compared. DHA levels were analyzed by a combination of GS/MS and H NMR. DHA was found in all three e-cigarettes, with substantially less in the sub-ohm, vertical coil device as compared to the horizontal coil devices (e.g., 0.088 g/puff vs. 2.29 g/puff, respectively). Correspondingly, the temperature of the wet layer of the wick for the vertical coil was relatively stable, compared to the wicks for the horizontal coils, upon increasing battery power output. This result is in agreement with prior studies of e-cigarette wicking efficiency and aerosol toxin formation. The temperature measurements reported are a simple means for comparing devices with different design properties during operation.
Toxic emissions resulting from sucralose added to electronic cigarette liquids.
El-Hage R, El-Hellani A, Haddad C … +5 more , Salman R, Talih S, Shihadeh A, Eissenberg T, Saliba NA
Aerosol Sci Technol · 2019 · PMID 36506805 · Full text
Electronic cigarettes (ECIGs) are appealing in part because of the many flavors of the liquids used in them. Concerns have been raised that some ECIG liquid flavors, especially those that are sweet, are attracting otherw...
Electronic cigarettes (ECIGs) are appealing in part because of the many flavors of the liquids used in them. Concerns have been raised that some ECIG liquid flavors, especially those that are sweet, are attracting otherwise nicotine-naïve youth to ECIGs. Sucralose is an artificial, non-caloric sweetener that is added to some ECIG liquids. In this study, we evaluated the toxicants, namely isomers of chloropropanols that can be produced when sucralose-containing ECIG liquid is aerosolized. An analytical separation method relying on solid-phase extraction (SPE) to isolate chloropropanols from the propylene glycol/glycerol matrix was developed. Chloropropanols were then derivatized by silylation before they were analyzed on GC-MS. The influence of different ECIG operating conditions on the generation of chloropropanols was studied by varying ECIG device design and power output and also the sucralose concentration of the liquid. Heated sucralose-containing ECIG liquids produce two toxic compounds that can be found in the resulting aerosols. The two chloropropanols, 3-monochloro-1,2-propanediol (3-MCPD) and 1,3-dichloropropanol (1,3-DCP) that were detected under all conditions were found to be correlated significantly with liquid sucralose content. Effective regulation of ECIGs will minimize user and bystander exposure to these and other ECIG toxicants.
Evaluation of total and inhalable samplers for the collection of carbon nanotube and carbon nanofiber aerosols.
Dahm MM, Evans DE, Bertke S … +1 more , Grinshpun SA
Aerosol Sci Technol · 2019 · PMID 35392279 · Full text
A growing number of carbon nanotubes and nanofibers (CNT/F) exposure and epidemiologic studies have utilized 25-mm and 37-mm open-faced cassettes (OFC) to assess the inhalable aerosol fraction. It has been previously est...
A growing number of carbon nanotubes and nanofibers (CNT/F) exposure and epidemiologic studies have utilized 25-mm and 37-mm open-faced cassettes (OFC) to assess the inhalable aerosol fraction. It has been previously established that the 37-mm OFC under-samples particles greater than 20 μm in diameter, but the size-selective characteristics of the 25-mm OFC have not yet been fully evaluated. This article describes an experimental study conducted to determine if the 25- and 37-mm OFCs performed with relative equivalence to a reference inhalable aerosol sampler when challenged with CNT/F particles. Side-by-side paired samples were collected within a small Venturi chamber using a 25-mm styrene OFC, 37-mm styrene OFC, 25-mm aluminum OFC, and Button Inhalable Aerosol Sampler. Three types of CNT/F materials and an Arizona road dust were used as challenge aerosols for the various sampler configurations. Repeated experiments were conducted for each sampler configuration and material. The OFC samplers operated at flow rates of 2 and 5 liters per minute. Results showed that the 25-mm OFC performed comparably to the Button Sampler when challenged with CNT/F aerosols, which was demonstrated in five of the six experimental scenarios with an average error of 20%. Overall, the results of this study indicate that the sampling efficiency of the 25- and 37-mm OFCs adequately followed the ISO/ACGIH/CEN inhalable sampling convention when challenged with CNT/F aerosols. Past exposure and epidemiologic studies that used these OFC samplers can directly compare their results to studies that have used other validated inhalable aerosol samplers.
Combining sensor-based measurement and modeling of PM and black carbon in assessing exposure to indoor aerosols.
Cox J, Cho SH, Ryan P … +7 more , Isiugo K, Ross J, Chillrud S, Zhu Z, Jandarov R, Grinshpun SA, Reponen T
Aerosol Sci Technol · 2019 · PMID 34334878 · Full text
Accurate, cost-effective methods are needed for rapid assessment of traffic-related air pollution (TRAP). Typically, real-time data of particulate matter (PM) from portable sensors have been adjusted using data from refe...
Accurate, cost-effective methods are needed for rapid assessment of traffic-related air pollution (TRAP). Typically, real-time data of particulate matter (PM) from portable sensors have been adjusted using data from reference methods such as gravimetric measurement to improve accuracy. The objective of this study was to create a correction factor or linear regression model for the real-time measurements of the RTI's Micro Personal Exposure Monitor (MicroPEM) and AethLab's microAeth® black carbon (AE51) sensor to generate accurate real-time data for PM (PM) and black carbon (BC) in Cincinnati metropolitan homes. The two sensors and an SKC PM Personal Modular impactor were collocated in 44 indoor sampling events for 2 days in residences near major roadways. The reference filter-based analyses conducted by a laboratory included particle mass (SKC PM and MicroPEM PM) and black carbon (SKC BC); these methods are more accurate than real-time sensors but are also more cumbersome and costly. For PM, the average correction factor, a ratio of gravimetric to real-time, for the MicroPEM PM and SKC PM utilizing the PM and was 0.94 and 0.83, respectively, with a coefficient of variation (CV) of 84% and 52%, respectively; the corresponding linear regression model had a CV of 54% and 25%. For BC, the average correction factor utilizing the BC and SKC BC was 0.74 with a CV of 36% with the associated linear regression model producing a CV of 56%. The results from this study will help ensure that the real-time exposure monitors are capable of detecting an estimated PM after an appropriate statistical model is applied.
Chemical Characterization of Nanoparticles and Volatiles Present in Mainstream Hookah Smoke.
Perraud V, Lawler MJ, Malecha KT … +6 more , Johnson RM, Herman D, Staimer N, Kleinman MT, Nizkorodov SA, Smith JN
Aerosol Sci Technol · 2019 · PMID 33041429 · Full text
Waterpipe smoking is becoming more popular worldwide and there is a pressing need to better characterize the exposure of smokers to chemical compounds present in the mainstream smoke. We report real-time measurements of...
Waterpipe smoking is becoming more popular worldwide and there is a pressing need to better characterize the exposure of smokers to chemical compounds present in the mainstream smoke. We report real-time measurements of mainstream smoke for carbon monoxide, volatile organic compounds and nanoparticle size distribution and chemical composition using a custom dilution flow tube. A conventional tobacco mixture, a dark leaf unwashed tobacco and a nicotine-free herbal tobacco were studied. Results show that carbon monoxide is present in the mainstream smoke and originates primarily from the charcoal used to heat the tobacco. Online measurements of volatile organic compounds in mainstream smoke showed an overwhelming contribution from glycerol. Gas phase analysis also showed that very little filtration of the gas phase products is provided by the percolation of mainstream smoke through water. Waterpipe smoking generated high concentrations of 4-100 nm nanoparticles, which were mainly composed of sugar derivatives and especially abundant in the first 10 min of the smoking session. These measured emissions of volatiles and particles are compared with those from a reference cigarette (3R4F) and represent the equivalent of the emission of one or more entire cigarettes for a single puff of hookah smoke. Considerations related to the health impacts of waterpipe smoking are discussed.
Condensational particle growth device for reliable cell exposure at the air-liquid interface to nanoparticles.
Tilly TB, Ward RX, Luthra JK … +8 more , Robinson S, Eiguren-Fernandez A, Lewis GS, Salisbury RL, Lednicky JA, Sabo-Attwood TL, Hussain SM, Wu CY
Aerosol Sci Technol · 2019 · PMID 33033421 · Full text
A first-of-its-kind aerosol exposure device for toxicity testing, referred to as the Dosimetric Aerosol Inhalation Device (DAVID), was evaluated for its ability to deliver airborne nanoparticles to lung cells grown as a...
A first-of-its-kind aerosol exposure device for toxicity testing, referred to as the Dosimetric Aerosol Inhalation Device (DAVID), was evaluated for its ability to deliver airborne nanoparticles to lung cells grown as air-liquid interface (ALI) cultures. For inhalation studies, ALI lung cell cultures exposed to airborne nanoparticles have more relevancy than the same cells exposed in submerged culture because ALI culture better represents the respiratory physiology and consequently more closely reflect cellular response to aerosol exposure. In DAVID, water condensation grows particles as small as 5 nm to droplets sized > 5 μm for inertial deposition at low flow rates. The application of DAVID for nanotoxicity analysis was evaluated by measuring the amount and variability in the deposition of uranine nanoparticles and then assessing the viability of ALI cell cultures exposed to clean-air under the same operational conditions. The results showed a low coefficient of variation, < 0.25, at most conditions, and low variability in deposition between the exposure wells, trials, and operational flow rates. At an operational flow rate of 4 LPM, no significant changes in cell viability were observed, and minimal effects observed at 6 LPM. The reliable and gentle deposition mechanism of DAVID makes it advantageous for nanoparticle exposure.
Computational Analysis of Deposition and Translocation of Inhaled Nicotine and Acrolein in the Human Body with E-cigarette Puffing Topographies.
Haghnegahdar A, Feng Y, Chen X … +1 more , Lin J
Aerosol Sci Technol · 2018 · PMID 30381781 · Full text
Recently, toxicants such as formaldehyde and acrolein were detected in electronic cigarette (EC) aerosols. It is imperative to conduct research and provide sufficient quantitative evidence to address the associated poten...
Recently, toxicants such as formaldehyde and acrolein were detected in electronic cigarette (EC) aerosols. It is imperative to conduct research and provide sufficient quantitative evidence to address the associated potential health risks. However, it is still a lack of informative data, i.e., high-resolution local dosimetry of inhaled aerosols in lung airways and other systemic regions, due to the limited imaging resolutions, restricted operational flexibilities, and invasive nature of experimental and clinical studies. In this study, an experimentally validated multiscale numerical model, i.e., Computational Fluid-Particle Dynamics (CFPD) model combined with a Physiologically Based Toxicokinetic (PBTK) model is developed to predict the systemic translocation of nicotine and acrolein in the human body after the deposition in the respiratory system. parametric analysis is performed for puff topography influence on the deposition and translocation of nicotine and acrolein in human respiratory systems and the systemic region. Results indicate that the puff volume and holding time can contribute to the variations of the nicotine and acrolein plasma concentration due to enhanced aerosol deposition in the lung. The change in the holding time has resulted in significant difference in the chemical translocation which was neglected in a large group of experimental studies. The capability of simulating multiple puffs of the new CFPD-PBTK model paves the way to a valuable computational simulation tool for assessing the chronic health effects of inhaled EC toxicants.
Fate of pyrazines in the flavored liquids of e-cigarettes.
El-Hage R, El-Hellani A, Salman R … +3 more , Talih S, Shihadeh A, Saliba NA
Aerosol Sci Technol · 2018 · PMID 30233107 · Full text
Popularity of electronic cigarettes (ECIGs) has increased tremendously among young people, in part due to flavoring additives in ECIG liquids. Pyrazines are an important class of these additives, and their presence in to...
Popularity of electronic cigarettes (ECIGs) has increased tremendously among young people, in part due to flavoring additives in ECIG liquids. Pyrazines are an important class of these additives, and their presence in tobacco cigarettes has been correlated with increased acceptability of smoking among smokers and bystanders. Pyrazine use by the tobacco industry is therefore thought to encourage smoking. However, the extent of transfer of pyrazines present in the liquid to aerosols upon vaping remains unclear. We present a simple analytical method to quantify six pyrazine derivatives in liquids and aerosols of ECIGs that allows the isolation of pyrazines from interfering compounds, like nicotine. Standard pyrazine solutions and commercial ECIG samples of different brands and flavors were tested for their pyrazine content in the liquids and in the generated aerosols from these solutions. Testing on ECIG commercial liquids revealed a heterogeneous distribution in the levels and types of pyrazines, with acetyl and alkyl pyrazines present in more than 70% of the samples. This method confirmed that pyrazine additives are common in ECIG and that labels do not usually reflect the type and quantity of pyrazines in the liquid. Pyrazines were not correlated with the nicotine content or the brand of the liquid. The aerosols showed similar pyrazine profiles to their corresponding liquids. The efficiency of transfer of pyrazines into the particle phase was approximately 46%. Therefore, addition of pyrazines to ECIGs should be regulated, because they act synergistically with nicotine to increase product appeal, ease smoking initiation, and discourage cessation.
Development of Polydisperse Aerosol Generation and Measurement Procedures for Wind Tunnel Evaluation of Size-Selective Aerosol Samplers.
Dart A, Krug JD, Witherspoon CL … +4 more , Gilberry J, Malloy Q, Kaushik S, Vanderpool RW
Aerosol Sci Technol · 2018 Aug · PMID 35169350 · Full text
Accurate development and evaluation of inlets for representatively collecting ambient particulate matter typically involves use of monodisperse particles in aerosol wind tunnels. However, the resource requirements of usi...
Accurate development and evaluation of inlets for representatively collecting ambient particulate matter typically involves use of monodisperse particles in aerosol wind tunnels. However, the resource requirements of using monodisperse aerosols for inlet evaluation creates the need for more rapid and less-expensive techniques to enable determination of size-selective performance in aerosol wind tunnels. The goal of recent wind tunnel research at the U.S. EPA was to develop and validate the use of polydisperse aerosols which provide more rapid, less resource-intensive test results which still meet data quality requirements necessary for developing and evaluating ambient aerosol inlets. This goal was successfully achieved through comprehensive efforts regarding polydisperse aerosol generation, dispersion, collection, extraction, and analysis over a wide range of aerodynamic particle sizes. Using proper experimental techniques, a sampler's complete size-selective efficiency curve can be estimated with polydisperse aerosols in a single test, as opposed to the use of monodisperse aerosols which require conducting multiple tests using several different particle sizes. While this polydisperse aerosol technique is not proposed as a regulatory substitute for use of monodisperse aerosols, the use of polydisperse aerosols is advantageous during an inlet's development where variables of sampling flow rate and inlet geometry are often iteratively evaluated before a final inlet design can be successfully achieved. Complete Standard Operating Procedures for the generation, collection, and analysis of polydisperse calibration aerosols are available from EPA as downloadable files. The described experimental methods will be of value to other researchers during development of ambient sampling inlets and size-selective evaluation of the inlets in aerosol wind tunnels.
Development of a Portable Aerosol Collector and Spectrometer (PACS).
Cai C, Thomas GW, Yang T … +3 more , Park JH, Gogineni SP, Peters TM
Aerosol Sci Technol · 2018 May · PMID 37654799 · Full text
This article presents the development of a Portable Aerosol Collector and Spectrometer (PACS), an instrument designed to measure particle number, surface area, and mass concentrations continuously and time-weighted mass...
This article presents the development of a Portable Aerosol Collector and Spectrometer (PACS), an instrument designed to measure particle number, surface area, and mass concentrations continuously and time-weighted mass concentration by composition from 10 nm to 10 μm. The PACS consists of a six-stage particle size selector, a valve system, a water condensation particle counter to detect number concentrations, and a photometer to detect mass concentrations. The stages of the selector include three impactor and two diffusion stages, which resolve particles by size and collect particles for later chemical analysis. Particle penetration by size was measured through each stage to determine actual collection performance and account for particle losses. The data inversion algorithm uses an adaptive grid-search process with a constrained linear least-square solver to fit a tri-modal (ultrafine, fine, and coarse), log-normal distribution to the input data (number and mass concentration exiting each stage). The measured 50% cutoff diameter of each stage was similar to the design. The pressure drop of each stage was sufficiently low to permit its operation with portable air pumps. Sensitivity studies were conducted to explore the influence of unknown particle density (range from 500 to 3,000 kg/m) and shape factor (range from 1.0 to 3.0) on algorithm output. Assuming standard density spheres, the aerosol size distributions fit well with a of -4.9% to 3.5%, of 3.3% to 27.6%, and values of 0.90 to 1.00. The fitted number and mass concentration biases were within ±10% regardless of uncertainties in density and shape. However, fitted surface area concentrations were more likely to be underestimated/overestimated due to the variation in particle density and shape. The PACS represents a novel way to simultaneously assess airborne aerosol composition and concentration by number, surface area, and mass over a wide size range.
Size-Selective Sampling Performance of Six Low-Volume "Total" Suspended Particulate (TSP) Inlets.
Vanderpool RW, Krug JD, Kaushik S … +3 more , Gilberry J, Dart A, Witherspoon CL
Aerosol Sci Technol · 2018 · PMID 29681677 · Full text
Several low-volume inlets (flow rates ≤16.7 liters per minute (Lpm)) are commercially available as components of low-cost, portable ambient particulate matter samplers. Because the inlets themselves do not contain intern...
Several low-volume inlets (flow rates ≤16.7 liters per minute (Lpm)) are commercially available as components of low-cost, portable ambient particulate matter samplers. Because the inlets themselves do not contain internal fractionators, they are often assumed to representatively sample "total" mass concentrations from the ambient air, independent of aerodynamic particle size and wind speed. To date, none of these so-called "TSP" inlets have been rigorously tested under controlled conditions. To determine their actual size-selective performance under conditions of expected use, wind tunnel tests of six commonly used omnidirectional, low-volume inlets were conducted using solid, polydisperse aerosols at wind speeds of 2, 8, and 24 km/hr. With the exception of axially-oriented, isokinetic sharp-edge nozzles operating at 5 and 10 Lpm, all low-volume inlets showed some degree of non-ideal sampling performance as a function of aerodynamic particle size and wind speed. Depending upon wind speed and assumed ambient particle size distribution, total mass concentration measurements were estimated to be negatively biased by as much as 66%. As expected from particle inertial considerations, inlet efficiency tended to degrade with increasing wind speed and particle size, although some exceptions were noted. The implications of each inlet's non-ideal behavior are discussed with regards to expected total mass concentration measurement during ambient sampling and the ability to obtain representative sampling for size ranges of interest, such as PM and PM. Overall test results will aid in low-volume inlet selection and with proper interpretation of results obtained with their ambient field use.
Continuous flow hygroscopicity-resolved relaxed eddy accumulation (Hy-Res REA) method of measuring size-resolved sodium chloride particle fluxes.
Meskhidze N, Royalty TM, Phillips BN … +6 more , Dawson KW, Petters MD, Reed R, Weinstein JP, Hook DA, Wiener RW
Aerosol Sci Technol · 2018 Jan · PMID 35615466 · Full text
The accurate representation of aerosols in climate models requires direct ambient measurement of the size- and composition-dependent particle production fluxes. Here, we present the design, testing, and analysis of data...
The accurate representation of aerosols in climate models requires direct ambient measurement of the size- and composition-dependent particle production fluxes. Here, we present the design, testing, and analysis of data collected through the first instrument capable of measuring hygroscopicity-based, size-resolved particle fluxes using a continuous-flow Hygroscopicity-Resolved Relaxed Eddy Accumulation (Hy-Res REA) technique. The Hy-Res REA system used in this study includes a 3D sonic anemometer, two fast-response solenoid valves, two condensation particle counters, a scanning mobility particle sizer, and a hygroscopicity tandem differential mobility analyzer. The different components of the instrument were tested inside the US Environmental Protection Agency's Aerosol Test Facility for sodium chloride and ammonium sulfate particle fluxes. The new REA system design does not require particle accumulation, and therefore avoids the diffusional wall losses associated with long residence times of particles inside the air collectors of traditional REA devices. A linear relationship was found between the sodium chloride particle fluxes measured by eddy covariance and REA techniques. The particle detection limit of the Hy-Res REA flux system is estimated to be ~3 × 10 m s. The estimated sodium chloride particle classification limit, for the mixture of sodium chloride and ammonium sulfate particles of comparable concentrations, is ~6 × 10 m s.
Aerosol size distribution measurement of electronic cigarette emissions using combined differential mobility and inertial impaction methods: Smoking machine and puff topography influence.
Mikheev VB, Ivanov A, Lucas EA … +3 more , South PL, Colijn HO, Clark PI
Aerosol Sci Technol · 2018 · PMID 32773918 · Full text
A combination of a real-time high resolution aerosol differential mobility spectrometer (DMS500) and an electrical low pressure impactor (used as a traditional impactor) was applied to simultaneously collect real-time da...
A combination of a real-time high resolution aerosol differential mobility spectrometer (DMS500) and an electrical low pressure impactor (used as a traditional impactor) was applied to simultaneously collect real-time data and analyze particle size by weighing the mass of the aerosol collected on the impactor stages. Nonrefillable fixed-power as well as refillable and power adjustable e-cigarettes (e-cigs) were tested at various puffing flow rates. Two types of smoking machines were used: a smoke cycle simulator that provides instantaneous straight sample delivery to the analyzer and a Human Profile Pump that utilizes two synchronized pistons and operates by sample pull-push mode. Chemical analysis of the major components of e-liquid (propylene glycol, vegetable glycerol, water, and nicotine) was made using a proton nuclear magnetic resonance method. Limited amounts of samples collected on impactor stages were analyzed by liquid chromatography time-of-flight mass-spectrometry to find newly formed semi- or low-volatile organic compounds in e-cig aerosol and by transmission electron microscopy to check for the presence of nanoparticles in e-cig emissions. Differential mobility and inertial impaction methods showed comparable particle size results. Method of aerosol generation (type of the smoking machine) as well as puffing topography affected the e-cig particle size. Newly formed semi- or low-volatile organic compounds as well as metal nanoparticles were found in e-cig aerosol.
Surgical Smoke Simulation Study: Physical Characterization and Respiratory Protection.
Elmashae Y, Koehler RH, Yermakov M … +2 more , Reponen T, Grinshpun SA
Aerosol Sci Technol · 2018 · PMID 31762538 · Full text
Exposure of operating room (OR) personnel to surgical smoke, a unique aerosol generated from the common use of electrocautery during surgical procedures, is an increasing health risk concern. The main objective of this s...
Exposure of operating room (OR) personnel to surgical smoke, a unique aerosol generated from the common use of electrocautery during surgical procedures, is an increasing health risk concern. The main objective of this simulation study was to characterize the surgical smoke exposure in terms of the particle number concentration and size distribution in a human breathing zone. Additionally, the performance of respiratory protective devices designed for ORs was examined using two commercially available N95 facepiece filtering respirators (FFRs) as well as the same FFRs modified with new faceseal technology. The tests were conducted in an OR-simulating exposure chamber with the surgical smoke generated by electrocautery equipment applied to animal tissue and measured in the breathing zone with four aerosol spectrometers. The simulated workplace protection factor of each tested respirator was determined for ten subjects by measuring the total aerosol concentrations inside and outside of a respirator. The peak of the particle size distribution was in a range of 60-150 nm. The concentration of particles generated during the simulated surgical procedure significantly exceeded the background concentration under all tested air exchange conditions. The data suggest that wearing N95 filtering facepiece respirators significantly decreased the human exposure to surgical smoke. The new faceseal technology provided significantly higher respiratory protection than the commercial N95 FFRs.
Trends in the oxidation and relative volatility of chamber-generated secondary organic aerosol.
Docherty KS, Corse EW, Jaoui M … +5 more , Offenberg JH, Kleindienst TE, Krug JD, Riedel TP, Lewandowski M
Aerosol Sci Technol · 2018 · PMID 31686721 · Full text
The relationship between the oxidation state and relative volatility of secondary organic aerosol (SOA) from the oxidation of a wide range of hydrocarbons is investigated using a fast-stepping, scanning thermodenuder int...
The relationship between the oxidation state and relative volatility of secondary organic aerosol (SOA) from the oxidation of a wide range of hydrocarbons is investigated using a fast-stepping, scanning thermodenuder interfaced with a high-resolution time-of-flight aerosol mass spectrometer (AMS). SOA oxidation state varied widely across the investigated range of parent hydrocarbons but was relatively stable for replicate experiments using a single hydrocarbon precursor. On average, unit mass resolution indicators of SOA oxidation (e.g., AMS and ) are consistent with previously reported values. Linear regression of H:C vs. O:C obtained from parameterization of and and elemental analysis of high-resolution spectra in Van Krevelen space both yield a slope of ~-0.5 across different SOA types. A similar slope was obtained for a distinct subset of toluene/NO reactions in which the integrated oxidant exposure was varied to alter oxidation. The relative volatility of different SOA types displays similar variability and is strongly correlated with SOA oxidation state ( ). On average, relatively low oxidation and volatility were observed for aliphatic alkene (including terpenes) and alkane SOA while the opposite is true for mono- and polycyclic aromatic hydrocarbon SOA. Effective enthalpy for total chamber aerosol obtained from volatility differential mobility analysis is also highly correlated with c indicating a primary role for oxidation levels in determining the volatility of chamber SOA. Effective enthalpies for chamber SOA are substantially lower than those of neat organic standards but are on the order of those obtained for partially oligomerized glyoxal and methyl glyoxal.
Electronic cigarette-generated aldehydes: The contribution of e-liquid components to their formation and the use of urinary aldehyde metabolites as biomarkers of exposure.
Conklin DJ, Ogunwale MA, Chen Y … +8 more , Theis WS, Nantz MH, Fu XA, Chen LC, Riggs DW, Lorkiewicz P, Bhatnagar A, Srivastava S
Aerosol Sci Technol · 2018 · PMID 31456604 · Full text
Electronic cigarettes (e-cigarette) have emerged as a popular electronic nicotine delivery system (ENDS) in the last decade. Despite the absence of combustion products and toxins such as carbon monoxide (CO) and tobacco-...
Electronic cigarettes (e-cigarette) have emerged as a popular electronic nicotine delivery system (ENDS) in the last decade. Despite the absence of combustion products and toxins such as carbon monoxide (CO) and tobacco-specific nitrosamines (TSNA), carbonyls including short-chain, toxic aldehydes have been detected in e-cigarette-derived aerosols up to levels found in tobacco smoke. Given the health concerns regarding exposures to toxic aldehydes, understanding both aldehyde generation in e-cigarette and e-cigarette exposure is critical. Thus, we measured aldehydes generated in aerosols derived from propylene glycol (PG):vegetable glycerin (VG) mixtures and from commercial e-liquids with flavorants using a state-of-the-art carbonyl trap and mass spectrometry. To track e-cigarette exposure in mice, we measured urinary metabolites of 4 aldehydes using ULPC-MS/MS or GC-MS. Aldehyde levels, regardless of abundance (saturated: formaldehyde, acetaldehyde >> unsaturated: acrolein, crotonaldehyde), were dependent on the PG:VG ratio and the presence of flavorants. The metabolites of 3 aldehydes - formate, acetate and 3-hydroxypropyl mercapturic acid (3-HPMA; acrolein metabolite) -- were increased in urine after e-cigarette aerosol and mainstream cigarette smoke (MCS) exposures, but the crotonaldehyde metabolite (3-hydroxy-1-methylpropylmercapturic acid, HPMMA) was increased only after MCS exposure. Interestingly, exposure to menthol-flavored e-cigarette aerosol increased the levels of urinary 3-HPMA and sum of nicotine exposure (nicotine, cotinine, -3'-hydroxycotinine) relative to exposure to a Classic Tobacco-flavored e-cigarette aerosol. Comparing these findings with aerosols of other ENDS and by measuring aldehyde-derived metabolites in human urine following exposure to e-cigarette aerosols will further our understanding of the relationship between ENDS use, aldehyde exposure and health risk.
Rapid Analysis of the Size Distribution of Metal-Containing Aerosol.
Park JH, Mudunkotuwa IA, Crawford KJ … +3 more , Anthony TR, Grassian VH, Peters TM
Aerosol Sci Technol · 2017 · PMID 28871214 · Full text
Conventional methods to measure the metallic content of particles by size are time consuming and expensive, requiring collection of particles with a cascade impactor and subsequent metals analysis by inductively coupled...
Conventional methods to measure the metallic content of particles by size are time consuming and expensive, requiring collection of particles with a cascade impactor and subsequent metals analysis by inductively coupled plasma mass spectrometry (ICP-MS). In this work, we describe a rapid way to measure the size distribution of metal-containing particles from 10 nm to 20 μm, using a nano micro-orifice uniform-deposit impactor (nano-MOUDI) to size-selective and collect particles that are then analyzed with a field portable X-ray fluorescence (FP-XRF) to determine metal composition and concentration. The nano-MOUDI was used to sample a stainless-steel aerosol produced by a spark discharge system. The particle-laden substrates were then analyzed directly with FP-XRF and then with ICP-MS. Results from FP-XRF were linearly correlated with results from ICP-MS (R = 0.91 for Fe and R = 0.84 for Cr). Although the FP-XRF was unable to detect Fe particles at mass per substrate loadings less than 2.5 μg effectively, it produced results similar to those using the ICP-MS at a mass per substrate loading greater than 2.5 μg.
Production of neutral molecular clusters by controlled neutralization of mobility standards.
Steiner G, Franchin A, Kangasluoma J … +3 more , Kerminen VM, Kulmala M, Petäjä T
Aerosol Sci Technol · 2017 Aug · PMID 28824221 · Full text
Measuring aerosols and molecular clusters below the 3 nm size limit is essential to increase our understanding of new particle formation. Instruments for the detection of sub-3 nm aerosols and clusters exist and need to...
Measuring aerosols and molecular clusters below the 3 nm size limit is essential to increase our understanding of new particle formation. Instruments for the detection of sub-3 nm aerosols and clusters exist and need to be carefully calibrated and characterized. So far calibrations and laboratory tests have been carried out using mainly electrically charged aerosols, as they are easier to handle experimentally. However, the charging state of the cluster is an important variable to take into account. Furthermore, instrument characterization performed with charged aerosols could be biased, preventing a correct interpretation of data when electrically neutral sub-3 nm aerosols are involved. This article presents the first steps to generate electrically neutral molecular clusters as standards for calibration. We show two methods: One based on the neutralization of well-known molecular clusters (mobility standards) by ions generated in a switchable aerosol neutralizer. The second is based on the controlled neutralization of mobility standards with mobility standards of opposite polarity in a recombination cell. We highlight the challenges of these two techniques and, where possible, point out solutions. In addition, we give an outlook on the next steps toward generating well-defined neutral molecular clusters with a known chemical composition and concentration. Published with license by American Association for Aerosol Research.
Transport phenomena governing nicotine emissions from electronic cigarettes: model formulation and experimental investigation.
Talih S, Balhas Z, Salman R … +8 more , El-Hage R, Karaoghlanian N, El-Hellani A, Baassiri M, Jaroudi E, Eissenberg T, Saliba N, Shihadeh A
Aerosol Sci Technol · 2017 · PMID 28706340 · Full text
Electronic cigarettes (ECIGs) electrically heat and aerosolize a liquid containing propylene glycol (PG), vegetable glycerin (VG), flavorants, water, and nicotine. ECIG effects and proposed methods to regulate them are c...
Electronic cigarettes (ECIGs) electrically heat and aerosolize a liquid containing propylene glycol (PG), vegetable glycerin (VG), flavorants, water, and nicotine. ECIG effects and proposed methods to regulate them are controversial. One regulatory focal point involves nicotine emissions. We describe a mathematical model that predicts ECIG nicotine emissions. The model computes the vaporization rate of individual species by numerically solving the unsteady species and energy conservation equations. To validate model predictions, yields of nicotine, total particulate matter, PG, and VG were measured while manipulating puff topography, electrical power, and liquid composition across 100 conditions. Nicotine flux, the rate at which nicotine is emitted per unit time, was the primary outcome. Across conditions, the measured and computed nicotine flux were highly correlated (r = 0.85, <.0001). As predicted, device power, nicotine concentration, PG/VG ratio, and puff duration influenced nicotine flux (<.05), while water content and puff velocity did not. Additional empirical investigation revealed that PG/VG liquids act as ideal solutions, that liquid vaporization accounts for more than 95% of ECIG aerosol mass emissions, and that as device power increases the aerosol composition shifts towards the less volatile components of the parent liquid. To the extent that ECIG regulations focus on nicotine emissions, mathematical models like this one can be used to predict ECIG nicotine emissions and to test the effects of proposed regulation of factors that influence nicotine flux.
Absorption/Transmission Measurements of PSAP Particle-Laden Filters from the Biomass Burning Observation Project (BBOP) Field Campaign.
Presser C, Nazarian A, Conny JM … +3 more , Chand D, Sedlacek A, Hubbe JM
Aerosol Sci Technol · 2017 · PMID 28690360 · Full text
Absorptivity measurements with a laser-heating approach, referred to as the laser-driven thermal reactor (LDTR), were carried out in the infrared and applied at ambient (laboratory) non-reacting conditions to particle-la...
Absorptivity measurements with a laser-heating approach, referred to as the laser-driven thermal reactor (LDTR), were carried out in the infrared and applied at ambient (laboratory) non-reacting conditions to particle-laden filters from a three-wavelength (visible) particle/soot absorption photometer (PSAP). The particles were obtained during the Biomass Burning Observation Project (BBOP) field campaign. The focus of this study was to determine the particle absorption coefficient from field-campaign filter samples using the LDTR approach, and compare results with other commercially available instrumentation (in this case with the PSAP, which has been compared with numerous other optical techniques). Advantages of the LDTR approach include 1) direct estimation of material absorption from temperature measurements (as opposed to resolving the difference between the measured reflection/scattering and transmission), 2) information on the filter optical properties, and 3) identification of the filter material effects on particle absorption (e.g., leading to particle absorption enhancement or shadowing). For measurements carried out under ambient conditions, the particle absorptivity is obtained with a thermocouple placed flush with the filter back surface and the laser probe beam impinging normal to the filter particle-laden surface. Thus, in principle one can employ a simple experimental arrangement to measure simultaneously both the transmissivity and absorptivity (at different discrete wavelengths) and ascertain the particle absorption coefficient. For this investigation, LDTR measurements were carried out with PSAP filters (pairs with both blank and exposed filters) from eight different days during the campaign, having relatively light but different particle loadings. The observed particles coating the filters were found to be carbonaceous (having broadband absorption characteristics). The LDTR absorption coefficient compared well with results from the PSAP. The analysis was also expanded to account for the filter fiber scattering on particle absorption in assessing particle absorption enhancement and shadowing effects. The results indicated that absorption enhancement effects were significant, and diminished with increased filter particle loading.
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