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A fully automated isotopic profile deconvoluted chromatogram (IPDC) algorithm (Fakouri Baygi et al. in Anal Chem 91:15509–15517, 2019) and user interactive HaloSeeker 1.0 (Léon et al. in Anal Chem 91:3500–3507, 2019) were compared to test the efficacy of these two computationally enhanced non-targeted screening (CENTS) tools in isolating unknown Br/Cl compounds using high-resolution mass spectrometry (HRMS) data. HaloSeeker depends on a user to monitor the performance of the peak picking algorithm and assign molecular formulas for each isotopic signature in an ergonomic interface. Alternatively, the IPDC algorithm automatically assigns and ranks candidate molecular formulas within a set of search criteria. Both CENTS tools were evaluated using fish and sediment data acquired at 22,000 (mHRMS) and > 100,000 (uHRMS) mass resolutions, respectively. The IPDC algorithm detected 85% of compounds detected by HaloSeeker as the first candidate compound in the sediment sample, with fewer false positives. In the sediment data, the IPDC algorithm detected several compounds such as clofoctol and chlorinated paraffins that were not reported using HaloSeeker 1.0. Upon further inspection, these compounds were isolated by the HaloSeeker program, but not reported by the user. HaloSeeker detected all significant and insignificant chemical ionization products (relative to IPDC), but additional false positives were isolated in the mHRMS polychlorinated biphenyl reference standard and trout sample. HaloSeeker detected 62% of the legacy contaminant features isolated by the IPDC algorithm in the fish data (mHRMS). The comparison of these two CENTS tools demonstrates that matrix complexity and mass resolution of the HRMS platform are the key factors when choosing automated and user interactive CENTS tools. [ABSTRACT FROM AUTHOR]

In the environment, the presence of ions from natural radioactivity may increase the rate of new particle formation through ion-induced nucleation. A thermal diffusion cloud chamber (TDCC) has been built to experimentally study ion-induced nucleation where the ions are produced by gaseous radioactive sources. The critical supersaturation values and nucleation rates for methanol, ethanol, 1-propanol, and 1-butanol vapors on ions produced within the volume of the chamber by alpha decay of 222Rn have been measured quantitatively at various radioactivity concentrations and supersaturations. The presence of ion tracks and the effect of an external electric field were also investigated. The alpha tracks and ion-induced nucleation formed by 222Rn decay become visible at the critical supersaturation that is below the value needed for homogeneous nucleation. At this supersaturation, the nucleation rates increase substantially with increasing 222Rn at low activity concentrations, but attain limiting values at higher concentrations. The experimental results indicate that the ionization by radon decay will promote ion-cluster formation and lower the free energy barriers. The formation of visible droplets is strongly dependent on the supersaturation. This study also confirms that the external electric field has a significant effect on the observed rates of nucleation. [ABSTRACT FROM AUTHOR]

Seven commercial cooking oils were investigated to determine the PM2.5 mass and ultrafine particle (UFP) emission rates and emission fluxes (rates per area). The results of this study showed that at 197°C soybean, safflower, canola, and peanut oils produced lower PM2.5 emission fluxes (6.1 × 105, 3.0 × 105, 5.4 × 105, and 3.9 × 105 μg/min/m2, respectively) than corn, coconut, and olive oils (2.7 × 106, 2.9 × 106, and 5.7 × 106 μg/min/m2, respectively). Similarly, the total particle number flux at 197°C was lower for soybean, safflower, and canola oils (3.5 × 1013, 8.6 × 1013, and 1.0 × 1014 #/min/m2, respectively) than the corn, coconut, olive, and peanut oils (2.4 × 1014, 1.4 × 1014, 1.7 × 1014, and 3.8 × 1014 #/min/m2, respectively). In general, oils with a higher smoke temperature resulted in lower particle concentrations over the measured temperature range (131-197°C). The percentage of UFP (particle diameter Dp 10-100 nm) to total particles (Dp 10-500 nm) ranged from 76 to 99% for this temperature range. Particles below 10 nm in diameter were not measured. The particle number size distribution showed a polydisperse behavior with major mode sizes ranging from 25 nm (for peanut oil) to 82 nm (for soybean oil) at an oil temperature of 197°C. Practical Implications The study presents particle number and mass concentrations, size distributions, emission rates, and emission fluxes from heating common cooking oils. The emission rates and emission fluxes can be used as inputs to models for indirect exposure analysis studies. The study may also be used to provide guidance on choosing oils that result in lower emission rates when heated. [ABSTRACT FROM AUTHOR]

Context: Electronic cigarettes (e-cigarettes) have earned considerable attention recently as an alternative to smoking tobacco, but uncertainties about their impact on health and indoor air quality have resulted in proposals for bans on indoor e-cigarette use. Objective: To assess potential health impacts relating to the use of e-cigarettes, a series of studies were conducted using e-cigarettes and standard tobacco cigarettes. Methods and materials: Four different high nicotine e-liquids were vaporized in two sets of experiments by generic 2-piece e-cigarettes to collect emissions and assess indoor air concentrations of common tobacco smoke by products. Tobacco cigarette smoke tests were conducted for comparison. Results: Comparisons of pollutant concentrations were made between e-cigarette vapor and tobacco smoke samples. Pollutants included VOCs, carbonyls, PAHs, nicotine, TSNAs, and glycols. From these results, risk analyses were conducted based on dilution into a 40 m3 room and standard toxicological data. Non-cancer risk analysis revealed 'No Significant Risk' of harm to human health for vapor samples from e-liquids (A-D). In contrast, for tobacco smoke most findings markedly exceeded risk limits indicating a condition of 'Significant Risk' of harm to human health. With regard to cancer risk analysis, no vapor sample from e-liquids A-D exceeded the risk limit for either children or adults. The tobacco smoke sample approached the risk limits for adult exposure. Conclusions: For all byproducts measured, electronic cigarettes produce very small exposures relative to tobacco cigarettes. The study indicates no apparent risk to human health from e-cigarette emissions based on the compounds analyzed. [ABSTRACT FROM AUTHOR]

Limonene ozonolysis was examined under conditions relevant to indoor environments in terms of temperatures, air exchange rates, and reagent concentrations. Secondary organic aerosols (SOA) produced and particle-bound reactive oxygen species (ROS) were studied under situations when the product of the two reagent concentrations was constant, the specific concentration combinations play an important role in determining the total SOA formed. A combination of concentration ratios of ozone/limonene between 1 and 2 produce the maximum SOA concentration. The two enantiomers, R-(+)-limonene and S-(−)-limonene, were found to have similar SOA yields. The measured ROS concentrations for limonene and ozone concentrations relevant to prevailing indoor concentrations ranged from 5.2 to 14.5 nmol/m3 equivalent of H2O2. It was found that particle samples aged for 24 h in freezer lost a discernible fraction of the ROS compared to fresh samples. The residual ROS concentrations were around 83–97% of the values obtained from the analysis of samples immediately after collection. The ROS formed from limonene ozonolysis could be separated into three categories as short-lived, high reactive, and volatile; semi-volatile and relatively stable; non-volatile and low-reactive species based on ROS measurements under various conditions. Such chemical and physical characterization of the ROS in terms of reactivity and volatility provides useful insights into nature of ROS. Practical Implications A better understanding of the formation mechanism of secondary organic aerosol generated from indoor chemistry allows us to evaluate and predict the exposure under such environments. Measurements of particle-bound ROS shed light on potential adverse health effect associated with exposure to particles. [ABSTRACT FROM AUTHOR]

The reactions of ozone with monoterpenes proceed via the formation of multiple oxygen- and carbon-centered free radical species. These radical species are highly reactive and thus, have generally not been measureable. A method for their detection and characterization is needed to preserve these radicals for a sufficiently long time to permit analyzes to be performed. Radical-addition reactions, also called spin trapping techniques, allow the detection of short-lived radicals. This approach has been applied to products from the -pinene/ozone reaction. Secondary organic aerosol (SOA) from a reaction chamber was collected on quartz fiber filters and extracted with a solution of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) (spin trap) followed by analysis with ion-trap tandem mass spectrometry (MSn) using electrospray ionization (ESI) in the positive scan mode. The DMPO adducts with radical species appear as positive ions [DMPO-R+H]+, [DMPO-OR+H]+ and [DMPO-O-OR+H]+ in full MS spectra of the samples. Tandem mass spectrometry (MS2) was performed to identify the radical species. The DMPO adducts with the C-centered radical species [DMPO-R+H]+ are characterized by m/z 114 [DMPO+H]+ in the MS2 spectra and with peaks that represent the loss of [DMPO+H]+. The DMPO adducts with O-centered radical species (RO· and ROO·) are identified by m/z 130 [DMPO-OH+H]+ and m/z 146 [DMPO-O-OH+H]+, respectively, and with peaks that correspond to the loss of those adducts. DMPO was also able to capture OH radicals from the particle phase, and the product ion fragmentation confirmed DMPO/OH structure providing evidence for particle-bound OH radicals. [ABSTRACT FROM AUTHOR]

The formation of secondary organic aerosol (SOA) produced from α-pinene ozonolysis was examined using a dynamic chamber system that allowed the simulation of ventilated indoor environments. Particle-bound reactive species (ROS) including peroxides, peroxy radicals and ions that could penetrate into the lungs and deliver oxidative stress to the tissue causing damage were quantitatively determined from filters collected from the chamber. ROS was determined using dichlorofluorescin such that resulting fluorescent intensities were converted to equivalent H2O2 concentrations. Measured ROS concentrations at α-pinene and ozone concentrations relevant to prevailing indoor concentrations ranged from 1.1 to 7.2 nmol/m3 of H2O2. Particle density was also determined from scanning mobility particle sizer measurements and mass collected onto filters to obtain volume and mass concentration, respectively. Partitioning theory reveals the fact that with increased SOA mass loading, even for more volatile species, partitioning onto particle phase is favored relative to low SOA mass loadings. Other recent studies have found changes in composition of the SOA depending on the precursor VOC concentrations. This behavior was reflected in these experiments in terms of a change of density. Measured densities ranged from 1.07 to 1.69 g/cm3. Practical Implications A better understanding of the formation mechanism of secondary organic aerosol generated from indoor chemistry allows us to evaluate and predict the exposure under such environments. Measurements of particle-bound reactive oxygen species (ROS) shed light on potential adverse health effect associated upon exposure to particles. [ABSTRACT FROM AUTHOR]

PM2.5 samples were collected at a centrally located urban monitoring site in Seoul, Korea, every third day from March 2003 to December 2006 and analyzed for their chemical constituents. Sources were identified using positive matrix factorization (PMF). A total of 393 samples were obtained during the sampling period, and 20 chemical species were measured. Nine PM2.5 source categories were identified providing physically realistic profiles and interesting insights into the source contributions to the ambient mass concentrations. The major contributors of PM2.5 were secondary nitrate (20.9%), secondary sulfate (20.5%), gasoline-fueled vehicles (17.2%), and biomass burning (12.1%), with lesser contributions from diesel emissions (8.1%), soil (7.4%), industry (6.7%), road salt and two-stroke vehicles (5.1%), and aged sea salt (2.2%). PM2.5 levels in Seoul were influenced by both local urban activities and regional-scale transport. Conditional probability function (CPF) results identified possible source directions of local sources such as motor vehicles (gasoline and diesel), industry, and road salt. Potential source contribution function (PSCF) results showed that possible source areas contributing to the elevated secondary particle concentrations (sulfate and nitrate) in Seoul to be the major industrial areas in China. [ABSTRACT FROM AUTHOR]

An ambient air quality study was undertaken in two cities (Pamplona and Alsasua) of the Province of Navarre in northern Spain from July 2001 to June 2004. The data were obtained from two urban monitoring sites. At both monitoring sites, ambient levels of ozone, NOx, and SO2 were measured. Simultaneously with levels of PM10 measured at Alsasua (using a laser particle counter), PM10 levels were also determined at Pamplona (using a beta attenuation monitor). Mean annual PM10 concentrations in Pamplona and Alsasua reached 30 and 28 μg m−3, respectively. These concentrations are typical for urban background sites in Northern Spain. By using meteorological information and back trajectories, it was found that the number of exceedances of the daily PM10 limit as well as the PM10 temporal variation was highly influenced by air masses from North Africa. Although North African transport was observed on only 9% of the days, it contributed the highest observed PM10 levels. Transport from the Atlantic Ocean was observed on 68% of the days; transport from Europe on 13%; low transport and local influences on 7%; and transport from the Mediterranean region on 3% of the days. The mean O3 concentrations were 45 and 55 μg m−3 in Pamplona and Alsasua, respectively, which were above the values reported for the main Spanish cities. The mean NO and NO2 levels were very similar in both sites (12 and 26 μg m−3, respectively). Mean SO2 levels were 8 μg m−3 in Pamplona and 5 μg m−3 in Alsasua. Hourly levels of PM10, NO and NO2 showed similar variations with the typically two coincident maximums during traffic rush hours demonstrating a major anthropogenic origin of PM10, in spite of the sporadic dust outbreaks. [ABSTRACT FROM AUTHOR]

The article discusses the study which examines the topology of nucleation rates in the products of pyrolysis of polymers. It conducts a molecular beam experiment wherein particles are generated from a supercooled glycerol vapor in a 99.99% nitrogen atmosphere. It is stated that the results of this study can promote the systematization of statements used for interpreting empirical data on the nucleation kinetics in the products of thermal degradation of polymer materials.

From late 1999 to early March 2000, measurements of particle number (particles 0.01–20 μm in aerodynamic diameter) concentrations were made inside of a townhouse occupied by two non-smoking adults and located in Reston, VA (approximately 25 miles northwest of Washington, DC). The particle size measurements were made using an SMPSTM and an APSTM as well as a Climet optical scattering instrument. In this study, positive matrix factorization (PMF) was used to study the indoor particle size distributions. The size distributions or profiles obtained were identified by relating the obtained source contributions to the source information provided by the occupants. Nine particle sources were identified, including two sources associated with gas burner use: boiling water and frying tortillas. Boiling water for tea or coffee was found to be associated only with the smallest particles, with a number mode close to the detection limit of the SMPS (i.e., 0.01 μm). Frying tortillas produced particles with a number mode at about 0.09 μm while broiling fish produced particles with a number mode at about 0.05 μm. A citronella candle was often burned during the study period, and this practice was found to produce a 0.2- μm modal number distribution. Other indoor particle sources identified included sweeping/vacuuming (volume mode at 2 μm); use of the electric toaster oven (number mode at 0.03 μm); and pouring of kitty litter (volume mode over 10 μm). Two outdoor sources were also resolved: traffic (number mode at about 0.15 μm) and wood smoke (major number mode at about 0.07 μm). The volume distributions showed presence of coarse particles in most of the resolved indoor sources probably caused by personal cloud emissions as the residents performed the various indoor activities. Practical Implications This study has shown that continuous measurements of indoor particle number and volume concentrations together with records of personal activities are useful for indoor source apportionment models. Each of the particle sources identified in this study produces distinct size distributions that may be useful in studying the mortality and morbidity effects of airborne particulate matter because they will have different penetrability and deposition patterns. [ABSTRACT FROM AUTHOR]

On-road experiments were conducted to determine the sensitivities of rats to real-world aerosol. This article summarizes the on-road aerosol and gas measurements and provides background information for the companion paper on the rat exposures. Measurements were carried out over 10 days, 6 h/day, driving a route from Rochester to Buffalo. Aerosol instrumentation used in this study included two scanning mobility particle sizers (SMPS) to determine the aerosol size distribution from 10 to 300 nm, 2 stand-alone condensation particle counters to determine the total aerosol number concentration, and an electrical aerosol detector to determine the aerosol length concentration. A thermal denuder (TD) was used with one of the SMPS instruments to determine the size distribution of the non-volatile fraction. Filter samples were collected and analyzed for elemental carbon, and gas analyzers measured ambient levels of CO, CO 2 , and NO. Average daily total aerosol number concentration ranged from 200,000 to 560,000 particles/cm 3 . Past studies on urban highways have measured total number concentrations ranging between 10 4 and 10 6 particles/cm 3 . The average daily NO concentration ranged from 0.10 to 0.24 ppm and the corresponding CO 2 concentration ranged from 400 to 420 ppm. The average daily geometric number mean particle size determined by the SMPS ranged from 15 to 20 nm. The TD reduced the average SMPS number concentration between 87 and 95% and the SMPS volume between 54 and 83%, suggesting that most of the particles consisted of volatile material. The TD also increased the geometric number mean diameter from 15 to 20 nm to 30 to 40 nm. [ABSTRACT FROM AUTHOR]

Within the International Atomic Energy Agency's coordinated research programs involving air quality monitoring, the participants have been provided with equipment for aerosol sampling and measurement. For aerosol mass measurements, a beta gauge was designed and constructed to provide the necessary performance in collected aerosol mass measurement at the minimum cost. A calibration for the beta gauge was performed to determine the precision of this unit. Two experiments with different size particles were conducted to calibrate the system. This calibration shows that the system provides satisfactory precision with a maximum deviation of approximately 8%. The bias between beta gauge and gravimetric method was found to be 6% on average when examining particles of different composition. [ABSTRACT FROM AUTHOR]

Presents a correction to the article "Unfilterable Geoaerosols, Their Use in the Search for Thermal, Mineral and Mineralized Waters, and Their Possible Influence on the Origin of Certain Types of Mineral Waters," published previously in the periodical "Environmental Geology."