Ultrafine Particles Research Articles

Quantifying Topography-Dependent Ultrafine Particle Exposure from Diesel Emissions in Appalachia Using Traffic Counts as a Surrogate Measure

Diesel particulate matter—primarily ultrafine particles (UFPs), defined as particles smaller than 0.1 µm—are released by diesel-powered vehicles, especially those used in heavy-duty hauling. While much of the existing research on traffic-related air pollution focuses on urban environments, limited attention has been paid to how complex topography influences the concentration of UFPs, particularly in areas with significant truck traffic. With a focus on Morgantown, West Virginia, an area distinguished by a steep topography, this study investigates how travel over two different terrain conditions affects UFP concentrations close to roadways. Specifically, we sought to determine if the truck count taken from simultaneous video evidence could be used as a surrogate for varying topography in determining the concentration of UFPs. This study shows that “TRUCK COUNT” and “TRUCK SPEED” have a linear relationship and yield a possible surrogate measure of the lung dose of UFP number concentration. Our results demonstrate a statistically significant (p < 0.1) linear relationship between truck count and UFP number concentration (R = 0.77 and 0.40), validating truck count along with truck speed as a medium effect surrogate for estimating near-road UFP exposure. Dose estimation using the Multiple-Path Particle Dosimetry (MPPD) model further revealed that approximately 30% of inhaled UFPs are deposited in the alveolar region, underscoring the public health relevance of this exposure pathway in topographically complex areas. This method ultimately awaits comparison with health effects to determine its true potential as a useful exposure metric.

Associations between all-cause and ischemic heart disease mortality and long-term ambient ultrafine particles exposure: a comparison of statistical and machine learning exposure models.

Associations between all-cause and ischemic heart disease mortality and long-term ambient ultrafine particles exposure: a comparison of statistical and machine learning exposure models.

Synergistic removal of ultra-fine coal particles and Ca2+/Mg2+ from mine wastewater via dual-stage adsorption prior to membrane filtration

Synergistic removal of ultra-fine coal particles and Ca2+/Mg2+ from mine wastewater via dual-stage adsorption prior to membrane filtration

Interaction Between Radon, Air Ions, and Ultrafine Particles Under Contrasting Atmospheric Conditions in Belgrade, Serbia

Radon’s radioactive decay is the main natural source of small air ions near the ground. Its exhalation from soil is affected by meteorological factors, while aerosol pollution reduces air ion concentrations through ion-particle attachment. This study aimed to analyze correlations between radon, ions, and air pollution under varying conditions and to assess potential health impacts. Measurements were taken at two sites: in early autumn at a suburban part of Belgrade with relatively clean air, and in late autumn in central Belgrade under polluted conditions, with low temperatures and high humidity. Parameters measured included radon, small air ions, particle size distribution, PM mass concentration, temperature, humidity, and pressure. Results showed lower radon concentrations in late autumn due to high soil moisture and absence of nocturnal inversions. Radon and air ion concentrations exhibited a strong positive correlation for both polarities under suburban conditions, whereas measurements in the urban setting revealed a weak negative correlation, despite radon concentrations in soil gas being approximately equal at both sites. Small ion levels were also reduced, mainly due to suppressed radon exhalation and increased aerosol concentrations, especially ultrafine particles. A strong negative correlation (r < −0.5) was found between small air ion concentrations and particle number concentrations in the 20–300 nm range, while larger particles (300–1000 nm and >1 µm) showed weak or no correlation due to their lower and more stable concentrations. In contrast, early autumn measurements showed a diurnal cycle of radon, characterized by nighttime maxima and daytime minima, unlike the consistently low values observed in late autumn.

Physical and chemical characteristics of soot particles from GDI engines: Roles of fuels, lubricants, and transient driving cycles.

Physical and chemical characteristics of soot particles from GDI engines: Roles of fuels, lubricants, and transient driving cycles.

Integrated monitoring of road traffic and airborne ultrafine particles at a camera-equipped urban intersection

Integrated monitoring of road traffic and airborne ultrafine particles at a camera-equipped urban intersection

An acoustic agglomeration method for segregation of micro– to nano–bubbles for the flotation of ultrafine particles

An acoustic agglomeration method for segregation of micro– to nano–bubbles for the flotation of ultrafine particles

Numerical investigations on the modelling of ultrafine particles in SSH-aerosol-v1.3a: size resolution and redistribution

Abstract. As the health impacts of ultrafine particles become better understood, accurately modelling size distribution and number concentration in chemistry-transport models is becoming increasingly important. The number concentration is strongly affected by processes linked to aerosol dynamics: coagulation, condensation, gas- and particle-phase partitioning, and nucleation. Coagulation is usually solved using an Eulerian approach, relying on a fixed discretization of particle sizes. In contrast, condensation and evaporation processes are rather solved using a Lagrangian approach, requiring redistribution of particles on the fixed-size mesh. Here, a new analytic formulation is presented to compute efficiently coagulation partition coefficients, allowing us to dynamically adjust the discretization of the coagulation operator to the size mesh evolution and therefore solve all the processes linked to aerosol dynamics with a dynamics mesh approach, avoiding the redistribution on the fixed-size grid. This new approach has the advantage of reducing the numerical diffusion introduced by condensation. The significance of these effects on number concentrations is assessed in an idealized box setting, as well as over greater Paris with the chemistry-transport model Polyphemus/Polair3D coupled to the aerosol model SSH-aerosol, using different size resolutions of the particle distribution.

A Study of Free Amino Acids Analysis in the Atmosphere Using LC-HRMS

This study aims to investigate both qualitative and quantitative methods for the simultaneous multicomponent and trace analysis of free amino acids (FAAs) in atmospheric particulate matter using LC-HRMS. The method was applied by collecting samples to assess the actual occurrence of FAAs in the atmosphere. The analytical technique utilized was LC-HRMS (Orbitrap), with a focus on the Amino Acid column, which demonstrated excellent separation performance, with peak detection beginning approximately five minutes after sample injection. A total of 15 FAA species were analyzed within a 20-minute run time. Accelerated solvent extraction (ASE) was effective, and the relatively low recovery rate was compensated for by using 15 internal standards. The matrix test confirmed that the method can be applied to actual particulate matter (PM) samples. Analysis of 13 PM samples collected over a two-month period revealed that L-valine was the most abundant FAA. FAAs in fine particulate matter accounted for approximately 6% of the total FAA, with 72% of this fraction found in ultrafine dust particles. This study advances the analytical method for trace-level detection of FAAs, facilitating their identification and quantification in atmospheric particulate matter.

Sonication-Assisted Surface Erosion and Its Impact on the Flotation of Ultrafine Smithsonite

Regulating the dissolution and interfacial behavior of minerals via external force fields is considered a promising strategy for enhancing the flotation of soluble minerals. This study explored the potential of ultrasound-assisted pulp conditioning in improving ultrafine smithsonite flotation. Specifically, we systematically evaluated the effects of ultrasonic pretreatment (UP) on the physicochemical properties of smithsonite suspensions (focusing on surface erosion behavior) and assessed subsequent flotation performance using flotation tests and modern analytical techniques. It has been found that UP can significantly modify smithsonite suspension characteristics, including particle morphology, ionic composition, electrokinetic properties, and pulp pH. Flotation results demonstrate that UP yields higher recovery compared to traditional stirring (TS) conditioning, especially at medium-to-high sodium oleate (NaOL) concentrations. Comparative analysis reveals that ultrasonic-assisted dissolution and ion-selective migration are the main factors driving improved flotation performance. Unlike TS, UP promotes greater zinc ion release, facilitates the dissolution–hydrolysis–precipitation equilibrium, generates more and finer nanoparticles in the bulk phase, and induces the deposition of hydrozincite on smithsonite surfaces. These changes increase active zinc sites for more stable NaOL adsorption, thereby enhancing the flotation of ultrafine smithsonite particles.

Bus-exposure matrix, a tool to assess bus drivers' exposure to physicochemical hazards.

Bus-exposure matrix, a tool to assess bus drivers' exposure to physicochemical hazards.

Aircraft emissions of ultrafine particles characterized by real-world near runway measurements

Aircraft emissions of (ultra)fine particles during landing and take-off operations pose increasing human health hazards for airport employees and near-airport communities. Measurements of in-operation aircraft are therefore crucial for characterizing real-world aircraft emissions, and their variability. In this work, we develop an approach that enables the gathering of large quantities of data on real-world aircraft-specific emissions. We use three types of portable PM sensors located ca. 200 m downwind of an operational runway at Amsterdam Airport Schiphol, over different seasons, to characterize the plumes from ca. 500 specific operations covering most aircraft types of the global flying fleet. High concentration peaks (in the order of 106 particles/cm3) of sub-25 nm particles are observed in the near field. While departure plumes exhibit higher particle number concentrations than arrival plumes, the values do not necessarily scale with aircraft size or engine thrust rating. We find large variability among aircraft types and engine models, highlighting the importance of incorporating real-world observations when assessing the impacts of aviation on the atmospheric composition and human health.

Aircraft Arrival and Departure Contributions to Ultrafine Particle Size Distribution in a Near-Airport Community.

Determining aviation-related contributions to ambient ultrafine particle (UFP) concentrations in complex, multisource environments is challenging; source-specific differences in particle size distribution may provide a mechanism for source attribution. We examined UFP concentrations and size distribution across 32 particle diameters at a monitoring site in close proximity to Boston Logan International Airport across a two-year period, incorporating covariates for flight activity and meteorology. Total particle number concentration (PNC) was ∼2-fold higher when the site was downwind of the airport. During these wind conditions, particles between 8 and 12 nm in diameter comprised the largest proportion of overall PNC observed, consistent with aircraft contributions. Particle size distribution differed substantially between hours of predominant aircraft arrivals (peak modal diameter 9-11 nm) versus departures (peak modal diameter 39-52 nm). Peak concentrations of particles between 9 and 11 nm were found in the winter and during afternoon hours. We conducted a principal component analysis (PCA) to confirm particle size distributions from aviation activity. PCA results showed that nucleation-mode particles (<30 nm in diameter), specifically those between 9 and 11 nm, were associated with landing aircraft on a nearby runway, especially when the monitor was downwind of the airport. Our findings confirm that aviation-specific UFP emissions are dominated by nucleation mode particles, with long-term size distribution information able to distinguish between aircraft operations in near-airport communities.

Comprehensive review of intake fraction methods for assessing traffic-related air pollution exposure: insights, variations, and future directions.

Traffic-related air pollution (TRAP) poses significant risks to human health, particularly in urban areas with high traffic volumes. Intake fraction (iF) quantifies the relationship between emissions and exposure, defined as the ratio of the total inhalation increment of all exposed individuals in a target population to the emissions from specific pollution sources over a certain period. The overarching objective of this study is to unravel the underlying value and significance of the iF method in evaluating TRAP exposure risks, while also exploring its future development trajectories and potential avenues for application. We conducted a comprehensive review of iF to assess TRAP exposure. We employed a search strategy to identify and analyze literature on iF methods related to TRAP exposure across academic databases covering the period from 2002 to 2024. After deduplication, title and abstract screening, and full-text review, we ultimately included 25 studies on iF related to TRAP. We classified the measurement methods of iF into four types: simple estimation method, dispersion simulation method, numerical simulation method, and exposure monitoring method. We found orders of magnitude of differences in iF among studies. Population density, pollutant concentration, and breathing rate explain a significant portion of the variations. iF values of nitrogen oxides (NOx), carbon monoxide (CO), and fine particulate matter (PM2.5) are higher than those of diesel particulate matter (DPM), ultrafine particles (UFP), and benzene. Compared to power plants, TRAP has higher iF values, emphasizing the control priority of TRAP. Future research should expand to under-researched regions, strengthen investigations on UFP and secondary pollutants, and refine iF calculation methods using high-resolution and mobility data.

An Experimental Investigation on Geopolymer Concrete Blended with Alccofine Cured Under Heat and Ambient Condition

Abstract - This study investigates the effects of Alccofine on the properties of geopolymer concrete cured under heat and ambient conditions. Geopolymer concrete specimens were prepared with varying proportions of Alccofine and cured at different temperatures. The results show that Alccofine improves the compressive strength, durability, and workability of geopolymer concrete. Heat curing enhances the early- age strength of geopolymer concrete, while ambient curing allows for slower strength development. The findings suggest that geopolymer concrete blended with Alccofine has potential applications in sustainable construction, particularly in projects requiring high strength and durability.Geopolymer concrete, an eco-friendly alternative to conventional Portland cement concrete, is synthesized using industrial by-products such as fly ash, activated by alkaline solutions. Alccofine, known for its ultrafine particle size and high reactivity, is introduced into the mix to enhance the mechanical and durability properties of GPC. The research evaluates the influence of different curing regimes—heat curing and ambient curing—on compressive strength, setting time, and microstructural characteristics. Results demonstrate that Alccofine significantly contributes to early strength development, particularly under heat curing, while also improving long-term performance under ambient conditions.

Estimation for the coefficient of variation in Gamma distribution: A generalized confidence interval approach with applications to PM2.5 dispersion measurement

. The coefficient of variation (CV) of PM2.5 concentrations serves as a critical metric for understanding the variability of ultrafine particulate matter, supporting comparative analyses, public health research, policy development, source identification, and air quality modeling. This study introduces a generalized confidence interval (GCI) for the coefficient of variation in the Gamma distribution, specifically applied to PM2.5 dispersion measurements. A comprehensive evaluation of various statistical methods focuses on coverage probability, average width, and relative bias across a range of sample sizes ( n = 10 , 20 , 30 , 50 , 100 , 200 ) and parameter settings ( θ = 1 , 2 , and τ = 0.10 , 0.20 , 0.25 , 0.30 , 0.35 , 0.40 , 0.45 , 0.50 , 0.7 , 1 ). The results highlight notable differences in method performance. The GCI method consistently achieves close-nominal coverage probabilities (0.95) with the narrowest confidence intervals, making it the most reliable choice, especially for small to moderate sample sizes and higher variability. At the same time, Mc-M emerges as a strong alternative, performing competitively for moderate to large sample sizes and lower variability.

Deposition characteristics of ultrafine particles of different shapes in an inertial impactor: CFD-DEM simulations and experiments

Deposition characteristics of ultrafine particles of different shapes in an inertial impactor: CFD-DEM simulations and experiments

Synthesized Nano-Titanium Dioxide (Nano-TiO2) via Ammonium Fluorotitanate ((NH4)2TiF6) Precipitation with Ammonia Solution

This study focuses on the chemical synthesis of nano-titanium dioxide (nano-TiO2) via ammonium fluorotitanate ((NH4)2TiF6) precipitation with ammonia solution, aiming to elucidate the effects of experimental parameters—including reaction temperature, duration, molar ratio of (NH4)2TiF6 to ammonia, and (NH4)2TiF6 concentration—on the particle size of synthesized nanoparticles, as well as the correlation between particle size and photocatalytic performance. The synthesized nanoparticles predominantly exhibited spindle-shaped morphology. Direct TEM imaging revealed the crystallization and growth mechanisms during synthesis: higher molar ratios, combined with lower temperatures and shorter durations, facilitated the formation of ultrafine particles, whereas lower molar ratios, with elevated temperatures and prolonged reaction times, yielded larger particles. Notably, nanorod structures emerged under low-temperature conditions with F− ion adsorption. To investigate the relationship between particle size and photocatalytic performance, a Taguchi method-inspired experimental design was employed to evaluate the positive or negative impacts of particle size on photocatalytic activity. An experimental matrix was constructed using coded values for each factor, and regression coefficients were calculated to quantify input-output correlations. Results demonstrate that titanium dioxide catalysts with a particle size range of 50–75 nm exhibit optimal photocatalytic efficiency.

Sources of ultrafine particles at a rural midland site in Switzerland

Abstract. Ultrafine particles (UFPs; i.e., atmospheric aerosol particles smaller than 100 nm in diameter) are known to be responsible for a series of adverse health effects as they can deposit in humans' bodies. So far, most field campaigns studying the sources of UFPs have focused on urban environments. This study investigates the outdoor sources of UFPs at the atmospheric monitoring station in Payerne, which represents a typical rural location in Switzerland. We aim to quantify the primary and secondary fractions of UFPs based on specific measurements between July 2020 and July 2021 complementing a series of operational meteorological, trace gas and in situ aerosol observations. To distinguish between primary and secondary contributions, we use a method that relies on measuring the fraction of non-volatile particles as a proxy for primary particles. We further compare our measurement results to previously established methods. We find that primary particles resulting from traffic and residential wood burning (direct emissions – mostly non-volatile BC-rich) contribute less than 40 % to the total number of UFPs, mostly in the Aitken mode. On the other hand, we observe local new particle formation (NPF) events (observed from ∼ 1 nm) evident from the increase in cluster ions (1.5–3 nm) and nucleation-mode particle (2.5–25 nm) concentrations, especially in spring and summer. These events, mediated by sulfuric acid, contribute to increasing the UFP number concentration, especially in the nucleation mode. Besides NPF, the chemical processing of particles emitted from multiple sources (including traffic and residential wood burning) contributes substantially to the nucleation-mode particle concentration. Under the present conditions investigated here, we find that secondary processes mediate the increase in UFP concentration to levels equivalent to those in urban locations, affecting both air quality and human health.

Emissions of Volatile Organic Compounds from Brake Wear and Their Role in Ultrafine Particle Nucleation

Emissions of Volatile Organic Compounds from Brake Wear and Their Role in Ultrafine Particle Nucleation