Ambient ultrafine particle (PM0.1): Sources, characteristics, measurements and exposure implications on human health

Investigation of a multi-frequency ultrasonic acoustic pressure source for acoustic agglomeration

This paper represents numerical and experimental investigations of an ultrasonic multifrequency piezoelectric acoustic pressure source whose target application is acoustic agglomeration of fine and ultrafine particles. The operation of source is based on three vibration modes at 25.83 kHz, 34.73 kHz and 52.41 kHz. Multi-frequency operation allows to obtain three different patterns of acoustic pressure levels which allows to increase performance of the agglomeration process while particles sizes change over time or process. Moreover, acoustic pressure levels, as well as their patterns, were investigated while the source was driven by rectangular and sawtooth signals. Excitation by nonharmonic signals ensured possibility of obtaining modified patterns which results changes in the acoustic pressure levels gradients and allows to obtain different amplitudes of particles vibrations in the agglomeration chamber. Results of numerical and experimental investigations have shown that the ultrasonic acoustic pressure source under excitation by square and sawtooth signals is able to provide maximum sound pressure in the range from 121.6 dB to 132.2 dB while maximum SPL values generated by harmonic signal were indicated in range from 116.4 dB to 129.3 dB. Finally, experimental investigations of acoustic fields impacting particle decrement in air flow have shown that generation of acoustic field by square and sawtooth-shaped signals is able to provide up to 21.38 % and 27.88 % decrement level of 0.3 µm and 1 µm sized particles.

Associations between Ultrafine Particles and Incident Dementia in Older Adults

Fine particulate matter (PM2.5) is linked to dementia risk, but ultrafine particles (UFPs, <100 nm) may be even more toxic due to their distinct physicochemical properties. However, evidence on UFPs and dementia remains limited. This study assessed the association between UFP exposure and Alzheimer's disease (AD) and related dementias (ADRD) among U.S. older adults. Using Medicare data, we analyzed ZIP code-level UFP exposure in 2017 for beneficiaries aged 65 and older residing in the contiguous U.S., applying Cox proportional hazard models to estimate AD and ADRD incidence (2018-2020) while considering comorbidities. Among ∼21 million participants for AD and ∼20 million for ADRD, each interquartile range increase in UFP exposure (3701.6 and 3668.5 particles/cm3, respectively) was associated with higher AD (HR: 1.026, 95% CI: 1.014-1.038) and ADRD (HR: 1.016, 95% CI: 1.008-1.023) risks. The association was linear within typical exposure levels and stronger in individuals with comorbidities. Geographically, the UFP-associated dementia risk was higher in rural areas than in urban areas, possibly due to different pollution sources. These findings underscore UFPs as neurotoxicants and highlight the need for targeted public health interventions to protect vulnerable populations.

Unveiling the Impact of Wildfires on Nanoparticle Characteristics and Exposure Disparities through Mobile and Fixed-Site Monitoring in Toronto, Canada

This study investigates the impacts of wildfires on nanoparticle characteristics and exposure disparities in Toronto, integrating data from a large-scale mobile monitoring campaign and fixed-site measurements during the unprecedented 2023 wildfire season. Our results reveal changes in particle characteristics during wildfire days, with particle number concentrations decreasing by 60% and particle diameter increasing by 30% compared to nonwildfire days. Moreover, the median lung deposited surface area (LDSA) levels rose by 31% during wildfire events. We employed gradient boosting models to estimate near-road LDSA levels on both wildfire and nonwildfire days. The LDSA ratio (wildfire/nonwildfire) exceeded 2.0 in certain areas along highways and in downtown Toronto. Furthermore, our findings show that marginalized communities faced greater LDSA increases than less marginalized ones. Under wildfire conditions, the LDSA ratio difference between the most and least marginalized groups was 16% for recent immigrants and visible minorities and 7% for seniors and children, both statistically significant. This study delivers critical insights into the spatiotemporal variations of nanoparticle characteristics during wildfire and nonwildfire periods, demonstrating the substantial health risks posed by increased LDSA levels and the inequitable distribution of these risks among Toronto's diverse population.

Importance of sub-23 nm particles in traffic environments: Particle number emission factors and extrathoracic deposition doses

New research suggests that exposure to ultrafine particles (UFPs; particle diameter dp < 100 nm) is particularly harmful to brain health. One pathway into the body is via deposition in the respiratory system, where the smallest UFPs deposit efficiently in human extrathoracic airways. Traffic is a major source of these particles, yet sub-23 nm (dp < 23 nm) particles are currently unregulated in engine emission testing worldwide, including the stringent requirements of the European Union, nor are there requirements for ambient monitoring. In this study, we report size-resolved particle number emission factors (EFs) for traffic and estimates of extrathoracic dose rates of sub-23 nm particles. The EFs and dose rates are based on measurements conducted in different urban environments, including roads, tunnels, an airport, and a riverside, in two Central European cities (Düsseldorf and Prague) from March to April 2022. A key difference between the cities is that Düsseldorf has a low-emission zone in its central area and a newer vehicle fleet compared to Prague. Overall, traffic-influenced sites had large EFs for sub-23 nm particles. In the highway and tunnel environments, EFs of particles with dp > 2.5 nm were between 2 and 18 times greater than the EFs of particles with dp > 23 nm. Near the airport, the EF of particles with dp > 23 nm was already high, being 2-9 times higher than in other environments. The number concentrations of sub-23 nm particles varied significantly within the studied cities, and dose rates (measured in billions of particles per hour) differed by up to a factor of ten or more depending on the location.

Emission reduction characteristics of heavy-fuel aircraft piston engine fueled with 100% HEFA sustainable aviation fuel

With the projected expansion of the general aviation sector and recent breakthroughs in sustainable aviation fuels (SAF), accurately measuring emissions from novel aircraft engines powered by SAF is paramount for evaluating the role of aviation industry in emission reduction trends and environmental consequences. Current SAF research primarily centers on low blend ratios, neglecting data on 100% SAF. This study bridges this gap by experimentally determining emissions indices for gaseous pollutants (CO, CO2, HC, NOx), total particulate matter (PM) counts and sizes, and non-volatile particulate matter (nvPM) number and mass concentrations from a heavy-fuel aircraft piston engines (HF-APE) using hydroprocessed esters and fatty acids-derived SAF (HEFA-SAF), adhering to airworthiness-standard sampling and measurement protocols. Additionally, nvPM morphology and structure are analyzed to auxiliarily assess the emission reduction. The results demonstrate that HEFA-SAF stands out for its marked reduction in both CO and HC gaseous pollutant compared to RP-3 aviation kerosene (RP3), as well as effectively reduces PM emissions compared to Diesel and RP3 across all load conditions. Notably, HEFA-SAF significantly curbs the generation of both nucleation-mode and accumulation-mode PM. Specifically, the use of HEFA-SAF leads to a 43% and 24% decrease in average nvPM number concentration, and a 65% and 53% reduction in average nvPM mass concentration respectively, compared to Diesel and RP3. At 50% load, nvPM produced by HEFA-SAF exhibits distinct nanostructural properties, characterized by fewer exposed pores and active sites within agglomerated particles. Rigorous emission testing has conclusively validated the substantial benefits of 100% HEFA-SAF in reducing emissions, offering a compelling rationale for the development of airworthiness regulations and environmental oversight frameworks designed to foster sustainable aviation practices.

Climate change, air pollution and chronic respiratory diseases: understanding risk factors and the need for adaptive strategies

Under the background of climate change, the escalating air pollution and extreme weather events have been identified as risk factors for chronic respiratory diseases (CRD), causing serious public health burden worldwide. This review aims to summarize the effects of changed atmospheric environment caused by climate change on CRD. Results indicated an increased risk of CRD (mainly COPD, asthma) associated with environmental factors, such as air pollutants, adverse meteorological conditions, extreme temperatures, sandstorms, wildfire, and atmospheric allergens. Furthermore, this association can be modified by factors such as socioeconomic status, adaptability, individual behavior, medical services. Potential pathophysiological mechanisms linking climate change and increased risk of CRD involved pulmonary inflammation, immune disorders, oxidative stress. Notably, the elderly, children, impoverished groups and people in regions with limited adaptability are more sensitive to respiratory health risks caused by climate change. This review provides a reference for understanding risk factors of CRD in the context of climate change, and calls for the necessity of adaptive strategies. Further interdisciplinary research and global collaboration are needed in the future to enhance adaptability and address climate health inequality.

Characterization of soot and crystalline atmospheric ultrafine particles

The extraction and characterization of atmospheric ultrafine particles (UFPs) is critical to understanding environmental health and climate dynamics. This study uses an aqueous extraction method to characterize the size distribution, shape, and composition of atmospheric UFPs. We propose a combined use of techniques rarely implemented in air quality analysis, such as atomic force microscopy (AFM), with more conventional methods, such as Transmission Electron microscopy (TEM) and Dynamic Light Scattering (DLS). DLS results indicate a hydrodynamic diameter range from 117 to 1069 nm and a polydispersity index of 0.3-0.79. The high polydispersity reflects the complexity of UFPs agglomeration processes. AFM identified NPs ranging from 10 to 25 nm; topographic images show soot and crystalline structures. High-resolution TEM analysis measured the interplanar distances of crystalline UFPs, showing the presence of calcium carbonates. TEM-EDS identified soot and crystalline particles with variable composition, from Si-enriched NPs to Ca-F-Cl-Na-Si, carbonates, chlorides, and Zn-Ti-enriched nanosilica. These findings provide valuable insights into the physicochemical properties of atmospheric dust, contributing to our knowledge and the potential implications for human health and the environment.

A molecular toxicological study to explore potential health risks associated with ultrafine particle exposure in cold and humid indoor environments

Environmental pollutants including ultrafine particulate matter (UFPs) and adverse meteorological conditions pose significant public health impacts, particularly affecting respiratory health. This study aims to elucidate the synergistic effects of cold-humid conditions and UFPs exposure on respiratory health, utilizing Carbon Black Nanoparticles (CB-NPs) as surrogates for UFPs. Through comprehensive lung function tests, histopathological examinations, and biomarker analyses, this research focuses on the modulation of oxidative stress signaling pathways and NF-κB activation. Male Balb/c mice were exposed to specific concentrations of CB-NPs (30-50 nm in diameter, 0.184 mg/(kg·day)) in a controlled environmental chamber mimicking cold (10°C/14°C) and humid (90 % RH) conditions over three weeks. The results indicate that exposure to CB-NPs alone increased lung function, oxidative stress (ROS, GSH, MDA), inflammation (IL-6, TNF-α, IL-1β), apoptosis (Caspase 3, Caspase 8, Caspase 9), and histopathological alterations in lung tissue. Furthermore, these effects were notably more severe under combined exposure with cold-humid conditions. These results suggest that the adverse effects of pollutants are not solely concentration-dependent but are exacerbated by specific environmental contexts. It is evident that Vitamin E (100 mg/kg/day) can attenuate these adverse effects, underscoring its potential as a protective agent against environmental stressor-induced air pollutants and cold humid conditions. Our findings suggest that the synergistic effects of environmental factors and pollutant exposure significantly impact respiratory health, providing valuable insights for the design of healthier indoor environments and the development of strategies to mitigate these risks.

Therapeutic Potential of Herbal Medicines in Combating Particulate Matter (PM)-Induced Health Effects: Insights from Recent Studies

Particulate matter (PM), particularly fine (PM2.5) and ultrafine (PM0.1) particles, originates from both natural and anthropogenic sources, such as biomass burning and vehicle emissions. These particles contain harmful compounds that pose significant health risks. Upon inhalation, ingestion, or dermal contact, PM can penetrate biological systems, inducing oxidative stress, inflammation, and DNA damage, which contribute to a range of health complications. This review comprehensively examines the protective potential of natural products against PM-induced health issues across various physiological systems, including the respiratory, cardiovascular, skin, neurological, gastrointestinal, and ocular systems. It provides valuable insights into the health risks associated with PM exposure and highlights the therapeutic promise of herbal medicines by focusing on the natural products that have demonstrated protective properties in both in vitro and in vivo PM2.5-induced models. Numerous herbal medicines and phytochemicals have shown efficacy in mitigating PM-induced cellular damage through their ability to counteract oxidative stress, suppress pro-inflammatory responses, and enhance cellular defense mechanisms. These combined actions collectively protect tissues from PM-related damage and dysfunction. This review establishes a foundation for future research and the development of effective interventions to combat PM-related health issues. However, further studies, including in vivo and clinical trials, are essential to evaluate the safety, optimal dosages, and long-term effectiveness of herbal treatments for patients under chronic PM exposure.

Performance of fine particulate matter data on air quality in an epidemiological study in Salvador, Brazil

OBJECTIVE

To evaluate the performance of satellite-derived PM2.5 concentrations against ground-based measurements in the municipality of Salvador (state of Bahia, Brazil) and the implications of these estimations for the associations of PM2.5 with daily non-accidental mortality.

METHODS

This is a daily time series study covering the period from 2011 to 2016. A correction factor to improve the alignment between the two data sources was proposed. Effects of PM2.5 were estimated in Poisson generalized additive models, combined with a distributed lag approach.

RESULTS

According to the results, satellite data underestimated the PM2.5 levels compared to ground measurements. However, the application of a correction factor improved the alignment between satellite and ground-based data. We found no significant differences between the estimated relative risks based on the corrected satellite data and those based on ground measurements.

CONCLUSION

In this study we highlight the importance of validating satellite-modeled PM2.5 data to assess and understand health impacts. The development of models using remote sensing to estimate PM2.5 allows the quantification of health risks arising from the exposure.

Nano to micron-size combustion particles in smokers' homes: Magnetic properties of tobacco and cigarette ashes

Cigarette emission comprises high-temperature combustion processes producing diverse harmful compounds, gases, and particulate matter that are spread through the air and can be taken by smokers and passive smokers involuntarily. We determined the magnetic properties of tobacco cigarettes from six commercial brands. We also monitored the emission of particulate matter in some smokers' homes using low-cost sensors and the PM2.5 dataset was studied through a time series analysis. In addition, compositional, morphological, and magnetic properties of cigarette ashes were studied and compared with available data. Unexpected positive mean values of specific magnetic susceptibility (χ = 3.7 × 10-8 m3kg-1) and saturation isothermal remanent magnetization (SIRM = 0.6×10-3 Am2kg-1) of tobacco cigarettes indicate the presence of "magnetic condiments" in this unburned material. In contrast, as a consequence of puff and smoldering burn, a magnetic increase of up to 35-fold the reference values of unburned material evidence an important neoformation of airborne tobacco-derived magnetic particle ToMP. Mixtures of these ToMPs with different sizes, from nano to micron-sized, comprise superparamagnetic SP, single-domain SD, and multidomain MD particles. This work provides new accurate information on specific tobacco product ingredients (not declared) and the unnoticed ToMP emission after smoking habits, which are needed for tobacco products, consumers and passive smokers (including vulnerable children) exposed to second-hand smoke. ToMPs and myriad other toxicants may be inhaled, escape from the inhalation system and penetrate biological barriers leading to long-term human health risks.

Assessment of the Physicochemical Properties of Ultrafine Particles (UFP) from Vehicular Emissions in a Commercial Parking Garage: Potential Health Implications

Vehicular emissions are a major culprit in the rise of urban air pollution. The particulate matter (PM) emitted from vehicular sources includes primarily ultrafine particles (UFPs) with aerodynamic diameters less than 0.1 µm (PM0.1) and is linked to adverse respiratory and cardiovascular health effects. Despite this knowledge, few exposure assessment studies exist that detail the physicochemical properties of PM in parking garages. In this study, airborne PM emitted by vehicles in a parking garage of a hospital in New Jersey was sampled, during winter and summer seasons, and physicochemically characterized. The results indicate that the mass concentrations of the UFPs in the garage were 2.51 µg/m3 and 3.59 µg/m3, respectively. These UFPs contained a large percentage of elemental carbon and toxic elements. They also contained polycyclic aromatic hydrocarbons (PAHs), having deleterious health effects. An inhalation particle modeling revealed that 23.61% of these UFPs are deposited in the pulmonary region of the lung, translating to a dose of 10.67 µg for winter and 15.25 µg for summer, over a typical 40 h work week. These high deposited levels of UFPs and their complex chemistry levels further warrant the need for toxicological assessment of UFPs related to vehicular emissions.

Atmospheric new particle formation identifier using longitudinal global particle number size distribution data

Atmospheric new particle formation (NPF) is a naturally occurring phenomenon, during which high concentrations of sub-10 nm particles are created through gas to particle conversion. The NPF is observed in multiple environments around the world. Although it has observable influence onto annual total and ultrafine particle number concentrations (PNC and UFP, respectively), only limited epidemiological studies have investigated whether these particles are associated with adverse health effects. One plausible reason for this limitation may be related to the absence of NPF identifiers available in UFP and PNC data sets. Until recently, the regional NPF events were usually identified manually from particle number size distribution contour plots. Identification of NPF across multi-annual and multiple station data sets remained a tedious task. In this work, we introduce a regional NPF identifier, created using an automated, machine learning based algorithm. The regional NPF event tag was created for 65 measurement sites globally, covering the period from 1996 to 2023. The discussed data set can be used in future studies related to regional NPF.

Characterizing sector-oriented roadside exposure to ultrafine particles (PM0.1) via machine learning models: Implications of covariates influences on sectors variability

Ultrafine particles (UFPs; PM0.1) possess intensified health risk due to their smaller size and unique spatial variability. One of major emission sources for UFPs is vehicle exhaust, which varies based on the traffic composition in each type of roadside sector. The current challenge of epidemiological UFPs study is limited characterization ability due to expensive instruments. This study assessed the UFPs particle number concentrations (UFPs PNC) exposure dose for typical healthy adults and children at three different roadside sectors, including industrial roadside (IN), residential roadside (RS), and urban background (UB). Furthermore, this study also developed and utilized machine learning (ML) algorithms that could accurately characterize the UFPs exposure dose and explain the covariates effects on the model outputs, representing the intra-urban variability of UFPs between sectors. It was found that the average inhaled UFPs dose for healthy adults and children during off-peak season (warm period) were 1.71 ± 0.19 × 1010; 1.28 ± 0.22 × 1010; 1.09 ± 0.18 × 1010 #/hour and 1.33 ± 0.15 × 1010; 0.99 ± 0.17 × 1010; 0.86 ± 0.14 × 1010 #/hour at IN, RS, UB. Inhaled UFPs were mainly deposited in tracheobronchial (TB) respiratory fraction for adults (67.7%) and in alveoli (ALV) fraction for children (67.5%). Among three ML algorithms implemented in this study, XGBoost possessed the highest UFPs PNC exposure dose estimation performances with R2 = 0.965; 0.959; 0.929 & RMSE = 0.79 × 108; 0.54 × 108; 0.15 × 105 #/hour at IN, RS, and UB which then followed by multiple linear regression (MLR), and random forest (RF). Furthermore, SHAP analysis from the XGBoost model has successfully pointed out the spatial variability of each roadside sector by quantifying the approximated contributions of covariates to the model's output. Findings in this study highlighted the potential use of ML models as an alternative for preliminary particle exposure source apportionment.

Assessing the particulate matter emission reduction characteristics of small turbofan engine fueled with 100 % HEFA sustainable aviation fuel

With the continuous increase in global air transportation, the impact of ultrafine particulate matter (PM) emissions from aviation on human health and environmental pollution is becoming increasingly severe. In addition to carbon reduction throughout the lifecycle, Sustainable Aviation Fuels (SAF) also represent a significant pathway for reducing PM emissions. However, due to issues such as airworthiness safety and adaptability, existing research has mostly focused on the emission performance of SAF when blended with traditional fuels at <50 %, leaving the emission characteristics of higher blending ratios to be explored. In this study, using measurement methods recommended by the International Civil Aviation Organization (ICAO), the PM emission reduction characteristics of small turbofan engines fueled with 100 % Hydroprocessed Esters and Fatty Acids (HEFA)-SAF were experimentally evaluated and compared with traditional fuels RP-3 and Diesel, while avoiding the interference of lubricant blending combustion. The results showed that the peak number concentration of particle size distribution (PSD), PM total number, as well as the number and mass concentration of non-volatile particulate matter (nvPM) decreased initially and then increased with rising thrust conditions. HEFA-SAF exhibits PSD with smaller diameters, and the Geometric Mean Diameter (GMD) ranges from 7.7 nm to 20.3 nm under all conditions. Both volatile particulates (vPM) and nvPM from HEFA-SAF are significantly reduced, with nvPM number emission index (EIn) being 92 % and 71 % lower than Diesel and RP-3, respectively. The nvPM mass emission index (EIm) also shows reductions of 96 % and 89 % compared to Diesel and RP-3. Microscopic characterization also indicated that using HEFA-SAF emitted fewer and smaller PMs. This study establishes a foundation for evaluating the effectiveness of 100 % SAF in reducing PM emissions within the aviation sector, and contributes to the airworthiness regulations development related to the use of SAF in a variety of application environments, alongside enhancing environmental protection measures.

Indoor Emissions Contributed the Majority of Ultrafine Particles in Chinese Urban Residences

Ultrafine particle (UFP) pollution should be controlled to reduce its effects on health. The design of control measures is limited owing to the uncertainty of source contributions in Chinese residences, where indoor UFP pollution is more severe than in Western residences. Herein, a source-specific, time-dependent UFP concentration model was developed by applying an infiltration factor model incorporating coagulation effects. A Monte Carlo framework with the UFP concentration model was employed to estimate the probabilistic distribution of source contributions in Chinese residences. The input parameter distributions were determined based on our survey and previous studies. The annually averaged indoor UFP concentration was estimated at (2.75 ± 1.71) × 104 #/cm3, ranging from 2.35 × 103 to 1.27 × 105 #/cm3 outside the kitchen, and at (5.48 ± 3.08) × 104 #/cm3, ranging from 2.90 × 103 to 1.94 × 105 #/cm3 in the kitchen. Indoor sources contributed more to indoor UFPs, accounting for 61% in the nonkitchen and 80% in the kitchen, surpassing their contribution to indoor PM2.5 in Chinese residences. Meanwhile, the indoor UFP emission contributions were higher than those in the United States, Canada, and Germany, owing to higher emissions from cooking and cigarette smoking. These results will aid in elucidating human exposure to UFPs and in designing more targeted control measures.

Mechanistic insights into cardiovascular effects of ultrafine particle exposure: A longitudinal panel study

BACKGROUND

Ultrafine particle (UFP) has been linked with higher risks of cardiovascular diseases; however, the biological mechanisms remain to be fully elucidated.

OBJECTIVES

This study aims to investigate the cardiovascular responses to short-term UFP exposure and the biological pathways involved.

METHODS

A longitudinal panel study was conducted among 32 healthy, non-smoking young adults in Shanghai, China, who were engaged in five rounds of follow-ups between December 2020 and November 2021. Individual exposures were calculated based on the indoor and outdoor real-time measurements. Blood pressure, arterial stiffness, targeted biomarkers, and untargeted proteomics and metabolomics were examined during each follow-up. Linear mixed-effect models were applied to analyze the exposure and health data. The differential proteins and metabolites were used for pathway enrichment analyses.

RESULTS

Short-term UFP exposure was associated with significant increases in blood pressure and arterial stiffness. For example, systolic blood pressure increased by 2.10 % (95 % confidence interval: 0.63 %, 3.59 %) corresponding to each interquartile increase in UFP concentrations at lag 0-3 h, while pulse wave velocity increased by 2.26 % (95 % confidence interval: 0.52 %, 4.04 %) at lag 7-12 h. In addition, dozens of molecular biomarkers altered significantly. These effects were generally present within 24 h after UFP exposure, and were robust to the adjustment of co-pollutants. Molecular changes detected in proteomics and metabolomics analyses were mainly involved in systemic inflammation, oxidative stress, endothelial dysfunction, coagulation, and disturbance in lipid transport and metabolism.

DISCUSSION

This study provides novel and compelling evidence on the detrimental subclinical cardiovascular effects in response to short-term UFP exposure. The multi-omics profiling further offers holistic insights into the underlying biological pathways.

Quantifying the contributions of road and air traffic to ambient ultrafine particles in two urban communities

Traffic-related activities are widely acknowledged as a primary source of urban ambient ultrafine particles (UFPs). However, a notable gap exists in quantifying the contributions of road and air traffic to size-resolved and total UFPs in urban areas. This study aims to delineate and quantify the traffic's contributions to size-resolved and total UFPs in two urban communities. To achieve this, stationary sampling was conducted at near-road and near-airport communities in Seattle, Washington State, to monitor UFP number concentrations during 2018-2020. Comprehensive correlation analyses among all variables were performed. Furthermore, a fully adjusted generalized additive model, incorporating meteorological factors, was developed to quantify the contributions of road and air traffic to size-resolved and total UFPs. The study found that vehicle emissions accounted for 29% of total UFPs at the near-road site and 13% at the near-airport site. Aircraft emissions contributed 14% of total UFPs at the near-airport site. Notably, aircraft predominantly emitted UFP sizes below 20 nm, while vehicles mainly emitted UFP sizes below 50 nm. These findings reveal the variability in road and air traffic contributions to UFPs in distinct areas. Our study emphasizes the pivotal role of traffic layout in shaping urban UFP exposure.

Particle emissions from heated tobacco products

INTRODUCTION

This study determines the particle emissions from five heated tobacco products (HTPs).

METHODS

An aethalometer is used for the determination of black carbon (BC) and an aerosol monitor for total particulate matter (PM) concentration and also PM fractions (1, 2.5, 4, and 10 μm) in the mainstream emissions of 5 HTPs: IQOS, LIL, PULZE, ILUMA, and GLO. Fifteen different flavors were used, five sticks per flavor, which were smoked using a peristaltic pump under both ISO and Canadian smoking regimes. The method repeatability was determined using 15 sticks of one flavor for each brand for each smoking regime.

RESULTS

All HTPs emit particles, and more than 99.7% of the particles emitted are smaller than 1 μm. Both BC and PM emissions show quite low repeatability. Particle emissions increase in relation to the heating temperature and the intensity smoking regime, and are depending on the flavor used. BC corresponds to a small percentage of total PM.

CONCLUSIONS

Although HTPs are promoted as products of reduced risk compared to conventional cigarettes, high particle concentrations are detected in their emissions, depending on the smoking regime, the flavor used, and the operation parameters. PM emissions vary significantly between different brands under the ISO smoking regime, probably due to the heating temperature. In contrast, PM emissions under the Canadian smoking regime do not vary significantly between different brands. This could probably be attributed to the fact that increased puff frequency does not allow the device to cool down between puffs, resulting in an increase in PM emissions for all the brands, but not dependent on the maximum heating temperature of the device. BC emissions only consist of a very small fraction of PM and do not vary significantly between different brands under both smoking regimes.

Assessment of seasonal variability of PM, BC and UFP levels at a highway toll stations and their associated health risks

As a part of their occupation, workers at toll stations are exposed to traffic emissions during the working shift, which sometimes stretches to 12 h. To assess the exposure and subsequent health risk of these workers, a study was performed on a highway toll station in India. PM1, PM2.5, PM10, BC and UFP concentration were determined inside a toll collectors' cabin and outside in a free-flowing traffic section (125 m from the toll cabin). The concentrations varied in the following range: PM1 (40.69-226.13 μg m-3), PM2.5 (49.71-247.36 μg m-3), PM10 (83.15-458.14 μg m-3) and BC (2.1-87.5 μg m-3) and UFP: 101-53705 pt cm-3. The mean concentration inside the cabin was 1.34 (PM1), 1.35 (PM2.5), 1.16 (PM10) and 2.91 (BC) times the concentration outside for the summer season. The corresponding levels in the winter season were 1.14 (PM1), 1.11 (PM2.5), 1.11 (PM10), 2.50 (BC) and 1.82 (UFP). In addition to the exhaust emission, the non-exhaust emissions such as resuspension of crustal particles, fly ash and bioaerosols were identified. Using the Multiple Path Particle Dosimetry model for two groups - adults (18-21 years) and adults (21+ years), it was estimated that the pulmonary deposition of in-cabin workers were 50% (PM2.5) -75% (PM1) higher than the workers outside the cabin. Particle mass deposition was found to be higher for adults (21+ years) than adults (18-21 years) for both the seasons. The study quantitatively assessed the health risk faced by the workers in terms of exposure concentration and deposition in respiratory tract. More such studies at different traffic mix and climate can provide better estimates of health risk of toll workers that can be used to devise appropriate strategies for control of it.

Detection of atmospheric aerosols and terrestrial nanoparticles collected in a populous city in southern Brazil

The main objective of this study is to analyze hazardous elements in nanoparticles (NPs) (smaller than 100 nm) and ultrafine particles (smaller than 1 µm) in Porto Alegre City, southern Brazil using a self-made passive sampler and Sentinel-3B SYN satellite images in 32 collection points. The Aerosol Optical Thickness proportion (T550) identification was conducted using images of the Sentinel-3B SYN satellite at 634 points sampled in 2019, 2020, 2021, and 2022. Focused ion beam scanning electron microscopy analyses were performed to identify chemical elements present in NPs and ultrafine particles, followed by single-stage cascade impactor to be processed by high-resolution transmission electron microscopy. This process was coupled with energy-dispersive X-ray spectroscopy and later analysis via secondary ion mass spectrometry. Data was acquired from Sentinel-3B SYN images, normalized to a standard mean of 0.83 µg/mg, at moderate spatial resolution (260 m), and modeled in the Sentinel Application Platform (SNAP) software v.8.0. Statistical matrix data was generated in the JASP software (Jeffreys's Amazing Statistics Program) v.0.14.1.0 followed by a K-means cluster analysis. The results demonstrate the presence of between 1 and 100 nm particles of the following chemical elements: Si, Al, K, Mg, P, and Ti. Many people go through these areas daily and may inhale or absorb these elements that can harm human health. In the Sentinel-3B SYN satellite images, the sum of squares in cluster 6 is 168,265 and in cluster 7 a total of 21,583. The use of images from the Sentinel-3B SYN satellite to obtain T550 levels is of great importance as it reveals that atmospheric pollution can move through air currents contaminating large areas on a global scale.

Loliolide in Sargassum horneri Alleviates Ultrafine Urban Particulate Matter (PM 0.1)-Induced Inflammation in Human RPE Cells

Owing to increasing air pollution due to industrial development, fine dust has been associated with threatening public health. In particular, ultrafine urban particulate matter (uf-UP, PM 0.1) can easily enter our bodies, causing inflammation-related diseases. Therefore, in the present study, we evaluated the effects of hydrothermal extracts of Sargassum horneri and its bioactive compound, loliolide, on uf-UP-induced inflammation as a potential treatment strategy for retinal disorders. Human retinal pigment epithelial cells (ARPE-19) stimulated with TNF-α or uf-UPs were treated with S. horneri extract and loliolide. S. horneri extracts exhibited anti-inflammatory effects on uf-UP-induced inflammation without cell toxicity through downregulating the mRNA expression of MCP-1, IL-8, IL-6, and TNF-α. UPLC-QTOF/MS analysis confirmed that the hydrothermal extract of S. horneri contained loliolide, which has anti-inflammatory effects. Loliolide effectively reduced the mRNA expression and production of proinflammatory chemokines (IL-8) and cytokines (IL-1β and IL-6) by downregulating the MAPK/NF-ĸB signaling pathway on TNF-α-stimulated inflammatory ARPE-19 cells. These effects were further confirmed in inflammatory ARPE-19 cells after stimulation with uf-UPs. Collectively, these results suggested the application of S. horneri as a functional ingredient for treating ocular disorders caused by particular matters.

Submicronic particulate matter (PM1), a "neglected killer" for HIV/AIDS patients in Hubei, China: Results from a cohort study from 2001 to 2020

BACKGROUND

Although with the progress of antiretroviral therapy, the life expectancy of HIV/AIDS patients was still not equal to that of normal people. Submicronic particulate matter (PM1) might play a role in mortality among people living with HIV/AIDS, However, cohort evidence is extensively scarce.

METHODS

This twenty-year open cohort study involved all individuals officially diagnosed with HIV/AIDS in Hubei Province from 2001 to 2020. Time-varying Cox proportional hazard models were applied to investigate the associations between long-term exposure to PM1 and mortality in HIV/AIDS patients. The concentration-response curves between PM1 and AIDS-related deaths/all-cause deaths were characterized by fitting restricted cubic spline models. These curves were then utilized to estimate the number of deaths attributed to PM1.

RESULTS

Long-term exposure to PM1 was significantly associated with AIDS-related deaths and all-cause death among HIV/AIDS patients, with excess risks of 2.33 % [95 % confidence interval (CIs): 1.62, 3.15] and 0.69 % (0.22, 1.17) for each 1 μg/m3 increase in annual PM1. HIV-positive people with lower initial CD4+ cell count levels or aged over 65 years old were more susceptible to PM1 exposure. We estimated about 844 AIDS-related deaths and 1175 all-cause deaths can be attributable to ambient PM1 exposure, accounting for 41.7 % and 23.8 % of the total deaths from corresponding causes, respectively.

CONCLUSIONS

Long-term exposure PM1 was a novel factor hindering the life spans of people living with HIV/AIDS. Early establishment of PM1 concentration standards and efforts to achieve them will bring substantial health benefits to people living with HIV/AIDS, especially in low- and middle-income countries facing the dual challenges of high air pollution and high AIDS prevalence.

Bridging the gap: harnessing liquid nanomachine know-how for tackling harmful airborne particulates

The emergence of "nanomotors", "nanomachines", and "nanorobotics" has transformed dynamic nanoparticle research, driving a transition from passive to active and intelligent nanoscale systems. This review examines two critical fields: the investigation of airborne particles, significant contributors to air pollution, and the rapidly emerging domain of catalytic and field-controlled nano- and micromotors. We examine the basic concepts of nano- and micromachines in motion and envision their possible use in a gaseous medium to trap and neutralize hazardous particulates. While past studies described the application of nanotechnology and nanomotors in various scenarios, airborne nano/micromachine motion and their control have yet to be thoroughly explored. This review intends to promote multidisciplinary research on nanomachines' propulsion and task-oriented applications, highlighting their relevance in obtaining a cleaner atmospheric environment, a critical component to consider for human health.

Accurate particulate matter emission measurements from biomass combustion: A holistic evaluation of full and partial flow dilution systems

Accurately measuring particulate matter emissions from biomass combustion is crucial for evaluating the performance of fuels, combustion appliances and flue gas cleaning methods. These measurements are essential for refining emission inventories for health risk assessments and environmental models and for defining pollution control strategies. However, as air quality standards become increasingly stringent and emission levels decrease, it is important to develop reliable, accurate measurement methods. This study presents a comprehensive evaluation of two particulate dilution systems, namely a full flow dilution (FFD) tunnel and a two-stage partial flow dilution system (porous tube diluter combined with ejector diluter, PTD + ED), for characterising the particle number size distribution from a wood pellet boiler. The maximum relative sampling errors due to not sampling isokinetically increase with particle size and dilution ratio (DR), but are less than 1% for particles smaller than 1 μm for both systems. The total particle number concentration with FFD is on average 35% lower than with PTD + ED, which suggests substantial particle loss during FFD. In addition with FFD, a strong negative correlation is observed between DR and the average particle size. On the other hand with PTD + ED, both the dilution air temperature and DR have no substantial influence on the particle number emissions. However, it is observed with both systems that the particle distribution is affected by coagulation, and this effect becomes more pronounced as dilution decreases. Overall, this work provides insights into the strengths and limitations of particulate dilution systems for accurately measuring emissions from biomass combustion, which can support the development of more reliable measurement methods and assist in implementing effective pollution control strategies.

Lensfree Air-Quality Monitoring of Fine and Ultrafine Particulate Matter Using Vapor-Condensed Nanolenses

Current commercial air-quality monitoring devices lack a large dynamic range, especially at the small, ultrafine size scale. Furthermore, there is a low density of air-quality monitoring stations, reducing the precision with which local particulate matter hazards can be tracked. Here, we show a low-cost, lensfree, and portable air-quality monitoring device (LPAQD) that can detect and measure micron-sized particles down to 100 nm-sized particles, with the capability to track and measure particles in real time throughout a day and the ability to accurately measure particulate matter densities as low as 3 μg m-3. A vapor-condensed film is deposited onto the coverslip used to collect particles before the LPAQD is deployed at outdoor monitoring sites. The vapor-condensed film increases the scattering cross section of particles smaller than the pixel size, enabling the sub-pixel and sub-diffraction-limit-sized particles to be detected. The high dynamic range, low cost, and portability of this device can enable citizens to monitor their own air quality to hopefully impact user decisions that reduce the risk for particulate matter-related diseases.