An Overview of Particulate Matter Measurement Instruments

Differential inflammation, oxidative stress and cardiovascular damage markers of nano- and micro-particle exposure in mice: Implications for human disease burden

Particulate matter (PM) poses a significant risk to human health; however, it remains uncertain which size fraction is especially harmful and what mechanisms are involved. We investigated the varying effects of particle size on specific organ systems using a custom mouse exposure system and synthetic PM (SPM). Whole-body exposure of mice showed that micrometer-sized fine SPM (2-4 μm) accumulated in the lungs, the primary entry organ, while nanometer-sized SPM (<250 nm) did not accumulate, suggesting a transition into circulation. Mice exposed to micro-SPM exhibited inflammation and NADPH oxidase-derived oxidative stress in the lungs. In contrast, nano-SPM-exposed mice did not display oxidative stress in the lungs but rather at the brain, heart, and vascular levels, supporting the hypothesis that they penetrate the lungs and reach the circulation. Sources of reactive oxygen species from micro-SPM in the lung are NOX1 and NOX2, driven by pulmonary inflammation, while oxidative stress from nano-SPM in the heart is mediated by protein kinase C-dependent p47phox phosphorylation, leading to NOX2 activation in infiltrated monocytes. Endothelial dysfunction and increased blood pressure were more pronounced in nano-SPM-exposed mice, also supported by elevated endothelin-1 and reduced endothelial nitric oxide synthase expression, which enhances constriction and diminishes vasodilation. Further, we estimated the cardiovascular disease burden of nano-particles in humans based on global exposure data and hazard ratios from an epidemiological cohort study. These results provide novel insights into the disease burdens of inhaled nano- and micro-particles (corresponding to fine and ultrafine categories), guiding future studies.

Particles emitted from smouldering peat: size-resolved composition and emission factors

Peat fires emit large quantities of particles and gases, which cause extensive haze events. Epidemiological studies have correlated wildfire smoke inhalation with increased morbidity and mortality. Despite this, uncertainties surrounding particle properties and their impact on human health and the climate remain. To expand on the limited understanding this laboratory study investigated the physicochemical characteristics of particles emitted from smouldering Irish peat. Properties investigated included number and mass emission factors (EFs), size distribution, morphology, and chemical composition. Fine particles with a diameter less than 2.5 μm (PM2.5), accounted for 91 ± 2% of the total particle mass and the associated mass EF was 12.52 ± 1.40 g kg-1. Transmission electron microscopy imaging revealed irregular shaped metal particles, spherical sulfate particles, and carbonaceous particles with clusters of internal particles. Extracted particle-bound metals accounted for 3.1 ± 0.5% of the total particle mass, with 86% of the quantified metals residing in the fraction with a diameter less than 1 μm. Redox active and carcinogenic metals were detected in the particles, which have been correlated with adverse health effects if inhaled. This study improves the understanding of size-resolved particle characteristics relevant to near-source human exposure and will provide a basis for comparison to other controlled and natural peatland fires.

Microscopic and spectroscopic analysis of atmospheric iron-containing single particles in Lhasa, Tibet

The Tibetan Plateau, known as the "Third Pole", is currently in a state of perturbation caused by intensified human activity. In this study, 56 samples were obtained at the five sampling sites in typical area of Lhasa city and their physical and chemical properties were investigated by TEM/EDS, STXM, and NEXAFS spectroscopy. After careful examination of 3387 single particles, the results showed that Fe should be one of the most frequent metal elements. The Fe-containing single particles in irregular shape and micrometer size was about 7.8% and might be mainly from local sources. Meanwhile, the Fe was located on the subsurface of single particles and might be existed in the form of iron oxide. Interestingly, the core-shell structure of iron-containing particles were about 38.8% and might be present as single-, dual- or triple-core shell structure and multi-core shell structure with the Fe/Si ratios of 17.5, 10.5, 2.9 and 1.2, respectively. Meanwhile, iron and manganese were found to coexist with identical distributions in the single particles, which might induce a synergistic effect between iron and manganese in catalytic oxidation. Finally, the solid spherical structure of Fe-containing particles without an external layer were about 53.4%. The elements of Fe and Mn were co-existed, and might be presented as iron oxide-manganese oxide-silica composite. Moreover, the ferrous and ferric forms of iron might be co-existed. Such information can be valuable in expanding our understanding of Fe-containing particles in the Tibetan Plateau atmosphere.

Improving Aerosol Characterization Using an Optical Particle Counter Coupled with a Quartz Crystal Microbalance with an Integrated Microheater

Aerosols, as well as suspended particulate matter, impact atmospheric pollution, the climate, and human health, directly or indirectly. Particle size, chemical composition, and other aerosol characteristics are determinant factors for atmospheric pollution dynamics and more. In the last decade, low-cost devices have been widely used in instrumentation to measure aerosols. However, they present some issues, such as the problem of discriminating whether the aerosol is composed of liquid particles or solid. This issue could lead to errors in the estimation of mass concentration in monitoring environments where there is fog. In this study, we investigate the use of an optical particle counter (OPC) coupled to a quartz crystal microbalance with an integrated microheater (H-QCM) to enhance measurement performances. The H-QCM was used not only to measure the collected mass on its surface but also, by using the integrated microheater, it was able to heat the collected mass by performing heating cycles. In particular, we tested the developed system with aerosolized saline solutions of sodium chloride (NaCl), with three decreasing concentrations of salt and three electronic cigarette solutions (e-liquid), with different concentrations of propylene glycol and glycerin mixtures. The results showed that the OPC coherently counted the salt dilution effects, and the H-QCM output confirmed the presence of liquid and solid particles in the aerosols. In the case of e-liquid aerosols, the OPC counted the particles, and the HQCM output highlighted that in the aerosol, there were no solid particles but a liquid phase only. These findings contribute to the refinement of aerosol measurement methodologies by low-cost sensors, fostering a more comprehensive understanding.

Human health impacts attributable to inhalation exposure of particulate matter (PM10 and PM2.5) during the Holi festival

OBJECTIVE

The present study focuses on residential areas of Delhi to identify the elevated levels of ambient PM10 and PM2.5 due to biomass burning followed by the coloring activity in the Holi festival celebrated at the end of the winter season. This study also focuses on the health risk assessment and mortality among different age groups due to the change in particulate matter levels during the Holi festival in Delhi, India.

MATERIALS AND METHODS

Secondary data of particulate matters have been procured from the Central Pollution Control Board (CPCB), Delhi Pollution Control Committee (DPCC), and Indian Institute of Tropical Meteorology (IITM), Pune for the period of the pre-, during, and post-Holi period for the year 2018-2020 at four selected residential locations in Delhi, India. The health impacts of particle inhalation were quantified using the AirQ + models.

RESULTS

The results indicated the levels of PM10 and PM2.5 rise about 3-4 times higher during the Holi festival than on normal days, resulting in health risks and causing an excess number of mortality and Asthma cases in Delhi. Such cases were also found to be higher in 2018, followed by 2019 and 2020 at all the selected locations in Delhi.

CONCLUSIONS

The study linked the increasing particulate levels in the Holi festival with the increased health risk through short-term exposure of the population. The excess number of cases (ENCs) of mortality, all causes of mortality among adults (age > 30 years) associated with short-term exposure to particulate were also identified.

Job Exposure Matrix, a Solution for Retrospective Assessment of Particle Exposure in a Subway Network and Their Long-Term Effects

INTRODUCTION

Health effects after long-term exposure to subway particulate matter (PM) remain unknown due to the lack of individual PM exposure data. This study aimed to apply the job exposure matrix (JEM) approach to retrospectively assess occupational exposure to PM in the Parisian subway.

METHODS

Job, the line and sector of the transport network, as well as calendar period were four JEM dimensions. For each combination of these dimensions, we generated statistical models to estimate the annual average PM10 concentration using data from an exhaustive inventory of the PM measurement campaigns conducted between 2004 and 2020 in the Parisian subway and historical data from the Parisian air pollution monitoring network. The resulting JEM and its exposure estimates were critically examined by experts using the uncertainty analysis framework.

RESULTS

The resulting JEM allows for the assignment of the estimated annual PM10 concentration to three types of professionals working in the subway: locomotive operators, station agents, and security guards. The estimates' precision and validity depend on the amount and quality of PM10 measurement data used in the job-, line-, and sector-specific models. Models using large amounts of personal exposure measurement data produced rather robust exposure estimates compared to models with lacunary data (i.e., in security guards). The analysis of uncertainty around the exposure estimates allows for the identification of the sources of uncertainty and parameters to be addressed in the future in order to refine and/or improve the JEM.

CONCLUSIONS

The JEM approach seems relevant for the retrospective exposure assessment of subway workers. When applied to available data on PM10, it allows for the estimation of this exposure in locomotive operators and station agents with an acceptable validity. Conversely, for security guards, the current estimates have insufficient validity to recommend their use in an epidemiological study. Therefore, the current JEM should be considered as a valid prototype, which shall be further improved using more robust measurements for some jobs. This JEM can also be further refined by considering additional exposure determinants.

A meta-analysis of particulate matter and nitrogen dioxide air quality monitoring associated with the burden of disease in sub-Saharan Africa

Exposure to air pollution is a fundamental obstacle that makes it complex to realize the Sustainable Development Goals (SDGs 3) for good health and wellbeing. It is for this reason that air pollution has been characterized as the global environmental health risk facing the current generation. The risks of air pollution on morbidity, and life expectancy are well documented. This feeds directly to the substantial body of the literature that exists regarding the burden of diseases associated with ambient air pollution. However, the bulk of this literature originates from developed countries. Whilst most of the sub-Saharan African studies extrapolate literature from developed countries to contextualize the risks of elevated air pollution exposure levels associated with the burden of disease. However, extrapolation of epidemiological evidence from developed countries is problematic given that it disregards the social vulnerability. Therefore, given this observation, it is ideal to evaluate if the monitoring executions of hazardous particulate matter and nitrogen dioxide do take into consideration the concerted necessary efforts to associate monitored air pollution exposure levels with the burden of disease. Therefore, based on this background, the current meta-analysis evaluated air quality monitoring associated with the burden of disease across sub-Saharan Africa. To this extent, the current meta-analysis strictly included peer-reviewed published journal articles from the sub-Saharan African regions to gain insight on air quality monitoring associated with the burden of disease. The collected meta-analysis data was captured and subsequently analyzed using Microsoft Excel 2019. This program facilitated the presentation of the meta-analysis data in the form of graphs and numerical techniques. Generally, the results indicate that the sub-Saharan Africa is characterized by a substantial gap in the number of regional studies that evaluate the burden of disease in relation with exposure to air quality.Implications: The work presented here is an original contribution and provides a comprehensive yet succinct overview of the monitoring associated with the burden of disease in sub-Saharan Africa. The author explores if the monitoring executions of hazardous particulate matter and nitrogen dioxide do take into considerations the concerted necessary efforts to associate monitored air pollution exposure levels with the burden of disease. The manuscript includes the most relevant and current literature in a field of study that has not received a deserving degree of research attention in recent years. This is especially true in sub-Saharan Africa, characterized by insufficient monitoring of air quality exposure concentrations.

Key challenges for in vitro testing of tobacco products for regulatory applications: Recommendations for dosimetry

The Institute for In Vitro Sciences (IIVS) is sponsoring a series of workshops to develop recommendations for optimal scientific and technical approaches for conducting in vitro assays to assess potential toxicity within and across tobacco and various next-generation products (NGPs) including heated tobacco products (HTPs) and electronic nicotine delivery systems (ENDSs). This publication was developed by a working group of the workshop members in conjunction with the sixth workshop in that series entitled "Dosimetry for conducting in vitro evaluations" and focuses on aerosol dosimetry for aerosol exposure to combustible cigarettes, HTP, and ENDS aerosolized tobacco products and summarizes the key challenges as well as documenting areas for future research.

Laboratory and on-road testing for brake wear particle emissions: a review

Brake wear emission is a significant contributor to vehicle-related particulate matter, especially in areas with high traffic density and braking frequency. Only recently, non-exhaust emissions from car brake wear have been regulated under Euro 7 regulation, which introduces emission limits for both brake and tires. It also introduces a standard brake particle assessment procedure which includes sampling procedure and measurement techniques defined in the Global Technical Regulation on brakes from light-duty vehicles up to 3.5 t. Over the years, various experimental setups have been tried leading to non-comparable results. The brake wear particle emissions, expressed as emission factors, are mostly estimated as particle mass or particle number and described using different units (e.g., mg/stop brake, mg/km brake; particle number/cm3) making the comparison between studies very difficult. The aim of the present literature review is to present the state-of-the-art of different experimental methods tuned for assessing brake wear emissions, including electric vehicles. The experiments are carried in close, semi-closed, and open systems, and depending on the experimental design, different sampling methods are applied to reduce particle transport loss and guarantee the efficiency of the particle sampling. Driving condition (e.g., speed and applied pressure), formulation of brake materials, and friction temperature have been found to strongly affect the emission characteristics of brake particles, and this needs to be considered when designing study procedures. The findings reported in this review can be beneficial to policy makers and researchers.

Imaging Radial Distribution Functions of Complex Particles by Relayed Dynamic Nuclear Polarization

The physical properties of many modern multi-component materials are determined by their internal microstructure. Tools capable of characterizing complex nanoscale architectures in composite materials are, therefore, essential to design materials with targeted properties. Depending on the morphology and the composition, structures may be measured by laser diffraction, scattering methods, or by electron microscopy. However, it can be difficult to obtain contrast in materials where all the components are organic, which is typically the case for formulated pharmaceuticals, or multi-domain polymers. In nuclear magnetic resonance (NMR) spectroscopy, chemical shifts allow a clear distinction between organic components and can in principle provide the required chemical contrast. Here, we introduce a method to obtain radial images of the internal structure of multi-component particles from NMR measurements of the relay of nuclear hyperpolarization obtained from dynamic nuclear polarization. The method is demonstrated on two samples of hybrid core-shell particles composed of a core of polystyrene with a shell of mesostructured silica filled with the templating agent CTAB and is shown to yield accurate images of the core-shell structures with a nanometer resolution.

Revisiting the atmospheric particles: Connecting lines and changing paradigms

Historically, the atmospheric particles constitute the most primitive and recent class of air pollutants. The science of atmospheric particles erupted more than a century ago covering more than four decades of size, with past few years experiencing major advancements on both theoretic and data-based observational grounds. More recently, the plausible recognition between particulate matter (PM) and the diffusion of the COVID-19 pandemic has led to the accretion of interest in particle science. With motivation from diverse particle research interests, this paper is an 'old engineer's survey' beginning with the evolution of atmospheric particles and identifies along the way many of the global instances signaling the 'size concept' of PM. A theme that runs through the narrative is a 'previously known' generational evolution of particle science to the 'newly procured' portfolio of knowledge, with important gains on the application of unmet concepts and future approaches to PM exposure and epidemiological research.

Sixteen-Year Monitoring of Particulate Matter Exposure in the Parisian Subway: Data Inventory and Compilation in a Database

The regularly reported associations between particulate matter (PM) exposure, and morbidity and mortality due to respiratory, cardiovascular, cancer, and metabolic diseases have led to the reduction in recommended outdoor PM10 and PM2.5 exposure limits. However, indoor PM10 and PM2.5 concentrations in subway systems in many cities are often higher than outdoor concentrations. The effects of these exposures on subway workers and passengers are not well known, mainly because of the challenges in exposure assessment and the lack of longitudinal studies combining comprehensive exposure and health surveillance. To fulfill this gap, we made an inventory of the PM measurement campaigns conducted in the Parisian subway since 2004. We identified 5856 PM2.5 and 18,148 PM10 results from both personal and stationary air sample measurements that we centralized in a database along with contextual information of each measurement. This database has extensive coverage of the subway network and will enable descriptive and analytical studies of indoor PM exposure in the Parisian subway and its potential effects on human health.

Optimization Study of Sampling Device for Semi-Volatile Oil Mist in the Industrial Workshop

A large number of metalworking fluids in industrial manufacturing processes generate high-concentrations of oil mist pollution, which is a typical semi-volatile aerosol and is generally composed of liquid particles and volatile gas components. Long-term exposure to oil mist pollution brings a series of occupational diseases to workers. For the semi-volatile aerosol, the traditional filter sampling method will lead to particle volatilization, which underestimates the concentration of particles and overestimates the concentration of gas. Therefore, this study combined the advantages of the electrostatic method and the Tenax tube adsorption method, to develop a more accurate measurement technology. First, a dichotomous sampler that could efficiently separate the gas and liquid phases of aerosols was optimized through a numerical model, which was validated by literature results. Next, a test table for oil mist sampling was built with a sampler which was fabricated by 3D printing, and the performance of the sampler was evaluated. The results show that the sampling technique can separate the gas and particulate phases of the oil mist efficiently and accurately. Compared with the traditional single sampling methods, the new sampler can better determine the true concentration of oil mist.

Spring 2020 Atmospheric Aerosol Contamination over Kyiv City

Extraordinarily high aerosol contamination was observed in the atmosphere over the city of Kyiv, Ukraine, during the March–April 2020 period. The source of contamination was the large grass and forest fires in the northern part of Ukraine and the Kyiv region. The level of PM2.5 load was investigated using newly established AirVisual sensor mini-networks in five areas of the city. The aerosol data from the Kyiv AERONET sun-photometer site were analyzed for that period. Aerosol optical depth, Ångström exponent, and the aerosol particles properties (particle size distribution, single-scattering albedo, and complex refractive index) were analyzed using AERONET sun-photometer observations. The smoke particles observed at Kyiv site during the fires in general correspond to aerosol with optical properties of biomass burning aerosol. The variability of the optical properties and chemical composition indicates that the aerosol particles in the smoke plumes over Kyiv city were produced by different burning materials and phases of vegetation fires at different times. The case of enormous PM2.5 aerosol contamination in the Kyiv city reveals the need to implement strong measures for forest fire control and prevention in the Kyiv region, especially in its northwest part, where radioactive contamination from the Chernobyl disaster is still significant.

Lab-on-a-Chip Platforms for Airborne Particulate Matter Applications: A Review of Current Perspectives

Lab-on-a-Chip (LoC) devices are described as versatile, fast, accurate, and low-cost platforms for the handling, detection, characterization, and analysis of a wide range of suspended particles in water-based environments. However, for gas-based applications, particularly in atmospheric aerosols science, LoC platforms are rarely developed. This review summarizes emerging LoC devices for the classification, measurement, and identification of airborne particles, especially those known as Particulate Matter (PM), which are linked to increased morbidity and mortality levels from cardiovascular and respiratory diseases. For these devices, their operating principles and performance parameters are introduced and compared while highlighting their advantages and disadvantages. Discussing the current applications will allow us to identify challenges and determine future directions for developing more robust LoC devices to monitor and analyze airborne PM.

Using Antenna Arrays with Only One Active Element for Beam Reconfiguration and Sensitive Study in Dielectric Media

Antenna array pattern reconfiguration is usually achieved by changing the relative amplitudes and/or phases of the excitation distribution present in the array, at the cost of complex feeding networks. In this work, the mechanical displacement of a parasitic array perpendicular to another array with a single driven element is proposed. Additionally, the antenna is optimized addressing the variation of its response led by changes of the environmental dielectric constant of a surrounding gaseous medium. In such a way, a novel multipurpose antenna of utmost simplicity is obtained. From the computation of the self and mutual impedances, a control of the antenna radiation pattern by means of the induced currents in the parasitic elements is modelled. To illustrate the procedure, the technique will be applied to the variation of the side lobe level of a pencil beam and to obtain a flat-topped broadside beam from the same pencil beam, something with high interest for satellite applications. The proposed methodology represents an advance on the development of multipurpose antennas which resounds in simplicity not only in the reconfiguration of antenna beams, but in applications for the detection of particulate matter and/or measurements of the atmospheric dielectric constant.

Effects of Air Pollution and Other Environmental Exposures on Estimates of Severe Influenza Illness, Washington, USA

Ecologic models of influenza burden may be confounded by other exposures that share winter seasonality. We evaluated the effects of air pollution and other environmental exposures in ecologic models estimating influenza-associated hospitalizations. We linked hospitalization data, viral surveillance, and environmental data, including temperature, relative humidity, dew point, and fine particulate matter for 3 counties in Washington, USA, for 2001-2012. We used negative binomial regression models to estimate the incidence of influenza-associated respiratory and circulatory (RC) hospitalizations and to assess the effect of adjusting for environmental exposures on RC hospitalization estimates. The modeled overall incidence rate of influenza-associated RC hospitalizations was 31/100,000 person-years. The environmental parameters were statistically associated with RC hospitalizations but did not appreciably affect the event rate estimates. Modeled influenza-associated RC hospitalization rates were similar to published estimates, and inclusion of environmental covariates in the model did not have a clinically important effect on severe influenza estimates.

Miniature Optical Particle Counter and Analyzer Involving a Fluidic-Optronic CMOS Chip Coupled with a Millimeter-Sized Glass Optical System

Our latest advances in the field of miniaturized optical PM sensors are presented. This sensor combines a hybrid fluidic-optronic CMOS (holed retina) that is able to record a specific irradiance pattern scattered by an illuminated particle (scattering signature), while enabling the circulation of particles toward the sensing area. The holed retina is optically coupled with a monolithic, millimeter-sized, refracto-reflective optical system. The latter notably performs an optical pre-processing of signatures, with a very wide field of view of scattering angles. This improves the sensitivity of the sensors, and simplifies image processing. We report the precise design methodology for such a sensor, as well as its fabrication and characterization using calibrated polystyrene beads. Finally, we discuss its ability to characterize particles and its potential for further miniaturization and integration.

Occupational exposure of librarians to mold spores and metal particles: a real-time case study

In a university library, activities typical of librarians, such as unpacking boxes, removing books from the shelves, dusting, packing boxes, cataloguing, conservation and repair, photocopying, setting materials for class, and walking in a main hallway, were found to reduce indoor air quality through the production of airborne mold spores, metal dusts, and particulate matter of different size bins. Analyzing three libraries, the activity of conservation generated 9000 spores/m3 of mold spores, nearing the exposure limit of 104 spores/m3 reported for Penicillium sp., and silver nanoparticles of about 15 µg/m3, that over 8 h would exceed the occupational exposure limit of 0.19 µg/m3. For none of the activities, the levels of particulate matter with a diameter lower than 2.5 µm (PM2.5) and 10 µm (PM10) did not exceed the 8-h time weight average limits of exposure. However, by analyzing the 5th percentile of the real-time PM10 data, values of about 1.5 mg/m3, which is concerning for occupational exposure. Measuring real-time exposures of PM could generate an estimation of levels of mold spores and metal dusts in libraries. We demonstrate a high Spearman’s rank correlation (0.70) between the 5th percentile of PM with a diameter lower than 1 µm and different metals. A high linearity (R2 = 0.85) is obtained between the total average of PM with a diameter lower than 10 µm and mold spores/m3.

Stochastic and Self-Organisation Patterns in a 17-Year PM10 Time Series in Athens, Greece

This paper utilises statistical and entropy methods for the investigation of a 17-year PM₁₀ time series recorded from five stations in Athens, Greece, in order to delineate existing stochastic and self-organisation trends. Stochastic patterns are analysed via lumping and sliding, in windows of various lengths. Decreasing trends are found between Windows 1 and 3500-4000, for all stations. Self-organisation is studied through Boltzmann and Tsallis entropy via sliding and symbolic dynamics in selected parts. Several values are below -2 (Boltzmann entropy) and 1.18 (Tsallis entropy) over the Boltzmann constant. A published method is utilised to locate areas for which the PM₁₀ system is out of stochastic behaviour and, simultaneously, exhibits critical self-organised tendencies. Sixty-six two-month windows are found for various dates. From these, nine are common to at least three different stations. Combining previous publications, two areas are non-stochastic and exhibit, simultaneously, fractal, long-memory and self-organisation patterns through a combination of 15 different fractal and SOC analysis techniques. In these areas, block-entropy (range 0.650-2.924) is significantly lower compared to the remaining areas of non-stochastic but self-organisation trends. It is the first time to utilise entropy analysis for PM₁₀ series and, importantly, in combination with results from previously published fractal methods.

Roadside vehicle particulate matter concentration estimation using artificial neural network model in Addis Ababa, Ethiopia

Currently, vehicle-related particulate matter is the main determinant air pollution in the urban environment. This study was designed to investigate the level of fine (PM_2.5) and coarse particle (PM₁₀) concentration of roadside vehicles in Addis Ababa, the capital city of Ethiopia using artificial neural network model. To train, test and validate the model, the traffic volume, weather data and particulate matter concentrations were collected from 15 different sites in the city. The experimental results showed that the city average 24-hr PM_2.5 concentration is 13%-144% and 58%-241% higher than air quality index (AQI) and world health organization (WHO) standards, respectively. The PM₁₀ results also exceeded the AQI (54%-65%) and WHO (8%-395%) standards. The model runs using the Levenberg-Marquardt (Trainlm) and the Scaled Conjugate Gradient (Trainscg) and comparison were performed, to identify the minimum fractional error between the observed and the predicted value. The two models were determined using the correlation coefficient and other statistical parameters. The Trainscg model, the average concentration of PM_2.5 and PM₁₀ exhaust emission correlation coefficient were predicted to be (R² = 0.775) and (R² = 0.92), respectively. The Trainlm model has also well predicted the exhaust emission of PM_2.5 (R² = 0.943) and PM₁₀ (R² = 0.959). The overall results showed that a better correlation coefficient obtained in the Trainlm model, could be considered as optional methods to predict transport-related particulate matter concentration emission using traffic volume and weather data for Ethiopia cities and other countries that have similar geographical and development settings.

Exposure levels to PM2.5 and black carbon for people with disabilities in rural homes of Colombia

Indoor exposure to air pollutants emitted by solid fuels used for cooking or heating homes remains as a problem to solve. The most affected people are newborns, mothers, children, and people with disabilities, due to the time they spend at home. This study is the first in a rural area of South America, which measures indoor air pollutants (PM_2.5 and black carbon) in different environments, inhabited by people with disabilities. The research was supported through a sociodemographic characterization, a methodology useful for future studies, continuous monitoring for 72 h of pollutants, and emission sources, cooking habits, and pre-existing diseases were identified. The primary sources of emissions are improved wood-burning stoves and their chimney. In households where firewood is used, the average concentrations of PM_2.5 were the highest (between 10.9 and 3302.5 μg/m³), as were the average concentrations of BC (average 72 h between 2.6 and 51.2 μg/m³) compared with the houses that use gas (average 72 h between 2.6 and 6 μg/m³). In 57% of the households visited, the World Health Organization (WHO) guidelines for PM_2.5 (25 μg/m³ for 24 h) were exceeded. The results reveal that rural concentrations of BC can be up to 2.5 times higher than those of an urban area with high vehicular traffic and high population density and could be used to establish a baseline that allows the implementation of control mechanisms to reduce pollution of indoor air.

Theoretical Design of the Scattering-Based Sensor for Analysis of the Vehicle Tailpipe Emission

Measurement regulations demand, among other requirements, the reduction of particulate matter emissions from diesel engines. Considering this, the establishment of a new measurement instrument for periodic emission control and detection of the Diesel Particulate Filter (DPF) performance after the vehicle exhaust is necessary. To fulfil these requirements, this paper proposes the design of a new, simple, low-weight layout after the vehicle tailpipe. In order to check the operation condition of the proposed sensor, different factors such as the temperature (−10 to 50 ℃) humidity (60%), and flow rate of the sampled emission (laminar condition) are considered. The proposed layout uses an optical particle counter as a portable instrument for real-time detection of the particle concentration after exhaust of the internal combustion engine.

Performance Assessment of Portable Optical Particle Spectrometer (POPS)

Accurate representation of atmospheric aerosol properties is a long-standing problem in atmospheric research. Modern pilotless aerial systems provide a new platform for atmospheric in situ measurement. However, small airborne platforms require miniaturized instrumentation due to apparent size, power, and weight limitations. A Portable Optical Particle Spectrometer (POPS) is an emerged instrument to measure ambient aerosol size distribution with high time and size resolution, designed for deployment on a small unmanned aerial system (UAS) or tethered balloon system (TBS) platforms. This study evaluates the performance of a POPS with an upgraded laser heater and additional temperature sensors in the aerosol pathway. POPS maintains its performance under different environmental conditions as long as the laser temperature remains above 25 °C and the aerosol flow temperature inside the optical chamber is 15 °C higher than the ambient temperature. The comparison between POPS and an Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) suggests that the coincidence error is less than 25% when the number concentration is less than 4000 cm⁻³. The size distributions measured by both of them remained unaffected up to 15,000 cm⁻³. While both instruments’ sizing accuracy is affected by the aerosol chemical composition and morphology, the influence is more profound on the POPS.

MEMS particle sensor based on resonant frequency shifting

Recently, as the concentration of fine dust in the atmosphere has increased due to an increase in the use of fossil fuel power plants, automobiles, and factories, it has been increasingly important to measure fine dust in the atmosphere. This is because exposure to fine dust is closely related to the incidence of respiratory and cardiovascular diseases and eventually affects mortality. In this paper, we introduce a MEMS particle sensor based on the resonance frequency shift according to added particle mass. The actuation is driven by Aluminum nitride (AlN), and the total thickness is 2.8 μm. A laser doppler vibrometer (LDV), an optical measuring instrument, was used to measure the resonance frequency of the sensor. Airborne particles naturally were deposited on the sensor. To show the frequency shift according to the particle mass, the frequency shift was measured by dividing the case where the deposited particle mass was small and large. In each case, the frequency shift according to the deposited particle mass was predicted and compared with the frequency shift measured by LDV. It was shown that the deposited particle mass and frequency shift are proportional. The deposition of particulate mass was estimated by image analysis. The frequency shift caused by the particle mass deposited on the sensor was defined as the sensitivity of the sensor. The estimated sensitivity of the sensor is 0.219 to 0.354 kHz/pg.

Comparison of Surgical Smoke Generated During Electrosurgery with Aerosolized Particulates from Ultrasonic and High-Speed Cutting

“Surgical smoke” is an airborne by-product of electrosurgery comprised of vapour and suspended particles. Although concerns exist that exposure may be harmful, there is a poor understanding of the smoke in terms of particle size, morphology, composition and biological viability. Notably, it is not known how the biological tissue source and cutting method influence the smoke. The objective of this study was to develop a collection method for airborne by-product from surgical cutting. This would enable comprehensive analyses of the particulate burden, composition and biological viability. The method was applied to compare the electrosurgical smoke generated (in the absence of any evacuation mechanism) with the aerosolized/airborne by-products generated by ultrasonic and high-speed cutting, from bone and liver tissue cutting. We report a wide range of particle sizes (0.93–806.31 μm for bone, 0.05–1040.43 μm for liver) with 50% of the particles being <2.72 μm (~PM_2.5) and 90% being <10 μm (PM₁₀). EDX and biochemical analysis reveal components of biological cells and cellular metabolic activity in particulate from liver tissue cut by electrosurgery and ultrasonic cutting. We show for the first time however that bone saws and ultrasonic cutting do not liberate viable cells from bone.

Inline Infrared Chemical Identification of Particulate Matter

The health and environmental effects of particulate matter (PM) in the air depend on several parameters. Besides particle size, shape, and concentration, the chemical nature of the PM is also of great importance. State-of-the-art PM sensors only detect the particle size and concentration. Small, low-cost sensors only identify PM according to PM2.5 and PM10 standards. Larger detectors measure the complete particle size distribution. However, the chemical composition of PM is not often assessed. The current paper presents the initial stages of the development of an infrared-based detector for the inline assessment of the chemistry of PM in the air. By combining a mini cyclone that is able to concentrate the particles at least a thousand fold and a hollow waveguide that aligns the flow of particles with infrared light, the feasibility of the concept was shown in this study. A clear differentiation between amorphous and crystalline silica was demonstrated at outdoor PM levels of lower than 1 mg per cubic meter.

Feasibility Study on Measuring the Particulate Matter Level in the Atmosphere by Means of Yagi-Uda-Like Antennas

In this work, the application of a technique for monitoring changes of the dielectric constant of the atmosphere caused by the presence of pollution is discussed. The method is based on changes in the reflection coefficient of the device induced by these dielectric constant variations of the surrounding medium. To that end, several Yagi–Uda-like antenna designs with different size limitations were simulated by using a Method-of-Moments software and optimized by means of a simulated annealing strategy. It has been found that the larger the optimal elements of the array are allowed to be, the higher the sensitivity reached. Thus, in a trade-off between sensitivity and moderate length (regarding flexibility purposes), the most promising solution has been built. This prototype has been experimentally tested in presence of an artificial aerosol made of PAO (polyalphaolefin) oil and black carbon inclusions of a size of 0.2 μm. As a result, potentials for developing a measurement procedure by means of changes in the characteristic parameters of the antenna led by different concentration levels of suspended particles in the surrounding medium are shown. In this manner, a local mapping of polluted levels could be developed in an easy, real-time, and flexible procedure.

Assessment of 10-nm Particle Number (PN) Portable Emissions Measurement Systems (PEMS) for Future Regulations

The particle number (PN) emissions of vehicles equipped with particulate filters are low. However, there are technologies that can have high PN levels, especially below the currently lower regulated particle size of 23 nm. Sub-23-nm particles are also considered at least as dangerous as the larger ultrafine particles. For this reason, the European Union (EU) is planning to regulate particles down to 10 nm. In this study we compared prototype portable emission measurement systems (PEMS) and reference laboratory systems measuring from 10 nm. The tests included cycles and constant speeds, using vehicles fuelled with diesel, gasoline or liquefied petroleum gas (LPG). The results showed that the PEMS were within ±40% of the reference systems connected to the tailpipe and the dilution tunnel. Based on the positive findings and the detection efficiencies of the prototype instruments, a proposal for the technical specifications for the future regulation was drafted.

Nanocrystals: An Overview of Fabrication, Characterization and Therapeutic Applications in Drug Delivery

Approximately 40 % drugs in the market are having poor aqueous solubility related problems and 70 % molecules in discovery pipeline are being practically insoluble in water. Nanocrystals is a prominent tool to solve the issue related to poor aqueous solubility and helps in improving the bioavailability of many drugs as reported in the literature. Nanocrystals can be prepared by top down methods, bottom up methods and combination methods. Many patented products such as Nanocrystals®, DissoCubes®, NANOEDGE® and SmartCrystals ®, etc., are available, which are based on these three preparation methodologies. The particle size reduction resulted into unstable nanocrystalline system and the phenomenon of Ostawald ripening occurs. This instability issue could be resolved by using an appropriate stabilizers or combination of stabilizers. The nanosuspensions could be transformed to the solid state to prevent particle aggregation in liquid state by employing various unit operations such as lyophilisation, spray drying, granulation and pelletisation. These techniques are well known for their scalability and continuous nanocrystal formation advantages. Nanocrystals can be characterized by using scanning electron microscopy, transmission electron microscopy, atomic force microscopy, differential scanning calorimetry, fourier transform infrared spectroscopy, powdered x- ray diffraction and photon correlation spectroscopy. The downscaling of nanocrystals will enable rapid optimization of nanosuspension formulation in parallel screening design of preclinical developmental stage drug moieties. One of the most acceptable advantages of nanocrystals is their wide range of applicability such as oral delivery, ophthalmic delivery, pulmonary delivery, transdermal delivery, intravenous delivery and targeting (brain and tumor targeting). The enhancement in market value of nanocrystals as well as the amount of nanocrystal products in the market is gaining attention to be used as an approach in order to get commercial benefits.

Anionic Surfactants and Traffic Related Emission from an Urban Area of Perak, Malaysia

Anionic surfactants are one of the pollutants derived from particulate matter (PM) and adversely affect the health of living organisms. In this study, the compositions of surfactants extracted from PM and vehicle soot collected in an urban area were investigated. A high-volume air sampler was used to collect PM sample at urban area based on coarse (> 1.5 µm) and fine (< 1.5 µm) mode particles. Meanwhile, the vehicle soot was collected randomly from the exhaust pipe of various types of diesel and petrol vehicles using a soft brush during dry days. The concentration of anionic surfactants, such as Methylene Blue Active Substances (MBAS), was determined by the colorimetric method using UV-Vis Spectrophotometer. Morphological properties of the PM and exhaust soot sample was studied using field-emission scanning electron microscope. Results revealed that the MBAS concentration was dominated by fine mode particles (6.03 ± 3.97 µmol g^-1), whereas heavy-duty vehicles, such as buses, demonstrated the highest surfactant concentration with an average value of 0.340 ± 0.180 µmol g^-1. The structure of collected PM for all samples mostly appeared to be an irregular shape with the size range of ultrafine particles (0.05-0.2 µm). The emission of surfactants from diesel and petrol vehicles, especially at urban areas, should be a major concern, because they could negatively affect human health and the environment.

Analysis and Modelling of PM2.5 Temporal and Spatial Behaviors in European Cities

Particulate matter with an aerodynamic diameter of less than 2.5 µm (PM2.5) is associated with adverse effects on human health (e.g., fatal cardiovascular and respiratory diseases), and environmental concerns (e.g., visibility impairment and damage in ecosystems). This study aimed to evaluate temporal and spatial trends and behaviors of PM2.5 concentrations in different European locations. Statistical threshold models using Artificial Neural Networks (ANN) defined by Genetic Algorithms (GA) were also applied for an urban centre site in Istanbul, to evaluate the influence of meteorological variables and PM10 concentrations on PM2.5 concentrations. Lower PM2.5 concentrations were observed in northern Europe. The highest values were found at traffic-related sites. PM2.5 concentrations were usually higher during the winter and tended to present strong increases during rush hours. PM2.5/PM10 ratios were slightly higher at background sites and the lower values were found in northern Europe (Helsinki and Stockholm). Ratios were usually higher during cold months and during the night. The statistical model (ANN + GA) allowed evaluating the combined effect of different explanatory variables (temperature, wind speed, relative humidity, air pressure and PM10 concentrations) on PM2.5 concentrations, under different regimes defined by relative humidity (threshold value of 79.1%). Important information about the temporal and spatial trends and behaviors related to PM2.5 concentrations in different European locations was developed.

Particulate Matter Measurement Indoors: A Review of Metrics, Sensors, Needs, and Applications

Many populations spend ∼90% of their time indoors, with household particulate matter being linked to millions of premature deaths worldwide. Particulate matter is currently measured using particle mass, particle number, and particle size distribution metrics, with other metrics, such as particle surface area, likely to be of increasing importance in the future. Particulate mass is measured using gravimetric methods, tapered element oscillating microbalances, and beta attenuation instruments and is best suited to use in compliance monitoring, trend analysis, and high spatial resolution measurements. Particle number concentration is measured by condensation particle counters, optical particle counters, and diffusion chargers. Particle number measurements are best suited to source characterization, trend analysis and ultrafine particle investigations. Particle size distributions are measured by gravimetric impactors, scanning mobility particle sizers, aerodynamic particle sizers, and fast mobility particle sizers. Particle size distribution measurements are most useful in source characterization and particulate matter property investigations, but most measurement options remain expensive and intrusive. However, we are on the cusp of a revolution in indoor air quality monitoring and management. Low-cost sensors have potential to facilitate personalized information about indoor air quality (IAQ), allowing citizens to reduce exposures to PM indoors and to resolve potential dichotomies between promoting healthy IAQ and energy efficient buildings. Indeed, the low cost will put this simple technology in the hands of citizens who wish to monitor their own IAQ in the home or workplace, to inform lifestyle decisions. Low-cost sensor networks also look promising as the solution to measuring spatial distributions of PM indoors, however, there are important sensor/data quality, technological, and ethical barriers to address with this technology. An improved understanding of epidemiology is essential to identify which metrics correlate most with health effects, allowing indoor specific PM standards to be developed and to inform the future of experimental applications.

Size, composition, morphology, and health implications of airborne incidental metal-containing nanoparticles

There is great concern regarding the adverse health implications of engineered nanoparticles. However, there are many circumstances where the production of incidental nanoparticles, i.e., nanoparticles unintentionally generated as a side product of some anthropogenic process, is of even greater concern. In this study, metal-based incidental nanoparticles were measured in two occupational settings: a machining center and a foundry. On-site characterization of substrate-deposited incidental nanoparticles using a field-portable X-ray fluorescence provided some insights into the chemical characteristics of these metal-containing particles. The same substrates were then used to carry out further off-site analysis including single-particle analysis using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Between the two sites, there were similarities in the size and composition of the incidental nanoparticles as well as in the agglomeration and coagulation behavior of nanoparticles. In particular, incidental nanoparticles were identified in two forms: submicrometer fractal-like agglomerates from activities such as welding and supermicrometer particles with incidental nanoparticles coagulated to their surface, herein referenced as nanoparticle collectors. These agglomerates will affect deposition and transport inside the respiratory system of the respirable incidental nanoparticles and the corresponding health implications. The studies of incidental nanoparticles generated in occupational settings lay the groundwork on which occupational health and safety protocols should be built.

Radon and PM10 concentrations in underground parking lots and subway stations with health risks in South Korea

This study examined the environmental factors that affect indoor radon (Rn) and particulate matter (PM₁₀) concentrations in underground public facilities such as subway stations and underground parking lots. Rn and PM₁₀ concentrations from March 2014 to October 2015 were evaluated at 40 subway stations and 19 underground parking lots. Average underground concentrations of Rn and PM₁₀ were 37.3 ± 17.1 Bq/m³ and 78.6 ± 15.1 μg/m³, respectively. There were significant difference in Rn concentration between sampling points, with the highest concentration 41.8 ± 18.1 Bq/m³ on subway platforms, while the highest concentration of PM₁₀ was 83.7 ± 13.8 μg/m³ in transfer pathways. Rn concentration showed positive correlation with PM₁₀ concentration (r = 0.380, p < 0.001). The highest Rn concentration occurred during fall season, followed by summer and spring. At 60-h exposure duration in underground subway stations and parking lots, the hazard quotient (HQ) of Rn exceeded 1 for children less than 1 year old and those between 8 and 10 years old.

Wearable sensors for multifactorial personal exposure measurements - A ranking study

Individuals are simultaneously exposed to multiple environmental stressors during their daily life. Studies of adverse health effects and their etiology as well as recommendations for a healthier life style demand for an assessment of multifactorial personal exposure, according to the exposome concept. A challenge is to record exposure while people are moving in heterogeneous urban environments. Therefore wearable sensor technologies are becoming a promising way to measure personal exposure continuously: indoors, outdoors and even on the move. So far, studies which test the accuracy and usability of wearable sensors for multiple stressors are lacking. Performance evaluations are important and should take place beforehand, especially to ensure the success of citizens-oriented studies. For the first time we rigorously examined the accuracy and application suitability of wearable sensors for acoustic noise, heat (temp), particle number counts (PNC) and geo-location (GPS) in different environments. We present an extensive device inter-comparison and a ranking of the sensors based on performance measures, Taylor diagrams, Bland-Altman plots, and ease-of-use aspects. The sensors showed moderate to high correlations with precision reference devices (r = 0.4-0.99). Differences between errors outdoors and indoors suggest that environmental conditions have impact upon the accuracy of the sensors. Reaction time, recording interval, and sensor ventilation are features that play a crucial role for both ease-of-use and accuracy. We conclude with a final performance () ranking: (GPS) >  (noise) >  (temp) >  (PNC). The results are relevant for future epidemiological studies of multifactorial exposure of individuals and their health and should guide the selection of wearables when persons are involved that are technically untaught. Inferences from multifactorial data are based on the performance of all sensors and the weakest chain links are PNC and temp sensors for which our article recommends urgent improvements.

Product Environmental Footprint (PEF) Pilot Phase—Comparability over Flexibility?

The main goal of the European product environmental footprint (PEF) method is to increase comparability of environmental impacts of products within certain product categories by decreasing flexibility and therefore achieving reproducibility of results. Comparability is supposed to be further increased by developing product category specific rules (PEFCRs). The aim of this paper is to evaluate if the main goal of the PEF method has been achieved. This is done by a comprehensive analysis of the PEF guide, the current PEFCR guide, the developed PEFCRs, as well as the insights gained from participating in the pilot phase. The analysis reveals that the PEF method as well as its implementation in PEFCRs are not able to guarantee fair comparability due to shortcomings related to the (1) definition of product performance; (2) definition of the product category; (3) definition and determination of the representative product; (4) modeling of electricity; (5) requirements for the use of secondary data; (6) circular footprint formula; (7) life cycle impact assessment methods; and (8) approach to prioritize impact categories. For some of these shortcomings, recommendations for improvement are provided. This paper demonstrates that the PEF method has to be further improved to guarantee fair comparability.

Nanoparticle exposures from nano-enabled toner-based printing equipment and human health: state of science and future research needs

Toner formulations used by laser printers (LP) and photocopiers (PC), collectively called "toner-based printing equipment" (TPE), are nano-enabled products (NEP) because they contain several engineered nanomaterials (ENM) that improve toner performance. It has been shown that during consumer use (printing), these ENM are released in the air, together with other semi-volatile organic nanoparticles, and newly formed gaseous co-pollutants such as volatile organic compounds (VOC). The aim of this review is to detail and analyze physico-chemical and morphological (PCM), as well as the toxicological properties of particulate matter (PM) emissions from TPE. The review covers evolution of science since the early 2000, when this printing technology first became a subject of public interest, as well as the lagging regulatory framework around it. Important studies that have significantly changed our understanding of these exposures are also highlighted. The review continues with a critical appraisal of the most up-to-date cellular, animal and human toxicological evidence on the potential adverse human health effects of PM emitted from TPE. We highlight several limitations of existing studies, including (i) use of high and often unrealistic doses in vitro or in vivo; (ii) unrealistically high-dose rates in intratracheal instillation studies; (iii) improper use of toners as surrogate for emitted nanoparticles; (iv) lack of or inadequate PCM characterization of exposures; and (v) lack of dosimetry considerations in in vitro studies. Presently, there is compelling evidence that the PM_0.1 from TPE are biologically active and capable of inducing oxidative stress in vitro and in vivo, respiratory tract inflammation in vivo (in rats) and in humans, several endpoints of cellular injury in monocultures and co-cultures, including moderate epigenetic modifications in vitro. In humans, limited epidemiological studies report typically 2-3 times higher prevalence of chronic cough, wheezing, nasal blockage, excessive sputum production, breathing difficulties, and shortness of breath, in copier operators relative to controls. Such symptoms can be exacerbated during chronic exposures, and in individuals susceptible to inhaled pollutants. Thus respiratory, immunological, cardiovascular, and other disorders may be developed following such exposures; however, further toxicological and larger scale molecular epidemiological studies must be done to fully understand the mechanism of action of these TPE emitted nanoparticles. Major research gaps have also been identified. Among them, a methodical risk assessment based on "real world" exposures rather than on the toner particles alone needs to be performed to provide the much-needed data to establish regulatory guidelines protective of individuals exposed to TPE emissions at both the occupational and consumer level. Industry-wide molecular epidemiology as well as mechanistic animal and human studies are also urgently needed.