Fine Particulates Research Articles

The Release of Incidental Nanoparticles During the Weathering of Gunshot Residue in Soils of a Shooting Range in Ontario, Canada

ABSTRACTGunshot residue is emitted as fine particulate matter upon the ignition of percussion-sensitive explosives among other additives in a firearm barrel. The particulates condense from a vapor phase and contain material from the Pb-Sb-Ba-bearing primer, S-bearing gunpowder, and the Pb-bearing bullet fragments. Shooters can inhale or ingest the fine particulates which also attach to their hands, clothing, and other surfaces. Estimation of the bioavailability of the emitted toxic Pb- and Sb-bearing particulates requires detailed knowledge of their mineralogical composition and those of their weathering products. For this purpose, gunshot residue particulates have been collected from soils in front of a firing line of a shooting range in Ontario, Canada. Bulk mineralogical and chemical features of the soils have been characterized using X-ray powder diffraction, inductively coupled plasma-mass spectrometry, and scanning electron microscopy. The focused ion-beam technique has been used to extract a section containing numerous altered gunshot residue particulates from a soil grain. Subsequent transmission electron microscopy shows for the first time that gunshot residue particulates are composed of metallic δ-Pb, α-Sb, galena (PbS), and an unidentified Ba-bearing phase. Weathering of the gunshot residue particulates results in the formation of incidental nanoparticles (i.e., not purposely engineered to occur at the nanometer scale) in the form of δ-Pb, massicot, PbO, and galena. The formation and mobilization of some of these nanoparticles within the soil grain suggest that their release during the weathering of bullets and gunshot residue contributes to the release of Pb into the environment. Hydrocerussite, Pb3(CO3)2(OH)2, cerussite, PbCO3, and massicot and anglesite, PbSO4, are the major secondary Pb-phases in and around altered GSR particulates. These phases form during the weathering of metallic Pb, massicot, and galena nanoparticles in a Ca-carbonate rich environment. Secondary Sb-bearing phases are valentinite, Sb2O3, and amorphous Sb-Pb phases (Sb:Pb ratio = 2:1–4:1). The latter phases have partially replaced large proportions of the Ca-carbonates surrounding the gunshot residue particulates. The larger abundance of the amorphous Sb-Pb phases relative to valentinite suggests that their solubility most likely controls the release of Sb into the bulk soil. The SEM and TEM characterizations and chemical analyses of mineral surface coatings and the colloidal fraction of a leachate from the collected surficial soils indicate that Pb occurs predominantly in the colloidal fraction, is often associated with sulfate-bearing colloids, and is sequestered in sulfate and carbonate/hydroxide coatings.

The Effect of Ventilation and Cooking Activities Indoor Fine Particulates in Apartments Towards

Abstract Indoor air pollution is currently being studied extensively because of its effects on the health and comfort of residents. The effects of indoor air pollution can be felt directly such as irritation to the eyes, nose to throat. This effect can also occur after several years such as respiratory infections, heart disease and cancer. Indoor air pollution such as particulate matter (PM2.5 and PM1) can be caused by occupant activities such as cooking, room cleaning and smoking by residents. Research on the effect of ventilation and cooking activities on the concentration of PM2.5 and PM1 in the room has not plentiful researched. So the purpose of this study is to determine the effect of those variables in indoor air conditions. The data was obtained by measurement and interview in this study. The method that served in this research is a multilevel approach using three models. The study observes that most of the variables affected the indoor concentration of PM1 and PM2.5. In addition, it was also observed that the large number of fans could improve air quality. During peak sessions especially the morning, the number of particulates is significantly higher. Whereas cooking with an open window causes the condition of fine particulates to be even worse. Therefore, the combination of indoor pollution sources and poor outdoor concentrations has an extremely health impact on the residents. The result of the study shows the importance of adjusting the time to close the window and the time to cook properly, so that the accumulation of fine particles in the room can be avoided. Further observation is required to investigate the concentration of outdoor space near apartments continuously to confirm this result.

Glow Spectral Characteristics of the Hard Coal Particles Surface during the Action of Laser Pulses in the Free Generation Mode

The luminescence spectra of coal fractions with dimensions d ≤ 63 μm were studied directly during the action of neodymium laser pulses (τi = 120 μs). Depending on the radiation energy density H, the luminescence spectra have a different character. The glow at minimum values of the laser pulse energy density $$H_{{{\text{cr}}}}^{{(1)}}$$ is associated with the ignition of fine coal particulates (~1 μm) present in the fractions, and with the ignition of reactive microprotrusions on the surface of larger coal particles. The luminescence spectra at this stage are of a non-thermal nature and are associated with the radiation of volatile molecules in the gas phase and their oxidation products. With an increase in the laser pulse energy density H, a thermal glow of the surface of larger coal particles is observed, which is described by the Planck formula at T = 3100 K. When H = $$H_{{{\text{cr}}}}^{{(2)}}$$ is reached, the surface of the coal particles ignites during the action of the laser pulse. Contributions to the spectra are the glow of the surface of coal particles, emitted carbon particles, and the glow associated with the emission of excited molecules H2, H2O, and CO2. With an increase in H > $$H_{{{\text{cr}}}}^{{(2)}}$$ , the processes leading to the glow of coal particles during a laser pulse are similar to those described above for $$H_{{{\text{cr}}}}^{{(2)}}$$ , but the glow intensity increases.

Associations between the chemical composition of PM2.5 and gestational diabetes mellitus

BackgroundFine particulate matter (PM2.5) is a complex mixture of fine particulates with large spatiotemporal heterogeneities in chemical compositions. While PM2.5 has been associated with gestational diabetes mellitus (GDM), little is known about the relationship between specific chemical components of PM2.5 and GDM. We examined the associations between GDM and pregnancy exposures to PM2.5 and its compositions, including sulfate (SO42−), ammonium (NH4+), nitrate (NO3−), organic matter (OM), black carbon (BC), mineral dust (DUST), and sea-salt (SS), and to identify critical windows of exposure. MethodsWe used data from the 2005–2015 Florida Vital Statistics Birth Records. A well-validated geoscience-derived model was used to estimate women's pregnancy exposures to PM2.5 and its compositions. Distributed lag models were used to examine the associations and to identify the critical windows of exposure. ResultsA total of 2,078,669 women were included. In single-pollutant models, after controlling for potential confounders, positive associations between PM2.5 and GDM were observed during the second trimester of pregnancy. We found positive associations between SO42−, NH4+, NO3−, OM and BC, with largest effect sizes observed in the 21–24 weeks of pregnancy. Negative associations were observed for DUST and SS. Consistent results for NH4+, OM, DUST and SS were observed in the multi-pollutant models. ConclusionsExposures to PM2.5 and its compositions (mainly NH4+, OM) during the second trimester are positively associated with GDM, especially for exposures during the 21–24 weeks of pregnancy. Further studies are needed to confirm the findings and examine the underlying mechanisms.

On analytical and experimental aspects of soap bubble stream charging

The paper discusses the applicability and advantages of using electrically charged soap bubbles as a route to produce fine sprays composed of highly charged particles, commonly named as electroaerosols. It is indicated that such low in energy demand process may produce very fine droplets or particulates charged to a level higher than that obtained using classical spray charging techniques, involving no bubbles. A process of a soap bubble electrical charging is thus initially studied on a simple analytical basis pointing out to a possibility of producing air bubbles with charge-to-mass (Q/m) ratio up to 60 mC/kg (constrained by the Rayleigh limit) while just 2 mC/kg is commonly considered as a threshold value for an effective particle charging process. Finite element 3D electrostatic simulation method (3D FEM) is then applied to assess a single bubble charging level achievable in a laboratory setup using a DC high-voltage biased bubble machine producing soap bubbles 23 mm in diameter on average. The 3D FEM simulation results postulate a single bubble maximum charging level approaching 25 nC at 41.5 kV charging voltage (constrained by the Rayleigh limit), corresponding to (Q/m) = 17.6 mC/kg. Finally, a stream of bubbles characterized by (Q/m) = 10.4 mC/kg was produced experimentally in the laboratory setup using a contact charging method at 40 kV DC supply. A discrepancy between 3D FEM-simulated results and experimental data was discussed on a shielding effect basis.Graphic abstract

Maternal Exposure to Fine and Coarse Particulate Matter and Congenital Malformations in Offspring Among Members of a Primary Health Care Service: A Population-Based Cohort

Background/Aim: Studies have suggested an association between particulate matter (PM) air pollution and certain congenital anomalies. However, to date, most studies have been based on anomalies that were ascertained at birth or up to 1 year of age. We investigated associations between exposures to PM during pregnancy and congenital anomalies using birth and childhood follow-up data from a leading health care provider in Israel.Methods: We conducted a retrospective population-based cohort study among 254,756 newborns to members of the Maccabi Health Services, 2004-2015. Malformation follow-up continued into childhood. Daily fine and coarse PM data at pixels of 1X1 km2 were obtained from prediction models that incorporated satellite data. The geographic coordinates of the mother’s residence for each birth were linked to the respective pixel and averaged over weeks 3-8 of each pregnancy. As the relationship between PM and congenital anomalies was non-linear, we used quintiles of exposure to estimate adjusted odds ratios (ORs) with logistic regression models.Results: We captured 31,087 isolated anomalies in the nervous (0.5%), eye-ear-face-neck (1.7%), circulatory (3.0%), digestive (3.1%), genital (3.4%) and urinary (0.5%) systems. For fine PM, positive associations were found across all quintiles when compared to the first quintile for urinary, digestive and circulatory systems. For example, for the urinary systems ORs for the second and fifth quintiles were 1.26 (95%CI: 1.05, 1.51) and 1.14 (95%CI: 0.93, 1.39), respectively, and for the digestive system the respective ORs were 1.09 (95%CI: 1.01, 1.17) and 1.20 (95%CI: 1.11, 1.29). Negative and null associations were found across all quintiles for eye-ear-face-neck and genital anomalies, respectively. Findings for coarse PM were null or negative.Conclusions: Our results suggest supralinear concentration-response relationship between exposure to fine PM and certain congenital anomalies. Information on late diagnosis of children with congenital anomalies is important in evaluating the burden of disease.

Insights into size-segregated particulate chemistry and sources in urban environment over central Indo-Gangetic Plain

Size-segregated airborne fine (PM2.1) and coarse (PM>2.1) particulates were measured in an urban environment over central Indo-Gangetic plain in between 2015 and 2018 to get insights into its nature, chemistry and sources. Mean (±1σ) concentration of PM2.1 was 98 (±76) μgm−3 with a seasonal high during winter (DJF, 162 ± 71 μgm-3) compared to pre-monsoon specific high in PM>2.1 (MAMJ, 177 ± 84 μgm−3) with an annual mean of 170 (±69) μgm−3. PM2.1 was secondary in nature with abundant secondary inorganic aerosols (20% of particulate mass) and water-soluble organic carbon (19%) against metal enriched (25%) PM>2.1, having robust signature of resuspensions from Earth’s crust and road dust. Ammonium-based neutralization of particulate acidity was essentially in PM2.1 with an indication of predominant H2SO4 neutralization in bisulfate form compared to Ca2+ and Mg2+-based neutralization in PM>2.1. Molecular distribution of n-alkanes homologues (C17–C35) showed Cmax at C23 (PM2.1) and C18 (PM>2.1) with weak dominance of odd-numbered n-alkanes. Carbon preference index of n-alkanes was close to unity (PM2.1: 1.4 ± 0.3; PM>2.1: 1.3 ± 0.4). Fatty acids (C12–C26) were characterized with predominance of even carbon with Cmax at n-hexadecanoic acid (C16:0). Low to high molecular weight fatty acid ratio ranged from 2.0 (PM>2.1) to 5.6 (PM2.1) with vital signature of anthropogenic emissions. Levoglucosan was abundant in PM2.1 (758 ± 481 ngm−3) with a high ratio (11.6) against galactosan, emphasizing robust contribution from burning of hardwood and agricultural residues. Receptor model resolves secondary aerosols and biomass burning emissions (45%) as the most influential sources of PM2.1 whereas, crustal (29%) and secondary aerosols (29%) were found responsible for PM>2.1; with significant variations among the seasons.

Role of preplaced silicon on a TIG processed SiC incorporated microalloyed steel

ABSTRACT Research aimed at enhancing the surface properties of carbon steels by incorporating fine silicon carbide particulates has had limited success because the dissolution of the ceramic occurred. This research considers a method of reducing SiC dissolution by generating a high Fe–Si liquid which protects the ceramic. Three particulate groups were investigated, (1) ∼ 5 µm SiC, (2) ∼45 µm Si +∼ 5 µm SiC, and (3) ∼45 µm Si, all incorporated into a microalloyed steel using a tungsten inert gas process. Detailed microhardness of the melt zones together with microstructural analysis showed that the addition of Si resulted in a cracked hard layer containing SiC. However, in Specimen 1, a thicker, hardcrack-free layer resulted from the microstructure developed by the dissolution of SiC.

An overlooked route of inhalation exposure to tap water constituents for children and adults: Aerosolized aqueous minerals from ultrasonic humidifiers

Fine particulates and aerosols emitted by commonly used, room-sized ultrasonic humidifiers may pose adverse health effects to children and adults. The literature documents adverse effects for children exposed to minerals emitted from humidifiers. This study performs novel and comprehensive characterization of bivariate particle size and element concentrations of emitted airborne aerosols and particles from ultrasonic humidifiers filled with tap water, including size distribution from 0.014 to 10 μm by scanning mobility particle sizer and AeroTrak; corresponding metal and elemental concentrations as a function of particle size by inductively coupled plasma mass spectrometer; and calculations of deposition fraction in human lungs for age-specific groups using the multi-path particle dosimetry model (MPPD). Deposition fraction is the ratio of mass deposited to total mass inhaled. When filled with tap water, water evaporated from emitted aerosols to form submicron particles that became essentially “dried tap water” with median size 146 nm and mean concentration of 211 μg-total elements/m3-air including 35 μg-calcium/m3-air in a room of 33.5 m3 and air exchange rate at ∼0.8 hr−1. Approximately 90% of emitted particles deposited in human lungs were <1 μm as shown by MPPD model. The smaller particles contained little water and higher concentration of minerals, while larger particles of >1 μm consisted of lower elemental concentrations and more water due to low evaporation. Deposition fraction in pulmonary region was ∼2-fold higher, and deposited particulate mass was 3.5-fold higher for children than adults, indicating greater inhalation exposure to children compared to adults. Modeled data of total particles mass per body weight (BW) that will deposit in adult and child lungs after 8-h humidifier exposure were respectively 2.8 μg/kg-BW and 9.8 μg/kg-BW, where calcium contributes 0.4 μg/kg-BW and 1.6 μg/kg-BW. This comprehensive study of bivariate inorganic chemical composition as a function of particle size expanded, quantified, and modeled exposure for children and adults to aerosolized calcium and other inorganic constituents in water.

Tribological response of waste tire rubber as micro-fillers in automotive brake lining materials

Elastomeric materials show promise as potential micro-fillers in brake linings. They can provide vibration damping and acoustic advantages in intermittent and abrupt impact applications such as braking. The elastomeric material can be salvaged from non-biodegradable automotive tires, thereby providing an opportunity to reuse materials that will otherwise be discarded in landfills. Both tribological and thermomechanical performances of the waste tire rubber were assessed to determine their potential for use as micro-fillers in the brake linings of commercial vehicles with a gross weight less than 16 tons. Accordingly, the brake lining materials were fabricated with fine waste tire rubber particulates (WTRPs) as the micro-fillers, phenolic-R resin as the binder, graphite as the dry lubricant, laterite as the co-filler, and coconut coir for natural fiber reinforcement. The effects of increasing the WTRP weight fraction on the brake response of the linings were analyzed, and the different compositions were benchmarked against a commercial brake lining. Mechanical characterization comprising compressive strength, hardness, density, and porosity studies were carried out. Frictional and wear characteristics of the linings were analyzed using a rotary tribometer with simultaneous thermal monitoring. The manufactured lining with 15 wt% WTRPs exhibited a mean friction coefficient of ~0.38, a specific volumetric loss rate of 1,662 µm3/(N·m), and improved thermal response. Using optical microscopy and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), wear surface morphology studies compared the relative development of primary and secondary plateaus and revealed the redistribution of wear debris, leading to the stability of the coefficient of friction.

Multimodal exponential families of circular distributions with application to daily peak hours of PM2.5 level in a large city

In this paper, we propose two multimodal circular distributions which are suitable for modeling circular data sets with two or more modes. Both distributions belong to the regular exponential family of distributions and are considered as extensions of the von Mises distribution. Hence, they possess the highly desirable properties, such as the existence of non-trivial sufficient statistics and optimal inferences for their parameters. Fine particulates (PM2.5) are generally emitted from activities such as industrial and residential combustion and from vehicle exhaust. We illustrate the utility of our proposed models using a real data set consisting of fine particulates (PM2.5) pollutant levels in Houston region during Fall season in 2019. Our results provide a strong evidence that its diurnal pattern exhibits four modes; two peaks during morning and evening rush hours and two peaks in between.

Classification of aerosols over Saudi Arabia from 2004–2016

Knowledge of aerosol size and composition is very important for investigating the radiative forcing impacts of aerosols, distinguishing aerosol sources, and identifying harmful particulate types in air quality monitoring. The ability to identify aerosol type synoptically would greatly contribute to the knowledge of aerosol type distribution at both regional and global scales, especially where there are no data on chemical composition. In this study, aerosol classification techniques were based on aerosol optical properties from remotely-observed data from the Ozone Monitoring Instrument (OMI) and Aerosol Robotic Network (AERONET) over Saudi Arabia for the period 2004–2016 and validated using data from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). For this purpose, the OMI-based Aerosol Absorption Optical Depth (AAOD) and Ultra-Violet Aerosol Index (UVAI), and AERONET-based AAOD, Ångström Exponent (AE), Absorption Ångström Exponent (AAE), Fine Mode Fraction (FMF), and Single Scattering Albedo (SSA) were obtained. Spatial analysis of the satellite-based OMI-AAOD showed the dominance of absorbing aerosols over the study area, but with high seasonal variability. The study found significant underestimation by OMI AAOD suggesting that the OMAERUV product may need improvement over bright desert surfaces such as the study area. Aerosols were classified into (i) Dust, (ii) Black Carbon (BC), and (iii) Mixed (BC and Dust) based on the relationships technique, between the aerosol absorption properties (AAE, SSA, and UVAI) and size parameters (AE and FMF). Additionally, the AE vs. UVAI and FMF vs. UVAI relationships misclassified the aerosol types over the study area, and the FMF vs. AE, FMF vs. AAE and FMF vs. SSA relationships were found to be robust. As expected, the dust aerosol type was dominant both annually and seasonally due to frequent dust storm events. Also, fine particulates such as BC and Mixed (BC and Dust) were observed, likely due to industrial activities (cement, petrochemical, fertilizer), water desalination plants, and electric energy generation. This is the first study to classify aerosol types over Saudi Arabia using several different aerosol property relationships, as well as over more than one site, and using data over a much longer time-period than previous studies. This enables classification and recognition of specific aerosol types over the Arabian Peninsula and similar desert regions.

Assessing Air Quality and Public Health Benefits of New York City's Climate Action Plans.

Strategies that reduce greenhouse gas (GHG) emissions may also provide significant public health benefits and their estimation can help prioritize the case for climate change mitigation policies. In 2014, New York City (NYC) committed to reduce GHG emissions by 80% by 2050 (80 × 50). In this analysis we quantified the air quality-related public health benefits of the policies outlined in the 80 × 50 strategy, compared sector-specific (buildings, energy, transportation) policy impacts, and assessed variations in benefits across NYC neighborhoods. We applied air quality modeling and health impact assessment tools to estimate expected changes in ambient PM2.5 and related health outcomes by Zip Code Tabulation Areas (ZCTA). Full implementation of 80 × 50 strategies would reduce PM2.5 (fine particulates) concentrations across NYC ZCTAs by 7% (3%, 10%) (ZCTA median, 10th, 90th percentile), avoiding between 160 and 390 premature deaths and 460 hospitalizations and emergency department visits for respiratory and cardiovascular disease each year, valued at $3.4 billion annually. Across all the policy scenarios we estimated 10 times more avoided asthma emergency department visits in low-income neighborhoods as compared to the wealthiest neighborhoods even though median declines in ambient PM2.5 were similar. Consideration of public health benefits helps to prioritize climate policy implementation and identify priority neighborhoods.

Air Quality during COVID-19 in Four Megacities: Lessons and Challenges for Public Health.

The study described in this manuscript analyzed the effects of quarantine and social distancing policies implemented due to the Coronavirus Disease 2019 (COVID-19) pandemic on air pollution levels in four western megacities: São Paulo in Brazil; Paris in France; and Los Angeles and New York in the United States. The study investigated the levels of four air pollutants—Carbon monoxide (CO), Ozone (O3), Fine Particulate (PM2.5) and Nitrogen dioxide (NO2)—during the month of March 2020, compared to 2015–2019, in the urban air of these metropolitan areas, controlling for meteorological variables. Results indicated reductions in the levels of PM2.5, CO and NO2, with reductions of the latter two showing statistical significance. In contrast, tropospheric ozone levels increased, except in Los Angeles. The beneficial health effects of cleaner air might also help prevent deaths caused by the epidemic of COVID-19 in megacities by diminishing pressure on hospitals and health equipment. Future actions for the re-starting of non-essential economic activities in these cities should take into consideration the overall importance of health for the individual, as well as for societies.

Smoking guns and volcanic ash: the importance of sparse tephras in Greenland ice cores

Volcanic ash (fine-grained tephra) within Greenland ice cores can complement the understanding of past volcanism and its environmental and societal impacts. The presence of ash in sparse concentrations in the ice raises questions about whether such material represents primary ashfall in Greenland or resuspended (remobilized) material from continental areas. In this article, we investigate this issue by examining tephra content in quasi-annual samples from two Greenland ice cores during a period of ca. 20 years and considering their relationships with sulphur and particulate data from the same cores. We focus on the interval 815–835 CE as it encompasses a phase (818–822 CE) of heightened volcanogenic sulphur previously ascribed to an eruption of Katla, Iceland. We find that tephra is a frequent but not continuous feature within the ice, unlike similarly sized particulate matter. A solitary ash shard whose major element geochemistry is consistent with Katla corroborates the attribution of the 822±1 CE sulphur peak to this source, clearly showing that a single shard can signify primary ashfall. Other tephras are present in similarly low abundances, but their geochemistries are less certainly attributable to specific sources. Although these tephra shards tend to coincide with elevated sulphur and fine (&lt;10 µm) particulates, they are not associated with increased coarse (&gt;10 µm) particle concentrations that might be expected if the shards had been transported by dust storms. We conclude that the sparse shards derive from primary ashfall, and we argue that low tephra concentrations should not be dismissed as insignificant.

Association between the incidence of acute respiratory diseases in children and ambient concentrations of SO2, PM10 and chemical elements in fine particles

The aim of this study consists of investigating the effects of the SO2, PM10, inorganic chemical elements and black carbon (BC) present in fine particulates on the acute outcomes of respiratory diseases in children up to 12 years of age living in Brazilian urban area in the southern hemisphere during the winter (2013) and summer (2013–2014) months. SO2 and PM10 concentration data were obtained from six air quality monitoring stations spatially distributed in the area. PM2.5 samples were collected at the same locations with a MiniVol sampler over a 24-h period on alternating days. The PM2.5 components were analysed using the energy dispersive X-ray fluorescence and reflectance techniques. Hospital care and admission events due to acute respiratory diseases (n = 8,987) of the coded groups JJ00-JJ99 of the International Code of Diseases (ICD-10) were obtained from three hospitals (one public and two private hospitals). To quantify the association of acute respiratory disease events with pollutant concentrations, a generalized additive model (GAM) with a Poisson distribution was applied. The results showed a greater risk of acute respiratory events due to exposure to SO2 with a relative risk of 1.28 (95% CI: 1.22–1.34) and to PM10 with a risk of 1.14 (95% CI: 1.09–1.20) on the day of exposure (lag 0). The chemical constituents present in the fine particles with the highest risk for acute respiratory diseases were Si with a risk of 1.22 (95% CI: 1.15–1.29), S with a risk of 1.09 (95% CI: 1.06–1.12), Ti with a risk of 1.09 (95% CI: 1.01–1.17), BC with a risk of 1.07 (95% CI: 1.03–1.11), Se with a risk of 1.03 (95% CI: 0.96–1.10) and Ni with a risk of 1.03 (95% CI: 0.96–1.10).

Organ-on-a-Chip: Opportunities for Assessing the Toxicity of Particulate Matter.

Recent developments in epidemiology have confirmed that airborne particulates are directly associated with respiratory pathology and mortality. Although clinical studies have yielded evidence of the effects of many types of fine particulates on human health, it still does not have a complete understanding of how physiological reactions are caused nor to the changes and damages associated with cellular and molecular mechanisms. Currently, most health assessment studies of particulate matter (PM) are conducted through cell culture or animal experiments. The results of such experiments often do not correlate with clinical findings or actual human reactions, and they also cause difficulty when investigating the causes of air pollution and associated human health hazards, the analysis of biomarkers, and the development of future pollution control strategies. Microfluidic-based cell culture technology has considerable potential to expand the capabilities of conventional cell culture by providing high-precision measurement, considerably increasing the potential for the parallelization of cellular assays, ensuring inexpensive automation, and improving the response of the overall cell culture in a more physiologically relevant context. This review paper focuses on integrating the important respiratory health problems caused by air pollution today, as well as the development and application of biomimetic organ-on-a-chip technology. This more precise experimental model is expected to accelerate studies elucidating the effect of PM on the human body and to reveal new opportunities for breakthroughs in disease research and drug development.

Influence of local meteorology on the chemical characteristics of fine particulates in Metropolitan Manila in the Philippines

The chemical characteristics of fine particulates in Metropolitan Manila, capital of the Philippines, were investigated. Week-long daily PM2.5 sampling observations were done in the months of May and October of 2018 in the Manila Bay area. May and October correspond to the boreal spring and fall monsoon transition periods, respectively. The sampling periods were selected to minimize the contribution of transboundary pollutants and to determine the influence of local mesoscale weather under similar synoptic flow conditions. Results show the daily average PM2.5 mass concentration for spring and fall to be 29.07 ±4.69 and 50.06 ±8.79 μg m−3, respectively. Most PM2.5 components were also found to be higher during fall. The difference in concentration between the two seasons is mainly due to the strong land/sea-breeze in spring induced by warmer land surface temperature. In spring, strong sea-breeze disperses PM2.5 inland, and the nighttime land-breeze serves as the outflow path of fine aerosols from Metropolitan Manila. In fall, the opposing flow of the weaker sea-breeze to the prevailing easterly produces stagnant air that leads to higher accumulated particulate concentration. Moreover, the suppressed outflow during fall season resulted in higher PM2.5 contribution of aged secondary aerosol components. Overall, the largest contributors to Metropolitan Manila PM2.5 mass concentration are the primary and secondary aerosols from local vehicular emissions, followed by soil dust and seasalt.

Possible contamination of the Abrolhos reefs by Fundao dam tailings, Brazil – New constraints based on satellite data

The Fundão dam, located in Mariana city, Minas Gerais State, southeastern Brazil, collapsed in November 2015, causing the discharge of over 50 million m3 of iron ore tailings in the Doce river basin. The mud generated by the disaster was composed of fine particulates (silt and clay), which are more sensitive to wind dispersion. Based on laboratory analyses and hydrodynamic modeling, early research postulates the hypothesis that the mud discharged in the ocean traveled 10,000 km up north and may have reached the Abrolhos coral reefs. This research aims to investigate further this hypothesis based on broad-scale remotely sensed data. Satellite images were used to estimate the suspended particulate matter (SPM) in the coastal zone before, during, and after the dam collapse. Results indicate that higher concentrations of SPM appeared during and post-collapse and were restricted to the coastal zone and its shallower regions, including beaches. However, we demonstrate that under exceptional circumstances the wind blew to the north, carrying fine particulate material and potentially-toxic metals derived from the iron ore tailings towards the northeastern Brazilian coastline and possibly the reefs of the Abrolhos Bank.

Electrostatic charged nanofiber filter for filtering airborne novel coronavirus (COVID-19) and nano-aerosols

The World Health Organization declared the novel coronavirus (COVID-19) outbreak as a pandemic on March 12, 2020. Within four months since outbreak in December 2019, over 2.6 million people have been infected across 210 countries around the globe with over 180,000 deaths. COVID-19 has a size of 60–140 nm with mean size of 100 nm (i.e. nano-aerosol). The virus can be airborne by attaching to human secretion (fine particles, nasal/saliva droplets) of infected person or suspended fine particulates in air. While NIOSH has standardized N95, N99 and N100 respirators set at 300-nm aerosol, to-date there is no filter standards, nor special filter technologies, tailored for capturing airborne viruses and 100-nm nano-aerosols. The latter also are present in high number concentration in atmospheric pollutants. This study addresses developing novel charged PVDF nanofiber filter technology to effectively capture the fast-spreading, deadly airborne coronavirus, especially COVID-19, with our target aerosol size set at 100 nm (nano-aerosol), and not 300 nm.The virus and its attached aerosol were simulated by sodium chloride aerosols, 50–500 nm, generated from sub-micron aerosol generator. PVDF nanofibers, which were uniform in diameter, straight and bead-free, were produced with average fiber diameters 84, 191, 349 and 525 nm, respectively, with excellent morphology. The fibers were subsequently electrostatically charged by corona discharge.The amounts of charged fibers in a filter were increased to achieve high efficiency of 90% for the virus filter but the electrical interference between neighbouring fibers resulted in progressively marginal increase in efficiency yet much higher pressure drop across the filter. The quality factor which measured the efficiency-to-pressure-drop kept decreasing. By redistributing the fibers in the filter into several modules with lower fiber packing density, with each module separated by a permeable, electrical-insulator material, the electrical interference between neighboring charged fibers was reduced, if not fully mitigated. Also, the additional scrim materials introduced macropores into the filter together with lower fiber packing density in each module both further reduced the airflow resistance. With this approach, the quality factor can maintain relatively constant with increasing fiber amounts to achieve high filter efficiency. The optimal amounts of fiber in each module depended on the diameter of fibers in the module. Small fiber diameter that has already high performance required small amounts of fibers per module. In contrast, large diameter fiber required larger amounts of fibers per module to compensate for the poorer performance provided it did not incur significantly additional pressure drop. This approach was applied to develop four new nanofiber filters tailored for capturing 100-nm airborne COVID-19 to achieve over 90% efficiency with pressure drop not to exceed 30 Pa (3.1 mm water). One filter developed meeting the 90% efficiency has ultralow pressure drop of only 18 Pa (1.9 mm water) while another filter meeting the 30 Pa limit has high efficiency reaching 94%. These optimized filters based on rigorous engineering approach provide the badly needed technology for protecting the general public from the deadly airborne COVID-19 and other viruses, as well as nano-aerosols from air pollution which lead to undesirable chronic diseases.