Fine Particulates Research Articles

The air quality of Palangka Raya, Central Kalimantan, Indonesia: The impacts of forest fires on visibility

ABSTRACT Airborne particles in urban Palangka Raya, Kalimantan from Oct 2011 until Oct 2020 have been collected and analyzed for PM2.5, PM10, and Black Carbon (BC) concentrations. Palangka Raya is a city that serves the capital of the Central Kalimantan province on the island of Borneo. Kalimantan is affected by peat fires that occur periodically. There were identified increases in PM2.5 and PM10 concentrations during El Niño periods. During the forest fire episode in September – October 2015, PM2.5 and PM10 concentrations increased significantly, to nearly 400 µg/m3 and 800 µg/m3, respectively, and visibility in the city was reduced to < 0.2 miles. The highest BC concentrations were observed during this massive forest fires episode. The regression analyses for PM2.5, PM10 and visibility in Palangka Raya during the period of 2011–2020, showed a non-linear correlation with reduction in visibility due to increased PM2.5 and PM10. There was no correlation for BC with visibility. Air quality in Palangka Raya was at a relatively good level with concentrations below the national ambient air quality standard when there were no forest fires event. Emissions from forest fires caused a substantial reduction in air quality reaching concentrations well above ambient air quality standards and are likely to have caused adverse health effects on the people living in the area. Implications: Indonesia has repeatedly experienced forest fires, especially on Kalimantan and Sumatera Islands, which burned large areas of peatland. The forest fires leading to increasing PM concentrations especially in the PM2.5 size range which influence visibility. The seasonal variations of BC in Palangka Raya and the relationships of fine particulates with visibility were assessed. The results of regression analyses for PM2.5 and PM10 to visibility during the period of 2011-2020 showed non-linear relationships. An increasing of PM2.5 and PM10 concentrations during El Nino periods were detected well above the ambient air quality standard. To ensure effective and continued handling and prevention of forest and peatland fires, the government set up a special task force and review on several rules, including laws and government regulations as well as governor regulations that permit the burning of forest and peatland areas. These results are expected to be used to formulate more effective mitigations in reducing forest fires events in Indonesia.

Chemical Characterization of Fine and Coarse Particulate Matter in Gopalganj District of Bihar

A sampling campaign was conducted in Gopalganj district of Bihar for assessing the mass concentration of PM2.5 and PM2.5-10 so as to correlate it with the air quality of the district. Concentration of a dozen of elements namely Cd, Cr, Cu, Mn, Ni, Pb, Zn, Fe, Ca, K, Na and Al were quantified. Sampling was done on nuclear polycabonate filters. For principal component analysis (PCA) of elements and mass concentration data, three main sources were identified as PM2.5 and PM2.5-10 concentration. They are resuspended crustal dust, industrial emissions and vehicles exhaust. The effect of weather conditions was also studied. It was found that pollution in summer was higher than those in winter. The PM2.5/PM2.5-10 ratio in summer was found to be in the range of 0.35 - 0.9 whereas the same ratio in winter was 0.20 - 0.50. The concentration of both types of particles exceeded the permissible WHO limits.

Environmental Risk Assessment Ascribed to Particulate Matter for Kota City, Rajasthan (India)

The present study analyses the current PM10 and PM2.5 pollution scenarios for Kota City (India) to evaluate human health and ecological environment risks associated with particulate matter pollution exposure. Particulate matter concentration revealed a falling trend during the research period, but PM10 and PM2.5 exceeded the Indian NAAQS and WHO standards. The dust ratio (PM10/PM2.5) has been increased over the years from 0.36 to 0.51. and continue to overgrow for Kota City, showing that fine particulates share more than 45% of total particulate matter. Kota exhibits a high exposure of population towards pollution compared to other megacities of the state. The ecological environment and health risk assessment showed the greater vulnerability of the people to potential risks caused by particulate matter as the risk level remained more than one throughout the research period. The exposure presents important conclusions to stakeholders and policymakers for the proper adoption of mitigation measures.

The polarization crossfire (PCF) sensor suite focusing on satellite remote sensing of fine particulate matter PM2.5 from space

Focusing on satellite remote sensing of fine particulate matter PM2.5 from space, the polarization crossfire (PCF) strategy has been developed, which includes the PCF satellite suite and the particulate matter remote sensing (PMRS) model. Expected to be the first dedicated satellite sensor for PM2.5 remote sensing globally, the PCF suite is composed by the Particulate Observing Scanning Polarimeter (POSP) and the Directional Polarimetric Camera (DPC) together, and will be launched on board the Chinese GaoFen-5(02) satellite in 2021. Since the cross-track polarimetric measurements of POSP fully cover the multi-viewing swath of DPC, the sophisticated joint measurements could be obtained from the PCF suite in the range of 380–2250 nm including intensity and polarization, by the means of pixel matching and the cross calibration from POSP to DPC. Based on the optimal estimation inversion framework and synthetic data of PCF, the retrieval performances of key aerosol parameters are systematically investigated and assessed for the PM2.5 estimation by the PMRS model. For the design of inversion strategy for PCF, we firstly test the retrievals of aerosol optical depth (AOD), fine mode fraction (FMF), aerosol layer height (H) and the fine-mode real part of complex refractive index (mrf) simultaneously with surface parameters from the synthetic PCF data, and then the columnar volume-to-extinction ratio of fine particulates (VEf), the aerosol effective density (ρf) and the hygroscopic growth factor of fine-mode particles (f(RH)) are further obtained by the corresponding empirical relationship. The propagation errors from aerosol parameters to PM2.5 retrieval are investigated with the key procedures of PMRS model. In addition, the influences of improving calibration accuracy of PCF on PM2.5 retrievals are discussed, as well as the retrieval feasibility of PM10 by PCF strategy.

Linear Modeling of Spectra of Fine Particulate Materials: Implications for Compositional Analyses of Primitive Asteroids

AbstractIn this study, we applied a sum to one constraint weighted least squares (STO WLS) model to thermal infrared (TIR) spectra of a suite of primitive asteroid analogs spectrally and volumetrically dominated by fine particulates (&lt;38 μm). Since coarse particulate emissivity spectra combine linearly, deriving compositions from these are fairly straightforward. Across the TIR it is not as straightforward for fine particulate emissivity spectra due to the nonlinear behavior that arises from volumetric scattering between particles when the particle size becomes comparable to the wavelength of light. Using a WLS model, mixed spectra may be deconvolved into areal percentages of each end member which we assume corresponds to their volume percentages. We used a spectral library of pure mineral spectra to model TIR spectra of a suite of physical mixtures and meteorites obtained under ambient (Earth‐like) and simulated asteroid environment (SAE) conditions collected for the OSIRIS‐REx team (Donaldson Hanna et al., 2021, https://doi.org/10.1029/2020JE006624). The STO WLS model underestimated the modal abundances of the dominant mineral phases by ∼25.0 ± 0.1% on average over the full spectral range and ∼22.0 ± 0.4% over a limited spectral range in all of the ambient and SAE physical mixture and meteorite spectra. Minor phases present in the mixtures and meteorites (abundances ≤5%) were typically not modeled. Also, phases not present in the mixtures were commonly selected (∼2 phases on average with an average abundance of ∼25.2 ± 1.9%) to get the best mathematical fit.

Toxic test scores: The impact of chemical releases on standardized test performance within U.S. schools

This paper estimates the effects of exposure to toxic chemicals, and individual airborne metals in particular, in early childhood on school-level standardized test performance a decade later. The analysis links the cohort-level proficiency of primary school students born in the United States in the early 2000s to Toxics Release Inventory exposure, exploiting variation in the timing and magnitude of toxicity risk within public school catchment areas to estimate the impact of early exposure on educational outcomes. Estimates of airborne toxicity, which account for composition, may better correspond to human health risks from air pollution than total fine particulates. One standard deviation higher aggregate airborne toxicity in the catchment area during the year in which most students were born causes cohorts to perform 0.016 standard deviations worse on statewide tests. Finally, airborne chromium is identified as a driver of this effect: a ten percent change in ambient chromium concentrations during the first year of life causes a decrease in standardized test proficiency of 0.01 standard deviations.

Synergistic effect of reductions in multiple gaseous precursors on secondary inorganic aerosols in winter under a meteorology-based redistributed daily NH3 emission inventory within the Beijing-Tianjin-Hebei region, China

Secondary inorganic aerosols (SIA) account for 20–60% of the total fine particulates in the Beijing-Tianjin-Hebei (BTH) region of China, indicating an urgent need to clarify the relationship among such compounds. The purpose of this study was to quantify the relationship between emissions of NH3, NOx, SO2, VOCs and SIA concentrations during a severe winter haze episode using an air quality model and a meteorology-based redistributed NH3 emission inventory within the BTH region. The results showed that the model performance regarding the NH3 simulations in January by the four emission inventories improved after the redistribution of daily NH3 emissions, with an increase of 0.02–0.13 in R, a 9–56% decrease in NMB, and a 7–51% decrease in NME. The updated simulations reproduced the daily observations of SIA, SO2, and NO2 well. A total of 125 sets of sensitivity simulations showed that a synergistic reduction in NH3 and VOCs was more efficient in terms of SIA control than simply reducing SO2 or NOx in the BTH region. If only NOx emissions were reduced, the SIA concentration would first increase and then decrease, and it could decline by another 0.86–8.03% in parallel with an equal NH3 emission cut. SIA could be reduced by approximately 22.68% with the most stringent inorganic precursors' control. Moreover, VOCs emission reductions could lead to a decrease in SIA, and the impact of VOCs on SIA was similar to that of NH3. The collaborative control of both inorganic precursors and VOCs was more effective than single-factor control measures for decreasing SIA, and the decline rate was approximately 29.26% under minimum emission conditions. This improved effectiveness was obtained because VOCs mitigation effectively decreases the ozone concentration, which in turn influences SIA formation. Finally, on the premise of a 60% SO2 cut, the reduction scheme NH3:VOCs:NOx = 4:4:1 was suggested for SIA control.

Evaluating health outcome metrics and their connections to air pollution and vulnerability in Southern California's Coachella Valley

The ongoing desiccation of California's Salton Sea has led to increasing concerns about air quality and health for its surrounding communities, including the nearby Coachella Valley – a region already experiencing severe air quality and health disparities. Here we explore spatial air pollution and human health disparities in the Coachella Valley with particular attention to disparities arising across population characteristics including both socioeconomic and demographic vulnerabilities. We use two different measures of respiratory and cardiovascular health outcomes at the individual and census tract levels – one measure based on a randomly sampled telephone survey and the other measure based on emergency room visitation data – to investigate the degree to which these health outcomes are connected to air pollution and socioeconomic metrics. We further investigate biases and differences between the health outcome metrics themselves and suggest opportunities to address them in future analyses and survey efforts. We find that more vulnerable communities are associated with higher levels of fine particulates, but lower levels of ozone. While emergency visit rates show a significant positive correlation with both pollutants, no such association is found when using surveyed health outcome data. The ratio of emergency visits versus survey rates shows a positive relationship with socioeconomic and demographic vulnerability, indicating that vulnerable communities are less likely to self-report diagnoses despite higher rates of respiratory or cardiovascular hospitalization. Additionally, survey respondents tend to show less vulnerability relative to their surrounding census-based demographics. These findings suggest the need for greater attention to health issues specifically within disadvantaged communities in the Coachella Valley, building upon and working within existing community networks and local resources, to better address current and projected health needs. Our findings also highlight disparities in air pollution exposure, health outcomes, and population characteristics in the Coachella Valley, providing context for crucial pollution reduction efforts in the face of increasing environmental threats.

Laboratory Performance Evaluation of Novel Bituminous Coal Pellet Combustion in an Automatic Heating Stove

Coal is China’s dominant energy source, among which bituminous coal is the most extensive and plentiful. Using bituminous coal resources to design a low-emission household fuel is very important for rural poverty areas. In this work, a new type of bituminous coal pellet (BCP) fuel using an automatic prototype pellet stove was designed for the first time. This study mainly shows the emission characteristic results of BCPs and some comparisons with other commercial solid fuels. Fuel property, PM2.5 morphology, and ash characteristics of the novel fuel were also assessed. In terms of fuel properties, BCPs had a cold compressive strength of 637.2 N, a heating value of 22.26 MJ/kg, and many fine pores in the cross-section for air entry. The real-time emissions of BCPs were stable during combustion. The emission factors of PM2.5 and CO of BCPs were 1.36–2.29 g/kg and 11.1–18.0 g/kg, which were significantly lower than those of bituminous chunk and bituminous briquette (p &lt; 0.05). PM2.5 and CO reduced emissions by 83–90% and 61–76%, respectively, compared with raw coal chunk. According to the chemical composition and morphological characteristics, the PM2.5 from BCP combustion can be divided into fine particulates, molten char particles, and char fragmentation. The ash from BCPs had a higher melting temperature (over 1300 °C), with removable ash agglomeration. Overall, the results presented in this study highlight that turning bituminous coal into pellets and burning them in automatic stoves could noticeably reduce PM2.5 and CO emissions, effectively improving rural air quality.

Development of spinel magnesium aluminate by modified solid state process and its characterization

Spinel magnesium aluminate synthesis by modified solid state process using AR grade oxide precursors in stoichometric (1:1) ratio was used after mild activation carried by agate-mortar pestle in dry condition. Thermal analyses were carried off for the mixed activated powder to determine the zone for phase formation (spinelization) which plays a pivotal role for annealing temperature selection. Followed by phase transition studied from thermal analyses, heat treatment of powders (annealing/sintering) in air was carried at various temperatures of 900˚C, 1050˚C and 1150˚C for variable durations. Phase development was confirmed after XRD analyses while FTIR determine the bonding of compound as well as required M−O coordinations for the required phase formation. Morphological analyses of annealed powders by SEM, FESEM represent dense agglomerates with fine particulates of spherical to hexagonal shape, irregular polygon with negligible interconnected porosity. Electronic transition of the compound developed was studied by UV–VIS followed by band gap estimation using Tauc relation. Band gap of the compound evolved was noted to be varying with temperature and soaking period.

Machine Learning Mid‐Infrared Spectral Models for Predicting Modal Mineralogy of CI/CM Chondritic Asteroids and Bennu

AbstractPlanetary surfaces can be complex mixtures of coarse and fine particles that exhibit linear and nonlinear mixing behaviors at mid‐infrared (MIR) wavelengths. Machine learning multivariate analysis can estimate modal mineralogy of mixtures and is favorable because it does not assume linear mixing across wavelengths. We used partial least squares (PLS) and least absolute shrinkage and selection operator (lasso), two types of machine learning, to build MIR spectral models to determine the surface mineralogy of the asteroid (101955) Bennu using OSIRIS‐REx Thermal Emission Spectrometer (OTES) data. We find that PLS models outperform lasso models. The cross‐validated root‐mean‐square error of our final PLS models (consisting of 317 unique spectra of samples derived from 13 analog mineral samples and eight meteorites) range from ∼4 to 13 vol% depending on the mineral group. PLS predictions in vol% of Bennu's average global composition are 78% phyllosilicate, 9% olivine, 11% carbonates, and 6% magnetite. Pyroxene is not predicted for the global average spectrum, though it has been detected in small amounts on Bennu. These mineral abundances confirm previous findings that the composition of Bennu is consistent with CI/CM chondrites with high degrees of aqueous alteration. The predicted mineralogy of two previously identified OTES spectral types vary minimally from the global average. In agreement with previous work, we interpret OTES spectral differences as primarily caused by relative abundances of fine particulates rather than major compositional variations.

Are sustainable drainage systems (SuDS) effective at retaining dissolved trace elements?

ABSTRACT Sustainable drainage systems (SuDS) are increasingly deployed to mitigate against increased trace element contaminant loads associated with urban and road runoff. However, there is a lack of research on their capabilities in removing these trace elements, particularly from the dissolved phase. Water samples were taken, following various rainfall events, from three different SuDS in Devon; one wetland pond adjacent to a busy dual carriageway, a new SuDS serving a housing estate and an established SuDS draining a mixed housing/light industrial area. A total of 15 elements were studied over the course of six rain events including the first flush of runoff. Removal rates varied within and between rain events as well as between types of SuDS. Although there was a general (modest) removal of dissolved elements within any given SuDS, this was not the case for all of the elements studied. Highest observed element concentrations entering the SuDS occurred at the onset of a rain event (first flush), the intensity of which, was related to the antecedent dry period. During high flows associated with intense rainfall, the SuDS could also act as a source of trace elements associated with fine particulates (e.g. lead) owing to resuspension of fine particulate material. Mature ponds with an abundance of macrophytes help retain solids and particulate metals, however poor maintenance leading to successional growth of shrubs and trees, reduces the efficiency of metal removal. This study highlighted the importance of long-term management planning to be included within any SuDs scheme.

Versatile nanofibrous filters against fine particulates and bioaerosols containing tuberculosis and virus: Multifunctions and scalable processing

• Novel nanofibrous membrane was simply made from mangosteen and Ag-PAN/PVDF. • Nanofilter is antimicrobial against gram +/− bacteria, tuberculosis and H1N1 virus. • Nanofilter is stable against severe weathering suitable for versatile filtration uses. • Breathable nanomasks show high filtering efficiency (PFE 94%, BFE 99%, VFE 98%). Herein, versatile, mechanically robust, and highly-scalable electrospun nanofibrous composite filters towards unprecedented potent antimicrobial and excellent filtering properties are successfully designed and fabricated. Experimentally, the nanofibrous polyacrylonitrile (PAN) blended with polyvinylidene fluoride (PVDF) is fabricated for the dual quality of both PAN’s filtering capability and PVDF’s hydrophobic nature. Achieved without toxic polymer crosslinking agents or high-temperature post-treatment curing/annealing, the nanomembrane shows high water repellency, high mechanical/thermal stabilities and good spinnability. The PAN/PVDF membranes loaded with natural extract mangosteen ( Garcinia mangostana L., GM) and a minimum amount of in situ synthesized silver nanoparticles are first developed by needle-based electrospinning and, later, by a scalable blown electrospinning system, which applied an air-assisted technique to enhance the production rate. Our respective face masks show not only high filtering efficiency towards fine particulate matters (PMs) (93.91% for 0.5 µm) and bioaerosols (bacterial filtration efficiency (BFE) of 99.2% and viral filtration efficiency (VFE) of 98.3%), but also antimicrobial abilities against gram-positive Staphylococcus aureus , gram-negative Klebsiella pneumonia , Mycobacterium smegmatis and Mycobacterium tuberculosis H37Ra bacteria. Moreover, by virus inhibition assay and rRT-PCR, the nanomembrane shows a 99.94% reduction of H1N1 influenza virus. Despite this unprecedented novel multifunctionality, it is easier to breathe than commercial face masks with similar particle filtering performance. The stability of the membrane against severe simulated weathering (ASTM G154:2006) was confirmed for potential use as filters in air conditioning or outdoor space.

Atmospheric particulate fractions from Nigerian crude oil spillage

Laboratory simulations of the spill behaviors of three different Nigerian crude oil samples over three media (fresh water, sea water and soil) were carried out with a view to determining the effect of crude oil spillage on emission of fine (PM2.5) and inhalable particulates fractions (PM10). The spillage experiments were carried out in an environmental test box fitted with equipment to regulate the micro climatic conditions (temperature and Relative humidity). The maximum concentrations of PM2.5 were 711, 689 and 680 µgm−3 while those of PM10 were 972, 946 and 940 µgm−3 for sample A, B and C respectively. These peak concentrations were obtained for spill conditions corresponding to fresh water at 45 °C and 49% relative humidity. The least concentrations of PM2.5 and PM10 emitted across all samples were 63 µgm−3 and 256 µgm−3 respectively and these corresponded to spillage over sea water at 15 °C and 80% relative humidity. These concentrations clearly exceeded the short time averaging period (24 h) standards set for PM2.5 and PM10 by the United States Environmental Protection Agency. Incessant crude oil spillages in the Nigerian oil fields are therefore predicted to cause degradation of air quality within a short duration from the spill.

Insights into Elemental Composition and Sources of Fine and Coarse Particulate Matter in Dense Traffic Areas in Toronto and Vancouver, Canada.

Traffic is a significant pollution source in cities and has caused various health and environmental concerns worldwide. Therefore, an improved understanding of traffic impacts on particle concentrations and their components could help mitigate air pollution. In this study, the characteristics and sources of trace elements in PM2.5 (fine), and PM10-2.5 (coarse), were investigated in dense traffic areas in Toronto and Vancouver, Canada, from 2015–2017. At nearby urban background sites, 24-h integrated PM samples were also concurrently collected. The PM2.5 and PM10-2.5 masses, and a number of elements (i.e., Fe, Ba, Cu, Sb, Zn, Cr), showed clear increases at each near-road site, related to the traffic emissions resulting from resuspension and/or abrasion sources. The trace elements showed a clear partitioning trend between PM2.5 and PM10-2.5, thus reflecting the origin of some of these elements. The application of positive matrix factorization (PMF) to the combined fine and coarse metal data (86 total), with 24 observations at each site, was used to determine the contribution of different sources to the total metal concentrations in fine and coarse PM. Four major sources were identified by the PMF model, including two traffic non-exhaust (crustal/road dust, brake/tire wear) sources, along with regional and local industrial sources. Source apportionment indicated that the resuspended crustal/road dust factor was the dominant contributor to the total coarse-bound trace element (i.e., Fe, Ti, Ba, Cu, Zn, Sb, Cr) concentrations produced by vehicular exhaust and non-exhaust traffic-related processes that have been deposited onto the surface. The second non-exhaust factor related to brake/tire wear abrasion accounted for a considerable portion of the fine and coarse elemental (i.e., Ba, Fe, Cu, Zn, Sb) mass at both near-road sites. Regional and local industry contributed mostly to the fine elemental (i.e., S, As, Se, Cd, Pb) concentrations. Overall, the results show that non-exhaust traffic-related processes were major contributors to the various redox-active metal species (i.e., Fe, Cu) in both PM fractions. In addition, a substantial proportion of these metals in PM2.5 was water-soluble, which is an important contributor to the formation of reactive oxygen species and, thus, may lead to oxidative damage to cells in the human body. It appears that controlling traffic non-exhaust-related metals emissions, in the absence of significant point sources in the area, could have a pronounced effect on the redox activity of PM, with broad implications for the protection of public health.

Cationic Nanocellulose as Promising Candidate for Filtration Material of COVID-19: A Perspective

The threat of the novel coronavirus (COVID-19) pandemic is worrying as millions of people suffered from this outbreak. The COVID-19 can be airborne by attaching to human nasal or saliva secretion of an infected person or suspended fine particulates in the air. Therefore, in order to minimize the risks associated with this pandemic, an efficient, robust and affordable air‐borne virus removal filters are highly demanded for prevention of spreading viruses in hospitals, transportation hubs, schools, and/or other venues with high human turn‐over. Respirators such as N95, N99 and N100 as well as surgical masks have been widely used. To date, there is no filter standards or special filter technologies tailored for effectively adsorbing the airborne viruses. Studies had shown the electrostatic fibers were capable to entrap the negatively charged viruses including COVID-19. Researchers believed that the positive surface charge of filtration material is an important key to efficiently adsorb the negatively charged viruses. Nanocellulose has emerged as a new class of biobased material with promising potential application in the filtration of viruses. Nanocellulose which is uniform in diameter and has excellent nanofibrillar morphology. To the best of our knowledge, lack of study is done to determine the efficiency of cationic nanocellulose as filtration material of COVID-19.

Air quality evaluation during COVID-19 in Southern Italy: the case study of Avellino city

The present study relies on the air quality evaluation during COVID-19 pandemic in Avellino, described in the last years and for several consecutive years, among the worst Italian cities in this context. The main purpose of this manuscript was to investigate the effects of quarantine and lockdown measures on air pollution. The concentrations of the main atmospheric pollutants (Carbon monoxide (CO), Ozone (O3), Fine Particulate (PM2.5 and PM10), Benzene (C6H6) and Nitrogen dioxide (NO2) were recorded during the period January–December 2020 using two stationary monitoring stations (AV1 and AV2) of the Regional Environmental Protection Agency (ARPAC). During the lockdown period (March 9-May 18, 2020), results indicated significant reductions only in the levels of CO, benzene and NO2, while for PM10 the limit of 50 μg m−3 was passed 8 times for AV1 and 13 times for AV2. The results showed the not predominant role of traffic on air quality in Avellino regards to PM levels and make it necessary a serious reflection about important and not extendable decisions to improve the air quality.

Non-Woven Textiles Formed from Contact Drawn Poly(ethylene oxide) Fibers Provide Tunable Filtration and Virucidal Properties via Entrapment of Silver Nanoparticles

Filtering facepiece respirators (FFRs) protect wearers from inhalation of fine particulates and help prevent transmission of airborne viruses. Here, an FFR material is produced by successive deposition of contact drawn poly(ethylene oxide) (PEO) fibers. Fibers are formed by immersing an array of pins in a highly viscous precursor solution of PEO and then rapidly removing the pins such that polymer entanglement occurs, forming multiple liquid bridges that rapidly dry as they extend. Tunable filtration is achieved by varying the number of PEO fiber elongation cycles. Placing the PEO textiles between two woven cotton cloths provides structural support and additional filtration capacity, achieving a maximum filtration efficiency of 95% with a corresponding initial pressure drop of 281 Pa. The entrapment of silver nanoparticles in the PEO fibers imparts virucidal properties to PEO-based textiles, as demonstrated by inactivation of a human coronavirus HCoV-OC43 and influenza A virus inoculum. The ability to tune filtration efficiency to application needs and provide advanced function through entrapment of active materials represents a versatile tool for limiting exposure to airborne particulates and pathogens.

Pollution characterization and source identification of nitrogen-containing species in fine particulates: A case study in Hefei city, East China

To identify the nitrogen sources in atmospheric particulate matter, the stable isotope technique has been proven as an effective method. In this study, PM2.5 samples at different pollution levels were collected from March 2018 to February 2019 in Hefei to analyze and compare the chemical composition. The results showed that the concentrations of PM2.5, total nitrogen (TN) and nitrogenous species, as well as the total nitrogen isotopic composition (δ15N) increased with the aggravation of pollution. Ammonium nitrogen (NH4+-N, 54%) was the dominant nitrogen-containing specie during the whole campaign, followed by nitrate nitrogen (NO3−-N, 34%) and organic nitrogen (ON, 12%). The δ15N was positively correlated with NH4+-N/TN but negatively correlated with NO3−-N/TN. NH4NO3 and NH4HSO4 were the dominant forms of the secondary inorganic aerosols. In addition, a significant positive correlation was observed between the temperature and δ15N. Nitrogen source identification of PM2.5 was conducted using Positive Matrix Factorization (PMF) model, δ15N values and Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The results indicated that the contributions of the four main nitrogen sources were obtained and shown in descending order: combustion and industrial emission (42.06%) > secondary aerosols (24.04%) > vehicle exhaust (23.57%) > re-suspended dust (10.33%). The nitrogen aerosols might be mainly influenced by local emissions on normal and slight pollution days, while by both local emissions and transport from other areas on moderate and serious pollution days. Furthermore, nitrogen-containing species in PM2.5 primarily originated from long/medium-distance transportation in two serious pollution events during the entire campaign.

The chemical composition and toxicological effects of fine particulate matter (PM2.5) emitted from different cooking styles

The mass, chemical composition and toxicological properties of fine particulates (PM2.5) emitted from cooking activities in three Hong Kong based restaurants and two simulated cooking experiments were characterized. Extracts from the PM2.5 samples elicited significant biological activities [cell viability, generation of reactive oxygen species (ROS), DNA damage and inflammation effect (TNF-α)] in a dose-dependent manner. The composition of PAHs, oxygenated PAHs (OPAHs) and azaarenes (AZAs) mixtures differed between samples. The concentration ranges of the Σ30PAHs, Σ17OPAHs and Σ4AZAs and Σ7Carbonyls in the samples were 9627–23,452 pg m−3, 503–3700 pg m−3, 33–263 pg m−3 and 158 – 5328 ng m−3, respectively. Cell viability caused by extracts from the samples was positively correlated to the concentration of benzo[a]anthracene, indeno[1,2,3-cd]pyrene and 1,4-naphthoquinone in the PM2.5 extracts. Cellular ROS production (upon exposure to extracts) was positively correlated with the concentrations of PM2.5, decaldehyde, acridine, Σ17OPAHs and 7 individual OPAHs. TNF-α showed significant positive correlations with the concentrations of most chemical species (elemental carbon, 16 individual PAHs including benzo[a]pyrene, Σ30PAHs, SO42−, Ca2+, Ca, Na, K, Ti, Cr, Mn, Fe, Cu and Zn). The concentrations of Al, Ti, Mn, Σ30PAHs and 8 individual PAHs including benzo[a]pyrene in the samples were positively correlated with DNA damage caused by extracts from the samples. This study demonstrates that inhalation of PM2.5 emitted from cooking could result in adverse human health effects.