Characterization of airborne dust samples collected from core areas of Kathmandu Valley

Characterization of soot and crystalline atmospheric ultrafine particles

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

In-depth characterization of particulate matter in a highly polluted urban environment at the foothills of Himalaya-Karakorum Region

In recent years, the rising levels of atmospheric particulate matter (PM) have an impact on the earth's system, leading to undesirable consequences on various aspects like human health, visibility, and climate. The present work is carried out over an insufficiently studied but polluted urban area of Peshawar, which lies at the foothills of the famous Himalaya and Karakorum area, Northern Pakistan. The particulate matter with an aerodynamic diameter of less than 10 µm, i.e., PM10 are collected and analyzed for mineralogical, morphological, and chemical properties. Diverse techniques were used to examine the PM10 samples, for instance, Fourier transform infrared spectroscopy, x-ray diffraction, and scanning electron microscopy along with energy-dispersive x-ray spectroscopy, proton-induced x-ray emission, and an OC/EC carbon analyzer. The 24 h average PM10 mass concentration along with standard deviation was investigated to be 586.83 ± 217.70 µg/m3, which was around 13 times greater than the permissible limit of the world health organization (45 µg/m3) and 4 times the Pakistan national environmental quality standards for ambient PM10 (150 µg/m3). Minerals such as crystalline silicate, carbonate, asbestiform minerals, sulfate, and clay minerals were found using FTIR and XRD investigations. Microscopic examination revealed particles of various shapes, including angular, flaky, rod-like, crystalline, irregular, rounded, porous, chain, spherical, and agglomeration structures. This proved that the particles had geogenic, anthropogenic, and biological origins. The average value of organic carbon, elemental carbon, and total carbon is found to be 91.56 ± 43.17, 6.72 ± 1.99, and 102.41 ± 44.90 µg/m3, respectively. Water-soluble ions K+ and OC show a substantial association (R = 0.71). Prominent sources identified using Principle component analysis (PCA) are anthropogenic, crustal, industrial, and electronic combustion. This research paper identified the potential sources of PM10, which are vital for preparing an air quality management plan in the urban environment of Peshawar.

Identification of sources of coarse mode aerosol particles (PM10) using ATR-FTIR and SEM-EDX spectroscopy over the Himalayan Region of India

This study attempts to examine the morphological, elemental and physical characteristics of PM10 over the Indian Himalayan Region (IHR) using FTIR and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis. The study aimed at source identification of PM10 by exploring the inorganic ions, organic functional groups, morphology and elemental characteristics. The pollution load of PM10 was estimated as 63 ± 22 μg m-3; 53 ± 16 μg m-3; 67 ± 26 μg m-3 and 55 ± 11 μg m-3 over Mohal-Kullu, Almora, Nainital and Darjeeling, respectively. ATR-FTIR spectrum analysis revealed the existence of inorganic ions (SiO44-, TiO2, SO42-, SO3-, NO3-, NO2-, CO32-, HCO3-, NH4+) and organic functional groups (C-C, C-H, C=C, C≡C, C=O, N-H, C≡N, C=N, O-H, cyclic rings, aromatic compounds and some heterogeneous groups) in PM10 which may arise from geogenic, biogenic and anthropogenic sources. The morphological and elemental characterization was performed by SEM-EDX, inferring for geogenic origin (Al, Na, K, Ca, Mg and Fe) due to the presence of different morphologies (irregular, spherical, cluster, sheet-like solid deposition and columnar). In contrast, particles having biogenic and anthropogenic origins (K, S and Ba) have primarily spherical with few irregular particles at all the study sites. Also, the statistical analysis ANOVA depicts that among all the detected elements, Na, Al, Si, S and K are site-specific in nature as their mean of aw% significantly varied for all the sites. The trajectory analysis revealed that the Uttarakhand, Jammu and Kashmir, the Thar Desert, Himachal Pradesh, Pakistan, Afghanistan, Nepal, Sikkim, the Indo-Gangetic Plain (IGP) and the Bay of Bengal (BoB) contribute to the increased loading of atmospheric pollutants in various locations within the IHR.

Morphological, Mineralogical, and Biochemical Characteristics of Particulate Matter in Three Size Fractions (PM10, PM2.5, and PM1) in the Urban Environment

Air pollution in megacities is increasing due to the dense population index, increasing vehicles, industries, and burning activities that negatively impact human health and climate. There is limited study of air pollution in many megacities of the world including Pakistan. Lahore is a megacity in Pakistan in which the continuous investigation of particulate matter is very important. Therefore, this study investigates particulate matter in three size fractions (PM1, PM2.5, and PM10) in Lahore, a polluted city in south Asia. The particulate matter was collected daily during the winter season of 2019. The average values of PM1, PM2.5, and PM10 were found to be 102.00 ± 64.03, 188.31 ± 49.21, and 279.73 ± 75.04 μg m-3, respectively. Various characterization techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX) were used. FT-IR and XRD techniques identified the minerals and compounds like quartz, peroxides, calcites and vaterite, feldspar group, kaolinite clay minerals, chrysotile, vaterite, illite, hematite, dolomite, calcite, magnesium phosphate, ammonium sulfate, calcium iron oxide, gypsum, vermiculite, CuSO4, and FeSO4. Morphology and elemental composition indicated quartz, iron, biological particles, carbonate, and carbonaceous particles. In addition, various elements like C, O, B, Mg, Si, Ca, Cl, Al, Na, K, Zn, and S were identified. Based on the elemental composition and morphology, different particles along with their percentage were found like carbonaceous- (38%), biogenic- (14%), boron-rich particle- (14%), feldspar- (10%), quartz- (9%), calcium-rich particle- (5%), chlorine-rich particle- (5%), and iron-rich particle (5%)-based. The main sources of the particulate matter included vehicular exertion, biomass consumption, resuspended dust, biological emissions, activities from construction sites, and industrial emissions near the sampling area.

Physico-chemical characterization of indoor settled dust in Children's microenvironments in Ikeja and Ota, Nigeria

Indoor dust is a collection of particles identified as a major reservoir for several emerging indoor chemical pollutants. This study presents indoor dust particles' morphology and elemental composition in eight children's urban and semi-urban microenvironments (A-H) in Nigeria. Samples were collected using a Tesco vacuum cleaner and analyzed with scanning electron microscopy coupled with an energy-dispersive X-ray (SEM-EDX). The morphology results confirm the presence of alumino silicates, mineral particles and flakes, fly ash and soot, and soot aggregates deposited on alumino silicate particles in the sampled microenvironments. These particles may trigger serious health concerns that directly or indirectly affect the overall well-being of children. From the EDX analysis, the trend of elements (w/w %) in the dust particles across the sampled sites was silicon (386) > oxygen (174)> aluminium (114) > carbon (34.5) > iron (28.0) > calcium (16.7) > magnesium (14.2) > sodium (7.92) > potassium (7.58) > phosphorus (2.22) > lead (2.04) > manganese (1.17) > titanium (0.21). Lead (Pb), a toxic and carcinogenic heavy metal, was observed in locations A and B. This is a concern without a safe lead level because of the neurotoxicity effect on children. As a result, further research on the concentrations, bioavailability, and health risk assessment of heavy metals in these sampled locations is recommended. Furthermore, frequent vacuum cleaning, wet moping and adequate ventilation systems will significantly reduce the accumulation of indoor dust-bound metals.

Insights into seasonal-variability of SVOCs, morpho-elemental and spectral characteristics of PM2.5 collected at a dense industrial site: Faridabad, Haryana, India

The development-oriented anthropogenic activities have led to intensive increase in emission of various organic pollutants, which contribute considerably to human health risk. In the present study, chemical, physical and spectral characterisation of fine particulate matter (PM_2.5), collected at Faridabad city, in northern India, were examined. Seasonal variation of organic compounds [n-alkanes, polyaromatic hydrocarbons (PAHs) and phthalic acid esters (PAEs)], and potential health risk of Polyaromatic hydrocarbons (PAHs) exposure using toxic equivalency potential (TEQ) approach had been assessed. These showed seasonal average values ranging from 156.4 ± 57.0 ng/m³ to 217.6 ± 72.9 ng/m³, 98.0 ± 21.4 ng/m³ to 177.8 ± 72.8 ng/m³, and 30.9 ± 11.9 ng/m³ to 82.5 ± 29.2 ng/m³, respectively, with the highest value for winter. It is noteworthy that unlike, n-alkanes and PAEs, PAHs were least during spring. The high molecular weight PAHs (BaP, BkF, DahA and IcdP) were found to exhibit higher TEQ values (ranging from 0.7 to 9.7) despite of their lower concentrations. The PAH diagnostic ratio, carbon preference index and total index revealed the enhanced impact of biogenic sources of emissions in comparison to diesel emission sources during winter.

Short-Term Effects: Elemental and Morphological Assessment of Aerosols Over Old Delhi Region, India

This study presents morphological and elemental characteristics of aerosols for the duration January-June, 2021, using Scanning Electron Microscope coupled with Energy Dispersive X-Ray (SEM–EDX). The results revealed that there were numerous spherical particles (D α ≤ 2.5 µm) but did not produced the expected EDX-spectra for elemental constituents. Limited deposited particles were observed which showed definite elemental constitutions. The results show that Cl, S, Al, Ca, K, Fe, Zn, Na, Mg, N, Tb, Ti, Ni, F, Cd, Cu, Mn, P and Cr were the overall determined elements, out of which Cl, S, Al, Ca, K, Fe, Zn, Na and Mg were the major constituents. Variation in particles’ shapes whether definite or irregular, columnar or spherical, flaky or aggregate or crystal-accumulation were attained on the basis of the major constituting element, majorly Ca-rich, S-rich, Cl-rich and Fe-rich. Interestingly, the physical characteristics of the particles varied with variation in elemental composition. All these indicate that there were specific sources contributing toward distinct particle-morphs. Ti, Tb and Cd need more analytical studies for their percent contribution. S, Cl and K contributed the most to the elemental composition as revealed by elemental relative proportion. Atomic weight percent curves for elements were slightly scattered during May. These probably played important role in defining the diversity indices, which was highest for April (2.17 ± 0.12). Particles containing six (P 6) to nine (P 9) elements dominated in this study, and particles containing seven elements (P 7) were generally observed.

Potential ecological and health risks of heavy metals for indoor and corresponding outdoor dust in Hefei, Central China

The harm caused by indoor dust has received increasing attention in recent years. However, current studies have ignored comparisons with the corresponding outdoor dust. This study aimed to investigate the distribution of heavy metals in indoor and corresponding outdoor dust and the ecological and health risks they pose in Hefei, Central China. We analyzed O/I (outdoor/indoor concentration ratios) values, background comparison, and correlation analysis (heavy metal concentrations vs. particle size) and found that Cu, Zn, and Cd mainly existed in indoor sources, while V, Co, and As mainly existed in outdoor sources, and both family sizes and floor number influenced the variation of O/I. Through a new potential ecological risk assessment method, we determined that Cd risk levels in indoor and outdoor dust were extreme and high to extreme, respectively. Additionally, the carcinogenic risks of Ni, As, and Cr were not negligible. The risk of indoor dust was higher than that of outdoor dust for the heavy metals studied, implying a poor indoor environment. Notably, indoor dust from families with smaller sizes, lower floors, and smokers had higher ecological and carcinogenic risks.

In-Depth Analysis of Physicochemical Properties of Particulate Matter (PM10, PM2.5 and PM1) and Its Characterization through FTIR, XRD and SEM–EDX Techniques in the Foothills of the Hindu Kush Region of Northern Pakistan

The current study investigates the variation and physicochemical properties of ambient particulate matter (PM) in the very important location which lies in the foothills of the Hindu Kush ranges in northern Pakistan. This work investigates the mass concentration, mineral content, elemental composition and morphology of PM in three size fractions, i.e., PM1, PM2.5 and PM10, during the year of 2019. The collected samples were characterized by microscopic and spectroscopic techniques like Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and scanning electron microscopy (SEM) coupled with energy-dispersive X-ray (EDX) spectroscopy. During the study period, the average temperature, relative humidity, rainfall and wind speed were found to be 17.9 °C, 65.83%, 73.75 mm and 0.23 m/s, respectively. The results showed that the 24 h average mass concentration of PM10, PM2.5 and PM1 were 64 µgm−3, 43.9 µgm−3 and 22.4 µgm−3, respectively. The 24 h concentration of both PM10 and PM2.5 were 1.42 and 2.92 times greater, respectively, than the WHO limits. This study confirms the presence of minerals such as wollastonite, ammonium sulphate, wustite, illite, kaolinite, augite, crocidolite, calcite, calcium aluminosilicate, hematite, copper sulphate, dolomite, quartz, vaterite, calcium iron oxide, muscovite, gypsum and vermiculite. On the basis of FESEM-EDX analysis, 14 elements (O, C, Al, Si, Mg, Na, K, Ca, Fe, N, Mo, B, S and Cl) and six groups of PM (carbonaceous (45%), sulfate (13%), bioaerosols (8%), aluminosilicates (19%), quartz (10%) and nitrate (3%)) were identified.

The mineralogical composition of coarse and fine particulate material, their fate, and sources in an industrialized region of southeastern Brazil

The particulate matter (PM) in the atmosphere may be composed of many elements and compounds, including toxic species and hazardous materials, which demand effective control of its emissions, starting with the knowledge of the sources. In this sense, the mineralogical analysis of the PM might be a powerful tool. Here, we present a comprehensive mineralogical characterization of the coarse and fine PM in an industrialized city southeast of Brazil, including a discussion about the transport, deposition, and potential sources associated. Elemental and mineralogical analyses by EDXRF and RSr-XRD were performed on SPM, TSP, PM₁₀, and PM_2.5. The results showed distinct mineralogical composition depending on the PM size. Mineral phases in SPM and TSP were majorly composed of hematite and quartz, while PM₁₀ and PM_2.5 were majorly composed of carbon, halite, sulfates, and carbon. The results show hazardous mineral phases associated with respiratory injuries in all PM size classes, such as hematite, pyrite, EC, and quartz. The XRD analysis also revealed primary particles of sulfate in the region close to industrial sources.

Masks for COVID-19

Sustainable solutions on fabricating and using a face mask to block the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread during this coronavirus pandemic of 2019 (COVID-19) are required as society is directed by the World Health Organization (WHO) toward wearing it, resulting in an increasingly huge demand with over 4 000 000 000 masks used per day globally. Herein, various new mask technologies and advanced materials are reviewed to deal with critical shortages, cross-infection, and secondary transmission risk of masks. A number of countries have used cloth masks and 3D-printed masks as substitutes, whose filtration efficiencies can be improved by using nanofibers or mixing other polymers into them. Since 2020, researchers continue to improve the performance of masks by adding various functionalities, for example using metal nanoparticles and herbal extracts to inactivate pathogens, using graphene to make masks photothermal and superhydrophobic, and using triboelectric nanogenerator (TENG) to prolong mask lifetime. The recent advances in material technology have led to the development of antimicrobial coatings, which are introduced in this review. When incorporated into masks, these advanced materials and technologies can aid in the prevention of secondary transmission of the virus.

Assessing volatile organic compound level in selected workplaces of Kathmandu Valley

Volatile organic compounds (VOCs) are one of the major contributors to poor indoor air quality. Due to advancements in sensor technologies, continuous if not regular monitoring total VOC (TVOC) and or some specific VOC in potential high risk workplaces is possible even in resource limited settings. In this study, we implemented a portable VOC sensor to measure concentration of TVOC and formaldehyde (HCHO) in six types of potential high risk workplaces (n = 56 sites) of Katmandu Valley. For comparison, concentration was also measured in immediate surroundings (n = 56) of all the sites. To get preliminary information on safety practices, a survey study was also conducted. The mean TVOC and HCHO concentration in the sites ranged from 1.5‒8 mg/m³ and <0.01–5.5 mg/m³, respectively. The indoor: outdoor TVOC and HCHO ratio (I/O) was found to be significantly higher (I/O > 1.5 and p < 0.05) in 34 (~61%) and 47 sites (∼84%), respectively. A strong positive correlation between HCHO and TVOC concentration was observed in furniture industry (R = 0.91) and metal workshops (R = 0.98). Interestingly, we found TVOC and HCHO concentration higher than WHO safe limit in ∼64% and ∼32% sites, respectively. A rough estimate of chronic daily intake (CDI) of formaldehyde showed that CDI is higher than WHO limit in four sites. These findings suggested that indoor air quality in the significant number of the workplaces is poor and possible measures should be taken to minimize the exposure.

Investigating the Mineral Composition of Peat by Combining FTIR-ATR and Multivariate Analysis

The mineral content of peat has received little attention until the last few decades, when peat cores have been increasingly used to study past dust deposition. Paleodust deposition is commonly reconstructed through elemental datasets, which are used to infer deposition rates, storminess patterns, mineral composition, source identification, and fertilization effects. To date, only a few studies have directly analyzed the mineralogy (by XRD and SEM) and particle size of peat mineral matter, and the conducted studies have usually been constrained by the need to remove a large amount of organic matter, which risks altering the mineral component. One alternative is to use quick, nondestructive techniques, such as FTIR-ATR, that require little sample preparation. In this study, we analyzed by FTIR-ATR both the bulk peat and ash fractions of a sequence taken in a minerogenic mire that covered a wide inorganic matter content range (6%–57%). Aided by principal component analysis on transposed IR spectral data, we were able to identify the main minerals in bulk peat and ash, quartz, mica (likely muscovite), K feldspar (likely microcline), and plagioclase (likely anorthite), which are consistent with the local geology of the mire catchment. Changes in mineral composition during the last ca. 2800 years were coeval with previously reconstructed environmental changes using the same core. Our results suggest that FTIR-ATR has great potential to investigate peat mineral matter and the processes that drive its compositional change.

ATR-FTIR and LC-Q-ToF-MS analysis of indoor dust from different micro-environments located in a tropical metropolitan area

Indoor dust is an important matrix that exposes humans to a broad spectrum of chemicals. The information on the occurrence of contaminants of emerging concern (CECs), their metabolites, and re-emerging contaminants in indoor dust is rather limited. As the indoor environment is exposed to various chemicals from personal care products, furniture, building materials, machineries and cooking/cleaning products, there is a high chance of the presence of hazardous contaminants in indoor dust. In the present study, dust samples were collected from four different micro indoor environments (photocopying centres, residential houses, classrooms, and ATM cabins) located in an urban environment located in India's southwestern part. The collected samples were subjected to ATR - FTIR and LC-Q-ToF-MS analyses. The ATR - FTIR analysis indicated the presence of aldehydes, anhydrides, carboxylic acids, esters, sulphonic acids, and asbestos - a re-emerging contaminant. A total of 19 compounds were identified from the LC-Q-ToF-MS analysis. These compounds belonged to various classes such as plasticisers, plasticiser metabolites, photoinitiators, personal care products, pharmaceutical intermediates, surfactants, and pesticides. To the best of our knowledge, this is the first report regarding the presence of CECs in indoor environments in Kerala and also the suspected occurrence of pesticides (metaldehyde and ethofumesate) in classroom dust in India. Another important highlight of this work is the demonstration of ATR-FTIR as a complementary technique for LC-Q-ToF-MS in the analysis of indoor pollution while dealing with totally unknown pollutants. These results further highlight the occurrence of probable chemically modified metabolites in the tropical climatic conditions in a microenvironment.

Morphology and mineralogy of ambient particulate matter over mid-Brahmaputra Valley: application of SEM–EDX, XRD, and FTIR techniques

Ambient particulate matter (PM), collected during a dust event over mid-Brahmaputra Valley of India, was characterized. The PM samples were analyzed using scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) techniques. The SEM micrographs revealed varied shapes of the PM, viz. spherical, irregular, angular, cluster, flaky, rod-like, crystalline and agglomerate structures indicating the probable nature of their sources and formation as biogenic, geogenic, or anthropogenic. Some biogenic particles like plant materials, pollens, and diatoms were captured under SEM. The presence of diatom in PM samples was indicative of wind-blown dust from the dried bed of the Brahmaputra River. The honeycomb-like structures of brochosomes secreted by the leafhoppers of the Cicadellidae family were also captured. On the contrary, the background sample had mostly carbonaceous particles. The XRD and FTIR analyses indicated the presence of quartz, feldspar, kaolinite, illite, augite, and calcium aluminum silicate, cerussite, calcite, montmorllonite, and organic carbon. The airmass backward trajectory analysis explained the local contribution of the dust.