Characterization of Airborne Particles Collected from Car Engine Air Filters Using SEM and EDX Techniques

Evaluating the ability of green roof plants in capturing air pollutants using biogas-digestate: Exploring physiological, biochemical, and anatomical characteristics

The undeniable impact of plants in reducing air pollution and the crucial role of nutrition in improving stress tolerance in plants has brought attention to the use of eco-friendly fertilizers. The objective of the study was to investigate how Biogas-digestate (BD) can enhance the tolerance of green roof plants in capturing air pollutants. Four plant species, namely reflexed stonecrop (Sedum reflexum), blue fescue (Festuca glauca), garden mum (Chrysanthemum morifolium), and Peppermint (Mentha piperita) were planted in three urban sites in Mashhad, Iran, with different levels of air pollution. The physiological, biochemical, and morphological characteristics of the treated plants were compared to assess their ability to trap air pollutants. The results showed that the treated M. piperita at Razavi with BD, exhibited the highest level of APTI. Although it was influenced by the site conditions, the determination of the optimum API yielded same results. The F. glauca treated in Khayyam had the highest proline content, while S. reflexum at the Honarestan site had the lowest H2O2 level, without significantly affecting BD. F. glauca, S. reflexum, and M. piperita exhibited the highest levels of SOD, PPO, and GPX activity, respectively, which were significantly increased by the BD treatment. Most of the heavy elements showed increased levels with BD treatment, and M. piperita had the highest concentrations of heavy elements. The leaf surfaces of S. reflexum and M. piperita, had the highest and lowest deposition of particulate matter (PMs), respectively. Carbon and oxygen constituted the majority of PMs on the surface of leaves at all three study locations. The following ranks included the elements Si, Ca, Mg, and Al. BD, particularly in the case of S. reflexum and M. piperita, enhanced the plants' tolerance to air pollution. It is recommended to cultivate S. reflexum using BD on the green roof in polluted areas due to its superior capacity to absorb PMs and the fact that it is not edible.

Assessment of plant species suitability in green walls based on API, heavy metal accumulation, and particulate matter capture capacity

One of the most pressing issues confronting the civilized and modern world is air pollution. Particulate matter (PM) is a well-known pollutant that contributes significantly to urban air pollution and has numerous short- and long-term adverse effects on human health. One method of reducing air pollution is to create green spaces, mainly green walls, as a short-term solution. The current study investigated the ability of nine plant species to reduce traffic-related PM using a green wall system installed along a busy road in Mashhad, Iran. The main aims were (1) estimate the tolerance level of plant species on green walls to air pollution using the air pollution tolerance index (APTI); (2) assess the PM capture on the leaves of green wall species using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, and accumulation of heavy metals using inductively coupled plasma (ICP); (3) select the most tolerance species for reducing air pollution using anticipated performance index (API). The plants' APTI values ranged from 5 to 12. The highest APTI value was found in Carpobrotus edulis and Rosmarinus officinalis, while Kochia prostrata had the lowest. Among the APTI constituents, leaf water content (R² = 0.29) and ascorbic acid (R² = 0.33) had a positive effect on APTI. According to SEM analysis, many PM_s were adsorbed on the adaxial and abaxial leaf surfaces, as well as near the stomata of Lavandula angustifolia, C. edulis, Vinca minor, and Hylotelephium sp. Based on EDX analysis, carbon and oxygen formed the highest amount (more than 60%) of metals detected in the elemental composition of PM deposited on the leaves of all species. The Sedum reflexum had the highest Cr, Fe, Pb, and As accumulation. The concentrations of all heavy metals studied in green wall plants were higher than in the control sample. Furthermore, the C. edulis is the best plant for planting in industrial, urban areas of the city based on APTI, biological, economic, and social characteristics. It concludes that green walls composed primarily of plants with small leaves can significantly adsorb PM and accumulation of heavy metal.

A Study on the Effect of Inlet Air Pollution on the Engine Component Wear and Operation

This paper systematically reviews the research progress in the field of the influence of air pollutants in the engine inlet on the accelerated wear of the elements of the association: piston, piston rings, cylinder liner (P-PR-CL), and plain bearing (journal–panel). It was shown at the outset that the primary component of air pollution is road dust. Its main components are dust grains of hard minerals (SiO2, Al2O3), which penetrate the oil film area between two frictionally mating surfaces causing their abrasive wear. Therefore, the effect of three dust parameters (grain size and hardness, and dust concentration in air) on the accelerated wear of the friction pair: piston, piston rings, cylinder liner(P-PR-CL), and plain bearing (journal–pan) is presented extensively. It was noted that the wear values of the same component were obtained by different researchers using different testing techniques and evaluated by different indices. It has been shown that the greatest wear of two frictionally cooperating surfaces is caused by dust grains with sizes equal to the thickness of the oil film at a given moment, which in typical combustion engine associations assumes varied and variable values in the range of 0–50 µm. The oil film thickness between the upper ring and the cylinder liner varies and depends on the crankshaft rotation angle, engine speed and load, and oil viscosity, and takes values less than 10 µm. It was shown that the maximum wear of the cylinder liner, resulting from the cooperation with the piston rings, occurs in the top dead centre (TDC) area and results from unfavorable (high temperature, low piston speed) operating conditions of these elements. From the extensive literature data cited, it follows that abrasive wear is caused by dust grains of specific dimensions, most often 5–20 µm, the greater the wear the greater the hardness of the grains and the sulfur content of the fuel. At the same time, it was shown that the main bearing, crankshaft bearing, and oil ring experienced maximum wear by a different range of particle size, respectively: 20–40, 5–10, and 20–80 μm. It was shown that the mass of dust that enters the engine cylinders and thus the wear of the components is determined by the concentration of dust, the value of which is definitely reduced by the air filter. However, it was pointed out that the low initial filtration efficiency and the presence of large dust grains in the purified air in the initial period of the filter operation (after replacement of the filter element with a new one) may have an impact on the accelerated wear of mainly (P-PR-CL) association. The next stage of the paper presents the effects of excessive wear of the cylinder liner and piston rings of the engine, resulting from actual vehicle operation and bench tests on the decrease in compression pressure and engine power, increase in the intensity of exhaust gas blow-by into the oil sump and increase in oil consumption and exhaust gas toxicity. This paper addresses the current problem of the effect of engine inlet air contaminants on the performance of the air flow meter, which is an essential sensor of the modern internal combustion engine. The phenomenon of deposition of contaminants (mineral dust, salt, carbon deposit, and moisture) on the measuring element (wire or layer anemometer) of the air flow meter has been analyzed. The empirical results presented show that the mineral dust layer on the measuring element of the air flow meter causes a 17.9% reduction in output voltage, and the dust and oil layer causes a 46.7% reduction in output voltage. This affects the decrease in engine power and exhaust toxicity.

Nonpharmacological measures to prevent allergic symptoms in pollen allergy: A critical review

Allergic rhinoconjunctivitis (hay fever) is the most common chronic disease in all industrialized nations. Therapy consists essentially in the use of anti-allergic and anti-inflammatory drugs, which mostly show a good and quick effect. With allergen-specific immunotherapy, there is also a causal possibility of tolerance induction. There is currently a considerable undersupply, as those affected trivialize the symptoms and often have concerns about long-term drug therapy. There is also great interest in using non-medicinal measures to prevent and/or relieve allergic symptoms on the assumption that these are free from side effects. In this publication, we present non-drug methods for which clinical studies are available in the literature. The methods have varying degrees of effectiveness. An evidence-based comparative assessment between the methods is not possible. There are also hardly any studies in comparison to standard drug therapy. A large number of the interventions consist of allergen reduction, e.g., with air filters, or cleaning of the mucous membranes with nasal irrigation, etc., none of which should be seen as a substitute but as a supplement to drug therapy.

Sequential SEM-EDS, PLM, and MRS Microanalysis of Individual Atmospheric Particles: A Useful Tool for Assigning Emission Sources

In this work, the particulate matter (PM) from three different monitoring stations in the Monterrey Metropolitan Area in Mexico were investigated for their compositional, morphological, and optical properties. The main aim of the research was to decipher the different sources of the particles. The methodology involved the ex situ sequential analysis of individual particles by three analytical techniques: scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), polarized light microscopy (PLM), and micro-Raman spectroscopy (MRS). The microanalysis was performed on samples of total suspended particles. Different morphologies were observed for particles rich in the same element, including prismatic, spherical, spheroidal, and irregular morphologies. The sequential microanalysis by SEM-EDS/PLM/MRS revealed that Fe-rich particles with spherical and irregular morphologies were derived from anthopogenic sources, such as emissions from the metallurgical industry and the wear of automobile parts, respectively. In contrast, Fe-rich particles with prismatic morphologies were associated with natural sources. In relation to carbon (C), the methodology was able to distinguish between the C-rich particles that came from different anthopogenic sources—such as the burning of fossil fuels, biomass, or charcoal—and the metallurgical industry. The optical properties of the Si-rich particles depended, to a greater extent, on their chemical composition than on their morphology, which made it possible to quickly and accurately differentiate aluminosilicates from quartz. The methodology demonstrated in this study was useful for performing the speciation of the particles rich in different elements. This differentiation helped to assign their possible emission sources.

Characterization, concentration and risk assessment of airborne particles using car engine air filter (case study: Tehran metropolis)

Atmospheric elements released into the atmosphere can enter the human body through inhalation, ingestion and dermal contact and are then deposited in the body. Trace elements have potential risks to human health. For this purpose, the particulate matter accumulated by car air filters (CAFs) was studied. The morphology and distribution of particle size were examined using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The concentration of elements in CAFs and CAF-estimated air for 30 elements in Tehran, Iran, was analyzed in winter and summer, from February to July 2017. Samples were determined by inductively coupled mass plasma spectrometry. The most abundantly detected elements in both CAFs and air in both seasons were Ca, Mg, Na and Fe. The shape of the particles was mostly irregular and spherical. Most of the particles were between 0.5 and 1.0 µm. The carcinogenic risks of inhalation exposure to Cr and Co in winter and summer were higher than the acceptable level (< 1 × 10^-4) for children and adults. The carcinogenic risks of As and Cr in both seasons were higher than 1 × 10^-4 for children and adults via dermal contact. Also, the carcinogenic risks of Cr in both seasons of ingestion exposure were higher than 1.00E-04 for children and adults. The integrated noncarcinogenic risks of all trace elements were higher than the safe level (= 1) for children and adults in both seasons.

Civilian science: the potential of participatory environmental monitoring in areas affected by armed conflicts

Legal and policy initiatives to address the environmental dimensions of armed conflicts and their impact on people, ecosystems and sustainable development are highly dependent on the availability of environmental data from conflict-affected areas. Socio-political and security conditions in these areas often impede data collection, while traditional models of post-conflict environmental assessments are limited in scope. In response, an increasing range of actors is utilising remote sensing and open source data collection to identify and estimate health and ecological risks during and after conflicts. This paper considers the role of participatory citizen science methodologies in complementing both remote monitoring and post-conflict assessments. It examines existing models and mechanisms for environmental data collection and utilisation in conflict contexts, and the extent to which the core values and principles of citizen science are transferable. We find that 'civilian science' is feasible and could be well-suited to conflict conditions. In addition to addressing gaps in data collection, it may also empower communities affected by environmental degradation, enhance their environmental human rights, supplement the often limited monitoring capacity of governmental agencies and facilitate cooperation and peacebuilding. The paper concludes by proposing methodological approaches for three common forms of environmental degradation associated with armed conflicts.

Dispersion and deposition estimation of fugitive iron particles from an iron industry on nearby communities via AERMOD

Emission of fugitive iron particles from anthropogenic sources can have significant effects on the human health and the environment. In this study, a regulatory air pollutant dispersion model (AERMOD) was implemented to predict the dispersion and deposition of fugitive iron particles towards a mid-sized residential area in Sultanate of Oman. The performance of the model was validated using air, soil, and dust fall samples. PM₁₀ was found as the most abundant iron particles in the soil samples. The results showed that the maximum daily concentration level of fugitive iron particles simulated through AERMOD was 7.19 μg/m³. Statistical analysis, including fractional bias (FB), normalized mean square error (NMSE), and predicted/observed ratio (Pred./Obs.), showed a reliable agreement in accuracy and precision between the datasets (for air samples FB = 0.024, NMSE = 0.001, Pred./Obs. = 0.976; for dust fall samples FB = -0.004, NMSE = 0.000, Pred./Obs. = 1.004). However, uncertainties and differences were from the external sources, such as other industries in the region. The results presented that the concentration levels were below the national and international guidelines proposed by the US Environmental Protection Agency (USEPA) and Omani Ambient Air Quality Standards (OAAQS). The methodology followed and the developed dispersion model can be generalized to other industries from which the dispersion of fugitive metal particles need to be evaluated as a potential route for human exposure. Graphical abstract ᅟ.