Dust Resuspension Research Articles

Long-Term Characterization of Indoor Air Quality at a Research Area Building: Comparing Reference Instruments and Low-Cost Sensors

Indoor particle number size distribution (0.3-10 μm), equivalent black carbon (eBC), and Ångström absorption exponent (AAE) data were collected in real conditions, over a ten-month period at a research area building, in a semirural site, to characterize indoor aerosol loading. Additionally, during the campaign, emissions from four indoor sources commonly used at the site (incense, traditional cigarettes, electronic cigarettes, and heat-not-burn products) were studied during short-term experiments with the support of ultrafine particle (UFP) monitoring. Two particle low-cost sensors (PM LCS), Sensirion SPS30 (0.3-10 μm), were evaluated in the long-term campaign and during fast emission processes, to assess their accuracy and reliability. Penetration and infiltration of both fine and coarse particles from outdoor traffic, domestic heating, and dust resuspension were inferred as the main sources of indoor aerosols on a long-term basis. Moreover, long-range transported dust aerosols were found to influence indoor coarse number concentration. Among the source events, heat-not-burn (HNB) product resulted in the lowest effect on indoor air quality, whereas the highest AAE values from incense and traditional cigarettes suggest the brown carbon (BrC) production. The highest emission of UFP was caused by electronic cigarettes (e-cig), which spanned particles from the ultrafine to the coarse fractions. This was likely due to the release of metal and silicate from the coil. Analysis of number size distributions of the four experiments revealed the emission of fine particles (0.3-1 μm) and super micron particles. SPS30s performance was satisfactory in terms of accuracy, precision, and durability, indicating that these devices are suitable for monitoring indoor air quality. Additionally, the two PM LCS were able to detect all simulated fast emission sources.

Source-specific risks assessment of size-resolved PM bound multiple toxicants: Variation of source-specific risks in respiratory tracts

Inhalation risks depend on the size distribution of ambient particulate matter (PM) bound toxicants, which are influenced by various sources. This study explored variations in source-specific risks across different respiratory tract regions and their association with size-resolved toxicants. Potentially toxic elements contribute significantly, accounting for over 93% of the inhalation risk, followed by polycyclic aromatic hydrocarbons at 0.3%–7%, and organophosphate esters at less than 0.01%. For adults, the contribution of non-cancer and cancer risks within respiratory tracts was as follows: upper respiratory tract (∼61%) > pulmonary (∼30%) region > tracheobronchial (∼8%) region. Differently, for children, the order was pulmonary (∼43%) > upper respiratory tract (∼41%) > tracheobronchial (∼17%). In the adult population, resuspended dust (RD) presented elevated non-cancer risks in the upper respiratory tract compared to the tracheobronchial and pulmonary regions, while coal combustion (CC), traffic emission (TE), and waste recycling or incineration (WI) contribute most to pulmonary risks. In contrast, for children, non-cancer risk associated with CC surpassed RD in the upper respiratory tract, whereas RD exceeded CC in the tracheobronchial region. This discrepancy arises because RD primarily consists of coarse PM with higher deposition fractions in the adults' upper respiratory tract and children's tracheobronchial region, while toxicants from CC, TE and WI, with PM < 0.43 μm, are inclined to have a greater impact on the pulmonary region. Regarding source cancer risks, RD exhibited a consistent decrease across all three respiratory tract regions, with primary dominance observed in industrial emissions (IE), CC, and TE sources.

Spatiotemporal prediction of particulate matter concentration based on traffic and meteorological data

Air pollution threatens worldwide human health, ecosystems, and climate change. Transportation is a major contributor to air pollution. However, the link between transportation and air pollution is intricate and influenced by multiple elements. This study employs spatiotemporal causal convolutional networks to predict air pollutants by utilizing traffic and meteorological data as inputs. Using Seoul, South Korea as a case study, a dataset of 25 regional air monitoring stations is used for prediction. The results confirm that wind speed and direction significantly impact PM2.5 dispersion, while humidity positively correlates with PM2.5 concentrations and temperature shows an inverse relationship. Additionally, vehicular traffic and subway passenger numbers exhibit positive associations, attributed to automotive emissions, road dust resuspension, and heightened human activity near subway stations, respectively. The model can potentially be utilized in a real-time air pollution tracking system to facilitate prompt interventions and reduce the harmful effects of air contamination on public health.

Wintertime investigation of PM10 concentrations, sources, and relationship with different meteorological parameters

Meteorological factors play a crucial role in affecting air quality in the urban environment. Peshawar is the capital city of the Khyber Pakhtunkhwa province in Pakistan and is a pollution hotspot. Sources of PM10 and the influence of meteorological factors on PM10 in this megacity have yet to be studied. The current study aims to investigate PM10 mass concentration levels and composition, identify PM10 sources, and quantify links between PM10 and various meteorological parameters like temperature, relative humidity (RH), wind speed (WS), and rainfall (RF) during the winter months from December 2017 to February 2018. PM10 mass concentrations vary from 180 – 1071 µg m−3, with a mean value of 586 ± 217 µg m−3. The highest concentration is observed in December, followed by January and February. The average values of the mass concentration of carbonaceous species (i.e., total carbon, organic carbon, and elemental carbon) are 102.41, 91.56, and 6.72 μgm−3, respectively. Water-soluble ions adhere to the following concentration order: Ca2+ > Na+ > K+ > NH4+ > Mg2+. Twenty-four elements (Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Co, Zn, Ga, Ge, As, Se, Kr, Ag, Pb, Cu, and Cd) are detected in the current study by PIXE analysis. Five sources based on Positive Matrix Factorization (PMF) modeling include industrial emissions, soil and re-suspended dust, household combustion, metallurgic industries, and vehicular emission. A positive relationship of PM10 with temperature and relative humidity is observed (r = 0.46 and r = 0.56, respectively). A negative correlation of PM10 is recorded with WS (r = − 0.27) and RF (r = − 0.46). This study’s results motivate routine air quality monitoring owing to the high levels of pollution in this region. For this purpose, the establishment of air monitoring stations is highly suggested for both PM and meteorology. Air quality standards and legislation need to be revised and implemented. Moreover, the development of effective control strategies for air pollution is highly suggested.

Seasonal variation in metals concentration associated with settled dust and their risk assessment in school children of Agra (India)

Metals associated with indoor dust are shown to be a key pollutant and resuspension of dust in critical microenvironments like schools can lead to detrimental health effects to children. The present study was carried out from December 2021 to November 2022 to examine variations in metal concentration with season and associated health risks from school dust in Agra, India. Dust samples were digested in aqua-regia followed by analysis for metals concentration by ICP-AES. Geo-accumulation (Igeo), pollution (PI), integrated pollution (IPI), and pollution load (PLI) indexes were used to determine metals contamination, Principal Component Analysis and Cluster Analysis were employed for the identification of causative sources of metals while USEPA health risk assessment models were utilized to assess the health risks in children. The results indicated that in all seasons settled dust of roadside schools of both regions accumulated higher concentrations of metals as compared to residential schools except semi-urban schools in post-monsoon season. The total metal concentration (mgkg−1) in school dust samples of Agra ranged from 62507–85037, 72477–97022, 48912–66083 to 58605–92290 in winter, summer, monsoon, and post-monsoon respectively. In all seasons, the PLI values of settled dust of all schools ranged from less than one to greater than unity which indicates pollution levels by metals. Further, Igeo values revealed that school dusts were moderately and heavily contaminated by Cd in all seasons. The assessment of health risk specifies ingestion as the main exposure route followed by dermal intake and inhalation. The Hazard Index value for all examined metals was lower than the safer limit of one while on the contrary for Pb, total cancer risk was higher the than safer limit via inhalation pathway. The findings of the study indicate that more investigations are required on potentially toxic metal contaminations in schools of Agra, especially for Pb, Cd and Cr.

Size Distribution as a Forensic Tool to Source Apportion Ambient PM

The particulate matter (PM) emitted from multiple sources contribute to air pollution near highways, affecting, mainly the commuters on road, dwellers and shopkeepers nearby. In this study, the size distribution of the PM near a highway, obtained using real time laser aerosol spectrometer, was used to apportion the contributions from vehicular traffic and road dust. Data on vehicle count and type were obtained for the selected highway stretch. The size distribution of emission from petrol and diesel vehicles and the size distribution of re-suspended dust were obtained through independent studies. Size based distribution of PM in the study area contributed by vehicles, were modelled using AERMOD using the vehicle emissions and vehicle count data. Aggregation of the modelled concentrations of PM of various size ranges with the contribution from re-suspended dust gave size based concentration distributions closely matching with that of PM in ambient air. The size based PM analyses showed that in the study area, 47.36%, 15.74%, and 15.46% of PM2.5, were contributed by diesel vehicles, petrol vehicles and suspended dust, respectively. The corresponding contributions to PM10 were, 14.42%, 10.59% and 68.35%. The emission studies on vehicles showed diesel vehicles contributing significantly higher concentration of PM to ambient air than petrol vehicles, with condition of vehicle influencing the amount of PM emitted. The use of particle size distribution pattern for preliminary source apportionment, demonstrated in this study, has promising environmental forensic applications as it provides a cheap and fast corroborative evidence for responsibility allocation.

Size-segregated characteristics of water-soluble oxidative potential in urban Xiamen: Potential driving factors and implications for human health

Oxidative potential (OP), defined as the ability of particulate matter (PM) to generate reactive oxygen species (ROS), has been considered as a potential health-related metric for PM. Particles with different sizes have different OP and deposition efficiencies in the respiratory tract and pose different health risks. In this study, size-segregated PM samples were collected at a coastal urban site in Xiamen, a port city in southeastern China, between August 2020 and September 2021. The water-soluble constituents, including inorganic ions, elements and organic carbon, were determined. Total volume-normalized OP based on the dithiothreitol assay was highest in spring (0.241 ± 0.033 nmol min−1 m−3) and lowest in summer (0.073 ± 0.006 nmol min−1 m−3). OP had a biomodal distribution with peaks at 0.25–0.44 μm and 1.0–1.4 μm in spring, summer, and winter and a unimodal pattern with peak at 0.25–0.44 μm in fall, which were different from the patterns of redox-active species. Variations in the seasonality of fine and coarse mode OP and their correlations with water-soluble constituents showed that the size distribution patterns of OP could be attributed to the combined effects of the size distributions of transition metals and redox-active organics and the interactions between them which varied with emissions, meteorological conditions and atmospheric processes. Respiratory tract deposition model indicated that the deposited OP and the toxic elements accounted for 47.9 % and 36.8 % of their measured concentrations, respectively. The highest OP doses and the excess lifetime carcinogenic risk (ELCR) were found in the head airway (>70 %). However, the size distributions of OP deposition and ELCR in the respiratory tract were different, with 63.9 % and 49.4 % of deposited ELCR and OP, respectively, coming from PM2.5. Therefore, attention must be paid to coarse particles from non-exhaust emissions and road dust resuspension.

Seasonal variations in concentrations of PM2.5 and tire wear particle of < 2.5 μm (TWP2.5) and polymeric components of PM2.5 at a bus stop

Air pollution is a global public health concern. Bus stops have heavy traffic and local emissions. PM2.5 was collected for 2 day at a bus stop each month for one year. Polymeric components in the PM2.5 samples were analyzed using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Seasonal variations of the polymeric components, PM2.5 concentration, and concentration of tire wear particles <2.5 μm (TWP2.5) were investigated. Various polymeric components were found, including natural rubber (NR) and curing agents from TWPs, bitumen originating from asphalt pavement wear particles (APWPs), plant-related components (PRCs), and poly (ethylene-terephthalate) (PET) from PET fabric lint. The PM2.5 concentrations at the bus stop were 4–124% higher than those in the regional background, and the annual average PM2.5 concentration at the bus stop was more than 1.5 times higher than that in the regional background. Non-exhanst sources such as abrasion of tires, brakes, and asphalt pavements, vehicle exhaust emissions, and road dust resuspension accounted for the high PM2.5 concentrations. The PM2.5 concentrations during winter were higher than those in the other seasons. On average, the additional generation of PM2.5 at the bus stop was approximately 10 μg/m3, while that in the winter was approximately 18 μg/m3. The annual average TWP2.5 concentration at the bus stop was 1.28 μg/m3 (0.7–1.8 μg/m3), and the seasonal order was winter > fall > spring > summer. TWP2.5 is directly generated by the abrasion of tire tread through the friction with the road surface and also is produced from primary TRWPs by pressing and breaking them upon the contact with tires while driving vehicles. The annual average contribution of TWP2.5 to the PM2.5 concentration at the bus stop was 5.5% (1.6–14.0%).

Mineral magnetic proxies for evaluation of anthropogenic pollution at children's playgrounds – a case study from Sofia city

Quality of the urban environment where children play is of great concern for protecting their health. Thus, fast and economically feasible proxy methods for assessment of urban environment are increasingly applied. In this study, settled dust from 13 playgrounds from Sofia city (Bulgaria), was investigated by mineral magnetism, portable X-ray fluorescence measurements, and scanning electron microscopy. The aim of the study was to evaluate the degree of anthropogenic pollution of playgrounds during winter and summer seasons and to identify pollution sources. Magnetic susceptibility (χ) was measured for two dust fractions - very coarse (grain sizes between 1 and 2 mm) and size fraction of d < 1 mm. In spite of this rough separation, systematic seasonal difference in χ of the two fractions is observed. Winter dust, containing larger amount of finer fraction shows lower χ. Regardless of lower relative content of d < 1 mm fraction, summer playground dusts are more strongly magnetic. Complex Pollution Load Index (PLI), calculated using contents of Cu, Zn, S, Pb (Potentially Toxic Elements (PTE)), shows higher contamination in summer dust, compared to winter. Anhysteretic and isothermal remanences of dust d < 1 mm demonstrate prevailing magnetically stable grains at playgrounds located at greater distance from major boulevards. Thermomagnetic analyses of magnetic susceptibility identified magnetite as the main magnetic mineral, although metallic iron was also evident in summer dust. Based on the meteorological models of atmospheric circulation over Sofia, the pollution sources suggested in a previous research, on one hand, and the carried out Factor Analysis, on the other hand, the results point out that in spite of higher PM10 dust load in winter, summer dust pollution causes stronger PTEs contamination. Factor analysis revealed four factors, explaining most of variability in the data. These factors were identified as: 1) re-suspension of soil and road dust; 2) fine particles magnetite of stable single domain grain size, originating probably from traffic exhaust and non-exhaust emissions; 3) emissions from installations burning waste materials; 4) coal burning.

From lowland plains to the Altiplano: The impacts of regional transport of wildfire smoke on the air quality of Bolivian cities

Wildfires emerged as a global concern in recent decades, because they deteriorate the air quality in urban centres situated downwind, impact human health, ecosystems and regional climate. In this study, we assessed the air quality of Bolivia's three largest metropolitan areas during the period 2017–2019 by analysing in situ criteria air pollutant data (PM10, O3 and NOx) coupled with satellite (aerosol optical depth AOD and total CO column), fire foci data, and airmass backward trajectories. The Bolivian lowland plains were highly impacted by smoke transported from the Amazon and Cerrado biomes. Due to its proximity to the fire foci, Santa Cruz was the most affected city, where PM10, CO and AOD increased between 1.3- and 3.9-fold in September (maximum fire activity) compared to April (lowest fire activity). In Cochabamba and La Paz-El Alto, the impacts of wildfires on AOD and CO were lower (15–16% increase). A case study of regional smoke in September 2019 using Cochabamba as an example revealed that: i) airmass trajectories passed over regions with high fire radiative power density in southern Bolivia, Paraguay and northern Argentina; ii) the advection of wildfire smoke caused unusual episodes of enhanced nocturnal O3 concentrations (20–45 μg/m3) over a four-day pollution event. The results indicated that local sources (e.g., motorised traffic, brick kilns and dust resuspension) largely contributed to deteriorate the air quality, particularly in the dry months, surpassing the World Health Organization recommendations for PM10, in La Paz-El Alto and Cochabamba. We highlight the need of international cooperation among South American countries to combat fire practices in the region, given the transboundary nature of the biomass burning plumes. Moreover, it is crucial to implement local measures aimed at tackling local air pollution sources, especially in a changing climate in which drier conditions can favour the onset and propagation of wildfires and accumulation of air pollutants.

Preliminary assessment of road dust from Portuguese motorways: chemical profile, health risks, and ecotoxicological screening

Among non-exhaust emissions, road dust resuspension represents a rather important contribution to particulate matter in urban areas. This study aimed to achieve a chemical characterisation of road dust particulate matter (PM10) on two motorway sections, one rural and one urban, and to explore the related health and ecotoxicological risks. Measured PM10 dust loadings reached very low levels (0.66–1.49 mg m-2) compared to equivalent studies in other road environments in Portugal and other countries. Emission factors ranged from 33 to 62 mg veh−1 km−1. The carbonaceous content represented 14% of the total PM10 mass, whereas the highest contribution to the mass was given by mineral matter. Elements such as Si, Al, Ca, Fe and K accounted for almost three quarters of the total element mass for all samples, whilst Cu and Zn, mostly associated with brake and tyre wear, were the most enriched elements in relation to the soil composition. Nonetheless, Ti and Zr presented the highest non-carcinogenic risks for human health. Despite the low amounts of particulate matter in the aqueous solution, the ecotoxicological screening with the Aliivibrio fisheri bioluminescence inhibition bioassay allowed to classify the samples as toxic.

Variability of airborne microbiome at different urban sites across seasons: a case study in Rome

Introduction: Biogenic fraction of airborne PM10 dominated by bacteria and fungi, has been recognized as serious environmental and human health issues in cities.Methods: In the present study, we combined a high-throughput amplicon sequencing of the bacterial 16S rRNA gene and the fungal internal transcribed spacer (ITS) region, with elemental analysis of airborne particulate matter (PM10) to investigate the community compositions and structures of PM10-associated bacteria and fungi across four different seasons in three urban sites of Rome with differential pollution rate.Results: In this study, а clear seasonal shift of bacterial and fungal community structure driven by PM10 mass concentrations and environmental factors, such as temperature and precipitations, has been identified. In addition, the seasonal impact of local sources and long-range transported air masses on the community structures of the microbes has been also postulated. Our data revealed that the lack of precipitation and the subsequent resuspension of dust produced by vehicular traffic might contribute to the maximum abundance of soil-associated microbes in winter and summer. However, the increase of PM10 concentrations favoured also by climatic conditions, domestic heating and dust advection event from African desert further shaped the community structure of winter. Across three seasons, the pollutant removal-hydrogen oxidation bacteria and the opportunist-human pathogenic fungi progressively increased with pollution levels, in the sequence from green to residential and/or polluted area close to the traffic roads, with highest fraction during winter.Discussion: Hence, our results highlight a close interrelationship between pollution, climatic factors and abundance of certain bacterial and fungal predicted functional groups also with potential implications for human health.

Road dust resuspension in a coastal Atlantic intermunicipal urban area with industrial facilities: Emission factors, chemical composition and ecotoxicity

Road dust resuspension in urban environments can be both a means of transport of pollutants across the various environmental compartments and a source of pollutants itself, becoming a potential threat to human health. With the aim of obtaining emission factors and achieving a detailed chemical characterisation of road dust (RD) in typical Portuguese cities, a sampling campaign was performed in the region of Aveiro. Locations were chosen for intercomparison in various urban environments with different land uses, from the busier city centre and university campus to residential neighbourhoods and harbour-commercial areas with industrial activities. PM10 samples were analysed for organic and elemental carbon (OC and EC) by a thermal-optical technique, elemental composition by PIXE, organic speciation by GC–MS, and ecotoxicology by a luminescence inhibition bioassay with Aliivibrio fischeri. A health risk assessment for elements and PAHs was carried out. Dust loadings of 1.9 ± 1.8 mg PM10 m−2 were registered overall, whereas in the most trafficked areas of city centre they reached more than three times the average. OC accounted for 6.5–15.5% of total PM10, but element oxides represented the largest mass fraction (61.4 ± 8.6%). A strong enrichment was detected mostly for typical traffic-related elements such as Cu, Zn, As, Br, Cr, Ni and Mo and interestingly, Rb and Se. The analysed organic compounds accounted for 3.66–11.0 mg g−1 PM10, including PAHs and aliphatics, with a clear dominance of plasticisers. Some other compounds attributed to non-vehicle sources, such as fatty acid alkyl esters, were also detected. As concerns the 16 priority PAHs, their total mass concentration ranged from 5.58 to 36.3 μg g−1 PM10, with clear variability between sampling spots. All samples caused an ecotoxicological reaction in the bioassay, but samples from harbour and commercial areas proved to be most toxic.

Assessment of heavy metal accumulation in dust and leaves of Conocarpus erectus in urban areas: Implications for phytoremediation

This study investigated the spatio-temporal variation of heavy metal concentrations in roadside dust and its correlation with heavy metal content in roadside plant leaves. Sixty re-suspended dust samples were collected from six locations during two seasons (dry and wet). Simultaneously, leaf samples of Conocarpus erectus were collected from the same locations. The samples were analyzed using an atomic absorption spectrophotometer to determine the concentrations of As, Cu, Fe, Cd, Pb, and Ni. The pH and conductivity of the dust were also analyzed using a glass electrode. The mean concentrations (μg/g) of heavy metals in the dust ranged from 0.337 to 6.34 for As, 10.60–55.39 for Cu, 542.17–1453.45 for Fe, 0.193–1.026 for Cd, 11.82–52.56 for Pb, and 10.19–29.27 for Ni in different seasons. Similarly, the concentrations of heavy metals in the leaf samples ranged from 0.031 to 1.70 for As, 6.90–13.19 for Cu, 263.09–576.16 for Fe, 0.299–1.33 for Cd, 0.019–17.82 for Pb, and 2.09–7.015 for Ni in different seasons. The correlation between heavy metal concentrations in different seasons was examined using Pearson's and Spearman's correlation methods. To compare the bioaccumulation ability, bio-concentration factors (BCF), comprehensive bio-concentration index (CBCI), and metal accumulation index (MAI) were calculated. The Conocarpus erectus MAI was consistent across different locations and seasons (24.49 ± 0.149). Based on CBCI, the bioaccumulation capacity of heavy metals they were ranged from 6.57 to 12.83 in the dry season and from 5.84 to 10.24 in the wet season. These findings provide valuable insights into the distribution and accumulation of heavy metals in roadside dust and plant leaves, highlighting the potential of Conocarpus erectus as a bio-accumulator for heavy metal pollution in urban environments. The results can be utilized to develop appropriate strategies for environmental management and pollution control in areas affected by vehicular pollution.

Particle number, mass, and surface area concentrations inside an underground metalliferous mine in Kazakhstan

Considerable scientific evidence shows that inhalation of diesel exhaust particles is associated with a wide range of adverse health effects. This study examined the concentrations of diesel particles in five stations of the operational phases of an underground mine in Kazakhstan. Real-time monitoring of particulate number concentration (PNC), lung deposited surface area (LDSA) concentrations, PM1, PM2.5, and PM10 concentrations in the mining operational area, and the breathing zone of the loader driver inside the loader cabin was conducted. The results showed that the highest average PNC and LDSA concentrations were 7 × 105 cm−3 and 4 × 103 μm2 cm−3, respectively, and most of the particles were in the sub-100 nm range. The concentrations level in the loader cabin area (LA), and operational area (OA) of mine was similar with respect to PM1 and PM2.5 as a result of the homogenous distribution of the PM inside the mine's operational phase. The major source of the PM1 and PM2.5 was the diesel engine, while the low LA/OA ratio for PM10 in this study suggested the source of the coarse particles was dust resuspension around the loader cabin.

Size-segregated source identification of water-soluble and water-insoluble metals and trace elements of coarse and fine PM in central Los Angeles

In this study, the water-solubility and sources of metals and trace elements in both fine and coarse particulate matter (PM) were investigated in Central Los Angeles. Sampling was performed in the winter, spring, and summer of 2022 at the Particle Instrumentation Unit (PIU) of the University of Southern California located in the proximity of I-110 freeway. Both fine and coarse PM samples were collected using Personal Cascade Impactors (PCIS) and chemically analyzed to determine their water-soluble and water-insoluble metal content. Principal Component Analysis (PCA) and Multiple Linear Regression (MLR) were used to determine the sources of soluble and insoluble metals and obtain their contributions to total metal concentration. Our results indicate that the water-solubility of most of the metals is higher in the fine size fraction compared to the coarse fraction. Seasonal variations in the water solubility of selected metals for both coarse and fine fractions were observed, with higher water-soluble metal concentrations in summer for several species (e.g., Fe, S, Pb, Cu, La, Ni, and Al), possibly due to higher photochemical processing, while in winter, almost all species exhibited higher insoluble fraction concentrations. The PCA and MLR analyses results showed that tire and brake wear was the most significant contributor to the total metals for both fine soluble and insoluble portions, accounting for 35% and 75% of the total metals, respectively. Combustion sources also contributed substantially to water-soluble metals for fine and coarse size ranges, representing 40% and 32% of the total metal mass, respectively. In addition, mineral dust and soil and re-suspended dust were identified as the highest contributors to coarse metals. The MLR analysis also revealed that secondary aerosols contributed 11% to the fine water-soluble metals. Our results suggest that non-tailpipe emissions significantly contribute to both coarse and fine PM metals in the Central Los Angeles region.

Spatial distributions of PM10-bound metal elements in the central part of western Taiwan and their potential emission sources and the carcinogenic health risks.

This study aimed to investigate the spatial distribution of metal elements in PM10 and their potential sources and associated health risks over a period of two years in eight locations in the central part of western Taiwan. The study revealed that the mass concentration of PM10 and the total mass concentration of 20 metal elements in PM10 were 39.0 μg m-3 and 4.74 μg m-3, respectively, with total metal elements accounting for approximately 13.0% of PM10. Of the total metal elements, 95.6% were crustal elements (Al, Ca, Fe, K, Mg, and Na), with trace elements (As, Ba, Cd, Cr, Co, Cu, Ga, Mn, Ni, Pb, Sb, Se, V, and Zn) contributing only 4.4%. Spatially, the inland areas exhibited higher PM10 concentrations due to lee-side topography and low wind speeds. In contrast, the coastal regions exhibited higher total metal concentrations because of the dominance of crustal elements from sea salt and crustal soil. Four primary sources of metal elements in PM10 were identified as sea salt (58%), re-suspended dust (32%), vehicle emissions and waste incineration (8%), and industrial emissions and power plants (2%). The positive matrix factorization (PMF) analysis results indicated that natural sources like sea salt and road dust contributed up to 90% of the total metal elements in PM10, while only 10% was attributed to human activities. The excess cancer risks (ECRs) associated with As, Co, and Cr(VI) were greater than 1 × 10-6, and the total ECR was 6.42 × 10-5. Although only 10% of total metal elements in PM10 came from human activities, they contributed to 82% of the total ECR.

Heavy vehicles’ non-exhaust exhibits competitive contribution to PM2.5 compared with exhaust in port and nearby areas

Heavy port transportation networks are increasingly considered as significant contributors of PM2.5 pollution compared to vessels in recent decades. In addition, evidence points to the non-exhaust emission of port traffic as the real driver. This study linked PM2.5 concentrations to varied locations and traffic fleet characteristics in port area through filter sampling. The coupled emission ratio-positive matrix factorisation (ER-PMF) method resolves source factors by avoiding direct overlap from collinear sources. In the port central and entrance areas, freight delivery activity emissions including vehicle exhaust and non-exhaust particles, as well as induced road dust resuspension, accounted for nearly half of the total contribution (42.5%–49.9%). In particular, the contribution of non-exhaust from denser traffic with high proportion of trucks was competitive and equivalent to 52.3% of that from exhaust. Backward trajectory statistical models further interpreted the notably larger-scale coverage of non-exhaust emissions in the port's central area. The distribution of PM2.5 were interpolated within the scope of the port and nearby urban areas, displaying the potential contribution of non-exhaust within 1.15 μg/m3–4.68 μg/m3, slightly higher than the urban detections reported nearby. This study may provide useful insights into the increasing percentage of non-exhaust from trucks in ports and nearby urban areas and facilitate supplementary data collection on Euro-VII type-approval limit settings.

Using a Gaussian model to estimate the level of particle matter concentration on paved and unpaved roads in urban environment: A case study

Introduction: In both developed and developing countries, re-suspension of dust particles along the road owing to tire and brake wear is the most common source of Particulate Matters (PM) pollution in metropolitan areas. This study in Douala analyses the effects of paved and unpaved roads on particle matters concentration thresholds in urban environments.&#x0D; Materials and methods: The United States Environmental Protection Agency (US EPA)'s model AP-42 equations were used to calculate the amount of particle matter emissions on the roads. Between 6 am and 8 pm, a traffic analysis using information from the city of Douala was conducted. The busiest times for traffic were from 8 to 9 a.m. and 6 to 7 p.m. We applied a two-dimensional Gaussian model to determine the particle concentration. Two different scenarios were taken into account: Compared to Scenario 2 (S2), Scenario 1 (S1) represents an unpaved road. The PM10 and PM2.5 types of particles were the main topics of interest.&#x0D; Results: We obtained for S , around 917.70 µg/m3 and 559.00 µg/m3 respectively for PM and PM . We got roughly 170.00 µg/m3 and 103.90 10 2.5 µg/m3 for S , respectively for the two particles. The amount of silt deposited on the road, the kind of road (paved or unpaved), the number, and the types of vehicles moving all influence the emission of road dust re-suspension. Regardless of particle size, these pollution levels are beyond World Health Organization (WHO) recommended norms.&#x0D; Conclusion: This study offers important information on Douala's pollution levels, which can be a significant cause of disease in the area and should be considered.

Modeling atmospheric microplastic cycle by GEOS-Chem: An optimized estimation by a global dataset suggests likely 50 times lower ocean emissions

Modeling atmospheric microplastic cycle by GEOS-Chem: An optimized estimation by a global dataset suggests likely 50 times lower ocean emissions