Size-segregated Particulate Matter Samples Research Articles

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.

Sources, chemical components, and toxicological responses of size segregated urban air PM samples in high air pollution season in Guangzhou, China

The sources, sizes, components, and toxicological responses of particulate matter (PM) have demonstrated remarkable spatiotemporal variability. However, associations between components, sources, and toxicological effects in different-sized PM remain unclear. The purposes of this study were to 1) determine the sources of PM chemical components, 2) investigate the associations between components and toxicology of PM from Guangzhou high air pollution season. We collected size-segregated PM samples (PM10–2.5, PM2.5–1, PM1–0.2, PM0.2) from December 2017 to March 2018 in Guangzhou. PM sources and components were analyzed. RAW264.7 mouse macrophages were treated with PM samples for 24 h followed by measurements of toxicological responses. The concentrations of PM10–2.5 and PM1–0.2 were relatively high in all samples. Water-soluble ions and PAHs were more abundant in smaller-diameter PM, while metallic elements were more enriched in larger-diameter PM. Traffic exhaust, soil dust, and biomass burning/petrochemical were the most important sources of PAHs, metals and ions, respectively. The main contributions to PM were soil dust, coal combustion, and biomass burning/petrochemical. Exposure to PM10–2.5 induced the most significant reduction of cell mitochondrial activity, oxidative stress and inflammatory response, whereas DNA damage, an increase of Sub G1/G0 population, and impaired cell membrane integrity were most evident with PM1–0.2 exposure. There were moderate or strong correlations between most single chemicals and almost all toxicological endpoints as well as between various toxicological outcomes. Our findings highlight those various size-segregated PM-induced toxicological effects in cells, and identify chemical components and sources of PM that play the key role in adverse intracellular responses. Although fine and ultrafine PM have attracted much attention, the inflammatory damage caused by coarse PM cannot be ignored.

Winter and spring variation in sources, chemical components and toxicological responses of urban air particulate matter samples in Guangzhou, China

The sources and chemical components of urban air particles exhibit seasonal variations that may affect their hazardousness to human health. Our aims were to investigate winter and spring variation in particulate matter (PM) sources, components and toxicological responses of different PM size fractions from samples collected in Guangzhou, China. Four size-segregated PM samples (PM10–2.5, PM2.5–1, PM1–0.2, and PM0.2) were collected separately during winter (December 2017 and January 2018) and spring (March 2018). All PM samples were analyzed for chemical components and characterized by source. RAW 264.7 macrophages were exposed to four doses of PM samples for 24 h. Cytotoxicity, oxidation, cell cycle, genotoxicity and inflammatory parameters were tested. PM concentrations were higher in the winter samples and caused more severe cytotoxicity and oxidative damage than to PM in the spring samples. PM in winter and spring led to increases in cell cycle and genotoxicity. The trends of size-segregated PM components were consistent in winter and spring samples. Metallic elements and PAHs were found in the largest concentrations in winter PM, but ions were found in the largest concentrations in spring PM. metallic elements, PAHs and ions in size-segregated PM samples were associated with most toxicological endpoints. Soil dust and biomass burning were the main sources of PM in winter, whereas traffic exhaust and biomass burning was the main source with of spring PM. Our results suggest that the composition of PM samples from Guangzhou differed during winter and spring, which led to strong variations in toxicological responses. The results demonstrate the importance of examining a different particle sizes, compositions and sources across different seasons, for human risk assessment.

Personal inhalation exposure to manganese and other trace metals in an environmentally exposed population: Bioaccessibility in size-segregated particulate matter samples

Exposure to environmental airborne manganese (Mn) can lead to neurotoxic disorders and cognitive deficits. The degree of exposure can be assessed by personal sampling of particulate matter (PM) or through biomarkers of exposure. The aim of this work was to characterise the personal exposure to airborne Mn and other trace metals by measuring their bioaccessibility in PM filters taken from personal samplers in an environmentally exposed adult population living in the vicinity of a ferromanganese alloy plant in Santander Bay (northern Spain). Concentrations of bioaccessible and non-bioaccessible Mn and other metals associated with coarse (PM10-2.5) and fine (PM2.5) modes were quantified from 24 h personal samplers in 130 participants divided into two groups according to their Mn exposure: highly (n = 65) and moderately (n = 65) exposed. Gastric fluid and artificial lysosomal fluid (ALF) were used in the bioaccessibility tests as surrogate agents for the body fluids that can come into contact with coarse and fine particles, respectively. The mean air Mn levels in PM10-2.5 and PM2.5 were 127.2 and 126.2 ng/m3, respectively, in the highly exposed group, and 18.6 and 31.7 ng/m3 in the moderately exposed group. The bioaccessibility (%) of Mn in gastric fluid and ALF was also found to be greater in the highly exposed group. The results indicate that people living near Mn alloy plants have an increased potential health risk for Mn exposure due to higher total air Mn concentrations and bioaccessibility.

Study on the Characteristics of Size-Segregated Particulate Water-Soluble Inorganic Ions and Potentially Toxic Metals during Wintertime in a High Population Residential Area in Beijing, China

Airborne particulate matter (PM) pollution often occurs in the wintertime in northern China, posing a potential threat to human health. To date, there are limited studies about the metals and inorganic ions to link source apportionments and health risk assessments in the different size-segregated PM samples. In this study, our samples were collected by a high-volume air sampler from 26 December 2018 to 11 January 2019 in a high population residential area (Beijing). Water-soluble inorganic ions, metal elements in the different size-segregated PM samples were determined for health risk assessments by inhalation of PM. During the sampling period in Beijing, the average concentrations of PM1.1 and PM1.1–2.0 were 39.67 ± 10.66 μg m−3 and 32.25 ± 6.78 μg m−3. Distinct distribution profiles characterized the different elements. The markers of coal combustion Pb, As, and Se had >52% of their mass concentration in PM1.1. The average mass ratios of (NO3− + NO2−)/SO42−, Cl−/Na+, Cl−/K+, and Cl−/(NO3− + NO2−) were 1.68, 6.58, 6.18, and 0.57, which showed that coal combustion and vehicle emissions were the main anthropogenic sources of PM in Beijing in winter. PM1.1 was the major contributor of Pb, Cd, and As for carcinogenic risks (CR) and hazard quotient (HQ). It was indicated that PM1.1 is more harmful than coarse PM. The toxic elements of Cr (VI) (1.12 × 10−6), V (0.69 × 10−6), and As (0.41 × 10−6) caused higher CR for children than Ni, Cd, Co, and Pb. Meanwhile, Pb (35.30 × 10−6) and Ni (21.07 × 10−6) caused higher CR for adults than As, Cr (VI), V, Co, and Cd, especially PM1.1. This study provides detailed composition data and the first report on human health in a high population residential area in Beijing.

Exploring the oxidative potential and respiratory deposition of size-segregated particulate matter at an urban site

According to the current understanding, the adverse health effects of particulate matter (PM) are produced by oxidative stress processes. Hence, the oxidative potential (OP) can be used as an exposure metric for more accurate approaches to the health response to ambient PM. This work explores the relationship between respiratory deposition of size-segregated PM and OP in the city of Santiago, Chile. Size-segregated PM samples were collected at an urban site using a Micro-Orifice Uniform Deposit Impactor (MOUDI) sampler. Dithiothreitol (DTT) loss rates were measured in aqueous PM extracts to estimate the OP for each sample. Size-segregated OP showed a bi-modal distribution with a maximum centered in the accumulation mode (0.18–3.2 μm) and other in the coarse mode (3.2–18 μm). The magnitude of the OP estimated in the accumulation mode was 2.9 ± 0.8 and 2.3 ± 0.6 times the magnitude of the OP estimated in the coarse and quasi-ultrafine mode, respectively. Respiratory deposition calculations indicated that PM3.2 (with diameter less than 3.2 μm) dominated the OP lung deposition with contributions ranging from 65 to 94% in different areas of the human respiratory tract. This was due to the deposition efficiency and greater surface area of these fractions that allowed more efficient adsorption of active redox chemical species. These results may account for the greater negative impact on the lung health of the fine fractions of PM. The characterization of the OP respiratory deposition related to different fractions of PM, can result in adequate metrics to evaluate human exposure to PM and its possible health impacts.

Spatial mapping and size distribution of oxidative potential of particulate matter released by spatially disaggregated sources

The ability of particulate matter (PM) to induce oxidative stress is frequently estimated by acellular oxidative potential (OP) assays, such as ascorbic acid (AA) and 1,4-dithiothreitol (DTT), used as proxy of reactive oxygen species (ROS) generation in biological systems, and particle-bound ROS measurement, such as 2′,7′-dichlorodihydrofluorescein (DCFH) assay. In this study, we evaluated the spatial and size distribution of OP results obtained by three OP assays (OPAA, OPDCFH and OPDTT), to qualitative identify the relative relevance of single source contributions in building up OP values and to map the PM potential to induce oxidative stress in living organisms. To this aim, AA, DCFH and DTT assays were applied to size-segregated PM samples, collected by low-pressure cascade impactors, and to PM10 samples collected at 23 different sampling sites (about 1 km between each other) in Terni, an urban and industrial hot-spot of Central Italy, by using recently developed high spatial resolution samplers of PM, which worked in parallel during three monitoring periods (February, April and December 2017). The sampling sites were chosen for representing the main spatially disaggregated sources of PM (vehicular traffic, rail network, domestic heating, power plant for waste treatment, steel plant) present in the study area. The obtained results clearly showed a very different sensitivity of the three assays toward each local PM source. OPAA was particularly sensitive toward coarse particles released from the railway, OPDCFH was sensible to fine particles released from the steel plant and domestic biomass heating, and OPDTT was quite selectively sensitive toward the fine fraction of PM released by industrial and biomass burning sources.

Episode-Based Analysis of Size-Resolved Carbonaceous Aerosol Compositions in Wintertime of Xinxiang: Implication for the Haze Formation Processes in Central China

To provide a comprehensive understanding of carbonaceous aerosol and its role in the haze formation in the Central Plains Urban Agglomeration of China, size-segregated particulate matter samples (PM1, PM2.5 and PM10) were continually collected from 20 December 2017, to 17 January 2018, in Xinxiang, the third largest city of Henan province. The results showed that the mean mass concentrations of PM1, PM2.5 and PM10 were 63.20, 119.63 and 211.95 μg·m−3, respectively, and the organic carbon (OC) and elemental carbon (EC) were 11.37 (5.87), 19.24 (7.36), and 27.04 (10.27) μg·m−3, respectively. Four pollution episodes that were categorized by short evolution patterns (PE1 and PE3) and long evolution patterns (PE2 and PE4) were observed. Meteorological condition was attributed to haze episodes evolution pattern. Carbonaceous components contributed to PE1 and PE2 under drier condition through transportation and local combustion emission, while they were not main species in PE3 and PE4 for haze explosive growth under suitable RH, whatever for the short or long evolution pattern. The atmospheric self-cleaning processes were analyzed by a case study, which showed the wet scavenging effectively reduced the coarse particles with a removal rate of 73%, while it was not for the carbonaceous components in fine particles that is hydrophobic in nature. These results highlight that local primary emissions such as biomass combustion were the important sources for haze formation in Central China, especially in dry conditions.

Specific sources of health risks caused by size-resolved PM-bound metals in a typical coal-burning city of northern China during the winter haze event

High particulate matter (PM) pollution frequently occurs in winter over northern China , resulting in threats to human health. To date, there are limited studies to link source apportionments and health risk assessments in the different size-resolved PM samples during high PM events. In this study, size-segregated PM samples were collected in Linfen, a typical coal-burning city, in northern China during a wintertime haze pollution. In addition to water-soluble ions and carbon contents, metallic elements in the different size-segregated PM samples were also determined for health risk assessments by inhalation of PM. During the sampling period, the average concentration of PM10 was 274 ± 57 μg m−3 with a major fraction (73%) of organic material and secondary-related aerosols, and an insignificant portion of trace elements (TEs, ~ 3%). The size distribution showed that As and Se, markers of coal combustion, exhibited a mono-modal distribution with a major peak at 0.4–0.7 μm and the others mostly possessed mono−/bi-modal patterns with a major peak at 3.3–5.8 μm. The cancer risk (CR) resulted from PM10 metals by inhalation was estimated to be 2.91 × 10−5 for children and 7.75 × 10−5 for adults while non-cancer risk (NCR) was 2.10 for children and 0.70 for adults. Chromium (Cr) was the dominant species (~89%) of cancer risk in PM10. Road dust was a major fraction (~65%) to total metals in coarse PM (dp > 3.3 μm) whereas coal combustion was a dominant source (~55%) in submicron (dp < 1.1 μm) PM metals. However, traffic emissions (40%) and coal combustion (36%) were the dominant sources of CR since both emissions contributed major fractions (74%) to Cr, especially in submicron PM which exhibited high deposition efficiency of TEs into respiratory tracts, resulting in high CR in Linfen City.

Spatial distribution of levoglucosan and alternative biomass burning tracers in atmospheric aerosols, in an urban and industrial hot-spot of Central Italy

Domestic biomass heating and wildfires strongly affect particulate matter (PM) concentration in the atmosphere. The individuation of alternative chemical tracers may provide a valuable tool to apportion different possible contributions to biomass burning. In this study, we used a new experimental procedure, based on high spatial resolution analyses of PM10, to assess the spatial distribution of levoglucosan (LVG) and evaluate the possible use of alternative biomass burning tracers in the Terni basin, a wide urban and industrial hot-spot of Central Italy, which includes several spatially disaggregated sources. Spatially-resolved chemical characterization of PM10 was obtained through the use of innovative samplers working in parallel in a dense monitoring network (20 sampling sites, about 1 km between each other), during wintertime. PM10 samples were analyzed for LVG, water-soluble organic carbon (WSOC) and water-soluble and insoluble fraction of 33 elements. Principal component analysis (PCA) on the obtained spatially-resolved data allowed us to identify biomass burning tracers across the polluted study area. Analyses of size-segregated PM samples showed the presence of LVG, and water-soluble Cd, Cs, K, Rb and Tl in particles with size fraction smaller than 1 μm, confirming them as tracers of combustion processes (mainly related to biomass burning). Pearson correlation coefficients demonstrated that concentrations of WSOC and water-soluble Cd, Cs, K, Rb and Tl were well correlated with the spatial variability of LVG concentration. The combined use of spatially and dimensionally resolved data was found to be particularly advantageous for the identification of alternative source tracers, which were used to reliably trace the main local biomass burning sources in the study area.

Oxidative potential of size-segregated PM in an urban and an industrial area of Italy

This work is focused on the relationship between the size distribution of some source tracers of atmospheric particulate matter (PM) and the oxidative potential (OP) of each PM size fraction. Size-segregated PM samples were collected by a multistage impactor (cut-sizes: 0.18, 0.32, 0.56, 1.0, 1.8, 3.2, 5.6, 10 and 18 μm) in two geographical areas of Italy (Rome and Ferrara), characterized by different strength of the main PM sources. The samples were analysed by three different acellular OP methods: dithiothreitol (DTT), dichlorofluorescein diacetate (DCFH) and ascorbate (AA) assay.Elemental (Li, Be, B, Na, Mg, Al, Si, P, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Zr, Nb, Mo, Cd, Sn, Sb, Te, Cs, Ba, La, Ce, W, Tl, Pb, Bi and U) and ionic (Cl−, NO3−, SO42−, Na+, NH4+, K+, Mg2+, Ca2+) composition of the same samples was also determined, in order to trace the contribution of the main PM sources. The size distribution of the OP values was compared to the size distribution of some PM source tracers, with the aim of identifying the PM sources that mostly influence the oxidative properties of atmospheric dust.AA assay resulted to be more sensitive towards coarse particles and OPAA showed a size distribution very similar to that of brake dust tracers. DTT and DCFH assays resulted instead more sensitive towards fine particles. OPDTT and OPDCFH values were comparable at the two sites; sources whose strength was very different in the two monitored areas (secondary contribution and, to a less extent, industrial sources) did not then contribute significantly to the measured OP values. The dimensional behaviour of OPDTT and OPDCFH was consistent with the contribution of biomass burning.

Heavy metals in industrially emitted particulate matter in Ile-Ife, Nigeria

Iron and steel smelting facilities generate large quantities of airborne particulate matter (PM) through their various activities and production processes. The resulting PM that contains a variety of heavy metals has potentially detrimental impacts on human health and the environment. This study was conducted to assess the potential health effects of the pollution from the heavy metals in the airborne PM sampled in the vicinity of secondary smelting operations in Ile-Ife, Nigeria. X-ray fluorescence (XRF) was used to determine the elemental concentration of Pb, Cr, Cd, Zn, Mn, As, Fe, Cu, and Ni in the size-segregated PM samples. Pollution Indices (PI) consisting of Contamination Factor (CF), Degree of Contamination (DC) and Pollution Index Load (PLI) and Target Hazard Quotient (THQ) were employed to assess the pollution risk associated with the heavy metals in the PM. CF, DC and PLI values were 3< CF <6, >32 and >1, respectively for the three sites, indicating deterioration of the ambient air quality in the vicinity of the smelter. The heavy metals in the airborne PM pose a severe health risk to people living in vicinity of the facility and to its workers. The diminished air quality with the associated health risks directly depends on the industrial emissions from steel production and control measures are recommended to mitigate the likely risks.

Day and night variation in chemical composition and toxicological responses of size segregated urban air PM samples in a high air pollution situation

Urban air particulate pollution is a known cause for adverse human health effects worldwide. China has encountered air quality problems in recent years due to rapid industrialization. Toxicological effects induced by particulate air pollution vary with particle sizes and season. However, it is not known how distinctively different photochemical activity and different emission sources during the day and the night affect the chemical composition of the PM size ranges and subsequently how it is reflected to the toxicological properties of the PM exposures. The particulate matter (PM) samples were collected in four different size ranges (PM10-2.5; PM2.5-1; PM1-0.2 and PM0.2) with a high volume cascade impactor. The PM samples were extracted with methanol, dried and thereafter used in the chemical and toxicological analyses. RAW264.7 macrophages were exposed to the particulate samples in four different doses for 24 h. Cytotoxicity, inflammatory parameters, cell cycle and genotoxicity were measured after exposure of the cells to particulate samples. Particles were characterized for their chemical composition, including ions, element and PAH compounds, and transmission electron microscopy (TEM) was used to take images of the PM samples. Chemical composition and the induced toxicological responses of the size segregated PM samples showed considerable size dependent differences as well as day to night variation. The PM10-2.5 and the PM0.2 samples had the highest inflammatory potency among the size ranges. Instead, almost all the PM samples were equally cytotoxic and only minor differences were seen in genotoxicity and cell cycle effects. Overall, the PM0.2 samples had the highest toxic potential among the different size ranges in many parameters. PAH compounds in the samples and were generally more abundant during the night than the day, indicating possible photo-oxidation of the PAH compounds due to solar radiation. This was reflected to different toxicity in the PM samples. Some of the day to night difference may have been caused also by differing wind directions transporting air masses from different emission sources during the day and the night. The present findings indicate the important role of the local particle sources and atmospheric processes on the health related toxicological properties of the PM. The varying toxicological responses evoked by the PM samples showed the importance of examining various particle sizes. Especially the detected considerable toxicological activity by PM0.2 size range suggests they're attributable to combustion sources, new particle formation and atmospheric processes.

Allergic Airway Inflammation is Differentially Exacerbated by Daytime and Nighttime Ultrafine and Submicron Fine Ambient Particles: Heme Oxygenase-1 as an Indicator of PM-Mediated Allergic Inflammation

Ambient particulate matter (PM) originates from a range of sources and differs in composition with respect to season, time of day, and particle size. In this study, ambient PM samples in the ultrafine and submicrometer fine range were tested for the potential to exacerbate a murine model of allergic airway inflammation when exposure occurs solely during allergic sensitization, but not during subsequent allergen challenge. Temporally resolved and size-segregated PM samples were used to understand how summer or winter, day or night, and ambient ultrafine and submicrometer fine particle size influence PM’s ability to exacerbate allergic inflammation. PM was collected in urban Fresno, CA. BALB/c mice were exposed to PM and house dust mite allergen (HDM) via intranasal aspiration on d 1, 3, and 5. HDM challenge occurred on d 12–14, with inflammation assessed 24 h following final challenge. While season or particle size did not predict allergic inflammation, daytime ultrafine and submicrometer fine particles significantly increased total cellular inflammation, specifically lymphocyte and eosinophil infiltration, compared to allergic controls. Further studies examined PM-mediated changes within the lung during the period where allergen sensitization occurred by measuring direct effects of PM on pulmonary oxidative stress and inflammation. Pulmonary levels of heme oxygenase-1 (HO-1), a biomarker of oxidative stress, but not cellular inflammation, demonstrated a remarkable correlation with the degree of allergic inflammation in animals sensitized to allergen and PM concomitantly, suggesting acute PM-mediated HO-1 levels may serve as a predictive indicator of a particle’s ability to exacerbate allergic airway inflammation.

Size distribution and seasonal variation of size-segregated particulate matter in the ambient air of Raipur city, India

In this study, size-segregated particulate matter samples were collected in Raipur, India from July 2009 to June 2010 by using eight-stage cascade impactor sampler. The annual average concentrations and associated standard deviation of PM10, PM2.5–10, PM2.5, and PM1 were 270.5 ± 105.5, 119.6 ± 44.6, 150.9 ± 78.6, and 72.5 ± 39.0 μg/m3, respectively. The PM10 and PM2.5 levels at Raipur, India were well above the annual National Ambient Air Quality Standards of India of 60 and 40 μg/m3 for PM10 and PM2.5, respectively. Particulate matter concentrations in winter were higher than those in summer and monsoon. Increased energy use and dry atmospheric conditions contributed to increasing particulate matter concentrations in winter, while increased rainfall precipitation contributed to decreasing particulate matter levels in the monsoon. Spearman correlation analysis between PM10 and PM2.5 revealed high correlation coefficients (r = 0.85), implying that PM10 and PM2.5 may have the same source of regions or that they are influenced by the same local conditions. The highest monthly values of air quality index occur in winter and spring, while they are reduced in summer and monsoon. The analysis showed that 25.0% of the days was unhealthy for sensitive people, 47.4% was unhealthy or very unhealthy, while 4.1% was considered as hazardous. A comparison of the exceedance factors indicated that PM10 and PM2.5 was the most significant polluting agent, causing maximum deterioration in the ambient air quality of Raipur, India.