Chemical Composition Of PM2 Research Articles

Seasonal variability of trace elements in fine particulate matter (PM2.5) in a coastal city of northern Poland - profile analysis and source identification.

A large group of trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V, and Zn) was measured for the first time in 226 air samples collected at a coastal monitoring station in Gdynia (northern Poland), in the period from January 12th to August 30th, 2019. The 24 h measurements included fine particle (PM2.5) concentrations, meteorological parameters and backward air mass trajectory analyses. The monthly mean PM2.5 mass concentration ranged from 17.3 μg m-3 to 55.0 μg m-3, and the peak value of 167 μg m-3 was found in February. Overall, considerable differences in the trace element concentrations were observed. However, their seasonal distributions were not similar. In particular, elements such as Cd, Cu, Mo, Ni, V and Zn showed significantly higher concentrations (p < 0.05) in winter compared to spring or summer. The winter peak of trace element concentrations in PM2.5 indicated that local power plants and fossil fuel/coal combustion in the residential sector were the major anthropogenic sources of air pollutants. Based on multivariate analysis (PCA) of the standardized database (14 elements and PM2.5), a significant contribution of different sources and processes was identified, i.e. local traffic emission, local/regional coal/oil burning in power plants and domestic heating units, industrial activities, petrochemical industry and maritime transport. The Cu/Fe ratios revealed that both local traffic and brake-wear emission considerably influenced the chemical composition of PM2.5. In addition, the results of the V/Ni ratio suggested local mixed industrial sources (petrochemical refinery and industrial plants) with possible contributions from the port area and shipping activities to the total PM2.5 loadings. The local ship emission was more pronounced during the summer period.

Spatio-temporal distribution and chemical composition of PM2.5 in Changsha, China

The rapid economic development and significant expansion of urban agglomerations in China have resulted in issues associated with haze and photochemical smog. Central China, a transitional zone connecting the eastern coast and western interior, suffers from increasing atmospheric pollution. This study performed a spatio-temporal analysis of fine particulate matter (PM2.5) pollution in Changsha, a provincial capital located in central China. Samples of PM2.5 were collected at five different functional areas from September 2013 to August 2014. The PM2.5 concentration at the five sampling sites was the highest in winter and the lowest in summer, with an average annual PM2.5 concentration of 105.2 ± 11.0 μg/m3. On average, residential sites had the highest concentrations of PM2.5 while suburban sites had the lowest. We found that inorganic ionic species were dominant (~48%), organic species occupied approximately 25%, whereas EC (~3.7%) contributed insignificantly to the total PM2.5 mass. Ion balance calculations show that the PM2.5 samples at all sites were acidic, with increased acidity in spring and summer compared with autumn and winter. Air quality in Changsha is controlled by four major air masses: (1) Wuhan and the surrounding urban clusters, (2) the Changsha-Zhuzhou-Xiangtan urban agglomeration and the surrounding cities, and (3) southern and (4) eastern directions. The north–south transport channel is the most significant air mass trajectory in Changsha and has a significant impact on PM2.5 pollution.

Correlation of Oxidative Potential with Ecotoxicological and Cytotoxicological Potential of PM10 at an Urban Background Site in Italy

Exposure to atmospheric particulate matter (PM) has detrimental effects on health, but specific mechanisms of toxicity are still not fully understood. In recent years, there has been a growing evidence that oxidative stress is an important mechanism of toxicity; however, when acellular oxidative potential (OP) data are correlated with the outcomes of in vitro (or in vivo) toxicological tests there are contrasting results. In this work, an analysis of PM10 health effect indicators was done, using the acellular Dithiotreitol (DTT) assay to retrieve OPDTT, the Microtox® test on Vibrio fischeri bacterium to assess the ecotoxicological potential, and the in vitro MTT assay on the human cell line A549 to estimate the cytotoxicological potential. The objective was to evaluate the correlation among acellular OPDTT and the results from toxicological and ecotoxicological bioassays and how these health-related indicators are correlated with atmospheric PM10 concentrations collected at an urban background site in Southern Italy. Results indicated that both bioassays showed time-dependent and dose-dependent outcomes. Some samples presented significant ecotoxic and cytotoxic response and the correlation with PM10 concentration was limited suggesting that these health endpoints depend on PM10 chemical composition and not only on exposure concentrations. OPDTT showed a statistically significant correlation with PM10 concentrations. MTT and Microtox outcomes were not correlated suggesting that the two toxicological indicators are sensitive to different physical-chemical properties of PM10. Intrinsic oxidative potential OPDTTM (DTT activity normalised with PM10 mass) was correlated with mortality observed with MTT test (normalized with PM10 mass); however, it was not correlated with Microtox outcomes.

Characteristics and source apportionment of PM2.5 on an island in Southeast China: Impact of sea-salt and monsoon

Abstract To study the combined effects of the East Asian monsoon and ocean emissions on wintertime and summertime PM2.5 in island cities, filter samples were collected simultaneously at four different functional sites. Based on the chemical compositions of PM2.5, and positive matrix factorization (PMF) model analysis, the pollution characteristics and sources were determined. Insignificant differences, and some correlation in PM2.5 reconstructed compositions were found among the sites (Pt-test > 0.05, P > .05), while significant differences, and no correlation, were found between winter and summer (PANOVA .05). There was more serious chloride depletion in summer (0.88 ± 0.05), caused by both significant Cl− depletion and Na+ enrichment, than in winter (0.18 ± 0.10). The concentrations of non-sea-salt-SO42− in winter were close to those in summer, but the sulfate oxidation ratio (SOR) in winter was much lower than that in summer. The results could be explained by the fact that sea-salt-SO42− has an important contribution to secondary inorganic aerosol on island cities. From both air trajectory clustering and PMF analysis, it was found that there was significant aerosol aging and regional transport in the island city during the East Asian monsoon, and that continental air masses control the variation of air pollution in winter, while sea breezes dominate the characteristics of PM2.5 in summer. This study helps to understand the characteristics and source mechanisms of PM2.5 pollution under complex meteorological conditions in island cities.

Emission factors and composition of PM2.5 from laboratory combustion of five Western Australian vegetation types

This study investigated the emission of PM10 and PM2.5 (particulates with diameters of less than 10 µm and 2.5 µm, respectively) and the chemical composition of PM2.5 from laboratory combustion of five Australian vegetation types (three grasslands, a woodland and a forest). A mix of plants representative of Banksia (woodland) and Jarrah (forest) and three types of grasses (Spinifex – Triodia basedowii; Kimberley grass – Sehima nervosum and Heteropogon contortus; and an invasive grass (Veldt) – Ehrharta calycina) were burnt in 9 combustion conditions comprised of 3 fuel moisture levels (dry, moist, wet) and 3 air flow rates (no, low and high flow). PM (particulate matter) samples were collected onto filters and measured using gravimetric analysis. PM2.5 was then extracted and analyzed for water-soluble metals and polycyclic aromatic hydrocarbons (PAH) concentrations. The largest proportion of PM10 (98%) from vegetation fires was PM2.5. Banksia yielded the highest PM2.5 emission factor (EF), followed by Jarrah and Spinifex. Veldt grass combustion generated significantly higher emissions of PM2.5 compared with the other two grass types. High moisture contents and flow rates resulted in larger emissions of PM2.5. A strong correlation (R2 = 0.84) was observed between the EF for PM2.5 and combustion efficiency, suggesting higher PM emission with lower combustion efficiencies. Potassium and sodium were the most abundant PM2.5-bound water soluble metals, accounting for more than 97% of the total mass of metals analyzed. PAHs were found in significant concentrations, including the carcinogenic benzo(a)pyrene. Pyrene and fluoranthene were the most abundant PAHs detected, accounting for nearly 40% mass of the total PAHs. Indeno(1,2,3-cd)pyrene and benzo(g,h,i)perylene ratio (IND/IND + BghiP) appeared to be produced in a diagnostic ratio that indicated that the PAHs were derived from vegetation fires rather than other sources of emissions. The EF for PM2.5 and its chemical composition (water-soluble metals and PAHs) were strongly influenced by the type of vegetation burned. The results presented in this study could be useful in predicting the risks of human health effects on firefighters and the public who may be exposed to regular bushfires in Australia.

Investigating the characteristics and source analyses of PM2.5 seasonal variations in Chengdu, Southwest China.

In 2015, comprehensive observations were carried out in Chengdu, Sichuan Province, China, to elucidate the seasonal variation characteristics of the concentrations, chemical compositions, and the sources of PM2.5 pollution. The meteorological parameters, gaseous pollutants and chemical compositions of PM2.5 were measured. The annual average concentration of PM2.5 in Chengdu was 67.44 ± 48.78 μg/m3. The highest seasonal PM2.5 mass concentration occurred in winter with an average of 103.04 ± 66.76 μg/m3, followed by spring, autumn, and summer, and the wind speed had an important impact on the diffusion of PM2.5. The seasonal variation characteristics of chemical components in PM2.5 were analysed. The contribution and chemical conversion ability of secondary aerosols increased with increasing of PM2.5 concentration. Source appointment of positive matrix factorization (PMF) shows that the main sources of PM2.5 were secondary aerosols, coal combustion, biomass burning, vehicle emissions, dust and industrial sources, which have more obvious seasonal differences than other sources, and secondary aerosols and coal combustion were the major sources. Conditional probability function (CPF) analysis showed that the local sources of high PM2.5 concentrations were mainly from the eastern and southeastern areas of Chengdu. Potential source contribution function (PSCF), concentration weighted trajectory (CWT) and backward trajectory cluster analyses indicated that the southern, southeast and eastern parts of the Sichuan Basin were the most likely potential sources of PM2.5, and the unique geographical and topographical factors in Chengdu play important roles in the transport and diffusion of pollutants in this region.

Review of PM Oxidative Potential Measured with Acellular Assays in Urban and Rural Sites across Italy

This work is an overview of the oxidative potential (OP) values up to date measured in Italy, with the aim to provide a picture of the spatial and seasonal variability of OP in the various geographical areas across Italy. The summarized works used the common acellular assays-based dithiothreitol (OPDTT), ascorbic acid (OPAA), glutathione (OPGSH), and 2′,7′-dichlorodfluorescein (OPDCFH) assays. The paper describes the association of OP responses with PM chemical composition, the sensitivity of various acellular OP assays to PM components and emission sources, and PM size distribution of the measured OP values. Our synthesis indicates that crustal and transition metals (e.g., Fe, Ni, Cu, Cr, Mn, Zn, and V), secondary ions and carbonaceous components (elemental carbon, EC, organic carbon, OC and water soluble carbon, WSOC) show significant correlations with OP across different urban and rural areas and size ranges. These chemical species are mainly associated with various PM sources, including residual/fuel oil combustion, traffic emissions, and secondary organic aerosol formation. Although the OP assays are sensitive to the same redox-active species, they differ in the association with PM chemical components. The DDT assay is mainly sensitive to the organic compounds that are mostly accumulated in the fine PM fraction, i.e., tracers of burning sources, and redox active organics associated with other markers of photochemical aging. In contrast, OPAA and OPGSH were mostly responsive to metals, mainly those related to non-exhaust traffic emissions (Cu, Zn, Cr, Fe, Ni, Mn, Sn, Cd, Pb), that are mainly accumulated in the coarse PM. Among the investigated sites, our synthesis shows larger OP values in Trentino region and the Po Valley, that may be explained by the high density of anthropogenic sources, and the orographic and meteorological characteristics, that favor the pollutants accumulation and aerosol photo-oxidative aging.

Temporal variation of suspended particles (TSP, PM10, and PM2.5) and chemical composition of PM10 in a site at the coast of the Gulf of Mexico

A study of temporal variations of particulate matter in different size fractions (TSP, PM10, PM2.5) was undertaken in the city of San Francisco de Campeche (SFC), in southeast Mexico, in the years 2014 and 2015 in order to assess the contribution of the chemical components. The samples were analyzed using X-ray fluorescence (XRF) and ion exchange chromatography (IC) for PM10. XRF identified the presence of Al, Si, P, S, K, Ca, Ti, Cr, Mn, Fe, Cu, and Zn. The results of a cluster analysis (CA) indicates a strong correlation of S and P in the three fractions due to agricultural land use and this may be related to the burning of biomass during the dry season. Also the CA also suggests that the elements Al, Si, K, Ca, Ti, Mn, and Fe can be associated with a geological origin. The results of the IC analysis show high levels of Na+, Cl−, and SO4−2 and the latter must be related to anthropogenic sources. The application of principal components analysis (PCA) suggests that Na+, Cl− and Mg+2 are associated with marine aerosols; NO3− and SO4−2 are from emissions related to fuel combustion due to increase in the number of motor vehicles in the city.

Differentiation of Particulate Matter Sources Based on the Chemical Composition of PM10 in Functional Urban Areas

Urban air quality is continuing to deteriorate. If we want to do something about this problem, we need to know the cause of the pollution. The big problem, not only in Europe, is the high concentrations of particulate matter (PM) in the urban environment. The origin of these particles can be different, including combustion, transport, industry, natural resources, etc. Particulate matter includes a large amount of the finest PM fractions, which can remain in the air for a long time, easily enter respiratory tracks, and damage human health. Particulate matter is also produced by the abrasion of different parts of roads and vehicle fleets and from resuspension road dust, which concerns matter with larger aerodynamic diameters. For this reason, we carried out a series of measurements at various measuring stations in Žilina, Slovakia, during different measuring seasons. The main objective was to find out the diversity of particulate matter sources in Žilina. The search for the particulate matter origin was carried out by particulate matter measurements, determination of the particulate matter fraction concentrations (PM10, PM2.5, and PM1), an investigation on the effect of secondary factors on the particulate matter concentrations, chemical analyses, and multivariate statistical analyses. Varied behavior of the particulate matter with respect to the measurement station and the measurement season was found. Differences in the concentrations of investigated chemical elements contained in the PM were found. Significant changes in the concentrations of particulate matter are caused not only by primary sources (e.g., road traffic in the city of Žilina), but mainly by the negative events (combination of air pollution sources and meteorological conditions). Maximum concentrations of particulate matter PM10 were measured during the winter season at the measuring station on Komenského Street: PM10 126.2 µg/m3, PM2.5 97.7 µg/m3, and PM1 90.4 µg/m3 were obtained using the gravimetric method. The coarse fraction PM2.5-10 was mainly represented by the chemical elements Mg, Al, Si, Ca, Cr, Fe, and Ba, and the fine fraction PM2.5 was represented by the chemical elements K, S, Cd, Pb, Ni, and Zn. Road transport as a dominant source of PM10 was identified from all measurements in the city of Žilina by using the multivariate statistical methods of principal component analysis (PCA) and factor analysis (FA).

Anthropogenic or non-anthropogenic particulate matter: Which one is more dangerous and how to differentiate between the effects?

The authors have observed that the function linking health outcomes with exposure to particulate-matter (PM) follows a biphasic pattern. It peaks around levels of PM10≤100 μg/m3, then weakens and rises again at PM10 levels in the range of hundreds. This could be due to a different nature of PM, the first peak reflecting a stronger anthropogenic and the second - weaker non-anthropogenic particles' effect. The current analysis is focused at the biphasic pattern on the association between PM levels with BG and asthma exacerbations. Pollutants were assessed by local monitoring stations and a satellitebased model. Local weekends/holidays were used to define nonanthropogenic levels of pollutants featured by lower Nitrogen Dioxide, the proxy for anthropogeneity. The association of PM10 with health outcomes within 24-48h lag was explored using spline functions of generalized additive models. Analysis of 546,420 BG tests (43,569 subjects) showed an almost linear association of PM10 with asthma with BG during the days with anthropogenic activity and no trend on other days. Analysis of asthmatic exacerbations within 1576 children showed no heterogeneity in association with PM10 by anthropogeneity levels, possibly indicating a mechanical impact on alveolar as the main trigger for exacerbations rather than PM10 chemical composition.

Concentrations and Adsorption Isotherms for Amphiphilic Surfactants in PM1 Aerosols from Different Regions of Europe.

Predicting the activation of submicrometer particles into cloud droplets in the atmosphere remains a challenge. The importance of surface tension, σ (mN m-1), in these processes has been evidenced by several works, but information on the "surfactants" lowering σ in actual atmospheric particles remains scarce. In this work, PM1 aerosols from urban, coastal, and remote regions of Europe (Lyon, France, Rogoznica, Croatia, and Pallas, Finland, respectively) were investigated and found to contain amphiphilic surfactants in concentrations up to 2.8 μg m-3 in the air and 1.3 M in the particle dry volume. In Pallas, correlations with the PM1 chemical composition showed that amphiphilic surfactants were present in the entire range of particle sizes, supporting recent works. This implied that they were present in hundreds to thousands of particles cm-3 and not only in a few large particles, as it has been hypothesized. Their adsorption isotherms and critical micelle concentration (CMC) were also determined. The low CMC obtained (3 × 10-5-9 × 10-3 M) implies that surface tension depression should be significant for all the particles containing these compounds, even at activation (growth factor ∼ 10). Amphiphilic surfactants are thus likely to enhance the CCN ability of submicrometer atmospheric particles.

The relationship between indoor and outdoor levels of PM10 and its chemical composition at schools in a coastal region in Spain

PM10 levels and its chemical composition were studied inside and outdoor of seven primary schools (3 in urban environment, 3 in industrial environment, 1 in rural environment) located in the Mediterranean coast in an area with an important industrial nucleus dedicated to the treatment of raw mineral materials. The main objective of this work is a comparison between these levels obtained inside and outside schools and also asses the influence of various natural and anthropogenic emission sources on particles concentrations found inside. The indoor airborne samples were collected using RespiCon TM. In the three outdoor sampling stations was used a minivol air sampler type 3.1 LVS of Derenda. PM10 Chemical composition was obtained by ICP-MS (elements) and ion chromatography The ratio I/O (indoor/outdoor) has been calculated taking into account only the samples taken in the same conditions. In all schools the ratio I/O for PM10 was greater than unity (between 1.3 and 7.8), indicating that existed significant indoor sources of these particles. In the three schools located in the industrial environment were collected PM10 samples inside and outside in non-teaching periods. Comparing the values of I/O when the classrooms were unoccupied with respect to the average value of these same schools when the classrooms are occupied, the behaviour is different depending on the location. On the other hand, a sample in an industrial school was obtained when some infrastructure works were being carried out outside of school. This caused a significant increase in the concentration of particles in the interior (I/O = 19.9). From the levels of As, Ni, Cd, Pb, Al, B, Zn, Mg, Sb, F−, ClO2-, NO3- and SO42- in PM10 inside and outside of each school, also the ratios I/O were calculated. These chemical ratios I/O were higher than unity in all cases and generally higher than those recorded in the case of PM10. Finally, Pearson correlation coefficients (r) between the elements and anions and the PM10, and between the different elements and anions were calculated for the purpose of establishing the existence of common emission sources.

Morphological characterization and chemical composition of PM2.5 and PM10 collected from four typical Chinese restaurants

AbstractIt is widely known that cooking contributes particulate matter (PM) to outdoor and indoor air. To research the morphology and chemical composition of PM10 and PM2.5 in cooking fumes, four C...

Climate impact on ambient PM2.5 elemental concentration in the United States: A trend analysis over the last 30 years

Weather impacts on the chemical composition of PM2.5 varies significantly over space and time given the diversity of particle components and the complex mechanisms governing particle formation and removal. In this study, we employed generalized additive models (GAMs) to estimate weather-associated changes in PM2.5 composition in the US during 1988–2017. We considered seven components of ambient PM2.5, which included elemental carbon (EC), organic carbon (OC), nitrate, sulfate, sodium, ammonium, and silicon. The impact of long-term weather changes on each PM2.5 component was defined in our study as “weather penalty”. During our study period, temperature increased in four regions, including the Industrial Midwest and Northeast during the warm and cold season; and Upper Midwest and West in the cold season. Wind speed decreased in the both seasons. Relative humidity increased in the warm season and decreased in the cold season. The weather changes between 1988 and 2017 were associated with most PM2.5 components during both warm and cold seasons. The direction and the magnitude of the weather penalty varied considerably over the space and season. In the warm season, our findings suggest a nationwide weather penalty for EC, OC, nitrate, sulfate, sodium, ammonium, and silicon of 0.04, 0.21, 0.04, 0.35, −0.01, 0.05, and 0.01 μg/m3, respectively. In the cold season, the estimated total penalty was 0.04, 0.21, 0.06, 0.04, −0.01, −0.02, and 0.02 μg/m3, respectively.

Reconstructed algorithm for scattering coefficient of ambient submicron particles

Ambient submicron particles (PM1) exert significant impacts on visibility degradation during severe pollution episodes of urban China. The U.S. IMPROVE algorithms are widely used for assessing the extinction effect of atmospheric aerosols, but only suitable for fine particulate matter. A proper algorithm for PM1 extinction estimation is lacking and becomes urgent, especially after the online measurement of PM1 species is routine by aerosol mass spectrometers. Here we conducted three-month in-situ measurements to explore mass scattering efficiencies (MSE) of PM1 major species at a supersite of eastern China. Results indicated that MSEs of ammonium sulfate and nitrate increase quickly and then keep stable with the mass accumulation, while those of organic matter keep at ∼5.5 m2/g but with a large vibration in the whole mass range. The algorithm for reconstructing PM1 dry scattering coefficient was derived from the integral of the variation patterns for the three PM1 species. The algorithm was then validated and compared with other empirical algorithms through separate field measurements. Good correlations between the reconstructed and measured dry scattering coefficient were observed with R square higher than 0.9 and slope of 1.01–1.05, indicating that the reconstructed algorithm can predict the dry scattering coefficient well based on PM1 chemical composition measurements in urban China. Our study is expected to provide observed insights on the variation of MSE in the wide mass range especially in the high region, as well as accurate formulas for ambient PM1 dry scattering apportionment.

Differences in chemical composition of PM2.5 emissions from traditional versus advanced combustion (semi-gasifier) solid fuel stoves

A common strategy to improve indoor air quality in households burning coal and biomass is the introduction of advanced combustion solid fuel stoves, which can use existing fuels yet emit fewer pollutants. Chemical composition of PM is affected by numerous combustion parameters, but is often not considered in energy transitions, despite varying toxicity among chemical components. We analyzed PM2.5 emissions from combustion of solid fuels (coal, wood, and straw; whole and pelletized) in a variety of stoves (cookstoves and heating stoves; traditional and semi-gasifier, including forced versus natural draft and fixed versus reciprocating grate). To assess the effects of fuel and stove type on PM2.5 composition, we measured elemental carbon (EC), organic carbon (OC), water-soluble OC, water-soluble inorganic ions (e.g. SO42−, Cl−, K+), and organic molecular markers. PM2.5 emissions from traditional stoves were mostly carbonaceous: 76–90% organic matter (OM), 5–6% EC, and less than 2% inorganic ions. In contrast, semi-gasifier stoves emitted more inorganic PM2.5: on average, ions comprised 65%, 9% was OM, and 4% was EC. Within the semi-gasifier cookstoves, forced-draft cookstove emissions had lower OM (1–3%) and higher ion concentrations (84–88%) than the natural-draft cookstove (5–14% OM, 30–83% ions). Levoglucosan was detected in PM2.5 from combustion of wood in the traditional cookstove and biomass pellets in the natural-draft semi-gasifier cookstove, but not from wood pellets in the forced-draft semi-gasifier cookstove. Across a range of different fuels and stoves, stove type influenced emitted PM composition more than fuel type, underscoring the impact of combustion conditions on PM chemical composition.

Characteristics of chemical composition and seasonal variations of PM2.5 in Shijiazhuang, China: Impact of primary emissions and secondary formation

North China registers frequent air pollution episodes from high PM2.5 concentrations. Shijiazhuang is located at the intensive industrial zone of this region, but there is insufficient data on the chemical composition of PM2.5 and its sources in this city. In this study, the chemical and seasonal characteristics of PM2.5 in Shijiazhuang were investigated based on 12-h integrated PM2.5 measurements made over eight 1-month periods in each season between June 2014 and April 2016 (486 samples). The eight-season average concentration of PM2.5 was 138.8 μg m−3, and the major chemical components were secondary inorganic aerosol (SIA) species of sulfate, nitrate, and ammonium (41.5%), followed by organic matter (25.9%). The mass concentration and most of the chemical components of PM2.5 showed clear seasonal variation, with a winter-high and summer-low pattern. SO42− and NO3− were the dominant components at each pollution level in summer and autumn (18.1%–30.6% and 14.2%–27.0%, respectively). Sufficient gaseous oxidants (O3) concentrations and suitable meteorology conditions were observed in these two seasons. Highest SOR (0.61), SO42−/EC(10.8) and NOR (0.58), NO3−/EC (5.9) were found in summer and autumn, which indicated intense secondary transformation in these two seasons. Organic matter was the dominant species in winter, which increased from 17.1 μg m−3 for clean days (28.7% of PM2.5) to 169.1 μg m−3 (38.4% of PM2.5). The accumulation of primary emissions (coal combustion and biomass burning) was responsible for the increasing OM trend (especially for POC). The highest and leading proportion of mineral dust occurred in spring (20.3%–46.5%) as a result of higher wind speeds (up to 3 m/s). Potential source contribution function (PSCF) analyses implied that the border areas of Hebei, Henan and Shandong Provinces, together with the central area of Shanxi Province, contributed significantly to the PM2.5 pollution in Shijiazhuang, especially in autumn and winter.

Understanding PM2.5‐Induced Oxidative Stress In Alveolar Macrophages

When oxidative stress exceeds normal levels, the antioxidant system of any eukaryotic organism can become overwhelmed. This may lead to various adverse health effects, including cardiovascular and pulmonary diseases. The risk for these conditions is heightened by increased exposure to particulate matter 2.5 (PM2.5), composed of transition metals and organic compounds 2.5μm or less in diameter. These particles reach the alveolar macrophages (AMs) in the respiratory tract, where they can induce an inflammatory response by producing excessive reactive oxygen species (ROS). During 2012 and 2013, samples of ambient PM2.5 samples were collected during periods of peak air pollution from Fresno and Claremont, CA. These samples were tested for their potential to induce a ROS response in the rat NR8383 AM cell line using the intracellular ROS‐sensitive fluorescent probe 2′‐7′‐Dichlorodihydrofluorescein diacetate. Interestingly, the specific cellular ROS response was dependent on the sample origin; strongly suggesting that the chemical composition of PM2.5 is a major determinant of its effect on AM ROS metabolism. The PM2.5 samples were characterized for their chemical content using chromatography and mass spectrometry based techniques. Two types of quinones (1,2‐Naphtaquinone, and 1,4‐Naphtaquinone) and one transition metal (Cu2+) were associated with samples that had a high capacity to create ROS in NR8383. Currently, each of the above components' potential to induce a cellular ROS response is being investigated using mock samples with concentration ranges similar to those of the PM2.5 samples. While establishing a cytotoxic link between PM2.5 and ROS, we also seek to understand the underlying biological mechanisms through which PM2.5 interacts with AM cells to produce excessive ROS. Previous studies have suggested the upregulation of heme oxygenase‐1 (HO‐1) during oxidative stress plays an essential role in intracellular ROS regulation. Our study consists of optimizing a gene knockdown protocol for HO‐1 in NR8383 to investigate the potential involvement of HO‐1 in a PM2.5‐induced ROS response. Having established an optimal protein concentration of 50μg to see distinct HO‐1 bands in western blots, a range of siRNA concentrations are being used in conjunction with our positive control, zymosan, to understand their cytotoxicity effects. Zymosan, extracted from the cell wall of saccharomyces cerevisiae, is a known inflammatory agent which stimulates ROS production in NR8383. Repeated trials of western blotting confirm that 4 hour zymosan treatments increase the HO‐1 protein levels in NR8383. The HO‐1 knockdown will be confirmed through quantitative reverse transcription polymerase chain reaction (qrt‐PCR) and western blotting. Cells with the HO‐1 knockdown will then be subjected to a fluorescence‐based microplate assay to monitor their PM2.5‐induced ROS response. We hypothesize enhanced ROS production in PM2.5 treated HO1‐knockdown cells due to the lack of the protective enzyme, HO‐1. Understanding the specific chemical components which have proved noxious to NR8383 and the biological mechanisms through which PM2.5 is able to induce ROS will help us understand exactly how pollution is pernicious and advocate for global reduction of PM2.5.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Exploratory and comparative analysis of the morphology and chemical composition of PM2.5 from regions with different socioeconomic characteristics

Chemical and physical properties of fine particulate matter (PM2.5) are related to emission sources. In order to determine chemical and physical differences, PM2.5 samples were collected at urban, rural and industrial areas of the metropolitan region of Rio de Janeiro (MRRJ), Brazil. The chemical characterization of the samples was performed using ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS), while the physical characterization was done by scanning electron microscopy–energy dispersive spectrometry (SEM-EDS). Through the use the Hybrid Single-Particle Lagrangian Integrated Trajectories (HYSPLIT) model, it was observed that all the studied sites presented the influence of ocean air masses. The industrial and rural sites showed to influence of continental air masses too, that carried aerosols with greater UV absorption compared to those observed in trajectories originating in the Atlantic Ocean. Among analyzed species, NO3− and SO42− ions and V, Pb and Sn elements were predominant in the urban site whereas in the rural and industrial sites Na+, SO42− were the major ions and Na, Zn and Ba were the elements with the higher concentrations. Through SEM-EDS analysis, the particles were classified into two categories, the first in terms of the morphological similarities and the second in function of the elemental composition. As observed in ICP-MS analysis, the elements K, Al, Ca, Fe, Cu, Zn, Ba and Mg were detected also in the individual particles analysis by SEM-EDS. These results showed that C, O and Si were predominant elements at all sites. The morphological and chemical analyses indicate that the influence of vehicular emissions as a common source at all sites. The analyses also showed that the urban sites present particles with more diverse morphologies compared to rural and industrial sites.

Seasonal Characteristics of the Chemical Composition of Fine Particles in Residences of Nanjing, China.

Indoor fine particulate matter (PM2.5) and its chemical composition is important for human exposure as people spend most of their time indoors. However, few studies have investigated the multiseasonal characteristics of indoor PM2.5 and its chemical composition in China. In this study, the chemical composition of PM2.5 samples in residences was analyzed over four seasons in Nanjing, China. Indoor water-soluble ions exhibited similar seasonal variations (winter > autumn > summer > spring) to those from outdoors (winter > autumn > spring > summer) except in summer. Whereas, indoor metallic elements exhibited a different seasonal pattern from that of outdoors. The highest concentrations of indoor metallic elements were observed in summer when the outdoor concentrations were low. The different seasonal variations of the chemical composition between indoor and outdoor PM2.5 indicated that people should consider both indoor and outdoor sources to reduce their exposure to air pollutants in different seasons. The carcinogenic risks for metallic elements were within the acceptable levels, while manganese (Mn) was found to have potential noncarcinogenic risk to humans. More attention should be paid to the pollution of Mn in the study area in the future. Moreover, the cumulative effect of noncarcinogenic PM2.5-bound elements should not be ignored.