PM2.5 source apportionment in a French urban coastal site under steelworks emission influences using constrained non-negative matrix factorization receptor model

Reduction of Outdoor and Indoor PM2.5 Source Contributions via Portable Air Filtration Systems in a Senior Residential Facility in Detroit, Michigan

Background: The Reducing Air Pollution in Detroit Intervention Study (RAPIDS) was designed to evaluate cardiovascular health benefits and personal fine particulate matter (particulate matter < 2.5 μm in diameter, PM2.5) exposure reductions via portable air filtration units (PAFs) among older adults in Detroit, Michigan. This double-blind randomized crossover intervention study has shown that, compared to sham, air filtration for 3 days decreased 3-day average brachial systolic blood pressure by 3.2 mmHg. The results also showed that commercially available HEPA-type and true HEPA PAFs mitigated median indoor PM2.5 concentrations by 58% and 65%, respectively. However, to our knowledge, no health intervention study in which a significant positive health effect was observed has also evaluated how outdoor and indoor PM2.5 sources impacted the subjects. With that in mind, detailed characterization of outdoor and indoor PM2.5 samples collected during this study and a source apportionment analysis of those samples using a positive matrix factorization model were completed. The aims of this most recent work were to characterize the indoor and outdoor sources of the PM2.5 this community was exposed to and to assess how effectively commercially available HEPA-type and true HEPA PAFs were able to reduce indoor and outdoor PM2.5 source contributions. Methods: Approximately 24 h daily indoor and outdoor PM2.5 samples were collected on Teflon and Quartz filters from the apartments of 40 study subjects during each 3-day intervention period. These filters were analyzed for mass, carbon, and trace elements. Environmental Protection Agency Positive Matrix Factorization (PMF) 5.0 was utilized to determine major emission sources that contributed to the outdoor and indoor PM2.5 levels during this study. Results: The major sources of outdoor PM2.5 were secondary aerosols (28%), traffic/urban dust (24%), iron/steel industries (15%), sewage/municipal incineration (10%), and oil combustion/refinery (6%). The major sources of indoor PM2.5 were organic compounds (45%), traffic + sewage/municipal incineration (14%), secondary aerosols (13%), smoking (7%), and urban dust (2%). Infiltration of outdoor PM2.5 for sham, HEPA-type, and true HEPA air filtration was 79 ± 24%, 61 ± 32%, and 51 ± 34%, respectively. Conclusions: The results from our study showed that intervention with PAFs was able to significantly decrease indoor PM2.5 derived from outdoor and indoor PM2.5 sources. The PAFs were also able to significantly reduce the infiltration of outdoor PM2.5. The results of this study provide insights into what types of major PM2.5 sources this community is exposed to and what degree of air quality and systolic blood pressure improvements are possible through the use of commercially available PAFs in a real-world setting.

Source apportionment of PM2.5 before and after COVID-19 lockdown in an urban-industrial area of the Lisbon metropolitan area, Portugal

The lockdowns held due to the COVID-19 pandemic conducted to changes in air quality. This study aimed to understand the variability of PM_2.5 levels and composition in an urban-industrial area of the Lisbon Metropolitan Area and to identify the contribution of the different sources. The composition of PM_2.5 was assessed for 24 elements (by PIXE), secondary inorganic ions and black carbon. The PM_2.5 mean concentration for the period (December 2019 to November 2020) was 13 ± 11 μg.m^-3. The most abundant species in PM_2.5 were BC (19.9%), SO₄ ^2- (15.4%), NO₃ ^- (11.6%) and NH₄ ⁺ (5.3%). The impact of the restrictions imposed by the COVID-19 pandemic on the PM levels was found by comparison with the previous six years. The concentrations of all the PM_2.5 components, except Al, Ba, Ca, Si and SO₄ ^2-, were significantly higher in the winter/pre-confinement than in post-confinement period. A total of seven sources were identified by Positive Matrix Factorisation (PMF): soil, secondary sulphate, fuel-oil combustion, sea, vehicle non-exhaust, vehicle exhaust, and industry. Sources were greatly influenced by the restrictions imposed by the COVID-19 pandemic, with vehicle exhaust showing the sharpest decrease. Secondary sulphate predominated in summer/post-confinement. PM_2.5 levels and composition also varied with the types of air mass trajectories.

Exhaust and non-exhaust contributions from road transport to PM10 at a Southern European traffic site

It is a well - established fact that road traffic is one of the main contributors to ambient levels of airborne particulate matter (APM). This study was carried out at a traffic site in which the PM₁₀ levels are monitored all year round. A trend analysis of these levels revealed that over a decade there was no discernible trend, with the PM₁₀ concentrations normally hovering around the EU limit values. In 2018, one of these limit values was exceeded. The contribution of traffic at the site was therefore investigated through a chemical speciation of 209 PM₁₀ samples collected throughout this year. The speciation data were used in a source apportionment exercise in which the output of the PMF model was further refined using the lesser-known, constraint weighted non - negative matrix factorization (CW - NMF) model. This technique enabled the isolation of two factors clearly related to traffic, which were labelled as "exhaust contribution" (responsible for 3.4% of the PM₁₀), "tire/brake wear contribution" (contributing 17% of the PM₁₀). Additionally, a factor including both traffic resuspended dust and crustal material was also isolated and labelled "road dust/crustal" factor. The two contributors to the factor jointly contribute 18% to the PM₁₀ and the contribution of the traffic resuspended dust was estimated at 7.3%. The traffic resuspended component of this factor together with the "tire/brake wear contribution" jointly make up the non-exhaust contribution of traffic - derived dust. Consonant with what has been known for quite some time, the exhaust fraction is the minor component of traffic PM₁₀. It is therefore, clear that policies aimed at controlling traffic derived PM₁₀ pollution at the receptor will have a minimal effect unless the non - exhaust emissions are adequately controlled.

Oxidative stress response in pulmonary cells exposed to different fractions of PM2.5-0.3 from urban, traffic and industrial sites

The aim of this work was to study the relationship between oxidative stress damages and particulate matter (PM) chemical composition, sources, and PM fractions. PM_2.5-0.3 (PM with equivalent aerodynamic diameter between 2.5 and 0.3 μm) were collected at urban, road traffic and industrial sites in the North of France, and were characterized for major and minor chemical species. Four different fractions (whole PM_2.5-0.3, organic, water-soluble and non-extractable matter) were considered for each of the PM_2.5-0.3 samples from the three sites. After exposure of BEAS-2B cells to the four different fractions, oxidative stress was studied in cells by quantifying reactive oxygen species (ROS) accumulation, oxidative damage to proteins (carbonylated proteins), membrane alteration (8-isoprostane) and DNA damages (8-OHdG). Whole PM_2.5-0.3 was capable of inducing ROS overproduction and caused damage to proteins at higher levels than other fractions. Stronger cell membrane and DNA damages were found associated with PM and organic fractions from the urban site. ROS overproduction was correlated with level of expression of carbonylated proteins, DNA damages and membrane alteration markers. The PM_2.5-0.3 collected under industrial influence appears to be the less linked to cell damages and ROS production in comparison with the other influences.

Chemical profiles of PM2.5 emitted from various anthropogenic sources of the Eastern Mediterranean: Cooking, wood burning, and diesel generators

The chemical profiles of PM_2.5 emitted from a non-road diesel generator, wood burning and cooking activities including chicken and beef charcoal grilling and general cooking activities were determined. The characterization included the carbonaceous fraction (OC/EC), water-soluble ions, elements, and organic species comprising n-alkanes, polycyclic aromatic hydrocarbons, carboxylic acids, levoglucosan, dioxins, furans, and dioxin-like polychlorinated biphenyls. The main component in the PM_2.5 from the different sources was carbonaceous matter with a mass contribution to PM_2.5 of 49% for cooking activities, 53% for wood burning, 66% for beef grilling, 72% for chicken grilling, and 74% for diesel generator with different OC/EC concentration ratios. The analysis of organic compounds contents using diagnostic ratios and indexes showed differences between the sources and revealed specific source markers. The water-soluble ions had the highest contribution in the cooking activities profile with 17% of PM_2.5 and the least in the chicken grilling profile (1.1%). Additionally, 29 analyzed elements were identified, and their contribution varied with the sources (ranging from 1% to 11% of PM_2.5). These findings could be used to differentiate these sources and could assist in the use of source apportionment methods.

Investigating the Sources of Urban Air Pollution Using Low-Cost Air Quality Sensors at an Urban Atlanta Site

Advances in low-cost sensors (LCS) for monitoring air quality have opened new opportunities to characterize air quality in finer spatial and temporal resolutions. In this study, we deployed LCS that measure both gas (CO, NO, NO₂, and O₃) and particle concentrations and co-located research-grade instruments in Atlanta, GA, to investigate the capability of LCS in resolving air pollutant sources using non-negative matrix factorization (NMF) in a moderately polluted urban area. We provide a comparison of applying the NMF technique to both normalized and non-normalized data sets. We identify four factors with different temporal trends and properties for both normalized and non-normalized data sets. Both normalized and non-normalized LCS data sets can resolve primary organic aerosol (POA) factors identified from research-grade instruments. However, applying normalization provides factors with more diverse compositions and can resolve secondary organic aerosol (SOA). Results from this study demonstrate that LCS not only can be used to provide basic mass concentration information but also can be used for in-depth source apportionment studies even in an urban setting with complex pollution mixtures and relatively low aerosol loadings.

Exploring sources and health risks of metals in Beijing PM2.5: Insights from long-term online measurements

To gain a comprehensive understanding of sources, health risks, and regional transport of PM_2.5-bound metals in Beijing, one-year continuous measurement (K, Fe, Ca, Zn, Pb, Mn, Ba, Cu, As, Se, Cr, and Ni) was conducted from December 2016 to November 2017 and Positive Matrix Factorization analysis (PMF) was applied for source apportionment. It was found that the seasonal variation of sources could vary significantly among metals. Sources of Ca, Ba, As, Se, and Cr did not show much seasonal variations, with the contribution of its predominant source higher than 35% in each season. However, the major sources of K, Fe, Zn, Pb, Mn, Cu, and Ni exhibited obvious seasonal variations. In addition, the characteristics of metals in haze episodes were comprehensively investigated. Haze episodes in Beijing were characterized by higher metal concentrations and health risks, which were about 2- 6 times higher than non-haze periods. Moreover, the types of haze episode were different in winter and spring. Haze episodes in winter were mostly influenced by coal combustion, the contribution of which increased greatly and accounted for about 30% of PM_2.5. The metals such as K, Zn, Pb, As, and Se significantly increased, which were mainly transported from south of Beijing. During haze episodes in spring, dust was an important source, which contributed to higher concentrations of crustal metals that transported from northwest of Beijing. To quickly and effectively identify source regions of metals in Beijing during haze episodes, a new diagnostic ratio method using Ca as a reference was developed. The ratios of some anthropogenic metals to Ca significantly increased when air mass was mainly from south of Beijing during haze episodes while the ratios remained constantly low in non-haze periods, when local emissions dominated. This method could be useful for rapid identification and control of metal pollution in Beijing.

Source attribution and quantification of atmospheric nickel concentrations in an industrial area in the United Kingdom (UK)

Pontardawe in South Wales, United Kingdom (UK), consistently has the highest concentrations of nickel (Ni) in PM₁₀ in the UK and repeatedly breaches the 20 ng m^-3 annual mean EU target value. Several local industries use Ni in their processes. To assist policy makers and regulators in quantifying the relative Ni contributions of these industries and developing appropriate emission reduction approaches, the hourly concentrations of 23 elements were measured using X-ray fluorescence alongside meteorological variables and black carbon during a four-week campaign in November-December 2015. Concentrations of Ni ranged between 0 and 2480 ng m^-3 as hourly means. Positive Matrix Factorization (PMF) was used to identify sources contributing to measured elements. Cluster analysis of bivariate polar plots of those factors containing Ni in their profile was further used to quantify the industrial processes contributing to ambient PM₁₀ concentrations. Two sources were identified to contribute to Ni concentrations, stainless-steel (which contributed to 10% of the Ni burden) and the Ni refinery (contributing 90%). From the stainless-steel process, melting activities were responsible for 66% of the stainless-steel factor contribution.

Source apportionment of atmospheric particle number concentrations with wide size range by nonnegative matrix factorization (NMF)

Quantifying the sources of atmospheric particles is essential to air quality control but remains challenging, especially for the source apportionment of particles based on number concentration with wide size range. Here, particle number concentrations (PNC) with size range 19-20,000 nm involving four modes Nucleation, Aitken, Accumulation, and Coarse are used to do source apportionment of PNC at the Guangdong Atmospheric Supersite (Heshan) during July-October 2015 by nonnegative matrix factorization (NMF) with 6 factors. For July 2015, separated source apportionments for three different size ranges from collocated instruments nano scanning mobility particle sizer (NSMPS), SMPS, and aerodynamic particle sizer (APS) and for two different size ranges (below and above 100 nm) show similar quantitative source information with that for the one whole size range. The mean absolute difference of contribution percentages of total particle number concentrations (TPNC) based on 5 unique apportioned sources is 5.6 % (4.3-7.6 %) for the instrument segregated apportionment and 4.2 % (0-5.3 %) for the size range segregated apportionment respectively, relative to the one whole apportionment. Moreover, the contribution percentages of TPNC are close to the weighted sum of contribution percentages of all size bins, with a mean absolute difference of 1.1 % (0-3.4 %). In both these two aspects, the consistency among different technical paths proves the matrix factorization by NMF is practically desirable and the simplicity of reducing some steps or calculations saves time. Besides, dust can be identified with the wide size range including larger than 3000 nm. Six apportioned sources in the 4 months are Accumulation (32.4 %), Nucleation (20.0 %), Aitken (15.2 %), traffic (14.6 %), dust (10.6 %), and Coarse (7.1 %). Therefore, NMF would serve as a promising tool for PNC source apportionment with wide size range and conducting the apportionment with the whole size range in one matrix factorization procedure and using the single TPNC contribution percentage are feasible.

Assignment of PM2.5 sources in western Japan by non-negative matrix factorization of concentration-weighted trajectories of GED-ICP-MS/MS element concentrations

Rapid economic growth in Asian countries has raised concerns about the influence of air pollutants transported to Japan by westerly winds. We coupled a gas exchange device (GED) with a tandem inductively coupled plasma mass spectrometer (ICP-MS/MS) to enable direct introduction of PM_2.5 to ICP and thus provide better data than could be obtained from samples collected by conventional filter methods. We used the GED-ICP-MS/MS system in Matsue City in western Japan to monitor in real time 29 elements in PM_2.5 at 10-min intervals and to estimate the pollutant sources by non-negative matrix factorization (NMF) of concentration-weighted air-mass trajectories. The trajectory analysis identified high V, As, Sn, and Sb concentrations over the ocean from Taiwan to Tsushima Strait. NMF analysis revealed that these elements could be decomposed to multiple factors that indicated a large contribution from oceanic areas. The elemental contributions of these factors were high for metals/metalloids with low melting points as oxides, strongly suggesting that they were sourced from combustion of ship fuel. Our results demonstrate that both emissions from ships at sea and land-based emissions from Japan and continental Asia contribute to PM_2.5 in Matsue City.

Exploring the external exposome using wearable passive samplers - The China BAPE study

Environmental exposures are one of the greatest threats to human health, yet we lack tools to answer simple questions about our exposures: what are our personal exposure profiles and how do they change overtime (external exposome), how toxic are these chemicals, and what are the sources of these exposures? To capture variation in personal exposures to airborne chemicals in the gas and particulate phases and identify exposures which pose the greatest health risk, wearable exposure monitors can be deployed. In this study, we deployed passive air sampler wristbands with 84 healthy participants (aged 60-69 years) as part of the Biomarkers for Air Pollutants Exposure (China BAPE) study. Participants wore the wristband samplers for 3 days each month for five consecutive months. Passive samplers were analyzed using a novel gas chromatography high resolution mass spectrometry data-processing workflow to overcome the bottleneck of processing large datasets and improve confidence in the resulting identified features. The toxicity of chemicals observed frequently in personal exposures were predicted to identify exposures of potential concern via inhalation route or other routes of airborne contaminant exposure. Three exposures were highlighted based on elevated toxicity: dichlorvos from insecticides (mosquito/malaria control), naphthalene partly from mothballs, and 183 polyaromatic hydrocarbons from multiple sources. Other exposures explored in this study are linked to diet and personal care products, cigarette smoke, sunscreen, and antimicrobial soaps. We highlight the potential for this workflow employing wearable passive samplers for prioritizing chemicals of concern at both the community and individual level, and characterizing sources of exposures for follow up interventions.

Assessment of the PM2.5 oxidative potential in a coastal industrial city in Northern France: Relationships with chemical composition, local emissions and long range sources

The objective of this work was to relate PM_2.5 Oxidative Potential (OP) data to PM composition and PM local and distant source contributions. PM_2.5 collected in Dunkerque, a coastal industrial city in North of France, was extensively characterized for major and minor chemical species. PM_2.5 filters were extracted using a synthetic pulmonary fluid to achieve OP estimation based on Ascorbic Acid (AA) and dithiothreitol (DTT) depletion assays. In order to evidence relationships between OP values, chemical composition and local and distant source contributions, correlation coefficient, Principal Component Analysis (PCA), concentration roses, polar plots and concentration weighted trajectories were used. Heterogeneous conclusions were drawn using the three first methods as the bivariate polar plots lead to dismiss some of the correlations evidenced using correlation coefficient and PCA. Both AA and DTT tests appeared complementary as they were not sensitive to the same species/source contribution. The bivariate polar plot representation of OP values versus wind direction and wind speed revealed that PM_2.5 concentration and combustion sources were linked to OP-AA, whereas emissions from integrated steelworks, electric steelworks, heavy fuel oil combustion and traffic non-exhaust significantly contribute to OP-DTT. Sea-salts, aged sea-salts, crustal, secondary sulfates and secondary nitrates sources were not found to contribute to OP values. Constant weighted trajectories evidenced several source regions responsible for high OP values with Belgium, Germany, Netherlands and France at the leader position. Contribution of inland regions appeared possibly related to the biomass and traffic related combustion while heavy fuel oil combustion could also be involved in the contribution of marine and coastal areas.

Particle-Bound PAHs and Elements in a Highly Industrialized City in Southern Italy: PM2.5 Chemical Characterization and Source Apportionment after the Implementation of Governmental Measures for Air Pollution Mitigation and Control

The present study was aimed at determining airborne concentrations of PAHs, Nitro-/Oxy-PAHs and elements in industrial and urban areas of Taranto, a site of environmental risk in Southern Italy, after the issue of strategic measures for air pollution mitigation and control by the Italian Environment Ministry in 2012. A PM_2.5 sampling campaign was carried out from 9 to 28 December 2014 at eight receptor sites, two placed in the urban settlement and five included in the high spatial resolution fence monitoring network of the biggest European steel plant. The integration of collected data with meteorological parameters and source apportionment analysis by Positive Matrix Factorization and bivariate polar plots allowed to discriminate among emission sources and estimate their contributions. Evidence on the effect of distinct processes (homogenization, sintering) occurring inside the steel plant on airborne concentrations of PAHs and selected elements was provided. The impact of emissions from the steel plant “core” on the surrounding area was observed at receptor sites downwind to it. Moreover, the extent of the effectiveness of mitigation measures, partially applied at the moment of study’s beginning, was demonstrated by mean and peak pollutant concentrations at all receptor sites up to one order of magnitude lower than those documented prior to 2012.

Hourly Elemental Composition and Source Identification by Positive Matrix Factorization (PMF) of Fine and Coarse Particulate Matter in the High Polluted Industrial Area of Taranto (Italy)

In the framework of an extensive environmental investigation, promoted by the Italian Health Ministry, the ISPESL (Istituto Superiore per la Prevenzione e la Sicurezza del Lavoro) and the CNR (Consiglio Nazionale della Ricerca), aerosol samples were collected in Taranto (one of the most industrialized towns in southern Italy) with high time resolution and analyzed by PIXE. The samples were collected in two periods (February–March and June 2004) and in two different sites: an urban district close to the industrial area and a small town 7 km N-NW of Taranto. The use of ‘‘streaker’’ samplers (by PIXE International Corporation) allowed for the simultaneous collection of the fine (<2.5 μm) and coarse (2.5–10 μm) fractions of particulate matter. PIXE analyses were performed with a 3 MeV proton beam from the 3 MV Tandetron accelerator of the INFN-LABEC laboratory. Particulate emissions as well as their atmospheric transport and dilution processes change within a few hours, but most of the results in literature are limited to daily time resolution of the input samples that are not suitable for tracking these rapid changes. Furthermore, since source apportionment receptor models need a series of samples containing material from the same set of sources in different proportions, a higher variability between samples can be obtained by increasing the temporal resolution rather than with samples integrated over a longer time. In this study, the high time resolution of the adopted approach allowed us to follow in detail the changes in the aerosol elemental composition due to both the time evolution of the industrial emissions and the time changes in meteorological conditions, and thus, transport pathways. Moreover, the location of the sampling sites, along the prevalent wind direction and in opposite positions with respect to the industrial site, allowed us to follow the impact of the industrial plume as a function of wind direction. Positive matrix factorization (PMF) analysis on the elemental hourly concentrations identified eight sources in the fine fraction and six sources in the coarse one.

Uncommon chemical species in PM2.5 and PM10 and its potential use as industrial and vehicular markers for source apportionment studies

Chemical characterization of PM_2.5 and PM₁₀ is important to identify potential compounds that induce biological responses that translate into cardio-respiratory health problems. This study shows the reliability of the use of crystalline phases, identified in samples from receptor sites, as source markers, helping researchers to infer the main sources of air pollution, even without the use of receptor models. PM_2.5 and PM₁₀ samples were collected at two sites in an urban industrialized region located at southeast of Brazil and analyzed by Synchrotron X-ray Diffraction to identify crystalline compounds. Results show 5 PM₁₀ and PM_2.5 species not previously reported in the literature. We propose reaction mechanisms for these species and identify specific sources for each crystalline phase found: BaTiO₃ was found in PM₁₀ receptor samples and proved to be a vehicular marker formed during brake action; maghemite (γ-Fe₂O₃), pyracmonite [(NH₄)₃Fe(SO₄)₃], ammonium perchlorate (NH₃OHClO₄) and potassium ferrate (K₂Fe₂O₄) were found in PM_2.5 proved to be markers of industrial activities. The crystalline phases found in PM samples from receptor sites and the mechanisms of reactions showed the reliability of the use of crystalline phases as source markers in the identification of potential sources of air pollution without misinterpretation of the likely source.

Association of emergency room visits for respiratory diseases with sources of ambient PM2.5

Previous studies have reported associations of short-term exposure to different sources of ambient fine particulate matter (PM_2.5) and increased mortality or hospitalizations for respiratory diseases. Few studies, however, have focused on the short-term effects of source-specific PM_2.5 on emergency room visits (ERVs) of respiratory diseases. Source apportionment for PM_2.5 was performed with Positive Matrix Factorization (PMF) and generalized additive model was applied to estimate associations between source-specific PM_2.5 and respiratory disease ERVs. The association of PM_2.5 and total respiratory ERVs was found on lag4 (RR = 1.011, 95%CI: 1.002, 1.020) per interquartile range (76 μg/m³) increase. We found PM_2.5 to be significantly associated with asthma, bronchitis and chronic obstructive pulmonary disease (COPD) ERVs, with the strongest effects on lag5 (RR = 1.072, 95%CI: 1.024, 1.119), lag4 (RR = 1.104, 95%CI: 1.032, 1.176) and lag3 (RR = 1.091, 95%CI: 1.047, 1.135), respectively. The estimated effects of PM_2.5 changed little after adjusting for different air pollutants. Six primary PM_2.5 sources were identified using PMF analysis, including dust/soil (6.7%), industry emission (4.5%), secondary aerosols (30.3%), metal processing (3.2%), coal combustion (37.5%) and traffic-related source (17.8%). Some of the sources were identified to have effects on ERVs of total respiratory diseases (dust/soil, secondary aerosols, metal processing, coal combustion and traffic-related source), bronchitis ERVs (dust/soil) and COPD ERVs (traffic-related source, industry emission and secondary aerosols). Different sources of PM_2.5 contribute to increased risk of respiratory ERVs to different extents, which may provide potential implications for the decision making of air quality related policies, rational emission control and public health welfare.

Investigating the plausibility of a PMF source apportionment solution derived using a small dataset: A case study from a receptor in a rural site in Apulia - South East Italy

Results of a methodological study on the use of Positive Matrix Factorization (PMF) with smaller datasets are being reported in this work. This study is based on 29 PM₁₀ and 33 PM_2.5 samples from a receptor in a rural setup in Apulia (Southern Italy). Running PMF on the two size fractions separately resulted in the model not functioning correctly. We therefore, augmented the size of the dataset by aggregating the PM₁₀ and PM_2.5 data. The 5-factor solution obtained for the aggregated data was fairly rotationally stable, and was further refined by the rotational tools included in USEPA PMF version 5. These refinements include the imposition of constraints on the solution, based on our knowledge of the chemical composition of the aerosol sources affecting the receptor. Additionally, the uncertainties associated with this solution were fully characterised using the improved error estimation techniques in this version of PMF. Five factors in all, were isolated by PMF: ammonium sulfate, marine aerosol, mixed carbonaceous aerosol, crustal/Saharan dust and total traffic. The results obtained by PMF were further tested inter alia, by comparing them to those obtained by two other receptor modelling techniques: Constrained Weighted Non-negative Matrix Factorization (CW - NMF) and Chemical Mass Balance (CMB). The results of these tests suggest that the solution obtained by PMF, is valid, indicating that for this particular airshed PMF managed to extract most of the information about the aerosol sources affecting the receptor - even from a dataset with a limited number of samples.

Characterization of size resolved atmospheric particles in the vicinity of iron and steelmaking industries in China

China currently faces environmental challenges of lower air quality, partly as a result of industrial activities. The aim of this study was to investigate the role of iron and steelmaking facilities to regional air quality in four selected industry dominated urban centres in China. Nine different particle size ranges present in atmospheric particles collected from four sites in Kunming (KM), Wuhan (WH), Nanjing (NJ) and Ningbo (NB) were analysed and compared with particles collected at one background site at the Ningbo Nottingham University (UN) with very little industrial influence in China. Similar mass concentration levels of particulate matter PM_2.1 and PM_1.1 were found at the three sites near older iron and steelmaking plants (KM, WH and NJ). Significantly lower levels of PM_2.1 and PM_1.1 were collected at the fourth site (NB), which is near to a modern and coastal iron and steelmaking plant. The particles collected had the highest mass concentration in the aerodynamic diameter range of 3.3-9.0 μm for all sites, except for the background site (UN). Scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, and inductively coupled plasma were used to determine the surface morphology and particle chemistry. Al, Ca, Fe, K, Mg, Na and Zn were found as the most abundant elements in all samples. The enrichment factors show that elements As, Cd, Cr, Cu, Pb and Zn were significantly enriched in particles, especially in fine particles, posing an adverse impact on human health. This study can be used to assist the development of particle monitoring programmes in the vicinity of industrial areas and also help to establish an elemental modality dataset on the exposure and risk assessments of atmospheric particles.

Cellular response and extracellular vesicles characterization of human macrophages exposed to fine atmospheric particulate matter

Exposure to fine atmospheric Particulate Matter (PM) is one of the major environmental causes involved in the development of inflammatory lung diseases, such as chronic obstructive pulmonary disease (COPD) or asthma. When PM is penetrating in the pulmonary system, alveolar macrophages represent the first line of defense, in particular by triggering a pro-inflammatory response, and also by their ability to recruit infiltrating macrophages from the bone marrow. The aim of this in vitro study was to evaluate the gene expression and cytokine production involved in the toxicological and inflammatory responses of infiltrating macrophages, as well as the Extracellular Vesicles (EVs) production, after their exposure to PM. The ability of these EVs to convey information related to PM exposure from exposed macrophages to pulmonary epithelial cells was also evaluated. Infiltrating macrophages respond to fine particles exposure in a conventional manner, as their exposure to PM induced the expression of Xenobiotic Metabolizing Enzymes (XMEs) such as CYP1A1 and CYP1B1, the enzymes involved in oxidative stress SOD2, NQO1 and HMOX as well as pro-inflammatory cytokines in a dose-dependent manner. Exposure to PM also induced a greater release of EVs in a dose-dependent manner. In addition, the produced EVs were able to induce a pro-inflammatory phenotype on pulmonary epithelial cells, with the induction of the release of IL6 and TNFα proinflammatory cytokines. These results suggest that infiltrating macrophages participate in the pro-inflammatory response induced by PM exposure and that EVs could be involved in this mechanism.

Analysis of Particulate Matter Concentration Variability and Origin in Selected Urban Areas in Poland

The work presents the results of research and analyses related to measurements of concentration and chemical composition of three size fractions of particulate matter (PM), PM10, PM2.5 and PM1.0. The studies were conducted in the years 2014–2016 during both the heating and non-heating season in two Polish cities: Wrocław and Poznań. The studies indicate that in Wrocław and Poznań, the highest annual concentrations of particulate matter (PM1.0, PM2.5, and PM10) were observed in 2016, and the mean concentrations were respectively equal to 18.16 μg/m3, 30.88 μg/m3 and 41.08 μg/m3 (Wrocław) and 8.5 μg/m3, 30.8 μg/m3 and 32.9 μg/m3 (Poznań). Conducted analyses of the chemical composition of the particulate matter also indicated higher concentrations of organic and elemental carbon (OC and EC), and water-soluble ions in a measurement series which took place in the heating season were studied. Analyses with the use of principal component analysis (PCA) indicated a dominating percentage of fuel combustion processes as sources of particulate matter emission in the areas considered in this research. Acquired results from these analyses may indicate the influence of secondary aerosols on air quality. In the summer season, a significant role could be also played by an influx of pollutants—mineral dust—originating from outside the analyzed areas or from the resuspension of mineral and soil dust.

Investigation on the near-field evolution of industrial plumes from metalworking activities

In a context where a significant fraction of the population lives near industrial areas, the main objectives of this study are to provide (a) new data on PM_2.5 chemical compositions, heavy-metal concentrations and trace gases released by metalworking activities and (b) new information on the near-field evolution (up to about a thousand meters) of such industrial plumes in terms of particle chemical composition and size distribution. For that purpose, a one-month field campaign was performed in an industrial area near the city of Dunkirk (Northern France), combining measurements of atmospheric dynamics and physico-chemical characterization of air masses. Comparisons between several elemental ratios (mainly Mn/Fe), particle size distributions and volatile organic compound (VOC) concentrations at the stacks and at a near-field site suggest that plumes of a ferromanganese alloy plant were quickly mixed with pollutants emitted by other sources (mainly other industries, possibly traffic and sea spray), in particular a neighboring steelworks, before reaching the sampling site. This led to the emergence of secondary particles related to condensation and/or aggregation phenomena inside the plumes. Metalworking emissions were also identified as a source of new particle formation, formed through the emission of gaseous precursors and their fast transformation and condensation, over a timescale of minutes before reaching the near-field site 800 m downwind. Ultrafine particles emitted at the stacks also quickly agglomerated to form larger particles before reaching the near-field site. These results show that, even over short distances, the chemical composition and size distribution of metalworking plumes may evolve rapidly and the characteristics of particles at the boundary of an industrial area (especially in contiguous urban areas) may differ from those emitted directly at the stacks.

Informed Weighted Non-Negative Matrix Factorization Using αβ-Divergence Applied to Source Apportionment

In this paper, we propose informed weighted non-negative matrix factorization (NMF) methods using an α β -divergence cost function. The available information comes from the exact knowledge/boundedness of some components of the factorization-which are used to structure the NMF parameterization-together with the row sum-to-one property of one matrix factor. In this contribution, we extend our previous work which partly involved some of these aspects to α β -divergence cost functions. We derive new update rules which are extendthe previous ones and take into account the available information. Experiments conducted for several operating conditions on realistic simulated mixtures of particulate matter sources show the relevance of these approaches. Results from a real dataset campaign are also presented and validated with expert knowledge.

PM2.5-Bound Toxic Elements in an Urban City in East China: Concentrations, Sources, and Health Risks

Concentrations of PM_2.5-bound trace elements have increased in China, with increasing anthropogenic emissions. In this study, long-term measurements of PM_2.5-bound trace elements were conducted from January 2014 to January 2015 in the urban city of Jinan, east China. A positive matrix factorization model (PMF) and health risk assessment were used to evaluate the sources and health risks of these elements, respectively. Compared with most Chinese megacities, there were higher levels of arsenic, manganese, lead, chromium, and zinc in this city. Coal combustion, the smelting industry, vehicle emission, and soil dust were identified as the primary sources of all the measured elements. Heating activities during the heating period led to a factor of 1.3–2.8 higher concentrations for PM_2.5 and all measured elements than those during the non-heating period. Cumulative non-carcinogenic and carcinogenic risks of the toxic elements exceeded the safety levels by 8–15 and 10–18 times, respectively. Arsenic was the critical element having the greatest health risk. Coal combustion caused the highest risk among the four sources. This work provides scientific data for making targeted policies to control air pollutants and protect human health.

Emission characterization of particulate matter in the ironmaking process

The study is to provide a detailed physical and chemical characterization of particles collected in the ironmaking process, including a bunker system, a cast house and a pulverized coal feeding system. Using gravimetric, scanning electron microscope coupled with energy dispersive X-ray spectrometry (SEM-EDS), X-ray fluorescence spectrometry (XRF), inductively coupled plasma optical emission spectrometry (ICP-OES) analyses, the size distribution, morphology, elemental composition and emission factor of particles were investigated. The contribution rates of cast house for emission factors of total suspended particulates (TSP), PM₁₀ and PM_2.5 are the largest, 57.0%, 75.5% and 83.3%, respectively. SEM-EDS analysis indicated that cast house particle shapes are mainly formed by polymerization from spherical particles and ultrafine particles, whose main component is Fe. But, the particles of the bunker system or the pulverized coal feeding system are mainly the large ones of irregular block or powder particles and the main component is carbon. The highest content of the element in particles of the bunker system and cast house is Fe, followed by C, Si, Ca and Al. The main elements of particles in the pulverized coal feeding system are C, Si, Al and Ca, and their contents are 63.6%, 7.83%, 3.07% and 1.47%, respectively.

Chemical Characteristics of Fine Particulate Matter in Poland in Relation with Data from Selected Rural and Urban Background Stations in Europe

Air pollution by particulate matter (PM) is recognized as a one of the most important environmental issue. A particular attention is being paid to fine PM fraction (PM2.5, PM1.0) due to its detrimental impact on human health and long-term persistence in the air. Presented work is an in-depth bibliometric study on the concentrations and chemical composition of PM2.5 among 27 rural and 38 urban/urban background stations dispersed across the Europe. Obtained results indicate that the chemical composition of PM2.5, in terms of mass concentrations and percentage contribution of main chemical constituents, is relatively different in various parts of Europe. Urban and urban background stations are typically characterized by higher share of total carbon (TC) in PM2.5, compared to rural background sites, mostly pronounced during the heating periods. The share of the secondary inorganic aerosol (SIA) is typically higher at rural background stations, especially in North-Western Europe. In general, the relative contribution of SIA in PM2.5 mass, both at rural and urban background stations, showed more or less pronounced seasonal variation, opposite to Polish measurement sites. Moreover, Poland stands out from the majority of the European stations by strong dominance of total carbon over secondary inorganic aerosol.

Characteristics and sources of trace elements in PM2.5 in two megacities in Sichuan Basin of southwest China

To characterize major trace elements in PM_2.5 and associated sources in two megacities, Chengdu (CD) and Chongqing (CQ), in Sichuan Basin of southwest China, daily PM_2.5 samples were collected at one urban site in each city from October 2014 to July 2015 and were analyzed for their contents of thirteen trace elements including four crustal elements (Al, Ca, Fe, and Ti), eight trace metals (K, Cr, Zn, Cu, Mn, Pb, Ni, and V), and As. Multiple approaches including correlation analysis, enrichment factor, principal component analysis, and conditional probability function (CPF) were applied to identify potential sources of these elements. Most of the measured trace elements in Sichuan Basin were found to have lower concentrations than in the other regions of China. K and Fe were the most abundant elements at CD with an annual mean concentrations of 720 ± 357 and 456 ± 248 ng m^-3, accounting for 34.6% and 21.9% of the total analyzed trace elements, respectively. Ca presented the highest concentration among all of the elements at CQ with annual mean of 824 ± 633 ng m^-3 (29.1% of the total). Crustal elements had the highest concentrations in spring while heavy metals had distinct seasonal variations typically with the highest concentrations in winter and the lowest in summer. Ti and Al were identified to be primarily from soil while most of the analyzed heavy metals (Cr, Mn, Cu, Zn, Pb, Ni) and As were from anthropogenic sources associated with coal combustion, industrial emission from glassmaking production and iron/steel manufacturing, and non-exhaust vehicle emission.

Influence of ship emissions on NOx, SO2, O3 and PM concentrations in a North-Sea harbor in France

The influence of in-port ship emissions on gases and PM₁₀ concentrations has been estimated in the port city of Calais, northern France, one of the busiest harbor in Europe, with numerous rotations of ferries or roll-on/roll-off cargo in average per day. NO_x, SO₂, O₃ and PM₁₀ concentrations were continuously measured over a three-month period, as well as real-time particle size distribution. A rural site located at Cape Gris-Nez, 20km from Calais, was considered to deduce intrinsic contribution of ship emissions at the harbor city. The average concentrations of the studied species as well as the pattern of the conditional bivariate probability function at the two sites evidenced that in-port shipping, especially during the maneuvering operations, has an important influence on the NO_x and SO₂ concentrations. The impact of shipping in the harbor of Calais on average concentrations was estimated to 51% for SO₂, 35% for NO, 15% for NO₂ and 2% for PM₁₀ in the studied period. Concentration peaks of SO₂ and NOx associated with an O₃ depletion appeared synchronized with departures and arrivals of ferries. For winds blowing from the harbor, when compared to the background level, the number of particles appeared 10 times higher, with the highest differences in the 30-67nm and the 109-167nm size ranges. The average impact of in-port ships on PM₁₀ concentrations was estimated to +28.9μg/m³ and concerned mainly the PM₁ size fraction (40%). Punctually, PM₁₀ can potentially reach a concentration value close to 100μg/m³.

Fine particles at a background site in Central France: Chemical compositions, seasonal variations and pollution events

To expand our knowledge of regional fine particles in Central France (Centre-Val de Loire region), a field observation study of PM_2.5 was carried out at Verneuil site (46.81467N, 2.61012E, 180m.a.s.l.) from 2011 to 2014. The mass concentrations of water-soluble inorganic ions (WSIIs), organic carbon (OC), elemental carbon (EC) and biomass burning tracer (Levoglucosan) in PM_2.5 were measured. Annual average PM_2.5 mass concentrations were 11.8, 9.5, 12.6 and 10.2μg·m^-3 in 2011, 2012, 2013 and 2014, respectively, three of four higher than the WHO guideline of 10μg·m^-3. Secondary inorganic aerosol (SIA) and organic matter (OM) appeared to be the major components in PM_2.5 in Verneuil, contributing 30.1-41.8% and 36.9-46.3%, respectively. Main chemical species were observed in the following order: winter≥spring>autumn>summer. Backward atmospheric trajectories were performed using Hysplit model and suggested that the PM_2.5 pollutants caused by atmospheric transport were mainly originated from European inland, mainly east to north-east areas. During the observation period, five pollution events were reported and indicated that not only the polluted air masses from central Europe but also the biomass burning from East Europe significantly influenced the air quality in Verneuil site.

Contributions of local and regional anthropogenic sources of metals in PM2.5 at an urban site in northern France

PM_2.5 have been related to various adverse health effects, mainly due to their ability to penetrate deeply and to convey harmful chemical components, such as metals inside the body. In this work, PM_2.5 were sampled at Saint-Omer, a medium-sized city located in northern France, in March-April 2011 and analyzed for their total carbon, water-soluble ions, major and trace elements. More specifically, the origin of 15 selected elements was examined using different tools including enrichment factors, conditional bivariate probability function (CBPF) representations, diagnostic ratios and receptor modelling. The results indicated that PM_2.5 metal composition is affected by both emissions of a local glassmaking factory and an integrated steelworks located at a distance of 35 km from the sampling site. For the first time, diagnostic ratios were proposed for the glassmaking activity. Therefore, metals in PM_2.5 could be attributed to the following anthropogenic sources: (i) local glassmaking industry for Sn, As, Cu and Cr, (ii) distant integrated steelworks for Ag, Fe, Cd, Mn, Rb and Pb, (iii) heavy fuel oil combustion for Ni, V and Co and (iv) non-exhaust traffic for Zn, Pb, Mn, Sb, and Cu. The impact of such sources on metal concentrations in PM_2.5 was assessed using a constrained receptor model. Despite their low participation to PM_2.5 concentration (2.7%), the latter sources were found as the main contributors (80%) to the overall concentration levels of the 15 selected elements in PM_2.5.

Size distribution, directional source contributions and pollution status of PM from Chengdu, China during a long-term sampling campaign

Long-term and synchronous monitoring of PM₁₀ and PM_2.5 was conducted in Chengdu in China from 2007 to 2013. The levels, variations, compositions and size distributions were investigated. The sources were quantified by two-way and three-way receptor models (PMF2, ME2-2way and ME2-3way). Consistent results were found: the primary source categories contributed 63.4% (PMF2), 64.8% (ME2-2way) and 66.8% (ME2-3way) to PM₁₀, and contributed 60.9% (PMF2), 65.5% (ME2-2way) and 61.0% (ME2-3way) to PM_2.5. Secondary sources contributed 31.8% (PMF2), 32.9% (ME2-2way) and 31.7% (ME2-3way) to PM₁₀, and 35.0% (PMF2), 33.8% (ME2-2way) and 36.0% (ME2-3way) to PM_2.5. The size distribution of source categories was estimated better by the ME2-3way method. The three-way model can simultaneously consider chemical species, temporal variability and PM sizes, while a two-way model independently computes datasets of different sizes. A method called source directional apportionment (SDA) was employed to quantify the contributions from various directions for each source category. Crustal dust from east-north-east (ENE) contributed the highest to both PM₁₀ (12.7%) and PM_2.5 (9.7%) in Chengdu, followed by the crustal dust from south-east (SE) for PM₁₀ (9.8%) and secondary nitrate & secondary organic carbon from ENE for PM_2.5 (9.6%). Source contributions from different directions are associated with meteorological conditions, source locations and emission patterns during the sampling period. These findings and methods provide useful tools to better understand PM pollution status and to develop effective pollution control strategies.

Fine and ultrafine atmospheric particulate matter at a multi-influenced urban site: Physicochemical characterization, mutagenicity and cytotoxicity

Particulate Matter (PM) air pollution is one of the major concerns for environment and health. Understanding the heterogeneity and complexity of fine and ultrafine PM is a fundamental issue notably for the assessment of PM toxicological effects. The aim of this study was to evaluate mutagenicity and cytotoxicity of a multi-influenced urban site PM, with or without the ultrafine fraction. For this purpose, PM_2.5-0.3 (PM with aerodynamic diameter ranging from 0.3 to 2.5 μm) and PM_2.5 were collected in Dunkerque, a French coastal industrial city and were extensively characterized for their physico-chemical properties, including inorganic and organic species. In order to identify the possible sources of atmospheric pollution, specific criteria like Carbon Preference Index (CPI) and PAH characteristic ratios were investigated. Mutagenicity assays using Ames test with TA98, TA102 and YG1041 Salmonella strains with or without S9 activation were performed on native PM sample and PM organic extracts and water-soluble fractions. BEAS-2B cell viability and cell proliferation were evaluated measuring lactate dehydrogenase release and mitochondrial dehydrogenase activity after exposure to PM and their extracts. Several contributing sources were identified in PM: soil resuspension, marine emissions including sea-salt or shipping, road traffic and industrial activities, mainly related to steelmaking or petro-chemistry. Mutagenicity of PM was evidenced, especially for PM_2.5, including ultrafine fraction, in relation to PAHs content and possibly nitro-aromatics compounds. PM induced cytotoxic effects at relatively high doses, while alteration of proliferation with low PM doses could be related to underlying mechanisms such as genotoxicity.