Composition Of PM2 Research Articles

Elemental composition of atmospheric PM10 during COVID-19 lockdown and recovery periods in Moscow (April-July 2020).

Changes in the concentrations of PM10-bound potentially toxic elements (PTEs) during the COVID-19 lockdown period and after the revocation of restrictions were analyzed using the data received at the Aerosol Complex of Moscow State University in April-July 2020. During the lockdown, the input of biomass combustion products enriched in PTEs from the Moscow region hindered the decrease in pollutant concentrations. After the introduction of the self-isolation regime, lower concentrations of most PTEs occurred due to the decrease in anthropogenic activity and the rainy meteorological conditions. After the revocation of restrictive measures, the PTE concentrations began to increase. Multivariate statistical analysis (APCA-MLR) identified the main sources of atmospheric pollutants as urban dust, non-exhaust traffic emissions, and combustion and exhaust traffic emissions. PM10 particles were significantly enriched with Sb, Cd, Sn, Bi, S, Pb, Cu, Mo, and Zn. The total non-carcinogenic and carcinogenic risks, calculated according to the U.S. EPA model, decreased by 24% and 23% during the lockdown; after the removal of restrictions, they increased by 61% and 72%, respectively. The study provides insight into the PTE concentrations and their main sources at different levels of anthropogenic impact.

Diverse chemical components of PM10 emitted from different coal combustions resulting in distinct cytotoxicity

Inhalable particles (PM10, particulate matters with an aerodynamic diameter < 10 μm) emitted from coal combustions is one of the most significant contributors to air pollution, endangering human health. The compositions of emissions and corresponding health risks of different types of coal sources are currently unclear. To address this, ten distinct types of coal were burnt, and original PM10 samples were collected using dilution channel samplers. Subsequently, we performed a componential analysis on the collected samples and conducted in vitro cytotoxicity tests. Results showed that PM10 from honeycomb, anthracite and industrial coals were dominated by water-soluble ions, while bituminous coal was dominated by carbonaceous components. Although heavy metal contents were lower than other investigated components in these PM10, they were still enriched in Fe, Pb and Zn. The NH4+, Cl- and SO42- account for a large proportion of water-soluble ions. PM10 induced obvious cytotoxicity to human lung cell A549, and the ability of anthracite coal to induce cellular TNF-α production was greater than that of honeycomb and bituminous coal. For IL-6, industrial coal elicited a stronger response than bituminous coal, followed by honeycomb and anthracite coal. Correlation analysis revealed that although heavy metals (Fe, Mn, Co, Ni, Cu) and water-soluble ions (K+, Ca2+, F-) accounted for less particle mass, they were strongly and significantly correlated with oxidative stress and inflammatory damage (r > 0.6, p < 0.05). Considering the actual coal consumption amount, our study identified restricting anthracite coal combustion should be a crucial focus for aerosol pollution control and public health protection policies. The results of the study not only increase the understanding of the chemical composition and cytotoxicity of PM10 from the perspective of source emissions, but also provide targeted advice on the control of coal combustion, which is of great significance in environmental research, public health policy and air pollution control efforts.

Seasonal Distribution and Source Apportionment of Chemical Compositions in PM2.5 in Nanchang, Inland Area of East China

PM2.5 was sampled in four seasons of 2021 in Nanchang. Organic carbon (OC), elemental carbon (EC), and water-soluble ions were the main chemical compositions in PM2.5. The annual average of OC/PM2.5 and EC/PM2.5 was 17.1% and 2.1%, respectively, while nine water-soluble ions were 56.7%. The order of each ion percentage in PM2.5 was NO3− &gt; SO42− &gt; K+ &gt; Na+ &gt; NH4+ &gt; Cl− &gt; NO2− &gt; Ca2+ &gt; Mg2+. The OC/EC (6.54, 13.17, 8.95, 7.99) and Char-EC/Soot-EC (0.88, 0.64, 1.32, 3.74) indicated that the carbon aerosols mainly originated from coal combustion, biomass combustion, and motor-vehicle emissions. High concentrations of Cl− and Ca2+ in spring were associated with dust sources. A good correlation between Na+, SO42−, and NO3− suggests the formation of Na2SO4 and NaNO3. The results of PM2.5 source apportionment by positive matrix factorisation (PMF) showed five main sources: motor-vehicle sources (18–33%), secondary sources (16–36%), coal combustion sources (16–30%), biomass-combustion sources (10–28%), and dust sources (5–7%). Backward trajectory clustering analysis showed PM2.5 in spring and autumn were more influenced by medium distance and local air but mainly influenced by local sources in winter.

Comprehensive characterization of wintertime submicron aerosol in a Nordic town influenced by residential wood combustion, traffic and industrial sources

Anthropogenic particulate matter with sizes smaller than 1 μm (PM1) is a concerning air pollutant that can affect human health. In this study, we present PM1 measurements performed in a small town in northern Finland that is exposed to contrasting sources (residential wood burning, traffic, industrial activities). The study was conducted in winter 2021, with a mobile laboratory equipped with sophisticated on-line aerosol instrumentation. The results showed a significant increase in particulate mass and number concentrations from biomass burning in residential areas and town centre due to the high share of residences using biomass burning. Organics and equivalent black carbon (eBC) clearly dominated the PM1 composition during the highest pollution levels, followed by inorganics (sulfate, nitrate and ammonium). PAHs and a few elements (e.g. K, Cl, Zn) were as well higher during evening. A source apportionment confirmed the association between high PM1 values and biomass burning, even though the traffic contribution was also important. PM1 measurements at an industrial area showed an increase in sulfate, organics, eBC, and a few elements (e.g. Cl, Na, Fe), and characteristic size distributions. Simultaneous measurements of lung deposited surface area (LDSA) of particles showed the source-specificity of biomass burning, traffic and industrial emissions on LSDA size distributions. Overall, the results enlighten the impact of relevant pollution sources on Nordic towns air quality during the coldest months and show the importance to also consider the chemical composition, particle numbers, and LDSA in future air quality metrics.

Elemental composition of PM10 in indoor environments of a scientific research institution and risk assessment

ABSTRACT Synchronized indoor and outdoor sampling campaigns of PM10 were performed in two research laboratories and a mechanical workshop in Mexico City, during the dry cold season. The goals were to measure indoor and outdoor gravimetric mass and elemental concentrations, recognize the origin of particles, penetration toward the indoor environments, and assess inhalation, ingestion, and dermal absorption risks to human health. Concentrations of 18 elements were measured with X-ray Fluorescence; selected samples were studied with Scanning Electron Microscopy. Mass concentrations were higher outdoors than indoors and elemental concentrations were similar. Enrichment factors identified several geogenic elements. Cluster Analysis recognized common sources of elements and penetration of outdoor particles to indoor environments. Particles emitted indoors could be identified. Exposure to Mn, Fe, Ni, Cu, Zn, and Pb particles produced low health risks; Cr may only cause an ingestion risk. Only outdoor Mn and Ni Hazard Quotients are higher outdoors than indoors.

Intense Desert Dust Event in the Northern Adriatic (March 2020); Insights From the Numerical Model Application and Chemical Characterization Results

AbstractThe uncharacteristically extreme outbreak of particulate matter took place over the Balkan region from 27 to 30 March 2020. Observations at air quality stations in Croatia recorded hourly PM10 concentrations up to 412 μgm−3. The meteorological analysis shows that the increase in PM10 concentrations was primarily due to the advection of dust from the deserts east of the Caspian Sea. The anticyclone north of Croatia and the cyclone over Anatolia formed a strong pressure gradient driving transport from the east. Both back trajectories and satellite products pointed to the dry Aral Sea as the main source of dust. A dust plume influenced the PM10 increase observed in Croatia, starting at the easternmost air quality stations. The modeling study shows that the vertical extent of the dust plume was up to ∼2 km. However, the chemical and morphological (scanning electron microscope analysis) composition of PM10 at the sites in the northeastern Adriatic Sea showed mainly the presence of Saharan dust. Prior to the advection of the Asian dust, the transport of Saharan dust, driven by Sharav cyclone, was observed in the PM10 values at several stations in the Adriatic Sea and on the Croatian mainland on 26 March 2020. Modeling results showed that the Saharan dust transport occurred at altitudes below ∼8 km. The mixing of the Asian and Saharan dust plumes over the Balkans was favored by the subsidence due to anticyclonic high‐pressure conditions and is the most likely explanation for the observed PM chemical and morphological results.

Characteristics and health risk assessments of fine particulate matter at the overground and underground subway sites in Chengdu

Fine particulate matter (PM2.5) associated with toxic components in the subway system is likely to lead to various diseases, which has raised public concern, but it has not been explored deeply. Therefore, this study aimed to reveal the characteristics and health effects of the PM2.5 in the subway system. The PM2.5 samples were collected from ticket counters, platforms, and carriages in the overground and underground subway systems in Chengdu, and the composition of PM2.5 at different sites was detected. The pollution degree of toxic elements in PM2.5 and the health risks were evaluated. The results showed that the concentrations of PM2.5, some elements (e.g., arsenic, barium, chromium, copper, iron, manganese, nickel, and antimony), and total carbon at the underground sites were higher than those at the corresponding overground sites, respectively. The pollution extent at underground sites was more severe than that at overground sites according to pollution load index. The subway workers had potential non-carcinogenic risks. The total cancer risks for subway workers were at a moderate level, and for passengers were at a low level in most conditions. The contributions of arsenic to the hazard index and total cancer risk were 74.22%–81.5% and 79.4%–85.3%, respectively. Overall, underground platforms and carriages were the locations with the highest health risks for subway workers and passengers respectively. Subway workers faced higher health risks than passengers and arsenic was identified as the predominant risk element. These results provide basic data for future subway air quality improvement.

Mist cannon trucks can exacerbate the formation of water-soluble organic aerosol and PM2.5 pollution in the road environment

Abstract. Mist cannon trucks have been widely applied in megacities in China to reduce the road dust, since they are considered to be more water saving and efficient than the traditional sprinkling trucks. However, their effect on the formation of water-soluble organic compounds and the pollution control of fine particles (PM2.5) remains unknown. We characterized the variations of chemical compositions in PM2.5 collected on the road sides during the simulated operations of mist cannon truck and traditional sprinkling truck via Fourier transform ion cyclotron resonance mass spectrometry and ion chromatography. The mass concentrations of water-soluble organic carbon in PM2.5 showed a significant increase (62 %–70 %) after air spraying. Furthermore, we found that water-soluble organic compounds, particularly organic nitrates, increased significantly via the interactions of reactive gas-phase organics, atmospheric oxidants and aerosol liquid water after air spraying, although the air spraying had a better effect on suppressing road dust than the ground aspersion. Moreover, the formation of PM2.5 on the road segment where the mist cannon truck passed by was promoted, with an increase of up to 13 % in mass concentration after 25–35 min, on average. Thus, the application of mist cannon trucks potentially worsens the road atmospheric environment through the increase in PM2.5 levels and the production of a large number of water-soluble organic compounds in PM2.5. The overall results provide not only valuable insights to the formation processes of water-soluble organic compounds associated with aerosol liquid water in the road environment but also management strategies to regulate the operation of mist cannon trucks in China.

Three-dimensional label-free visualization of the interactions of PM2.5 with macrophages and epithelial cells using optical diffraction tomography

Particulate matter ≤ 2.5 µm (PM2.5) poses health risks related to various diseases and infections. However, the interactions between PM2.5 and cells such as uptake and cell responses have not been fully investigated despite advances in bioimaging techniques, because the heterogeneous morphology and composition of PM2.5 make it challenging to employ labeling techniques, such as fluorescence. In this work, we visualized the interaction between PM2.5 and cells using optical diffraction tomography (ODT), which provides quantitative phase images by refractive index distribution. Through ODT analysis, the interactions of PM2.5 with macrophages and epithelial cells, such as intracellular dynamics, uptake, and cellular behavior, were successfully visualized without labeling techniques. ODT analysis clearly shows the behavior of phagocytic macrophages and nonphagocytic epithelial cells for PM2.5. Moreover, ODT analysis could quantitatively compare the accumulation of PM2.5 inside the cells. PM2.5 uptake by macrophages increased substantially over time, but uptake by epithelial cells increased only marginally. Our findings indicate that ODT analysis is a promising alternative approach to visually and quantitatively understanding the interaction of PM2.5 with cells. Therefore, we expect ODT analysis to be employed to investigate the interactions of materials and cells that are difficult to label.

High contribution of new particle formation to ultrafine particles in four seasons in an urban atmosphere in south China

Ultra fine particles (UFP) cover the size range of both nucleation mode particles (NUC, Dp < 25 nm) and Aitken mode particles (AIT, 25 nm < Dp < 100 nm), and play important roles in radiative forcing and human health. In this study, we identified new particle formation (NPF) events and undefined events, explored their potential formation mechanism, and quantified their contributions to UFP number concentration (NUFP) in urban Dongguan of the Pearl River Delta (PRD) region. Field campaigns were carried out in four seasons in 2019 to measure particle number concentration in the size range of 4.7–673.2 nm, volatile organic compounds (VOCs), gaseous pollutants, chemical compositions in PM2.5, and meteorological parameters. The frequency of the occurrence of NPF, as indicated by a significant increase in NUC number concentration (NNUC), was 26 %, and that of the undefined event, as indicated by substantial increases in NNUC or AIT number concentration (NAIT), was 32 % during the whole campaign period. The NPF events mainly occurred in autumn (with a frequency of 59 %) and winter (33 %) and only occasionally in spring (4 %) and summer (4 %). On the contrary, the frequencies of the undefined events were higher in spring (52 %) and summer (38 %) than in autumn (19 %) and winter (22 %). The burst periods of the NPF events mainly occurred before 11:00 Local Time (LT), while those of the undefined events mainly occurred after 11:00 LT. Accompanied to NPF events were low concentrations of VOCs and high concentrations of O3. The undefined events by NUC or AIT were associated with the upwind transport of newly formed particles. Source apportionment analysis suggested that NPF and undefined events were the largest contributor to NNUC (51 ± 28 %), NAIT (41 ± 26 %), and NUFP (45 ± 27 %), while coal combustion and biomass burning, and traffic emission were the second largest contributor to NNUC (22 ± 20 %) and NAIT (39 ± 28 %), respectively.

119 Differential Alveolar Toxicity of Exhaust and Non-Exhaust Fine Particulate Matter

Abstract Introduction Airborne fine particulate matter (diameter &amp;lt;2.5μm; PM2.5) is a leading risk factor for ill health and premature death. Road vehicle technology is decreasing exhaust-derived PM emissions but poorly characterised, unregulated non-exhaust PM persists. This study aimed to characterise the toxicology of brakewear PM2.5 (BWPM) from 4 brakepad types, and roadwear PM, compared to diesel exhaust PM2.5 (DEP). Methods An alveolar type-II epithelial cell line (ATIIER:KRASv12) was exposed to 3.9-31.6µg/cm2 PM2.5 generated from 4 brake pad types (low-metallic/semi-metallic/non-asbestos organic [NAO]/ceramic), roadwear, or DEP for 2-24h. PM composition was determined by ICP-MS, cytotoxicity by LDH and MTT assays, cytokine release by ELISA, gene expression by RT-qPCR and RNA-Seq, and protein expression by western blot. Results NAO and ceramic BWPM, enriched in copper and zirconium, exerted greatest increases in cytotoxicity, cytokine release (IL-6: NAO 26-fold, ceramic 20-fold; p&amp;lt;0.05), and oxidative stress-related (HMOX1 – NAO 28-fold, ceramic 26-fold, p&amp;lt;0.001) and metal homeostasis genes (MT1G: NAO 197-fold, ceramic 183-fold; p&amp;lt;0.001), consistently greater than roadwear PM or DEP. Amelioration by copper-chelating tetraethylenepentamine implicated BWPM copper. RNA-Seq showed NAO and ceramic BWPM induced most differentially expressed genes vs. control, related to inflammatory, oxidative stress, heat-shock, and hypoxia responses. Effects on hypoxia signalling were confirmed through HIF1α western blot and HIF-signalling reporter assay. Conclusions NAO and ceramic BWPM were the most potent across multiple endpoints. Future work will study the relevance of HIF-related responses, which have been implicated in fibrotic lung disease. Understanding source-dependent toxicity may facilitate manufacturing- and healthcare-related mitigation of PM toxicity.

75 Effect of Atmospheric Aging on Soot Particle Toxicity in Airway Epithelial-Endothelial Co-Culture Models at the Air–Liquid Interface

Abstract Secondary organic aerosols (SOAs) formed from anthropogenic or biogenic volatile precursors in the atmosphere substantially contribute to the ambient fine particulate matter (PM2.5) burden, which has been associated with adverse human health effects. However, there is only limited evidence of their differential toxicological impact. To study those effects, we generated different aerosols by atmospheric aging of volatile biogenic (β-pinene) or anthropogenic (naphthalene) precursors of SOA that condensed on soot particles (SPs). In-depth, physicochemical aerosol characterization revealed very similar physical properties for SOAβPIN-SP and SOANAP-SP, but distinct differences in chemical composition. For example, SOANAP-SP was associated with the formation of more oxidized and more aromatic SOAs with a higher oxidative potential compared to β-pinene. By exposing a co-culture model system consisting of lung epithelial cells (A549) and endothelial cells (EA.hy926) at the air-liquid interface to different aerosol concentrations, we aimed to discriminate toxicological effects. Integrated transcriptomic and metabolomics analysis revealed induction of stress-related airways remodeling and an early type I immune response, for the A549 cells, especially after the exposure to SOANAP-SP. The underlying EA.hy926 cells showed similar transcriptomic changes in early response genes and genes related to cardiovascular pathologies after exposure to both SOA types, however to a greater extent after SOANAP-SP. While fresh SP without coating by SOA evinced only minor changes in both cell lines. Altogether, this supports the assumption of a pivotal role of atmospheric chemistry and the chemical PM composition on the toxicological outcomes and highlights the importance of organic compounds on cellular effects.

Chemical-composition characteristics of PM1 and PM2.5 and effects on pH and light-extinction coefficients under different pollution levels in Zhengzhou, China

Atmospheric particulate matter (PM) is a significant pollutant in the atmosphere. An increase in PM2.5 concentration notably diminishes atmospheric visibility and leads to haze formation. PM1, a type of atmospheric PM with smaller particle size, has a more pronounced effect on visibility and aerosol pH compared to PM2.5. In this study, PM1 and PM2.5 samples were collected in August, November, and December of 2020, as well as in April of 2021 in Zhengzhou. The chemical composition, aerosol pH, and light-extinction coefficients (bext) of PM1 and PM2.5 were analyzed based on the aerosol concentrations in three pollution categories. Throughout the sampling period, the average mass concentrations of PM1 and PM2.5 were 56.2 and 71.9 μg m−3, respectively, with nitrate constituting 24.3% of PM2.5. This highlights the severe submicron-level particulate pollution in Zhengzhou. Differences in the composition of PM1 and PM2.5 led to variations in aerosol water content, but the combined effect on aerosol pH was minimal. PM1 displayed a stronger negative correlation with visibility because SNA (NO3−, SO42−, and NH4+) was primarily concentrated in PM1. The bext of nitrate consistently increased during the pollution period, reaching 58% during the moderate pollution phase. This result suggests that the extinction contribution of nitrate was the main factor contributing to the decreased visibility in Zhengzhou. Reducing nitrogen oxide emissions can lower PM2.5 concentrations and enhance visibility. Additionally, controlling nitrate production can achieve a secondary reduction in aerosol concentration by decreasing the aerosol water content, which in turn reduces the secondary formation of PM. This study is beneficial for formulating measures to reduce the concentration of PM2.5 and reducing pollution.

Decryption analysis of antimony pollution sources in PM2.5 through a multi-source isotope mixing model based on lead isotopes

Antimony (Sb) in PM2.5 has attracted close attention as a new air pollutant due to its extensive use in daily life. The identification of antimony sources in PM2.5 by scientific methods is important to control its pollution. In this study, the Sb and other elements concentrations and Pb isotopic compositions in PM2.5 and possible pollution sources (soil, road dust, traffic emission, coal-fired fly ash, local factory emission dust and cement dust) were analyzed. The results showed that the Sb in the PM2.5 samples had seasonal change. The enrichment factors of Sb in PM2.5 samples were all above 100 in four seasons, which indicated anthropogenic pollution. The average value of potential ecological risk index was at extremely high-risk level greater than 320. Based on Pearson correlation coefficient and hierarchical cluster analysis results, the pollution sources of antimony and lead in PM2.5 samples were highly consistent which means that Pb isotopes might be a new and feasible tracer for Sb pollution in air. The sources analysis results based on Pb isotopes indicated that the proportion of Pb and Sb from coal-fired fly ash was the highest in winter (47.7%) and inclined to road dust in spring (34.5%), but it was mainly from traffic emissions in summer and autumn (34.2% and 32.8%). This study showed that Pb isotope tracing can be applied to predict the potential pollution sources, and it was also a feasible substitute for tracing Sb pollution in PM2.5.

Cognitive Development and Prenatal Air Pollution Exposure in the CHAMACOS Cohort.

Because fine particulate matter [PM, with aerodynamic diameter ()] is a ubiquitous environmental exposure, small changes in cognition associated with exposure could have great societal costs. Prior studies have demonstrated a relationship between in utero exposure and cognitive development in urban populations, but it is not known whether these effects are similar in rural populations and whether they persist into late childhood. In this study, we tested for associations between prenatal exposure and both full-scale and subscale measures of IQ among a longitudinal cohort at age 10.5 y. This analysis used data from 568 children enrolled in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS), a birth cohort study in California's agricultural Salinas Valley. Exposures were estimated at residential addresses during pregnancy using state of the art, modeled surfaces. IQ testing was performed by bilingual psychometricians in the dominant language of the child. A higher average over pregnancy was associated with full-scale IQ points [95% confidence interval (CI): , ], with decrements specifically in Working Memory IQ (WMIQ) and Processing Speed IQ (PSIQ) subscales [WMIQ (95% CI: , ) and PSIQ (95% CI: , 0.16)]. Flexible modeling over the course of pregnancy illustrated mid-to-late pregnancy (months 5-7) as particularly susceptible times, with sex differences in the timing of susceptible windows and in which subscales were most affected [Verbal Comprehension IQ (VCIQ) and WMIQ in males; and PSIQ in females]. We found that small increases in outdoor exposure in utero were associated with slightly lower IQ in late childhood, robust to many sensitivity analyses. In this cohort there was a larger effect of on childhood IQ than has previously been observed, perhaps due to differences in PM composition or because developmental disruption could alter the cognitive trajectory and thus appear more pronounced as children get older. https://doi.org/10.1289/EHP10812.

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 PM2.5 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 PM2.5 was assessed for 24 elements (by PIXE), secondary inorganic ions and black carbon. The PM2.5 mean concentration for the period (December 2019 to November 2020) was 13 ± 11 μg.m−3. The most abundant species in PM2.5 were BC (19.9%), SO42− (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 PM2.5 components, except Al, Ba, Ca, Si and SO42−, 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. PM2.5 levels and composition also varied with the types of air mass trajectories.

Source apportionment of ambient PM2.5 in an industrialized city using dispersion-normalized, multi-time resolution factor analyses

Ambient fine particulate matter (PM2.5) data were collected in the lower City of Hamilton, Ontario to apportion the sources of this pollutant over an 18-month period. Hamilton has complex topographical features that may result in worsened air pollution within the lower city, thus, dispersion-normalized, multi-time resolution factor analysis (DN-MT-FA) was used to identify and quantify contributions of factors in a manner that reduced the influence of local meteorology. These factors were secondary organic aerosols type 1 (SOA_1), particulate nitrate (pNO3), particulate sulphate (pSO4), primary traffic organic matter (PTOM), Steel/metal processing and vehicular road dust emissions (Steel & Mobile) and, secondary organic aerosols type 2 (SOA_2) with origins ranging from mainly regional to mainly local. Factors that were mainly local (PTOM, Steel & Mobile, SOA_2) contributed up to 17% of the average PM2.5 mass while mixed local/regional factors (pNO3, pSO4) made up 43% on average, indicating the potential for further reduction of harmful PM concentrations locally. Of particular interest from a health protection perspective, was the composition of PM2.5 on days when an exceedance of the 24-hr WHO air quality guideline for this pollutant was observed. In general, SOA_1 was found to drive summer exceedances while pNO3 dominated in the winter. During the summer period, SOA_1 was attributable to wildfires in the northern parts of Canada while local traffic sources in winter contributed to the high levels of pNO3. While local, industrial factors only had minor relative mass contributions during exceedances, they are high in highly oxidized organic species (SOA_2) and toxic metals (Steel & Mobile). Thus, they are likely to have more impacts on human health. The methods and results described in this work will be useful in understanding prevalent sources of particulate matter pollution in the ambient air in the presence of complex topography and meteorological effects.

Fungal aerosols in rabbit breeding environment: Metagenetic insight into PM2.5 based on third-generation sequencing technology

Fungal aerosols are a vital environmental hazard factor impeding the development of the rabbit breeding industry and threatening public health. This study aimed to determine fungal abundance, diversity, composition, diffusion, and variability in aerosols in rabbit breeding environments. Twenty PM2.5 filter samples were collected from five sampling sites (i.e. En5, In, Ex5, Ex15, and Ex45) in a modern rabbit farm in Linyi City, China. Fungal component diversity at the species level was analyzed in all samples using third-generation sequencing technology. Results revealed that fungal diversity and community composition in PM2.5 significantly differed across different sampling sites, and different pollution levels. The highest concentrations of PM2.5 and fungal aerosols (i.e., 102.5 μg/m3 and 18.8 × 103 CFU/m3, respectively) were found at Ex5, and these concentrations were found to decrease as the distance from the exit increased. However, no significant correlation was observed between the internal transcribed spacer (ITS) gene abundance and overall PM2.5 levels, except for Aspergillus ruber and Alternaria eichhorniae. Although most fungi are not pathogenic to humans, zoonotic pathogenic microorganisms that cause pulmonary aspergillosis (e.g., Aspergillus ruber) and invasive fusariosis (e.g., Fusarium pseudensiforme) were observed. The relative abundance of A. ruber was higher at Ex5 than that at In, Ex15, and Ex45 (p < 0.01), and the relative abundance of the fungal species decreased with an increase in distance from the rabbit houses. Moreover, four potential novel strains of Aspergillus ruber were discovered, with 82.9%–90.3% of the nucleotide and amino acid sequences similar to those of reference strains. This study highlights the importance of rabbit environments as a source in shaping fungal aerosol microbial communities. To the best of our knowledge, this is the first study to uncover the initial characteristics of fungal biodiversity and dispersion of PM2.5 in rabbit breeding environments, contributing to infectious disease control and prevention in rabbits.

Elemental composition and origin of PM10 in a fire station in Poland. Real-time results from the XRF analysis

Elemental composition and origin of PM10 in a fire station in Poland. Real-time results from the XRF analysis

Comparison of PM2.5 Monitoring Data Using Light Scattering and Beta Attenuation Methods: A Case Study in Seoul Metro Subway

A study on monitoring PM2.5 concentrations at an underground subway station using light scattering and beta attenuation methods was conducted. Six optical particle counters (OPCs), which were representative of the light scattering method and had 16 size channels, were installed at different sampling sites in the waiting room and platforms to compare PM2.5 concentrations, determine PM2.5 /PM10 ratios, and characterize the size distribution based on particle number. In terms of the beta attenuation method, a beta-ray attenuation monitor (BAM) was set up at the platform to compare it with OPCs for one month. It was found that 1h-average PM2.5 concentrations varied at different sampling sites depending on PM composition, while 24h-average PM2.5 concentrations were independent of the sampling sites. There was a significant difference between the means of 1h-average PM2.5 concentrations observed by the BAM and OPC when PM2.5 contributed to less than 50% or higher than 80% of PM10. In contrast, the 24h-average PM2.5 concentrations observed by the BAM and OPC showed the same patterns as each other with an insignificant difference. Therefore, an OPC can be used to monitor the 24h-average PM2.5 concentration in an underground subway station. However, the use of OPC to measure the 1h-average PM2.5 concentration should consider PM composition and other factors. In addition, more frequent calibration is needed on a regular basis.