Tire Wear Chemicals in the Urban Atmosphere: Significant Contributions of Tire Wear Particles to PM2.5.

Tire wear particles (TWPs) containing tire wear chemicals (TWCs) are of global concern due to their large emissions and potential toxicity. However, TWP contributions to urban fine particles are poorly understood. Here, 72 paired gas-phase and PM2.5 samples were collected in the urban air of the Pearl River Delta, China. The concentrations of 54 compounds were determined, and 28 TWCs were detected with total concentrations of 3130-317,000 pg/m3. Most p-phenylenediamines (PPDs) were unstable in solvent, likely leading to their low detection rates. The TWCs were mainly (73 ± 26%) in the gas phase. 2-OH-benzothiazole contributed 82 ± 21% of the gas-phase TWCs and benzothiazole-2-sulfonic acid contributed 74 ± 18% of the TWCs in PM2.5. Guangzhou and Foshan were "hotspots" for atmospheric TWCs. Most TWC concentrations significantly correlated with the road length nearby. More particulate TWCs were observed than model predictions, probably due to the impacts of nonexchangeable portion and sampling artifacts. Source apportionment combined with characteristic molecular markers indicated that TWPs contributed 13 ± 7% of urban PM2.5. Our study demonstrates that TWPs are important contributors to urban air pollution that could pose risks to humans. There is an urgent need to develop strategies to decrease TWP emissions, along with broader urban air quality improvement strategies.

Ambient air pollution and survival in childhood cancer: A nationwide survival analysis.

BACKGROUND: Particulate matter consisting of fine particles measuring 2.5 microns or less in diameter (PM2.5), a component of air pollution, has been linked to adverse health outcomes. The objective of this study was to assess the association between ambient PM2.5 exposure and survival in children with cancer in the United States. METHODS: Individuals aged birth to 19 years who were diagnosed with cancer between January 1, 2004, and December 31, 2019, were selected from the National Cancer Database. The association between the annual PM2.5 level at the patient's zip code of residence at the time of diagnosis and overall survival was evaluated using time-varying Cox proportional hazards models (crude and adjusted for diagnosis year and age). To address concerns that exposure to air pollution is correlated with other social determinants of health, the authors tested the association between PM2.5 levels and survival among sociodemographic subgroups. RESULTS: Of the 172,550 patients included, 27,456 (15.9%) resided in areas with annual PM2.5 concentrations above the US Environmental Protection Agency (EPA) annual PM2.5 standard of 12 µg/m3. Residing in these high-pollution areas was associated with worse overall survival (adjusted hazard ratio [aHR], 1.06; 95% confidence interval [CI], 1.012-1.10). Similarly, when PM2.5 was evaluated as a linear measure, each unit increase in PM2.5 exposure was associated with worse survival (aHR, 1.011; CI, 1.005-1.017). Exposure to PM2.5 at levels above the EPA standards was also significantly associated with worse overall survival among sociodemographic subgroups. CONCLUSIONS: Exposure to PM2.5 was significantly associated with worse overall survival among children with cancer, even at levels below EPA air quality standards. These results underscore the importance of setting appropriate air quality standards to protect the health of this sensitive population. PLAIN LANGUAGE SUMMARY: The authors investigated how living in areas with high air pollution (defined as particulate matter consisting of fine particles measuring 2.5 microns or less in diameter; PM2.5) affects the overall survival of children with cancer in the United States. The results indicated that children living in areas with higher PM2.5 levels, and even at levels below prior and current US Environmental Protection Agency standards, had lower survival rates than children living in areas with lower levels of PM2.5. This finding emphasizes the need for stricter air quality standards to better protect children, particularly those with serious health conditions like childhood cancer.

Enhancement of fine particle removal through flue gas cooling in a spray tower with packing materials.

The efficient removal of fine particles from coal-fired flue gas poses challenges for conventional electrostatic precipitators and bag filters. Recently, a novel approach incorporating deep cooling of the flue gas has been proposed to enhance the removal of gaseous pollutants and particles. However, the achievable efficiency and underlying mechanisms of particle capture within the gas cooling system remain poorly understood. This study aims to elucidate the effectiveness of gas cooling in enhancing the removal of particles through a laboratory-scale spray tower equipped with packing materials. The results demonstrate a significant increase in particle removal efficiency, from 63.4 % to over 98 %, as the temperature of the spray liquid decreases from 20℃ to -20℃. Notably, this enhancement is particularly pronounced for particles sized 0.1-1 µm, with efficiency rising from approximately 40 % to 95 %, effectively eliminating the penetration window. Moreover, we find that the spray flow rate positively influences particle removal capability, while the height of the packing section exhibits an optimal value. Beyond this optimal height, particle removal performance may decline due to an inadequate liquid-to-packing ratio. To provide insight into the capture process, we introduce a single-droplet model demonstrating that particle capture is primarily enhanced through the augmented thermophoretic force.

Residential radon decay products are associated with cough and phlegm in patients with COPD.

Radon decay products attach to particulate matter (referred to as particle radioactivity, PR) has been shown to be potential to promote airway damage after inhalation. In this study, we investigated associations between PR with respiratory symptoms and health-related quality of life (HRQL) in patients with COPD. 141 male patients with COPD, former smokers, completed the St. George's Respiratory Questionnaire (SGRQ) after up to four 1-week seasonal assessments (N=474) of indoor (home) and ambient (central site) particulate matter ≤ 2.5 µm in diameter (PM2.5) and black carbon (BC). Indoor PR was measured as α-activity (radiation) on PM2.5 filter samples. The ratio of indoor/ambient sulfur in PM2.5 (a ventilation surrogate) was used to estimate α-PR from indoor radon decay. SGRQ responses assessed frequent cough, phlegm, shortness of breath, wheeze, and chest attacks in the past 3 months. Multivariable linear regression with generalized estimating equations accounting for repeated measures was used to explore associations, adjusting for potential confounders. Median (IQR) indoor α-PR was 1.22 (0.62) mBq/m3. We found that there were positive associations between α-PR with cough and phlegm. The strongest associations were with estimated α-PR of indoor origin for cough (31.1 % increase/IQR, 95 %CI: 8.8 %, 57.8 %), and was suggestive for phlegm (13.0 % increase/IQR, 95 %CI: -2.5 %, 31.0 %), similar adjusting for indoor BC or PM2.5. α-PR of indoor origin was positively associated with an increase in SGRQ Symptoms score [1.2 units/IQR; 95 %CI: -0.3, 2.6] that did not meet conventional levels of statistical significance. Our results suggested that exposure to indoor radon decay products measured as particle radioactivity, a common indoor exposure, is associated with cough, and suggestively associated with phlegm and worse HRQL symptoms score in patients with COPD.

Quantifying the impact of damming on phosphorus reallocation: Finer particles offset the reduction in soluble reactive phosphorus (SRP) by decreasing suspended sediment concentration.

In this research, an innovative approach to quantify the impact of damming on phosphorus (P) reallocation between suspended sediments (SS) and water was proposed. P allocation can be described by the surface complexation model, with the impact of damming quantified by four variables: P load, suspended sediment concentration (SSC), particle size, and pH. Iron/aluminium (Fe/Al) oxide-adsorbed P (Fe/Alo-P) was identified as the exchangeable P during adsorption/desorption equilibrium with a series of heterogeneous sediment samples from two large Asian rivers, the Mekong River and the Yellow River. In both rivers, the Fe/Alo-P concentration increased from the tail towards the dam of the reservoirs, primarily attributed to the decrease in particle size from the tail towards the dam of the reservoirs. The Fe/Alo-P concentration in the Lancang River was higher than that in the Yellow River, ranging from 14.5 to 119.9 mg kg-1 and from 14.5 to 22.1 mg kg-1, respectively. The soluble reactive P (SRP) concentration decreased with decreasing SSC, while finer suspended sediment particles containing more Fe/Alo-P greatly offset the reduction in SRP concentration. When the maximum Fe/Alo-P concentration in the finest particles of SS was assumed to be 100 mg kg-1, the P equilibrium concentration (ce) decreased from 0.028 mg L-1 to 0.008 mg L-1 when the SSC decreased from 64 g L-1 to 1 g L-1 for SS with a median grain size (D50) of 32 µm and an Fe/Alo-P concentration of 11 mg kg-1. However, ce increased from 0.008 mg L-1 to 0.021 mg L-1 when the D50 of SS decreased from 32 µm to 4 µm with an SSC of 1 g L-1 and an Fe/Alo-P concentration of 76 mg kg-1 for 4-µm SS. The SRP concentration is sensitive to the Fe/Alo-P concentration in SS, and the P allocation ratio between sediments and water is comparable.

Hyperlocal Air Pollution Mapping: A Scalable Transfer Learning LUR Approach for Mobile Monitoring.

Addressing the challenge of mapping hyperlocal air pollution in areas without local monitoring, we evaluated unsupervised transfer learning-based land-use regression (LUR) models developed using mobile monitoring data from other cities: CORrelation ALignment (Coral) and its inverse distance-weighted modification (IDW_Coral). These models mitigated domain shifts and transferred patterns learned from mobile air quality monitoring campaigns in Copenhagen and Rotterdam to estimate annual average air pollution levels in Amsterdam (50m road segments) without involving any Amsterdam measurements in model development. For nitrogen dioxide (NO2), IDW_Coral outperformed Copenhagen and Rotterdam LUR models directly applied to Amsterdam, achieving MAE (4.47 µg/m3) and RMSE (5.36 µg/m3) comparable to a locally fitted LUR model (AMS_SLR) developed using Amsterdam mobile measurements collected for 160 days. IDW_Coral yielded an R2 of 0.35, similar to that of the AMS_SLR based on 20 collection days, suggesting a minimum requirement of 20-day mobile monitoring to capture city-specific insights. For ultrafine particles (UFP), IDW_Coral's citywide predictions strongly correlated with previously published mixed-effect models fitted with 160-day Amsterdam measurements (Pearson correlation of 0.71 for UFP and 0.72 for NO2). IDW_Coral demands no direct measurements in the target area, showcasing its potential for large-scale applications and offering significant economic efficiencies in executing mobile monitoring campaigns.

Tracking fine particles in urban and rural environments using honey bees as biosamplers in Mexico.

This work explores the efficiency of honey bees (Apis mellifera) as biosamplers of metal pollution. To understand this, we selected two cities with different urbanization (a medium-sized city and a megacity), and we collected urban dust and honey bees captured during flight. We sampled two villages and a university campus as control areas. The metal content in dust was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Atomic Force Microscopy (AFM) and Scanning electron microscopy (SEM) were used to investigate the shape and size distribution of the particles, and to characterize the semiquantitative chemical composition of particles adhered to honey bee's wings. Principal Component Analysis (PCA) shows a distinctive urban dust geochemical signature for each city, with component 1 defining V-Cr-Ni-Tl-Pt-Pb-Sb as characteristic of Mexico City and Ce-As-Zr for dust from Hermosillo. Particle count using SEM indicates that 69% and 63.4% of the resuspended dust from Hermosillo and Mexico City, respectively, corresponds to PM2.5. Instead, the particle count measured on the honey bee wings from Hermosillo and Mexico City is mainly PM2.5, 91.4% and 88.9%, respectively. The wings from honey bees collected in the villages and the university campus show much lower particle amounts. AFM-histograms confirmed that the particles identified in Mexico City have even smaller sizes (between 60 and 480 nm) than those in Hermosillo (between 400 and 1400 nm). Particles enriched in As, Zr, and Ce mixed with geogenic elements such as Si, Ca, Mg, K, and Na dominate honey bee' wings collected in Hermosillo. In contrast, those particles collected from Mexico City contain V, Cr, Ni, Tl, Pt, Pb, and Sb. Such results agree with the urban dust data. This work shows that honey bees are suitable biosamplers for the characterization of fine dust fractions by microscopy techniques and reflect the urban pollution of the sites.

Temporal variations and chemical characteristics of marine PM2.5 at Dongsha Islands, South China Sea: Three-year measurement.

The study of long-range transport effects on marine fine particles (PM2.5), particularly in remote sites such as the Dongsha Islands, is pivotal for advancing our understanding of air pollution dynamics on a regional scale and for formulating effective environmental policies. PM2.5 concentrations were examined over three consecutive years and grouped based on their transport routes. The backward trajectory simulation revealed that high PM2.5 concentrations were observed in the West Channel, originating from North and Central China, the Korean Peninsula, and the Japanese Islands, opposed to the East Channel. High PM2.5 concentrations, commonly observed in winter and spring, were mainly attributed to the Asian Northeastern Monsoons. Water-soluble inorganic ions constituted the major components, accounting for 37.8-48.7% of PM2.5, and followed by metal elements (15.5-20.0%), carbons (7.5-13.3%), levoglucosan (0.01-0.17%), and organic aerosols (0.2-2.2%). Secondary inorganic aerosols as the dominant source accounted for 8.3-24.7% of PM2.5, while sea salts were the secondary major contributor. High levoglucosan contribution (3.8-7.2%) in winter and spring was attributed to biomass burning, mainly from the Indochina Peninsula. Chemical mass balance receptor modeling resolved that major sources of PM2.5 were secondary sulfate, sea salts, fugitive dust, and industrial boilers. This study concluded that the long-range transport of PM2.5 gradually increased since fall, contributing 52.1-74.3%, highlighting its substantial impact on PM2.5 in all seasons except summer.

Sources, trigger points, and effect size of associations between PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) and fractional exhaled nitric oxide (FeNO): A panel study with 16 follow-up visits over 4 years.

Exposure to fine particulate matter (PM2.5) is a significant concern for respiratory health. However, the sources, trigger points, and effect size of specific associations between PM2.5 components, particularly polycyclic aromatic hydrocarbons (PAHs) and the airway inflammatory marker fractional exhaled nitric oxide (FeNO) have not been fully explored. In this study, 69 healthy college students were enrolled and followed up 16 times from 2014 to 2018. Individual FeNO was measured and ambient air PM2.5 samples were collected for 7 consecutive days before each follow-up. PAHs were quantified using Gas Chromatography-Mass Spectrometry. Linear mixed-effect regression models were employed to evaluate the associations between PM2.5-bound PAHs and FeNO. Additionally, PMF (Positive Matrix Factorization) was utilized to identify sources of PM2.5-bound PAHs and assess their impact on FeNO. Throughout the study, the average (SD) of ΣPAHs concentrations was 78.50 (128.9) ng/m3. PM2.5 and PM2.5-bound PAHs were significantly associated with FeNO at various lag days. Single-day lag analyses revealed maximum effects of PM2.5 on FeNO, with an increase of 7.71% (95% CI: 4.67%, 10.83%) per interquartile range (IQR) (48.10 µg/m3) increase of PM2.5 at lag2, and ΣPAHs showed a maximum elevation in FeNO of 6.40% (95% CI: 2.33%, 10.63%) at lag4 per IQR (57.39 ng/m3) increase. Individual PAHs exhibited diversity peak effects on FeNO at lag3 (6 of 17), lag4 (9 of 17) in the single-day model, and lag0-5 (8 of 17) (from lag0-1 to lag0-6) in the cumulative model. Source apportionment indicated coal combustion as the primary contributor (accounting for 30.7%). However, a maximum effect on FeNO (an increase of 21.57% (95% CI: 13.58%, 30.13%) per IQR increase) was observed with traffic emissions at lag4. The findings imply that strategic regulation of particular sources of PAHs, like traffic emissions, during specific periods could significantly contribute to safeguarding public health.

Mortality burden of cardiovascular disease attributable to ambient PM2.5 exposure in Portugal, 2011 to 2021.

BACKGROUND: Exposure to high levels of environmental air pollution causes several health outcomes and has been associated with increased mortality, premature mortality, and morbidity. Ambient exposure to PM2.5 is currently considered the leading environmental risk factor globally. A causal relationship between exposure to PM2.5 and the contribution of this exposure to cardiovascular morbidity and mortality was already demonstrated by the American Heart Association. METHODS: To estimate the burden of mortality attributable to environmental risk factors, a comparative risk assessment was performed, considering a "top-down" approach. This approach uses an existing estimate of mortality of the disease endpoint by all causes as a starting point. A population attributable fraction was calculated for the exposure to PM2.5the overall burden of IHD and stroke was multiplied by the PAF to determine the burden attributable to this risk factor. The avoidable burden was calculated using the potential impact fraction (PIF) and considering the WHO-AQG 2021 as an alternative scenario. RESULTS: Between 2011 and 2021, the ambient exposure to PM2.5 resulted in a total of 288,862.7 IHD YLL and a total of 420,432.3 stroke YLL in Portugal. This study found a decreasing trend in the mortality burden attributable to PM2.5 exposure, for both males and females and different age-groups. For different regions of Portugal, the same trend was observed in the last years. The mortality burden attributable to long-term exposure to PM2.5 was mainly concentrated in Lisbon Metropolitan Area, North and Centre. Changes in the exposure limits to the WHO recommended value of exposure (WHO-AQG 2021) have a reduction in the mortality burden due to IHD and stroke attributable to PM2.5 exposure, in Portugal. CONCLUSION: Between 2011 and 2021, approximately 22% and 23% of IHD and stroke deaths were attributable to PM2.5 exposure. Nevertheless, the mortality burden attributable to cardiovascular diseases has been decreasing in last years in Portugal. Our findings provide evidence of the impact of air pollution on human health, which are crucial for decision-making, at the national and regional level.

[Water-soluble Inorganic Ion Content of PM2.5 and Its Change Characteristics in Urban Area of Beijing in 2022].

To explore the content and variation characteristics of water-soluble ions of atmospheric fine particles (PM2.5) in a Beijing urban area and put forward the pollution prevention and control scheme, the water-soluble ions, gaseous precursors (SO2, NO2), and meteorological factors (temperature, RH) of PM2.5 in 2022 were analyzed and determined. The results showed that the water-soluble ions with the highest proportion in PM2.5 in the Beijing City urban area were NO3-, NH4+, and SO42-, accounting for 52.7% of PM2.5. The mass concentrations of PM2.5 and SNA were lower than the historical results, whereas the proportion of SNA, SOR, and NOR was higher than the historical results. This showed that the fine particulate matter pollution in Beijing has been significantly improved, but it still has strong secondary pollution characteristics. NO3-/SO42-(2.2) was higher than those of historical and nearby provinces and cities, reflecting the expanding influence of mobile sources. In terms of seasonal variation, PM2.5 showed the characteristic of high in autumn and low in summer. The proportion of NO3- was the highest in autumn, spring, and winter; the proportion of SO42- was the highest in summer; and the proportion of NH4+ changed little in each season. The seasonal variation rules of NOR and SOR were almost opposite, which reflected the difference in transformation factors between NOR and SOR. The main forms of SNA in the Beijing urban area were NH4NO3 and (NH4)2SO4. The neutralization degree of cations and anions was the highest in winter, the cation NH4+ was slightly insufficient in summer, and NH4+ was in excess in spring and autumn. The Beijing urban area was an ammonia-rich environment. In terms of pollution level, RH, particulate matter moisture, and water-soluble ions mass concentration all increased with the increase in pollution level, and SNA increased fastest, with its proportion in PM2.5 increasing first and then stabilizing, whereas the contribution rate of other water-soluble ions decreased gradually. In terms of spatial distribution, the mass concentration relationship of SNA at the central urban area and suburbs was NO3- > SO42- > NH4+, which reflected the pollution characteristics dominated by NO3-. The highest contribution rate of SNA to PM2.5 occurred in the eastern region, the central urban area, and the transmission point, indicating that the secondary reaction was relatively active in the central urban area and the eastern region, and the regional transport was also an important source of secondary ions.

Impacts of ship emissions and sea-land breeze on urban air quality using chemical characterization, source contribution and dispersion model simulation of PM2.5 at Asian seaport.

Fine particulate matter (PM2.5) emitted from marine transportation, bulk materials handling at the docks, and dust dispersion has garnered increased attention, particularly in the interface between port and urban areas. This study explored the inter-transport of PM2.5 between Kaohsiung Harbor and neighboring Metro Kaohsiung. Chemical analyses of PM2.5 samples from four sites include water-soluble ions, metallic elements, carbons, anhydrosugars, and organic acids to establish PM2.5's chemical fingerprints. The CALPUFF air dispersion model is employed to simulate the spatiotemporal distribution of PM2.5 in Kaohsiung Harbor and adjacent urban areas. A clear seasonal and diurnal variation of PM2.5 concentrations and chemical composition was observed in both harbor and urban areas. The high correlation of nighttime PM2.5 levels between the port and urban areas suggests inter-transport phenomena. Sea salt spray, ship emissions, secondary aerosols, and heavy fuel-oil boilers exhibit higher levels in the port area than in the urban area. In Metro Kaohsiung, mobile sources, fugitive dust, and waste incinerators emerge as major PM2.5 contributors. Furthermore, sea breeze significantly influences PM2.5 dispersion from Kaohsiung Harbor to Metro Kaohsiung, particularly in the afternoon. The average contribution of PM2.5 from ships' main engines in Kaohsiung Harbor ranges from 2.9% to 5.3%, while auxiliary engines contribute 3.8%-8.3% of PM2.5 in Metro Kaohsiung.

New health index derived from oxidative potential and cell toxicity of fine particulate matter to assess its potential health effect.

Toxicological data and exposure levels of fine particulate matters (PM2.5) are necessary to better understand their health effects. Simultaneous measurements of PM2.5 oxidative potential (OP) and cell toxicity in urban areas (Beijing, China and Gwangju, Korea) reveal their dependence on chemical composition. Notably, acids (Polar), benzocarboxylic acids, and Pb were the chemical components that affected both OP and cell toxicity. OP varied more significantly among different locations and seasons (winter and summer) than cell toxicity. Using the measured OP, cell toxicity, and PM2.5 concentration, a health index was developed to better assess the potential health effects of PM2.5. The health index was related to the sources of PM2.5 derived from the measured chemical components. The contributions of secondary organic aerosols and dust to the proposed health index were more significant than their contributions to PM2.5 mass. The developed regression equation was used to predict the health effect of PM2.5 without further toxicity measurements. This new index could be a valuable health metric that provides information beyond just the PM2.5 concentration level.

Insights into PM2.5 pollution of four small and medium-sized cities in Chinese representative regions: Chemical compositions, sources and health risks.

Fine particles (PM2.5) pollution is still a severe issue in some cities in China, where the chemical characteristics of PM2.5 remain unclear due to limited studies there. Herein, we focused on PM2.5 pollution in small and medium-sized cities in key urban agglomerations and conducted a comprehensive study on the PM2.5 chemical characteristics, sources, and health risks. In the autumn and winter of 2019-2020, PM2.5 samples were collected simultaneously in four small and medium-sized cities in four key regions: Dingzhou (Beijing-Tianjin-Hebei region), Weinan (Fenwei Plain region), Fukang (Northern Slope of the Tianshan Mountain region), and Bozhou (Yangtze River Delta region). The results showed that secondary inorganic ions (43.1 %-67.0 %) and organic matter (OM, 8.6 %-36.4 %) were the main components of PM2.5 in all the cities. Specifically, Fukang with the most severe PM2.5 pollution had the highest proportion of SO42- (31.2 %), while the dominant components in other cities were NO3- and OM. The Multilinear Engine 2 (ME2) analysis identified five sources of PM2.5 in these cities. Coal combustion contributed most to PM2.5 in Fukang, but secondary sources in other cities. Combined with chemical characteristics and ME2 analysis, it was preliminarily determined that the primary emission of coal combustion had an important contribution to high SO42- in Fukang. Potential source contribution function (PSCF) analysis results showed that regional transport played an important role in PM2.5 in Dingzhou, Weinan and Bozhou, while PM2.5 in Fukang was mainly affected by short-range transport from surrounding areas. Finally, the health risk assessment indicated Mn was the dominant contributor to the total non-carcinogenic risks and Cr had higher carcinogenic risks in all cities. The findings provide a scientific basis for formulating more effective abatement strategies for PM2.5 pollution.

8-Bromo-cAMP attenuates human airway epithelial barrier disruption caused by titanium dioxide fine and nanoparticles.

Titanium dioxide fine particles (TiO2-FPs) and nanoparticles (TiO2-NPs) are the most widely used whitening pigments worldwide. Inhalation of TiO2-FPs and TiO2-NPs can be harmful as it triggers toxicity in the airway epithelial cells. The airway epithelium serves as the respiratory system's first line of defense in which airway epithelial cells are significant targets of inhaled pathogens and environmental particles. Our group previously found that TiO2-NPs lead to a disrupted barrier in the polarized airway epithelial cells. However, the effect of TiO2-FPs on the respiratory epithelial barrier has not been examined closely. In this study, we aimed to compare the effects of TiO2-FPs and TiO2-NPs on the structure and function of the airway epithelial barrier. Additionally, we hypothesized that 8-Bromo-cAMP, a cyclic adenosine monophosphate (cAMP) derivative, would alleviate the disruptive effects of both TiO2-FPs and TiO2-NPs. We observed increased epithelial membrane permeability in both TiO2-FPs and TiO2-NPs after exposure to 16HBE cells. Immunofluorescent labeling showed that both particle sizes disrupted the structural integrity of airway epithelial tight junctions and adherens junctions. TiO2-FPs had a slightly more, but insignificant impact on the epithelial barrier disruption than TiO2-NPs. Treatment with 8-Bromo-cAMP significantly attenuated the barrier-disrupting impact of both TiO2-FPs and TiO2-NPs on cell monolayers. Our study demonstrates that both TiO2-FPs and TiO2-NPs cause comparable barrier disruption and suggests a protective role for cAMP signaling. The observed effects of TiO2-FPs and TiO2-NPs provide a necessary understanding for characterizing the pathways involved in the defensive role of the cAMP pathway on TiO2-induced airway barrier disruption.

Suspended particulate matter <2.5 µm (SPM2.5) in shallow lakes: Sedimentation resistance and bioavailable phosphorus enrichment after sediment resuspension.

Resuspended particulate matter in shallow lakes contributes remarkable phosphorus (P) concentrations to the water column that potentially support algal/cyanobacterial growth. However, only fine particulate matter can be retained in the water column for a long time after sediment resuspension events. The size at which fine particulate matter has ecological implications remains undefined. This research defined suspended particulate matter with a median grain size <2.5 µm (SPM2.5) in shallow lakes, which resists sedimentation and enriches bioavailable P. The relationship between the size of suspended particulate matter (SPM) and water disturbance was characterized by conducting a lab-scale jar test with sediments in a shallow lake. The sedimentation of completely resuspended particulate matter occurred under a series of turbulence shear rates (G) ranging from 0 to 50 s-1. When G was larger than 20 s-1, the SPM had a median grain size (D50) ranging from 9 µm to 11 µm for the three samples. When G was <10 s-1, only SPM <2.5 µm remained in suspension. The SPM larger than 2.5 µm settled when G was between 10 s-1 and 20 s-1, and the SPM remained in complete suspension when G was larger than 20 s-1. Furthermore, P fractionation was conducted on different size-grouped particles that were sorted using gravity sedimentation. The concentration of iron/aluminium bound-P (Fe/Al-P) decreased exponentially as the particle size increased. The concentration of Fe/Al-P in SPM2.5 ranged from 902.8 mg/kg to 1212.1 mg/kg, accounting for over 80 % of extractable total phosphorus. SPM2.5 contributed a remarkable amount of bioavailable P to the algal/cyanobacterial biomass in the shallow lake with frequent sediment resuspension.

Reduction potential of ammonia emissions and impact on PM2.5 in a megacity of central China.

Ammonia control has attracted attention due to the possibility for fine particles (PM2.5) mitigation. Based on past decade ammonia emissions assessments and future predictions, this study seasonally evaluated the ammonia emissions reduction potential in 2025 and 2030 in Wuhan, a Central China megacity, according to the short-term and long-term predictable policies. Furthermore, combined with the reduction potential, PM2.5 components observation and thermodynamic model, the effectiveness of implementing ammonia emission control to reduce PM2.5 by 2025 and 2030 was explored seasonally. Results indicated that the total ammonia emissions are expected to decrease by 19.6-33.9% in 2025 and 2030 under positive reduction scenarios, or increase by 8.9-11.7% in the absence of any intervention. Livestock holds the largest potential for reducing ammonia emissions accounting for 46.4-52.5% of the total. Improvement of human excrement management in rural regions also contributes a 35-37% potential. Despite the implementation of exhaust requirements, ammonia emissions from vehicles in 2030 are expected to continue to increase by 55.3% and 23.5% under the regular (S1) and enhanced (S2) reduction strategy scenarios, respectively. Seasonally, the most potential source of ammonia reduction in spring, summer and fall remains livestock. While in winter, non-agricultural sources dominate the reduction potential. Further results indicated that by ammonia control is expected to decrease PM2.5 concentration up to 5% (less than 1 µg m-3) in 2025-2030. Despite the better effectiveness in winter, ammonia control won't be an effective way to reduce PM2.5 in Central China in future, from the management policies and areal ammonia-rich conditions.

Enhanced mitigation of inhalable particles and fine particle-bound PAHs from a novel hazardous waste-power plant candidate.

Emissions of the inhalable particle (dp < 10 µm, PM10) and their harmful compositions from combustion sources have high potential on health risk with nearly no regulation. This study investigates the particle size distribution (PSD), as well as the removal mechanism of PM10 and fine particle (FP)-bound polycyclic aromatic hydrocarbons (PAHs) from the flue gas of a hazardous waste thermal treatment system. It has ultralow regulated emission and becomes a candidate of power generation module. A series of the advanced scrubbers, cyclonic demister, and baghouse was equipped for multi-pollutant control. The moderate or intense low oxygen dilution (MILD) combustion effectively inhibited the PM2.5 generation by volumetric oxidation. Advanced scrubbers removed PM1, PM2.5, and PM10 by 85.24, 68.68, and 97.60%, respectively, which achieved by local supersaturation, heterogeneous condensation of water vapor, and the growth of fine PM. Moreover, the scrubbers effectively scavenged the course PM10 containing the high-molecular-weight PAH homologs onto the water phase but promoted the condensation and absorption of the lighter homologs onto the fine particle surface (dp ∼5.3 µm). The size window (dp = 0.3-1.0 µm) of the minimum efficiency reporting value of a BH filtration led to the peak of FP-PAH mass and BaP equivalent (BaPeq) toxicity at dp = 0.1-0.4 and 0.1-0.8 µm, respectively. Consequently, the synergy of MILD combustion and the SCB-CYC-BH system effectively inhibited the PM2.5, PM10, PM2.5-PAHs, and FP-PAH levels from a waste thermal treatment process and further mitigated the potential health risk.

Mechanism through which the hsa-circ_0000992- hsa- miR- 936-AKT3 regulatory network promotes the PM2.5-induced inflammatory response in human bronchial epithelial cells.

BACKGROUND: Studies have shown that fine particulate matter (PM2.5) remains a significant problem in developing countries and plays a critical role in the onset and progression of respiratory illnesses. Circular RNAs (circRNAs) are involved in many pathophysiological processes,but their relationship to PM2.5 pollution is largely unexplored. OBJECTIVES: To elucidate the functional role of hsa_circ_0000992 in PM2.5-induced inflammation in a human bronchial epithelial cell line (16HBE) and to clarify whether the competing endogenous RNA (ceRNA) mechanism is involved in the interrelationships between hsa_circ_0000992 and hsa-miR-936 and the inflammatory signaling pathways. METHODS: Detection of inflammatory factors in 16HBE cells exposed to PM2.5 by RT-qPCR and ELISA.High throughput sequencing and bioinformatics analysis methods were used to screen circRNA.The bioinformatics analysis method western blotting and dual-luciferase reporter gene system were used to verify mechanisms associated with circRNA. RESULTS: PM2.5 cause inflammation in the 16HBE cells. High throughput sequencing and RT-qPCR result revealed that the expression of hsa_circ_0000992 was markedly up-regulated in 16HBE exposed to PM2.5. The binding sites between hsa_circ_0000992 and hsa-miR-936 was confirmed by dual-luciferase reporter gene system.Western blotting and RT-qPCR showed that hsa_circ_0000992 can interact with hsa-miR-936 to regulate AKT serine/threonine kinase 3(AKT3),thereby activating the PI3K/AKT pathway and ultimately promoting the expression of interleukin (IL)- 1ß and IL-8. CONCLUSION: PM2.5 can induce the inflammatory response in 16HBE cells by activating the PI3K/AKT pathway. The expression of hsa_circ_0000992 increased when PM2.5 stimulated 16HBE cells,and the circRNA could then regulate the inflammatory response.Hsa_circ_0000992 regulates the hsa-miR-936/AKT3 axis through the ceRNA mechanism,thereby activating the PI3K/AKT signaling pathway,increasing the expression of cellular inflammatory factors,and promoting PM2.5-induced respiratory inflammation.

Long-term exposure to ambient air pollution and inflammatory response in the KORA study.

Previous studies consistently showed an association between fine atmospheric particulate matter (PM2.5) and cardiovascular diseases. Concerns about adverse health effects of ultrafine particles (UFP) are growing but long-term studies are still scarce. In this study, we examined the association between long-term exposure to ambient air pollutants and blood biomarkers of inflammation and coagulation, including fibrinogen, high-sensitivity C-reactive protein (hs-CRP), serum amyloid A (SAA) adiponectin and interleukin-6 (IL-6), measured in the German KORA-S4 cohort study (1999-2001). IL-6 was available for older participants only, who were therefore considered as a subsample. Annual mean concentrations of UFP (as particle number concentration), particulate matter in different particles sizes (PM10, PMcoarse, PM2.5, PM2.5 absorbance), ozone (O3), and nitrogen oxides (NO2, NOX) were estimated by land-use regression models and assigned to participants' home addresses. We performed a multiple linear regression between each pollutant and each biomarker with adjustment for confounders. Per 1 interquartile range (IQR, 1945 particles/cm3) increase of UFP, fibrinogen increased by 0.70 % (0.04; 1.37) and hs-CRP increased by 3.16 % (-0.52; 6.98). Adiponectin decreased by -2.53 % (-4.78; -0.24) per 1 IQR (1.4 µg/m3) increase of PM2.5. Besides, PM2.5 was associated with increased IL-6 in the subsample. In conclusion, we observed that long-term exposure to air pollutants, including both fine and ultrafine particles, was associated with higher concentrations of pro-inflammatory and lower concentrations of an anti-inflammatory blood biomarkers, which is consistent with an increased risk for cardiovascular disease observed for long-term exposure to air pollutants.