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Evidence suggests that myocardial interstitial fibrosis, resulting from cardiac remodeling, may possibly be influenced by mechanisms activated through the inhalation of airborne pollutants. However, limited studies have explored the relationship between lifetime exposure to carbon-based particles and cardiac fibrosis, specially using post-mortem samples. This study examined whether long-term exposure to air pollution (estimated by black carbon accumulated in the lungs) is associated with myocardial fibrosis in urban dwellers of megacity of Sao Paulo. Data collection included epidemiological and autopsy-based approaches. Information was obtained by interviewing the next of kin and through the pathologist's report. The individual index of exposure to carbon-based particles, which we designed as the fraction of black carbon (FBC), was estimated through quantification of particles on the macroscopic lung surface. Myocardium samples were collected for histopathological analysis to evaluate the fraction of cardiac fibrosis. The association between cardiac fibrosis and FBC, age, sex, smoking status and hypertension was assessed by means of multiple linear regression models. Our study demonstrated that the association of FBC with cardiac fibrosis is influenced by smoking status and hypertension. Among hypertensive individuals, the cardiac fibrosis fraction tended to increase with the increase of the FBC in both groups of smokers and non-smokers. In non-hypertensive individuals, the association between cardiac fibrosis fraction and FBC was observed primarily in smokers. Long-term exposure to tobacco smoke and environmental particles may contribute to the cardiac remodeling response in individuals with pre-existing hypertension. This highlights the importance of considering hypertension as an additional risk factor for the health effects of air pollution on the cardiovascular system. Moreover, the study endorses the role of autopsy to investigate the effects of urban environment and personal habits in determining human disease. [Display omitted] • Study exploring epidemiological and autopsy-based approaches of Sao Paulo dwellers. • Association of black carbon and cardiac fibrosis depends on smoking and hypertension. • Hypertensive are more sensitive to effects of air pollution on cardiac remodeling. • Effects on cardiorespiratory health standpoint support pollutants control policies. [ABSTRACT FROM AUTHOR]

A series of adsorbents (activated carbons, ACs) were synthesized by physical and chemical activation of olive stones (OS) and their textural and chemical characteristics determined by complementary techniques such as N 2 and CO 2 physisorption, pH of the point zero of charge (pH PZC), HRSEM or XPS. Samples with a wide range of physicochemical properties were obtained by fitting the activation procedure. The performance of these adsorbents in filters working under dynamic conditions was studied by determining the corresponding breakthrough curves for the ethylene removal. The physicochemical transformations of OS during activation were related with the adsorptive performance of derivative ACs. Results were compared to those obtained using commercial carbons, in particular ACs, carbon black or carbon fibers, in order to identify the properties of these materials on influencing the adsorptive performance. In general, ACs from OS perform better than the commercial samples, being also easily regenerated and properly used during consecutive adsorption cycles. CO 2 -activation showed to be the best synthesis option, leading to granular ACs with a suitable microporosity and surface chemistry. These results could favour the integration of this type of inexpensive materials on devices for the preservation of climacteric fruits, in a clear example of circular economy by reusing the agricultural residues. [Display omitted] • Activated carbons (ACs) were prepared from biomass by different activation methods. • Physical activation by steam leads to a larger and wider porosity than that by CO 2. • Chemical activation with KOH was the most severe method developing porosity. • ACs by CO 2 show the best physico-chemical properties for ethylene adsorption. • Ethylene adsorption is completely reversible, spent ACs being easily regenerated. [ABSTRACT FROM AUTHOR]

The current study presents for the first time how recovered carbon black (rCB) obtained directly from the industrial-scale end-of-life tires (ELTs) pyrolysis sector is applied as a precursor for activated carbons (ACs) with application in CO 2 capture. The rCB shows better physical characteristics, including density and carbon structure, as well as chemical properties, such as a consistent composition and low impurity concentration, in comparison to the pyrolytic char. Potassium hydroxide and air in combination with heat treatment (500–900 °C) were applied as agents for the conventional chemical and physical activation of the material. The ACs were tested for their potential to capture CO 2. Ultimate and proximate analysis, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), Raman spectroscopy, thermogravimetric analysis (TGA), and N 2 /CO 2 gas adsorption/desorption isotherms were used as material characterization methods. Analysis revealed that KOH-activated carbon at 900 °C (AC-900K) exhibited the highest surface area and a pore volume that increased 6 and 3 times compared to pristine rCB. Moreover, the AC-900K possessed a well-developed dual porosity, corresponding to the 22% and 78% of micropore and mesopore volume, respectively. At 0 °C and 25 °C, AC-900K also showed a CO 2 adsorption capacity equal to 30.90 cm3/g and 20.53 cm3/g at 1 bar, along with stable cyclic regeneration after 10 cycles. The high dependence of CO 2 uptake on the micropore volume at width below 0.7–0.8 nm was identified. The selectivity towards CO 2 in relation to N 2 reached high values of 350.91 (CO 2 /N 2 binary mixture) and 59.70 (15% CO 2 /85% N 2). [Display omitted] • rCB from industrial-scale ELTs pyrolysis was used to synthesize ACs. • The mechanism of CO 2 adsorption has been deeply investigated. • Carbon materials possessed high CO 2 /N 2 adsorption selectivity and cyclic stability. • rCB/ACs have the potential to exceed the low quality boundaries of ACs. • Producing rCB/ACs valorises ELTs waste stream, incentivising circular economy. [ABSTRACT FROM AUTHOR]

Examples of biochar as an alternative to traditional plastic fillers, like carbon black, are numerous and growing. However, in the agricultural mulch film application, both the polymer and its fillers are pushed to their mechanical limit to obtain an effective product, using the least amount of plastic. Through a combined techno-economic analysis (TEA) and life cycle assessment (LCA), this study characterizes the use of carbon-negative biochar as an opacity filler in mulch film applications. Due to its larger particle size, the biochar demands additional thickness to achieve equivalent opacity as carbon black in films. A thicker film translates to additional polymer demand, and a significant increase in price and environmental impact. A comparable formulation for an equal price ($623 per mulched ha) as a 2.6 wt % carbon black with 25 μm thickness was derived, needing 15 wt % biochar and a thickness of 30 μm. The biochar formulation resulted in a slightly higher global warming potential (3% increase), but much larger impact in the land use category (+339%), and the sample was deemed not fit for use in the intended mulch application. These results indicate that in applications where the polymeric matrix and its fillers are pushed to their mechanical limit, the displacement of traditional fillers by biochar is challenging. However, biochar derived from waste biomass (thus reducing land use impact) remains a valid, environmentally beneficial solution to displace traditional fillers for non-extreme plastic uses (commodity plastics) and thicker composites. • Various films formulations containing biochar were manufactured and characterized for mulch film applications. • Opacity of biochar containing films depended on both loading and thickness and a model was proposed. • A combined techno-economic analysis and life cycle assessment showed that biochar is not a competitive option yet in film. • Biochar formulations required additional thickness, detrimental to the cost and the environmental impact of the film. [ABSTRACT FROM AUTHOR]

Carbon black nanoparticles (CBNPs) and cadmium (Cd) are major components of various air pollutants and cigarette smoke. Autophagy and inflammation both play critical roles in understanding the toxicity of particles and their components, as well as maintaining body homeostasis. However, the effects and mechanisms of CBNPs and Cd (CBNPs-Cd) co-exposure on the human respiratory system remain unclear. In this study, a CBNPs-Cd exposure model was constructed to explore the respiratory toxicity and combined mechanism of these chemicals on the autophagy-lysosome pathway in the context of respiratory inflammation. Co-exposure of CBNPs and Cd significantly increased the number of autophagosomes and lysosomes in human bronchial epithelial cells (16HBE) and mouse lung tissues compared to the control group, as well as the groups exposed to CBNPs and Cd alone. Autophagic markers, LC3II and P62 proteins, were up-regulated in 16HBE cells and mouse lung tissues after CBNPs-Cd co-exposure. However, treatment with Cq inhibitor (an indicator of lysosomal acid environment) resulted in a substantial decreased co-localization fluorescence of LC3 and lysosomes in the CBNPs-Cd combination group compared with the CBNPs-Cd single and control groups. No difference in LAMP1 protein expression was observed among the exposed groups. Adding 3 MA alleviated inflammatory responses, while applying the Baf-A1 inhibitor aggravated inflammation both in vitro and in vivo following CBNPs-Cd co-exposure. Factorial analysis showed no interaction between CBNPs and Cd in their effects on 16HBE cells. We demonstrated that co-exposure to CBNPs-Cd increases the synthesis of autophagosomes and regulates the acidic environment of lysosomes, thereby inhibiting autophagy-lysosome fusion and enhancing the inflammatory response in both 16HBE cells and mouse lung. These findings provide evidence for a comprehensive understanding of the interaction between CBNPs and Cd in mixed pollutants, as well as for the prevention and control of occupational exposure to these two chemicals. • CBNPs and Cd co-exposure increases inflammation in respiratory epithelial cells. • CBNPs and Cd co-exposure targets autophagosome formation and autophagy-lysosomal fusion. • CBNPs and Cd co-exposure disrupts the lysosomal acidic environment. • CBNPs and Cd co-exposure aggravates inflammation by blocking autophagic flux. [ABSTRACT FROM AUTHOR]

We used black carbon data from a mobile monitoring campaign in Oakland, USA measuring street segments up to 40 times and compared a data-only, LUR model and mixed-model approach with a long-term average, represented by the average concentration based on 40 drive days on that street segment. The mixed model outperformed the data-only and LUR model estimates, with 80% explained variance after 5 drive days and 90% after 14 drive days. The data-only approach needed 8 and 15 to achieve an explained variance of 80% and 90%, respectively, The LUR model never achieved an explained variance higher than 70%. The mixed model is a scalable approach, as it can be used before all street segments in a domain are measured by developing a LUR model and adds information with increasing repeats per street segment. [ABSTRACT FROM AUTHOR]

Early life exposure to air pollution, such as particulate matter ≤2.5 μm (PM 2.5), may be associated with obesity and adverse cardiometabolic health outcomes in childhood. However, the toxicity of PM 2.5 varies according to its chemical composition. Black carbon (BC) is a constituent of PM 2.5 , but few studies have examined its impact on childhood cardiometabolic health. Therefore, we examined relationships between prenatal and early childhood exposure to BC and markers of adiposity and cardiometabolic health in early childhood. This study included 578 mother-child pairs enrolled in the Healthy Start study (2009–2014) living in the Denver-metro area. Using a spatiotemporal prediction model, we assessed average residential black carbon levels during pregnancy and in the year prior to the early childhood follow-up visit at approximately 5 years old. We estimated associations between prenatal and early childhood BC and indicators of adiposity and cardiometabolic biomarkers in early childhood (mean 4.8 years; range, 4.0, 8.3), using linear regression. We found higher early childhood BC was associated with higher percent fat mass, fat mass index, insulin, and homeostatic model assessment for insulin resistance (HOMA-IR), and lower leptin and waist circumference at approximately 5 years old, after adjusting for covariates. For example, per interquartile range (IQR) increase in early childhood BC (IQR, 0.49 μg/m3) there was 3.32% higher fat mass (95% CI; 2.05, 4.49). Generally, we did not find consistent evidence of associations between prenatal BC and cardiometabolic health outcomes in early childhood, except for an inverse association between prenatal BC and adiponectin, an adipocyte-secreted hormone typically inversely associated with adiposity. Higher early childhood, but not in utero , ambient concentrations of black carbon, a component of air pollution, were associated with greater adiposity and altered insulin homeostasis at approximately 5 years old. Future studies should examine whether these changes persist later in life. • Black carbon concentrations during pregnancy and in early childhood for the offspring were estimated.. • Body composition and biomarkers of cardiometabolic health were measured in children at approximately 5 years of age. • Higher early childhood black carbon concentrations were associated with greater adiposity and altered insulin homeostasis. • Overall, prenatal black carbon was not associated with cardiometabolic outcomes in early childhood. [ABSTRACT FROM AUTHOR]

Fine particulate matter (PM 2.5) exposure is a known risk factor for numerous adverse health outcomes, with varying estimates of component-specific effects. Populations with compromised health conditions such as diabetes can be more sensitive to the health impacts of air pollution exposure. Recent trends in PM 2.5 in primarily American Indian- (AI-) populated areas examined in previous work declined more gradually compared to the declines observed in the rest of the US. To further investigate components contributing to these findings, we compared trends in concentrations of six PM 2.5 components in AI- vs. non-AI-populated counties over time (2000–2017) in the contiguous US. We implemented component-specific linear mixed models to estimate differences in annual county-level concentrations of sulfate, nitrate, ammonium, organic matter, black carbon, and mineral dust from well-validated surface PM 2.5 models in AI- vs. non-AI-populated counties, using a multi-criteria approach to classify counties as AI- or non-AI-populated. Models adjusted for population density and median household income. We included interaction terms with calendar year to estimate whether concentration differences in AI- vs. non-AI-populated counties varied over time. Our final analysis included 3108 counties, with 199 (6.4%) classified as AI-populated. On average across the study period, adjusted concentrations of all six PM 2.5 components in AI-populated counties were significantly lower than in non-AI-populated counties. However, component-specific levels in AI- vs. non-AI-populated counties varied over time: sulfate and ammonium levels were significantly lower in AI- vs. non-AI-populated counties before 2011 but higher after 2011 and nitrate levels were consistently lower in AI-populated counties. This study indicates time trend differences of specific components by AI-populated county type. Notably, decreases in sulfate and ammonium may contribute to steeper declines in total PM 2.5 in non-AI vs. AI-populated counties. These findings provide potential directives for additional monitoring and regulations of key emissions sources impacting tribal lands. [Display omitted] • PM 2.5 components levels on average were lower in AI- vs. non-AI-populated counties • NH 4 + and SO 4 2− levels lower at baseline, higher over time in AI-populated counties • NO 3 − levels lower throughout study period in AI-populated counties • Ammonium sulfate reflect similar trends to total PM 2.5 by AI-populated county type [ABSTRACT FROM AUTHOR]

PM2.5 still poses a threat to public health even at very low levels. Black carbon (BC) is a key component of PM2.5. Macrophage extracellular traps (METs) are a means by which macrophages capture and destroy invading pathogens. Necroptosis is an inflammatory programmed cell death. However, there is no research on the crosstalk mechanism between necroptosis and METs after BC exposure. In our study, fluorescence labeling, fluorescent probes, qPCR, and immunofluorescence were applied. Our research found that under normal physiological conditions, when macrophages receive external stimuli (in our experiment, phorbol 12-myristate 13-acetate (PMA)), they will form METs, thus exhibiting innate immune function. However, exposure to BC can cause necroptosis in macrophages accompanied by increased levels of ROS and cytosolic calcium ions as well as altered expression of inflammatory factors and chemokines that prevent the formation of METs, and weakening innate immune function. Notably, inhibition of necroptosis restored the formation of METs, indicating that necroptosis inhibits the formation of METs. Our experiment will enrich the understanding of the mechanism of macrophage injury caused by BC exposure, provide a new direction for studying harmful atmospheric particle toxicity, and propose new therapeutic insights for diseases caused by atmospheric particulate matter. This study is the first to explore the crosstalk mechanism between necroptosis and METs after BC exposure. [Display omitted] • Black carbon (BC) can cause necroptosis in macrophages. • BC can prevent the formation of macrophage extracellular traps (METs). • BC induced necroptosis inhibits the formation of METs. • Necroptosis and METs could interconvert. • This study is the first to investigate the crosstalk mechanism between necroptosis and METs after BC exposure. [ABSTRACT FROM AUTHOR]

Additional various carbon and free riboflavin could improve anaerobic digestion of waste activated sludge (WAS). However, these substances were not reused. In this study, a reusable riboflavin and carbon black (RCB) co-modified filler was developed and combined with alkaline pretreatment for enhancing the production of volatile fatty acids (VFAs) and methane during anaerobic digestion of WAS. The results showed that RCB-modified fillers exhibited a promoting effect on the reduction of alkali-pretreated WAS. The amounts of the accumulated VFAs mainly containing acetate and the produced methane rose with the increased concentration of immobilized riboflavin (0–0.75 g/L) in the presence of 4 g/L carbon black. When the alkaline pretreatment time of WAS increased from 3 d to 8 d, the amount of methane production increased from 22.8% to 63.9% in the presence of 0.75 g/L riboflavin and 4 g/L carbon black compared with that without RCB-modified fillers. Moreover, 0.75 g/L riboflavin and 4 g/L carbon black had a synergetic effect on promoting methane production via broadening extracellular electron transfer pathways. During this process, microbial dehydrogenase activity, electron transport system activity and coenzyme F420 were enhanced. Microbial community analysis showed that RCB-modified filler addition promoted the enrichment of Syntrophomonas and Pseudomonas involved in direct interspecies electron transfer (DIET). These results indicated that DIET establishment was accelerated. Meanwhile, the populations of acetic acid-producing bacteria including Rikenellaceae_RC9_gut_group and Proteiniphilum , aceticlastic and acid-tolerant methanogenic archaea including Methanosarcina and Methanosaeta , RumEn_M2 were increased. These results indicate that RCB-modified fillers coupled with alkaline pretreatment is an effective method to promote the production of methane during anaerobic digestion of WAS. • A reusable riboflavin and carbon black (RCB) co-modified filler was prepared. • Immobilized riboflavin promoted the production of VFAs and methane. • Carbon black and riboflavin had a synergetic effect on methane production. • RCB-modified filler addition enriched Syntrophomonas and Pseudomonas. • Methanosarcina and RumEn_M2 dominated in RCB-modified filler reactor. [ABSTRACT FROM AUTHOR]

Evidence is less about the associations between fine particulate matter (PM 2.5) components and hypertension. We aimed to examine the long-term effects of PM 2.5 components on prevalence of hypertension, diastolic blood pressure (DBP) and systolic blood pressure (SBP). We included participants between March 1, and July 31, 2021, from 13 provinces in China. Geocoded residential address was used for exposure assignment. Mixed-effect regression was used to assess 3-year average concentrations of PM 2.5 and its components (black carbon, organic matter, nitrate, ammonium, and sulfate) on prevalence of hypertension, DBP and SBP with covariate-adjusted. SHapley Additive exPlanation was used to compare the contribution of PM 2.5 components to hypertension, DBP, and SBP. Sex and age subgroup were also analyzed. We enrolled a total of 113,159 participants aged ≥18 years. Long-term exposure to PM 2.5 and its components (black carbon, organic matter, nitrate, ammonium, and sulfate) had associations with prevalence of hypertension, with the Odds Ratios and 95% confidence interval (CI) of 1.06 (95% CI : 1.03–1.09), 1.07 (95% CI : 1.04–1.09), 1.07 (95% CI : 1.04–1.10), 1.05 (95% CI : 1.01–1.08), 1.03 (95% CI : 1.00–1.06), and 1.03 (95% CI : 1.00–1.04), respectively. Effects of that except for black carbon on DBP with per interquartile upticks of concentration were 0.23 (95% CI : 0.11–0.35), 0.17 (95% CI : 0.04–0.29), 0.35 (95% CI : 0.21–0.48), 0.40 (95% CI : 0.28–0.52), and 0.25 (95% CI : 0.13–0.26), respectively. Ammonium was associated with SBP, corresponding to an increase of 0.18 (95% CI : 0.01–0.35). Males had higher risks of DBP (Z = 2.54–6.08, P < 0.001). Older people were substantially more affected by PM 2.5 and its components. Nitrate showed the highest contribution to hypertension, DBP and SBP compared with other components. Long-term exposure to PM 2.5 and its components had adverse consequences on prevalence of hypertension, DBP and SBP, especially for males and older people. Nitrate contributed the highest to hypertension, DBP and SBP. Findings may have implications for pollution and hypertension control. • Exposure to fine particulate matter (PM 2.5) components was related to hypertension. • PM 2.5 , nitrate and ammonium were associated with diastolic blood pressure. • Exposure to ammonium was associated with systolic blood pressure. • Nitrate contributed the highest to hypertension and blood pressure. • A nationwide study from 13 provinces in China during March 1, and July 31, 2021. [ABSTRACT FROM AUTHOR]

Metabolic syndrome (MetS) is considered a main public health issue as it remarkably adds the risk of cardiovascular disease, leading to a heavy burden of disease. There is growing evidence linking fine particulate matter (PM 2.5) exposure to MetS. However, the influences of PM 2.5 constituents, especially in children and adolescents, remain unclear. Our study was according to a national analysis among Chinese children and adolescents to examine the associations between long-term exposure to PM 2.5 main constituents and MetS. A total of 10,066 children and adolescents aged 10–18 years were recruited in 7 provinces in China, with blood tests, health exams, and questionnaire surveys. We estimated long-term exposures to PM 2.5 mass and its five constituents, containing black carbon (BC), organic matter (OM), inorganic nitrate (NO 3 −), sulfate (SO 4 2−), and soil particles (SOIL) from multi-source data fusion models. Mixed-effects logistic regression models were used with the adjustment of a variety of covariates. In the surveyed populations, 2.9% were classified as MetS. From the single-pollutant models, we discovered that long-term exposures to PM 2.5 mass, BC, OM, NO 3 −, as well as SO 4 2−, were significantly associated with the prevalence of MetS, with odds ratios (ORs) per 1 μg/m3 that were 1.02 (95% confidence interval (CI): 1.01, 1.03) for PM 2.5 mass, 1.24 (95% CI: 1.14, 1.35) for BC, 1.07 (95% CI: 1.04, 1.11) for OM, 1.09 (95% CI: 1.04, 1.13) for NO 3 −, and 1.14 (95% CI:1.04, 1.24) for SO 4 2−. The influence of BC on the prevalence of MetS was robust in both the multi-pollutant model and the PM 2.5 -constituent joint model. The paper indicates long-term exposure to PM 2.5 mass and specific PM 2.5 constituents, particularly for BC, was significantly associated with a higher MetS prevalence among children and adolescents in China. Our results highlight the significance of establishing further regulations on PM 2.5 constituents. • 10,066 children and adolescents from 7 province with blood tests were involved. • Long-term exposure to PM 2.5 mass was significantly associated with the childhood MetS. • Black carbon exposure has a robust positive association with childhood MetS. [ABSTRACT FROM AUTHOR]

Previously, we found increased rates of ST-elevation myocardial infarction (STEMI) associated with increased ultrafine particle (UFP; <100 nm) concentrations in the previous few hours in Rochester, New York. Relative rates were higher after air quality policies and a recession reduced pollutant concentrations (2014–2016 versus 2005–2013), suggesting PM composition had changed and the same PM mass concentration had become more toxic. Tier 3 light duty vehicles, which should produce less primary organic aerosols and oxidizable gaseous compounds, likely making PM less toxic, were introduced in 2017. Thus, we hypothesized we would observe a lower relative STEMI rate in 2017–2019 than 2014–2016. Using STEMI events treated at the University of Rochester Medical Center (2014–2019), UFP and other pollutants measured in Rochester, a case-crossover design, and conditional logistic regression models, we estimated the rate of STEMI associated with increased UFP and other pollutants in the previous hours and days in the 2014–2016 and 2017–2019 periods. An increased rate of STEMI was associated with each 3111 particles/cm3 increase in UFP concentration in the previous hour in 2014–2016 (lag hour 0: OR = 1.22; 95% CI = 1.06, 1.39), but not in 2017–2019 (OR = 0.94; 95% CI = 0.80, 1.10). There were similar patterns for black carbon, UFP 11–50nm , and UFP 51–100nm. In contrast, increased rates of STEMI were associated with each 0.6 ppb increase in SO 2 concentration in the previous 120 h in both periods (2014–2016: OR = 1.26, 95% CI = 1.03, 1.55; 2017–2019: OR = 1.21, 95% CI = 0.87, 1.68). Greater rates of STEMI were associated with short term increases in concentrations of UFP and other motor vehicle related pollutants before Tier 3 introduction (2014–2016), but not afterwards (2017–2019). This change may be due to changes in PM composition after Tier 3 introduction, as well as to increased exposure misclassification and greater underestimation of effects from 2017 to 2019. • Rate of ST-elevation myocardial infarction (STEMI) associated with UFP from 2014-2016 • Similar associations with black carbon, UFP 11-50 nm , and UFP 50-100 nm. • No STEMI/UFP associations from 2017 to 2019 (after Tier 3 vehicles introduced). • Results may be due to changes in UFP/PM composition, STEMI cohort, or exposure error. [ABSTRACT FROM AUTHOR]

Better knowledge of the sources of black carbon (BC) and ultrafine particles (UFPs) in urban roadway region will provide helpful information for improving road air pollution caused by vehicle emissions. For this purpose, we conducted daily observation of BC and UFPs at two trafficked sites (intersection and roadside), and a background site in Xi'an, China. The concentration data of BC and UFPs measured were combined with Aethalometer model and UFPs source apportion model, to determine and analyze the sources of BC in an urban road region. Further, the source and variation characteristics of primary and secondary UFPs at the roadside sites were clarified. The results showed that average BC concentrations at the intersection, roadside, and background were respectively 3577 ± 2771, 3078 ± 2343, and 1914 ± 1229 ng/m3. The BC source apportionment results revealed contribution rates of on-board fossil fuel combustion (BC ff) at the intersection and near the road of ca. 78.7% and 73.6%, respectively. Moreover, the proportion of particles number concentrations directly emitted from vehicles and nucleated upon emission (47%) was lower than that of particles formed during the dilution and cooling of vehicle emissions and by in-situ new particle formation (53%) at the roadside site. At 49%, the proportion of primary particles number was slightly higher at the intersection. The impacts of new particle-formation events on the diurnal variation of secondary particles were explored. Generally, the majority of BC originated from traffic exhausts, while the secondary particles from non-traffic sources are dominant at the road intersections. By providing a better understanding of near-road pollution issues, this study's findings can be useful for taking effective regulatory efforts to improve air quality and reduce people's exposure to traffic-pollutants in an urban environment. [ABSTRACT FROM AUTHOR]

Since the Air Pollution Prevention and Control Action Plan (air clean plan) issued in 2013, air quality has been in continuous improvement. The second stage of air clean plan since 2018 was focused on O 3 controlling, but it still didn't decline so significantly as PM 2.5. This study conducted a long-term observation on black carbon (BC) and utilized the observational data of other air pollutants (PM 2.5 , PM 10 , NO 2 , SO 2 , CO and O 3), the meteorological elements and the vertical sounding data of PBL in Nanjing. In the daytime (08:00–20:00), PM 2.5 kept decreasing from 2015 to 2020 at the rate of 4.8 μg⋅m−3⋅a−1, however, BC increased at the rate of 0.6 μg⋅m−3⋅a−1, which has led to the continuous growth of BC/PM 2.5 (0.9%⋅a−1). However, during this period, O 3 was relatively stable and, in 2020, it returned below its value in 2015 after slight increases in 2017 and 2018. Meanwhile, the average surface temperature had increased by around 1.0 °C during 2015–2019 at the rate of 0.3 °C⋅a−1. Also, the average height of the inversion layer had increased significantly by 494.0 and 176.7 m at 20:00 and 08:00, whose growth ratio was up to 57% and 25%, respectively. The above observation results have formed a set of chain reactions as follows. The growth of the surface BC caused the surface temperature to rise due to the increasing heating effect of BC. The continuous growth of the surface temperature made it easier for the PBL height to develop, which led to the lift of the inversion layer in the PBL and the larger atmospheric environment capacity. Ultimately, it is conducive to the diffusion of the near surface pollutants, thus helping reduce their concentrations, which offsets the increasing tendency of O 3 and add to the decreasing trend of PM 2.5. This phenomenon is the most remarkable in summer, with the fastest increasing rate of temperature (0.8 °C⋅a−1) and O 3 (3.9 μg⋅m−3⋅a−1) during 2015–2019 (excluding 2020 to erase the great effect of COVID-19 lockdown on emissions). [ABSTRACT FROM AUTHOR]

Previous research has shown that walking and cycling could help alleviate stress in cities, however there is poor knowledge on how specific microenvironmental conditions encountered during daily journeys may lead to varying degrees of stress experienced at that moment. We use objectively measured data and a robust causal inference framework to address this gap. Using a Bayesian Doubly Robust (BDR) approach, we find that black carbon exposure statistically significantly increases stress, as measured by Galvanic Skin Response (GSR), while cycling and while walking. Augmented Outcome Regression (AOR) models indicate that greenspace exposure and the presence of walking or cycling infrastructure could reduce stress. None of these effects are statistically significant for people in motorized transport. These findings add to a growing evidence-base on health benefits of policies aimed at decreasing air pollution, improving active travel infrastructure and increasing greenspace in cities. • Galvanic skin response (GSR) measurements are used as a proxy measure of stress. • Increases in black carbon would cause significant higher GSR during active travel (i.e. cycling and walking). • Greenspace is associated with lower GSR for people in active travel modes. • Active travel infrastructure (cycleways / pedestrian paths) is also associated with lower GSR while walking or cycling. [ABSTRACT FROM AUTHOR]

Traditional cooking with solid fuels (biomass, animal dung, charcoals, coal) creates household air pollution that leads to millions of premature deaths and disability worldwide each year. Exposure to household air pollution is highest in low- and middle-income countries. Using data from a stepped-wedge randomized controlled trial of a cookstove intervention among 230 households in Honduras, we analyzed the impact of household and personal variables on repeated 24-h measurements of fine particulate matter (PM 2.5) and black carbon (BC) exposure. Six measurements were collected approximately six-months apart over the course of the three-year study. Multivariable mixed models explained 37% of variation in personal PM 2.5 exposure and 49% of variation in kitchen PM 2.5 concentrations. Additionally, multivariable models explained 37% and 47% of variation in personal and kitchen BC concentrations, respectively. Stove type, season, presence of electricity, primary stove location, kitchen enclosure type, stove use time, and presence of kerosene for lighting were all associated with differences in geometric mean exposures. Stove type explained the most variability of the included variables. In future studies of household air pollution, tracking the cooking behaviors and daily activities of participants, including outdoor exposures, may explain exposure variation beyond the household and personal variables considered here. • Household and personal variables can explain variation in household air pollution. • We analyzed repeated measures of PM 2.5 and BC over a three-year period • Stove type, season, electricity, and kerosene were linked to exposure differences. • Multivariable models explained between 37% and 49% of variation in exposures. [ABSTRACT FROM AUTHOR]

Traditional cooking with solid fuels (biomass, animal dung, charcoals, coal) creates household air pollution that leads to millions of premature deaths and disability worldwide each year. Exposure to household air pollution is highest in low- and middle-income countries. Using data from a stepped-wedge randomized controlled trial of a cookstove intervention among 230 households in Honduras, we analyzed the impact of household and personal variables on repeated 24-h measurements of fine particulate matter (PM 2.5) and black carbon (BC) exposure. Six measurements were collected approximately six-months apart over the course of the three-year study. Multivariable mixed models explained 37% of variation in personal PM 2.5 exposure and 49% of variation in kitchen PM 2.5 concentrations. Additionally, multivariable models explained 37% and 47% of variation in personal and kitchen BC concentrations, respectively. Stove type, season, presence of electricity, primary stove location, kitchen enclosure type, stove use time, and presence of kerosene for lighting were all associated with differences in geometric mean exposures. Stove type explained the most variability of the included variables. In future studies of household air pollution, tracking the cooking behaviors and daily activities of participants, including outdoor exposures, may explain exposure variation beyond the household and personal variables considered here. • Household and personal variables can explain variation in household air pollution. • We analyzed repeated measures of PM 2.5 and BC over a three-year period • Stove type, season, electricity, and kerosene were linked to exposure differences. • Multivariable models explained between 37% and 49% of variation in exposures. [ABSTRACT FROM AUTHOR]

India's air quality is in a dismal state, with many studies ascribing it to PM 2.5. Most of these corroborate that carbonaceous aerosol (CA) constitute significant fraction of PM 2.5. However, investigations on the effect of long-term meteorological or emission changes on PM 2.5 and its components, and their associated health effects are rare. In this work, WRF-Chem simulations for three seasons over four years (2016–2019) were carried out to cogitate the spatial and temporal changes in PM 2.5 and its components in India. Model predicted PM 2.5 concentrations were in good agreement with the ground-based observations for 25 cities. PM 2.5 was highest in winter and lowest in pre-monsoon. PM 2.5 reduced by ∼8% in Indo-Gangetic Plain (IGP) but increased by ∼38% and ∼130% in south and northeast India, respectively, from 2016 to 2019. IGP witnessed three times higher average PM 2.5 concentrations than south India. No significant interannual change in CA contributions was observed, however, it peaked in the winter season. Other inorganics (OIN) were the major component of PM 2.5, contributing more than 40%. Primary organic aerosol (POA) fractions were higher in north India, while secondary inorganic aerosol (SIA) dominated south India. Transport and residential sectors were the chief contributors to CA across India. Biomass burning contributed up to ∼23% of PM 2.5 in regions of IGP during post-monsoon, with CA fractions up to 50%. Associations between PM 2.5 and its components with daily inpatient admissions from a tertiary care centre in Delhi showed that PM 2.5 and OIN had lower associations with daily hospital admissions than CA. Every 10 μg/m3 increase in POA, black carbon (BC), and secondary organic aerosol (SOA) were associated with ∼1.09%, ∼3.07% and ∼4.93% increase in the risk of daily hospital admissions. This invigorates the need for more policies targeting CA rather than PM 2.5 to mitigate associated health risks, in India. [ABSTRACT FROM AUTHOR]

Household air pollution (HAP) from cooking with solid fuels has been associated with adverse respiratory effects, but most studies use surveys of fuel use to define HAP exposure, rather than on actual air pollution exposure measurements. To examine associations between household and personal fine particulate matter (PM 2.5) and black carbon (BC) measures and respiratory symptoms. As part of the Prospective Urban and Rural Epidemiology Air Pollution study, we analyzed 48-h household and personal PM 2.5 and BC measurements for 870 individuals using different cooking fuels from 62 communities in 8 countries (Bangladesh, Chile, China, Colombia, India, Pakistan, Tanzania, and Zimbabwe). Self-reported respiratory symptoms were collected after monitoring. Associations between PM 2.5 and BC exposures and respiratory symptoms were examined using logistic regression models, controlling for individual, household, and community covariates. The median (interquartile range) of household and personal PM 2.5 was 73.5 (119.1) and 65.3 (91.5) μg/m3, and for household and personal BC was 3.4 (8.3) and 2.5 (4.9) x10−5 m−1, respectively. We observed associations between household PM 2.5 and wheeze (OR: 1.25; 95%CI: 1.07, 1.46), cough (OR: 1.22; 95%CI: 1.06, 1.39), and sputum (OR: 1.26; 95%CI: 1.10, 1.44), as well as exposure to household BC and wheeze (OR: 1.20; 95%CI: 1.03, 1.39) and sputum (OR: 1.20; 95%CI: 1.05, 1.36), per IQR increase. We observed associations between personal PM 2.5 and wheeze (OR: 1.23; 95%CI: 1.00, 1.50) and sputum (OR: 1.19; 95%CI: 1.00, 1.41). For household PM 2.5 and BC, associations were generally stronger for females compared to males. Models using an indicator variable of solid versus clean fuels resulted in larger OR estimates with less precision. We used measurements of household and personal air pollution for individuals using different cooking fuels and documented strong associations with respiratory symptoms. • Multi-country study of measured personal and household air pollution. • Measured air pollution exposure associated with respiratory symptoms. • Household measures more strongly associated than personal measures. • PM2.5 measures more strongly associated than black carbon measures. • Larger associations for female compared to male individuals. [ABSTRACT FROM AUTHOR]

Black carbon (BC) is a product of incomplete combustion, present in urban aerosols and sourcing mainly from road traffic. Epidemiological evidence reports positive associations between BC and cardiovascular and respiratory disease. Despite this, BC is currently not regulated by the EU Air Quality Directive, and as a result BC data are not available in urban areas from reference air quality monitoring networks in many countries. To fill this gap, a machine learning approach is proposed to develop a BC proxy using air pollution datasets as an input. The proposed BC proxy is based on two machine learning models, support vector regression (SVR) and random forest (RF), using observations of particle mass and number concentrations (N), gaseous pollutants and meteorological variables as the input. Experimental data were collected from a reference station in Barcelona (Spain) over a 2-year period (2018–2019). Two months of additional data were available from a second urban site in Barcelona, for model validation. BC concentrations estimated by SVR showed a high degree of correlation with the measured BC concentrations (R2 = 0.828) with a relatively low error (RMSE = 0.48 μg/m3). Model performance was dependent on seasonality and time of the day, due to the influence of new particle formation events. When validated at the second station, performance indicators decreased (R2 = 0.633; RMSE = 1.19 μg/m3) due to the lack of N data and PM 2.5 and the smaller size of the dataset (2 months). New particle formation events critically impacted model performance, suggesting that its application would be optimal in environments where traffic is the main source of ultrafine particles. Due to its flexibility, it is concluded that the model can act as a BC proxy, even based on EU-regulatory air quality parameters only, to complement experimental measurements for exposure assessment in urban areas. •Black carbon data are not available from EU reference air quality monitoring networks. •A machine-learning proxy was developed to fill this gap. •The proxy uses regulated and non-regulated air quality metrics as input. •The model predicted measured BC concentrations with R2 = 0.82 and RMSE = 0.48 μg/m3. •New particle formation events critically impacted the model's performance. [ABSTRACT FROM AUTHOR]

Atmospheric aging of black carbon (BC) leads to changes in its physiochemical properties, exerting complex effects on environment and climate. In this study, we have conducted laboratory chamber experiments to investigate the effects of BC aging on its morphology, hygroscopicity and optical properties by exposing monodisperse fresh BC particles to ambient ubiquitous species of nitrogen dioxide (NO 2), sulfur dioxide (SO 2) and ammonia (NH 3) in absence of UV light. We show a rapid aging from highly fractal to compacted aggregates for the monodisperse BC particles with an initial diameter of 150 nm, with decline in the dynamic shape factor (χ) from about 1.8 to nearly 1. The effective density of the monodisperse BC particles increases from ∼0.54 to 1.50 g cm−3 accordingly. The aging process leads to that the light scattering, absorption, and single scattering albedo of the monodisperse BC particles are strongly enhanced by factors of 7.0, 1.8 and 3.0 respectively. By comparing with the BC aging from other mechanisms, we reveal a critical role of the composition of the coating materials on BC in determining its light absorption enhancement. Moreover, due to strong water uptake capacity of the aged BC particles, the light absorption enhancement (E abs) could be 40–60% higher at humid atmosphere compared with dry conditions. This BC aging process from NO 2 oxidation of SO 2 may occur commonly in polluted regions and thus considerably alter its effects on regional air quality and climate. [ABSTRACT FROM AUTHOR]

As the most important contributors to global warming in recent decades, anthropogenic carbon dioxide (CO 2) and black carbon (BC) play significant roles in driving the global/regional hydrological cycle. Most of previous studies on the climate effects of CO 2 and BC focused on tropics and monsoon regions. The influences and their differences of CO 2 and BC on the precipitation in Northern Hemisphere mid-latitudes (NHML) have not been paid enough attention. Here we investigate the NHML precipitation responses to a tenfold increase in BC and a doubling of CO 2 by analyzing the multi-model simulation results from the Precipitation Driver Response Model Intercomparison Project (PDRMIP). Our results show that the NHML precipitation changes induced by BC and CO 2 distinctly differ in trends and seasons. The increased BC will reduce the NHML precipitation, especially in summer, whereas the doubled CO 2 will enhance the regional precipitation, mainly in winter. The differences between the BC and CO 2 induced NHML precipitation changes are most distinct in Central Asia and central North America. Further analyses reveal the underlying mechanisms of the distinct responses of precipitation: the decrease in NHML precipitation induced by BC aerosols mainly results from the dynamic effect by reducing the temperature gradient, thereby weakening the zonal wind, while the increased precipitation by CO 2 is caused by the increase in atmospheric water vapor through the thermodynamic effect. The results of these simulations are helpful for understanding the mechanism of anthropogenic precipitation changes in mid-latitudes. • Multi-model simulated NHML precipitation changes induced by BC and CO 2 are compared. • Precipitation responses to increased BC and CO 2 differ in trends and seasons. • BC changes precipitation by dynamic process, whereas CO 2 by thermodynamic process. [ABSTRACT FROM AUTHOR]

Little is known about personal characteristics and systemic responses to particulate pollution in patients with COPD. Assess whether diabetes, obesity, statins and non-steroidal anti-inflammatory medications (NSAIDs) modify associations between indoor black carbon (BC) and fine particulate matter ≤2.5 μm in diameter (PM 2.5) on systemic inflammation and endothelial activation. 144 individuals with COPD without current smoking and without major in-home combustion sources were recruited at Veterans Affairs Boston Healthcare System. PM 2.5 and BC were measured in each participant's home seasonally for a week (up to 4 times; 482 observations) and plasma biomarkers of systemic inflammation [C-reactive protein (CRP); interleukin-6 (IL-6)] and endothelial activation [soluble vascular adhesion molecule-1 (sVCAM-1)] measured. Linear mixed effects regression with a random intercept was used, and effect modification assessed with multiplicative interaction terms and stratum specific estimates. Median (25%ile, 75%ile) indoor BC and PM 2.5 were 0.6 (0.5,0.7) μg/m3 and 6.8 (4.8,10.4) μg/m3, respectively. Although p-values for effect modification were not statistically significant, there were positive associations (%-increase/interquartile range; 95% CI) between CRP and BC greater among non-statin (18.8%; 3.6–36.3) than statin users (11.1%; 2.1–20.9). There were also positive associations greater among non-statin users between PM 2.5 and CRP. For IL-6, associations with BC and PM 2.5 were also greater among non-statin users. Associations between CRP and BC were greater (20.3%; 4.5–38.5) in persons with diabetes than without diabetes (10.3%; 0.92–20.6) with similar effects of PM 2.5. There were no consistent associations that differed based on obesity. Effect modification was not observed for NSAID use, or with any factor considered with sVCAM-1. Associations between indoor BC and PM 2.5 and CRP were greater in patients with diabetes and those not taking statins, and with IL-6 if not taking statins. These results suggest that these characteristics may modify the systemic response to indoor BC and PM 2.5 in persons with COPD. • Greater associations between in-home BC and PM2.5 with CRP in non-statin users. •Greater associations between in-home BC and PM2.5 with CRP and IL-6 in diabetics. •NSAID use and BMI ≥ 30 did not modify BC and PM2.5 and biomarker associations. •COPD patients not using statins or with diabetes may be more susceptible to BC/PM. [ABSTRACT FROM AUTHOR]

Due to the lack of black carbon (BC) measurement data in some cases, elemental carbon (EC) is often used as a surrogate of BC, with a simple assumption that they are interchangeable. Such assumption will inevitably lead to uncertainties in radiative forcing estimation and health impact assessment. In order to quantitatively and systematically evaluate the relationship between BC and EC as well as factors responsible for their difference, 3-year collocated equivalent BC (eBC) and EC measurements with 1-h resolution were performed in Beijing, China continuously from 2016 to 2019. EBC concentration was measured by the multi-wavelength aethalometer (AE-33) based on optical analysis, while EC concentration was determined by semi-continuous OC/EC analyzer with thermal-optical method. The results showed that around 90% of eBC concentration was higher than that of EC, with average difference between eBC and EC as 1.21 μg m−3 (accounting for 33% of average eBC in Beijing). EBC and EC concentrations exhibited strong correlation (r = 0.90) during the whole study period, but the slopes (or eBC/EC ratio) and correlation coefficients varied across seasons (spring: 1.67 and 0.94; summer: 0.91 and 0.65; fall: 1.15 and 0.88; winter: 1.09 and 0.91, respectively). Based on the information from shell/core ratios by Single Particle Soot Photometer (SP2), source apportionment results by positive matrix factorization model, and chemical composition of PM 2.5 , the differences between eBC and EC concentrations were found to be primarily related to BC aging process and secondary components as evidenced by strong positive correlation with secondary species (e.g., secondary organic carbon and nitrate). This study provided seasonal specific conversion factors of eBC and EC in Beijing and helpful reference for other areas, which will contribute new knowledge of carbonaceous aerosol and reduce uncertainty in assessing future climate change and health studies of BC. • About 90% of eBC mass were higher than EC in Beijing based on 3-year measurement. •EBC and EC were strongly correlated whereas eBC/EC ratios varied with season. •The difference between eBC and EC was related to BC aging and secondary species. [ABSTRACT FROM AUTHOR]

Previous studies have indicated that black carbon (BC) potentially induces snow albedo reductions across northern China. However, the effects of other light-absorbing particles (LAPs, e.g., mineral dust, MD), snow grain shape, or BC–snow mixing state on snow albedo have been largely ignored. Here we evaluate the BC- and MD-induced snow albedo reductions and radiative forcings (RFs) using an updated Snow, Ice, and Aerosol Radiation radiative transfer model, considering all of the potential factors that can be derived from the field observations across northern China. The results highlight that the LAP-induced albedo reductions for nonspherical snow grains are 2%–30% less than those for spherical grains. Furthermore, BC–snow internal mixing can significantly enhance albedo reduction by a factor of 1.42–1.48 relative to external mixing, with snow grain radius ranging from 100 to 1000 μm. The mean regional BC + MD-induced snow albedo reductions are amplified by the increase of snow grain radius, ranging from 0.012 to 0.123 for fresh snow to 0.016–0.227 for old snow. Finally, we discuss the relative contributions of BC and MD to the albedo reductions and RFs, highlighting the dominant role of BC in reducing snow albedo across northern China. • There are 1–2 orders of magnitude more mineral dust than black carbon in snow. • Black carbon–snow internal mixing yields an additional 40%–50% albedo reduction. • Snow nonsphericity decreases the mean albedo reductions by 2%–30%. [ABSTRACT FROM AUTHOR]

This study investigates potential influence of urban trees on black carbon (BC) removal by Norway spruce and silver birch along with the BC formation, mass concentration in air, and source apportionment. The main sources of BC in urban areas are transport, household and industry. BC concentrations monitored in urban background station in Vilnius (Lithuania) showed that biomass burning was a significant contributor to BC emissions even during warm period of the year. Therefore, BC emission levels were determined for the most common biomass fuels (mixed wood pellets, oak, ash, birch and spruce firewood) and two types of agro-biomass (triticale and rapeseed straw pellets) burned in modern and old heating systems. The highest emissions were obtained for biomass fuels especially birch firewood. BC aerosol particles produced by the condensation mechanism during the combustion processes were found in all samples taken from the leaf surface. The short-term effect of BC exposure on photosynthetic pigments (chlorophyll a and b ; and carotenoids) in the foliage of one-year-old Norway spruce and silver birch seedlings was evaluated by the experiment carried out in the phytotron greenhouse. The seedlings showed different short-term responses to BC exposure. All treatments applied in the phytotron greenhouse resulted in lower chlorophyll content in spruce foliage compared to natural conditions but not differed for birch seedlings. However, the exposure of BC particles on the spruce and birch seedlings in the phytotron increased the content of photosynthetic pigments compared to the control seedlings in the phytotron. Overall, urban trees can help improve air quality by reducing BC levels through dry deposition on tree foliage, and needle-like trees are more efficient than broad-leaved trees in capturing BC. Nevertheless, a further study could assess the longer-term effects of BC particles on tree biochemical and chemical reactions. • Traffic and biomass burning similarly contribute to BC emissions during warm season in urban background areas. • The highest BC emissions were from birch firewood and the lowest from mixed wood pellets. • BC aerosol particles were found in all samples taken from the leaf surface. • BC reduced chlorophyll content in fumigated Norway spruce needles compared to natural conditions. • Larger agglomerates were found on needles of conifers than on leaves of deciduous tree species. [ABSTRACT FROM AUTHOR]

Since the COVID-19 pandemic, ventilation on transport has been improved to control the aerosol transmission. We utilized portable monitors to measure real-time concentrations of PM 10 , PM 2.5 , PM 1.0 and black carbon (BC) on six modes of transport and estimate personal exposures under the epidemic prevention. The mean concentrations of PM 10 , PM 2.5 , PM 1.0 and BC measured on transport were 18.8 ± 19.4, 16.6 ± 16.5, 12.2 ± 10.8 and 4.1 ± 6.9 μg/m3, respectively. It reduced PM levels on subway to apply the full fresh air mode rather than partial recirculation mode. Airplane had the lowest concentrations and the highest decay rates, implying the most efficient ventilation and filtration. PM were higher on intra-city transport than inter-city, and significantly increased on arrival at stations. BC and BC/PM ratios were higher on road transport than rail transport, indicating the contribution of exhaust emissions. The ventilation mode to exchange air with the outside and the positive association between concentrations and decay rates on high-speed train suggested filtration efficiency should be improved simultaneously with enhancing ventilation. Wearing facemasks on transport further protects passengers against PM exposure, which reduced personal exposure concentrations on four modes of transport lower than 10 μg/m3, the World Health Organization guideline. • It's the first study to report PM levels on transport after the COVID-19 pandemic. • It reduces PM levels on subway to apply the full filtered fresh air mode. • Using efficient ventilation and HEPA filtration, airplane had the lowest PM levels. • Filtration efficiency should be improved simultaneously with enhancing ventilation. • Lower PM exposure concentration is a side benefit of wearing facemasks. [ABSTRACT FROM AUTHOR]

Ambient equivalent black carbon (BC) measurements spanning from June to October have been carried out over an adjoining location of Satopanth and Bhagirath-Kharak Glaciers (3858m, amsl) of Central Himalaya during the year 2019. Hourly BC varied from 12 ng m−3 to 439 ng m−3 during the entire period of observation. Monthly averaged BC values showed the highest concentration during June (230.96 ± 85.46 ng m−3) and the lowest in August (118.02 ± 71.63 ng m−3). The decrease in BC during monsoon months is attributed to limited long-range transport and rapid wet scavenging processes. Transport model studies indicate a higher retention time of tracer in Uttarakhand, Punjab, Haryana, and adjacent polluted valley regions with increased biomass burning (BB) incidences. The high rate of BC influx during June, September, and October was attributed to transport from the polluted Indo-Gangetic Plain (IGP) region, wildfires, and vehicular emissions in the valley region. Higher equivalent brown carbon (BrC) influx is linked to BB, especially wood-burning, during intense forest fires at slopes of mountains. Data obtained from limited BC observations during the 2011–19 period showed no significant BC influx change during post-monsoon. The strong correlation between BC mass and BB affirms the dominant role of BB in contributing BC to the Glacier region. Increased TOA forcing induced by surface darkening and BC atmospheric radiative heating indicate an additional warming and possible changes of the natural snow cycle over the glacier depending on the characteristics and extent of debris cover. • Black carbon observation over the adjoining region of Satopanth, Bhagirath-Kharak Glaciers of Central Himalaya at an altitude of 3858 m, ASL. • BC dominated in premonsoon with a drastic decrease in monsoon months. • BC's diurnal variability pattern is different from polluted environments due to a lack of immediate local sources. • Forest fire incidences and locally generated BC from vehicles, tourist activities are dominating the region • Long-range and valley-mountain transport of BC towards Glacier largely depends on the convective activities during the premonsoon. • Atmospheric BC aerosol heating and snow albedo radiative forcing can cause possible disruption of the natural snow cycle depending on the debris cover characteristics of the Glacier surface. [ABSTRACT FROM AUTHOR]

Black carbon (BC), an important indicator of traffic-related air pollution (TRAP) in urban environments, is receiving increased attention because of its adverse health effects. Personal exposure (PE) of adults to BC has been widely studied, but little is known about the exposure of young children (toddlers) to BC in cities. We carried out a pilot study to investigate the integrated daily PE of toddlers to BC in a city-state with a high population density (Singapore). We studied the impact of urban traffic on the PE of toddlers to BC by comparing and contrasting on-road traffic flow (i.e., volume and composition) in Singapore in 2019 (before the COVID-19 pandemic) and in 2020 (during the COVID-19 pandemic). Our observations indicate that the daily BC exposure levels and inhaled doses increased by about 25% in 2020 (2.9 ± 0.3 μg m−3 and 35.5 μg day−1) compared to that in 2019 (2.3 ± 0.4 μg m−3 and 28.5 μg day−1 for exposure concentration and inhaled dose, respectively). The increased BC levels were associated with the increased traffic volume on both weekdays and weekends in 2020 compared to the same time period in 2019. Specifically, we observed an increase in the number of trucks as well as cars/taxis and motorcycles (private transport) and a decline in the number of buses (public transport) in 2020. The implementation of lockdown measures in 2020 resulted in significant changes in the time, place and duration of PE of toddlers to BC. The recorded daily time-activity patterns indicated that toddlers spent almost all the time in indoor environments during the measurement period in 2020. When we compared different ventilation options (natural ventilation (NV), air conditioning (AC), and portable air cleaner (PAC)) for mitigation of PE to BC in the home environment, we found a significant decrease (>30%) in daily BC exposure levels while using the PAC compared to the NV scenario. Our case study shows that the PE of toddlers to BC is of health concern in indoor environments in 2020 because of the migration of the increased TRAP into naturally ventilated residential homes and more time spent indoors than outdoors. Since toddlers' immune system is weak, technological intervention is necessary to protect their health against inhalation exposure to air pollutants. [Display omitted] • Our case study shows daily toddler's exposure to BC is higher in 2020 than in 2019. • An increase in the number of private transports was observed. • We also found a decline in the number of public transport. • The portable air cleaner is most effective at reducing indoor BC. [ABSTRACT FROM AUTHOR]

Fine particulate matter (PM 2.5) is a complex mixture of fine particulates with large spatiotemporal heterogeneities in chemical compositions. While PM 2.5 has been associated with gestational diabetes mellitus (GDM), little is known about the relationship between specific chemical components of PM 2.5 and GDM. We examined the associations between GDM and pregnancy exposures to PM 2.5 and its compositions, including sulfate (SO 4 2−), ammonium (NH 4 +), nitrate (NO 3 −), organic matter (OM), black carbon (BC), mineral dust (DUST), and sea-salt (SS), and to identify critical windows of exposure. We used data from the 2005–2015 Florida Vital Statistics Birth Records. A well-validated geoscience-derived model was used to estimate women's pregnancy exposures to PM 2.5 and its compositions. Distributed lag models were used to examine the associations and to identify the critical windows of exposure. A total of 2,078,669 women were included. In single-pollutant models, after controlling for potential confounders, positive associations between PM 2.5 and GDM were observed during the second trimester of pregnancy. We found positive associations between SO 4 2−, NH 4 +, NO 3 −, OM and BC, with largest effect sizes observed in the 21–24 weeks of pregnancy. Negative associations were observed for DUST and SS. Consistent results for NH 4 +, OM, DUST and SS were observed in the multi-pollutant models. Exposures to PM 2.5 and its compositions (mainly NH 4 +, OM) during the second trimester are positively associated with GDM, especially for exposures during the 21–24 weeks of pregnancy. Further studies are needed to confirm the findings and examine the underlying mechanisms. • Exposure to PM 2.5 and its compositions are linked to gestational diabetes mellitus. • The 21–24 weeks of pregnancy is the most critical window of exposure to PM 2.5. • The results may inform future studies on the mechanisms and interventions. [ABSTRACT FROM AUTHOR]