Search Results (296)

This paper examines how local firm entry affects air pollution and whether the Air Pollution Prevention and Control Action Plan (APPCAP) changes this relationship. Using a county–month panel for 2010–2020, we match the Chinese Industrial and Commercial Enterprise Registration Database with county-level monthly PM2.5 data to measure new firm entry and its sectoral composition. To address the potential endogeneity of firm entry, we use the opening of high-speed rail as an instrumental variable. The results show that firm entry significantly increases county-level PM2.5 concentrations. This effect is highly heterogeneous across industries, with stronger pollution effects in sectors such as wholesale and retail, manufacturing, and accommodation and catering. We further find that the APPCAP significantly weakens the positive effect of firm entry on air pollution. Additional evidence suggests that the policy improves air quality not only by tightening environmental constraints, but also by shifting firm entry toward relatively cleaner industries. This paper explains the environmental consequences of local economic expansion from the perspective of incremental firm entry and provides new evidence on the joint role of environmental regulation and industrial restructuring in air pollution control. Full article

Translating fine-resolution air pollution surfaces into health equity assessments requires aggregating exposure to administrative units, yet the equity implications of this choice are rarely tested. This study links annual 300 m nitrogen dioxide (NO₂) surfaces from the New York City Community Air Survey (2009–2023) with childhood asthma emergency department (ED) visit rates across 42 neighborhoods, comparing area-weighted, population-weighted, and residential-weighted aggregation throughout. Strong spatial convergence was observed in both NO₂ and ED burden (Pearson correlations between 2009 baseline levels and Theil–Sen slopes of −0.96 and −0.95). Panel first-difference estimation yielded a significant within-neighborhood association between NO₂ decline and ED rate decline (coefficient 0.022, p-value below 0.05). The most deprived fifth of neighborhoods received 47% of the total avoided ED burden, four times the share of the least deprived fifth. However, NO₂ reductions were nearly equal across poverty quintiles. The pro-poor distribution of health benefits was driven by baseline health inequality, not by differential pollution reduction. The three aggregation methods produced near-identical results for all metrics because within-neighborhood exposure variability was uncorrelated with poverty (r = −0.14). In cities where baseline disease burden is concentrated in disadvantaged communities, broad-based air quality improvement may contribute to pro-poor health gains without targeted intervention. Full article

Application of polyacrylonitrile-derived carbon fiber (CF) as a thermal insulation material is restricted by inherently high thermal conductivity. Encapsulation of poly(p-phenylene benzobisoxazole) (PBO) on CF was supposed to improve the mechanical and heat resistance of CF, which would be desired to improve mechanical and thermal-insulating performances. In this work, PBO molecules were uniformly coated onto the surface of air plasma-treated CF. Carbonized PBO-encapsulated CF (CF@CPBO) was prepared via thermal treatment at 600–1400 °C. At higher carbonization temperatures, CF@CPBO exhibited a cleaner surface, more radial graphite layers within fibers, enhanced crystallinity of carbon layers (amorphous to 0.337 nm of interplanar spacing), reduced defective/graphitic content (0.959–0.909 of I_D/I_G), decline in surface O content (20.1–9.6 at.%) and improved symmetry of the C-C deconvoluted peak. After weaving them into a net and compression molding, CF@CPBO felts with a random distributed structure (no voids and no fiber bundles) presented improved compression strength (10.5–25.6% of enhancement than unmodified CF) and excellent compression-recovery performance (130.9–110.8 MPa) through 10 cycles. Thermal conductivity values of CF@CPBO felts at 30–1800 °C were 0.13–1.42 W/m/K, which were 42.2–62.6% of unmodified CF. This work proposes an efficient strategy for regulating the high-performance organic fiber structure through heat treatment-induced processes. Full article

Coal-fired power units remain integral to electricity supply in many regions while facing increasingly stringent environmental expectations. Bridging reliable generation with sustainability requires more than end-of-pipe controls; it demands continuous intelligence embedded in plant operations. This study introduces an industry-oriented monitoring framework that transforms historical operational records into actionable foresight, enabling on-the-fly orchestration of combustion conditions to anticipate sulfur oxide (SOx) concentrations. Leveraging 919 empirical data points collected in 2019 from Unit 8 of the Taichung Thermal Power Plant, the framework integrates robust data governance, targeted feature curation, and a neural network-based analytics core. Eight process variables—sulfur content, coal feed rate, fixed carbon, grinding rate, calorific value, excess air, air flow, and boiler efficiency—emerge as the most influential drivers through systematic selection and feature importance attribution. The resulting forecasting module exhibits near-perfect alignment with observed emissions (R² = 0.99), enabling near-real-time guidance for setpoint adjustments and facilitating compliance strategies under varying load and fuel-quality conditions. Beyond accuracy, the system is architected for scalability and portability, aligning with Industry 4.0 paradigms by coupling continuous sensing, data-driven decision support, and stakeholder transparency. By reframing emission oversight as a proactive, intelligent service rather than a static reporting function, the proposed approach advances operational resilience, regulatory compliance, and community trust, with direct implications for resource efficiency and circular economy initiatives across heavy industry. The framework reduces potential SOx emissions and improves energy utilization efficiency under varying operational conditions. This approach contributes to environmental sustainability by enabling proactive emission reduction and cleaner production practices. It supports regulatory compliance and aligns with global sustainability goals, including SDG 7 and SDG 13. Full article

In the present study, a kinetic model was developed for the process of oxidative desulfurization of light gas oil with 7329 ppm sulfur using a newly synthesized nanocomposite catalyst. The batch reactor experiments were conducted at different thermal conditions (313–373 K) and reaction times (30–90 min) to explain this endeavor of desulfurization performance as a function of these variables, targeting the design of a reliable reactor system. Carbon nanofibers (CNFs) were integrated into the support γ-Al₂O₃ at various concentrations of 5%, 7.5%, and 10% to improve mechanical properties, surface area, and distribution of active metals. The nanocomposite support was impregnated with molybdenum trioxide (MoO₃) and iron oxide (Fe₂O₃) to form four variants of the catalyst: CAT-1 with 10% MoO₃ + 5% Fe₂O₃/Al₂O₃ + 5% CNF, CAT-2 with 10% MoO₃ + 5% Fe₂O₃/Al₂O₃ + 7.5% CNF, CAT-3 with 10% MoO₃ + 5% Fe₂O₃/Al₂O₃ + 10% CNF, and CAT-4 with 10% MoO₃ + 5% Fe₂O₃/Al₂O₃ with no CNF. CAT-3 had the best effectiveness for sulfur removal with 87.5% at 373 K and a reaction time of 90 min. The model predicts a maximum sulfur removal rate of 99.86% under optimal conditions of 550 K and 200 min (for an initial sulfur concentration of 7329 ppm). The experimental and modeling results therefore indicate the potential of the developed catalyst system, while the optimum condition at 550 K and 200 min should be interpreted as a model-predicted outcome. The development of such highly efficient nanocatalysts for deep desulfurization is a crucial advancement in green chemistry, directly contributing to the production of cleaner fuels to mitigate air pollution and supporting the aims of the United Nations Sustainable Development Goals (SDGs), particularly SDG 9 (Industry, Innovation, and Infrastructure) and SDG 12 (Responsible Consumption and Production). From a sustainability perspective, the proposed ODS system supports cleaner fuel production and reduced sulfur-derived emissions, while operating-condition optimization helps improve process efficiency in support of more sustainable refining strategies. Full article

The transportation sector, a major source of urban air pollution and CO₂ emissions, is the focus of extensive research aimed at developing cleaner and more efficient technologies. In this context, hydrogen–methane blends (HCNG) represent a promising alternative fuel, combining the zero-carbon combustion potential of hydrogen with the availability and cleaner profile of methane. This solution can be implemented in existing internal combustion engines, enabling a technically and economically feasible transition toward more sustainable mobility. This work investigates the use of an HCNG blend in a bus originally powered by natural gas, focusing on pollutant emissions under real driving conditions representative of typical urban operation. Measurements were performed using a Portable Emission Measurement System installed on-board. Two test campaigns were carried out: the first using methane, and the second using an HCNG blend (15% H₂, 85% CH₄ by volume), over identical urban and extra-urban routes with varying drivers and traffic conditions. Results show a reduction in CO₂ emissions with HCNG, along with a more significant decrease in CO, HC, and PN emissions, while NOx exhibited a slight increase due to unchanged engine calibration. The analysis also includes the RPA index, which is related to fuel energy release characteristics, indicating improved vehicle responsiveness and torque delivery with HCNG. Full article

With the progressive decline of tailpipe emissions, non-exhaust sources such as brake wear are becoming an increasingly important contributor to traffic-related particulate matter in urban environments. In this context, improving real-world characterization of brake wear particles is essential for air-pollution assessment, source apportionment, and the development of cleaner and more sustainable road transport systems. Here, we investigated the emissions levels, particle size distribution and elemental composition of particles released during harsh real-world braking events by a single light-duty vehicle braking system equipped with an original manufacturer (OEM) non-asbestos organic (NAO) pad formulation. Using a direct on-vehicle sampling system combined with real-time particle sizing and high-resolution microscopy, we observed that particle emissions remained close to background levels at speeds up to 100 km/h, but rose sharply at 120 km/h, reaching 3.7 × 10⁷ #/cm³ in the 8–10 nm size range. This increase suggests that higher speeds are associated with elevated particle emissions, likely due to the higher braking temperatures reached at increased vehicle speeds. The emitted particles were mainly spherical agglomerates rich in iron, titanium, barium, zirconium, and sulphur, consistent with NAO pad formulations. Our results show that the investigated NAO pad system can deteriorate under thermal stress, potentially leading to higher levels of nanoparticle emissions compared to low-metallic or semi-metallic pads investigated under similar conditions. These findings provide real-world evidence relevant to urban air quality research, support the refinement of non-exhaust emissions inventories, and highlight the importance of thermally resilient friction-material formulations for mitigating residual particulate emissions in increasingly cleaner transport systems. Full article

Corporate carbon reduction is essential for sustainable development, yet little is known about whether equity linkages within supply chains facilitate firms’ low-carbon transition. Using data on Chinese A-share listed firms from 2008 to 2022, this study examines the effect of supply chain shareholding, defined as equity ownership by suppliers and customers in a focal firm, on corporate carbon emission intensity. We find that supply chain shareholding significantly reduces corporate carbon emission intensity, and this result remains robust after a series of robustness and endogeneity tests. Mechanism analyses show that supply chain shareholding lowers carbon emission intensity by strengthening corporate green governance, promoting green innovation, and facilitating cleaner production. Further analyses indicate that this effect is more pronounced under stricter air quality requirements, in regions with stronger environmental regulation, and among heavily polluting industries. These findings highlight the role of supply chain governance in corporate carbon reduction and suggest that equity linkages within supply chains can support firms’ low-carbon transition. Full article

The transport sector is a major contributor to urban air pollution and greenhouse gas emissions in Pakistan, posing significant challenges to sustainable development and climate commitments. This study develops the first technology-resolved, high-resolution, multi-pollutant emission inventory and scenario analysis for Pakistan’s transport sector, addressing key gaps in previous studies that lacked integrated multi-pollutant assessments, comprehensive coverage of non-road sources, and long-term scenario comparisons. The analysis integrates road and non-road transport sources within the Greenhouse Gas–Air Pollution Interactions and Synergies (GAINS) modeling framework. Emissions are projected for 2024–2050 under a business-as-usual (BAU) scenario and three mitigation pathways: an Electric Vehicle Transition (EVT) emphasizing transport electrification, a Euro-VI scenario focusing on stringent fuel and vehicle emission standards, and an integrated nationally determined contribution strategy (NDC+) scenario combining electrification, regulatory improvements, and structural transport reforms. In 2024, transport-related emissions are estimated at approximately 22 kt of fine particulate matter (PM_2.5), over 300 kt of nitrogen oxides (NO_x), and nearly 39 Mt of carbon dioxide (CO₂), alongside substantial emissions of other gaseous pollutants and short-lived climate forcers. By 2050, the NDC+ scenario achieves the largest reductions relative to business-as-usual, demonstrating that coordinated electrification and emission control strategies can simultaneously reduce air pollution and greenhouse gas emissions. The results demonstrate strong synergies between climate mitigation and air quality improvement, showing that integrated strategies combining electrification with stringent emission standards can simultaneously reduce greenhouse gas emissions and major air pollutants while advancing cleaner and more sustainable mobility. This analysis provides a consistent and policy-relevant evidence base derived from best-available data and modeling tools to support Pakistan’s NDC implementation, sustainable mobility planning, and integrated air quality and climate strategies, with lessons transferable to other rapidly developing economies. Full article

This two-week pilot study within the Horizon Europe EDIAQI project evaluated the real-life performance of portable air filtration units in two office environments (a small office and a shared kitchen) under continuous device operation and daily filter replacement. Indoor particle concentrations were monitored continuously using low-cost sensors (LCS) from three providers and supported by gravimetric measurements, while daily activity logs documented occupancy patterns, printing, cooking, and other source events together with purifier ON/OFF status. Particulate matter (PM) mass concentrations showed no systematic improvement during purifier ON periods; instead, temporal variability was dominated by indoor activities and episodic emissions, with occasional short-term peaks around filter replacement suggestive of minor resuspension. Chemical analysis provided a clearer picture: polycyclic aromatic hydrocarbons (PAHs) responded differently across fractions and compositions. Across monitored locations, high-molecular-weight PAHs in the PM₁ fraction decreased during purifier ON periods (approximately 30% lower on average), whereas low-molecular-weight PAHs measured in total suspended particles (TSP) were higher during ON periods, indicating that semi-volatile fractions and activity/ventilation dynamics can outweigh simple filtration effects. Overall, the findings highlight a gap between laboratory-derived filtration performance metrics and outcomes in occupied, mixed-source indoor environments and emphasise the importance of device sizing, placement, airflow mixing, and complementary source control and ventilation strategies when deploying filtration-based IAQ interventions. Full article

Air pollution is one of the major environmental challenges threatening global sustainable development and human health. The World Health Organization identifies it as a critical factor contributing to non-communicable diseases and inequality, especially in vulnerable populations such as children. The findings highlight the negative effects of environmental degradation on physical health and underline the urgent need to incorporate health metrics, such as children’s fitness, into sustainability monitoring frameworks and public policies aiming at cleaner and healthier urban environments. The aim of this study was to examine the association between ambient particulate pollution and cardiorespiratory fitness in school-aged children from two rural villages in southern Spain characterised by relatively higher and lower levels of particulate matter. A total of 938 children (primary and secondary school levels) participated in a naturalistic pre–post study design. Cardiorespiratory fitness was assessed using the 6 min walk test, where maximal oxygen uptake (VO₂max) was estimated. Assessments were conducted before and after a period characterised by unfavourable air-quality conditions in the higher-pollution village. The students were assigned by convenience into an experimental [n = 476 (EG)] and a control group [n = 462 (CG)]. The t-test, repeated measures analysis and MANOVA test were used in order to report differences within and between groups, as well as time-points and academic levels. The significance level was set at p < 0.05. Significant differences between groups were reported within the pre-test period, showing elevated pre-test values in the CG compared to the EG. The EG showed a higher pre–post difference in estimated VO₂max compared to the CG for primary education level (16.19%, ES(d) = 0.91 vs. 3.07%, ES(d) = 0.26; p < 0.001, respectively); secondary education (EG: 12.29%, ES = 0.91 vs. CG: 1.69, ES(d) = 0.16); and the whole population (EG: 14.72%, ES = 0.91 vs. CG: 2.84, ES = 0.25). It seems that the environmental context, and specifically the air pollution in the area of residence, may be an important factor to consider in relation to the assessment of physical fitness in the school-aged youth population. Full article

Maritime transport is essential for global trade, yet ship emissions remain a major source of air pollution in coastal and port areas, with potential impacts on local air quality and human health. Cruise ships are particularly relevant in urban ports because, beyond propulsion, they require a continuous onboard energy supply for hotel services while berthed. This study develops a bottom-up emission inventory for cruise ship calls at Istanbul Galataport during the 2024 season, estimating CO₂ as a greenhouse gas (GHG) and NO_x, SO_x, and particulate matter (PM) as air-quality pollutants generated during manoeuvring and hotelling phases. Ship technical characteristics (engine type, installed main and auxiliary power, engine speed class, and year of build) were obtained from the IHS database, while port call activity data were provided by the terminal operator. Emission factors were primarily based on the IMO Third Greenhouse Gas Study and complemented with established literature sources to address missing vessel information and ensure methodological consistency. Results indicate that hotelling dominates total emissions, reflecting the high auxiliary power demand during berths. Results show that total annual emissions from 164 cruise ship calls amount to approximately 31,360 t·y⁻¹ of CO₂, 370 t·y⁻¹ of NO_x, 350 t·y⁻¹ of SO_x, and 44 t·y⁻¹ of PM. Hotelling operations account for the dominant share of emissions, contributing more than 90% of total CO₂ and the majority of NO_x and SO_x emissions, due to sustained auxiliary engine demand during berth stays. These findings confirm that cruise ship activity represents a significant localized emission source in densely populated port environments and provide a quantitative baseline for evaluating mitigation measures such as shore power, cleaner fuels, and operational strategies aimed at reducing at-berth emissions. Full article

Atmospheric aerosols in Southeast Asia, influenced by climate and seasonal circulation, are examined here. This study analyzes the impact of the 2015 El Niño and monsoonal variability on aerosol properties over Penang, Malaysia, from 2015–2019. Aerosol Optical Depth (AOD), Ångström Exponent (AE), Fine Mode Fraction (FMF), and Single Scattering Albedo (SSA) were analyzed using AERONET observations, complemented by satellite-derived fire data and NOAA HYSPLIT back-trajectory analysis. Pronounced seasonal variability was observed, with elevated AOD during the Southwest Monsoon (0.72 ± 0.15) associated with biomass burning and mixed urban aerosols, and lower AOD during the Northeast Monsoon (0.47 ± 0.12) due to cleaner maritime air masses. The inter-monsoon period exhibited the lowest AOD (0.28 ± 0.10), reflecting enhanced wet scavenging and mixed aerosol sources. Interannually, the 2015 El Niño recorded substantially higher aerosol loading, including extreme AOD events (>1.75), driven by intensified regional fire activity under dry conditions. A statistically significant but weak correlation (R² = 0.12, p = 0.047) indicates biomass burning contributed to AOD, though transport processes were the dominant driver. Trajectory analysis confirmed that aerosols originated from fire-affected Sumatra during the Southwest Monsoon and from the South China Sea during the Northeast Monsoon. These results show that climate and winds drive aerosol changes, so regional monitoring and cross-border air management in Southeast Asia are needed. Full article

This study evaluated the effects of different provisional luting cement removal methods on the shear bond strength (SBS) of resin cement to dentin following immediate dentin sealing (IDS) performed with two adhesive systems. A total of 168 extracted, caries-free human third molars were used, of which 144 were allocated for SBS testing and 24 for scanning electron microscopy (SEM) analysis. Specimens were assigned according to the IDS protocol (no IDS, IDS with OptiBond FL, or IDS with G2-Bond), followed by provisional cementation using an eugenol-free temporary cement. Contaminated surfaces were subsequently cleaned with a hand scaler, aluminum oxide (Al₂O₃) air abrasion, or Katana Cleaner prior to final bonding with a dual-cure resin cement. SBS was measured after 24 h of water storage, and surface morphology was evaluated by SEM at 2500× magnification. IDS significantly increased SBS under uncontaminated conditions, with G2-Bond-based IDS exhibiting higher bond strength values than specimens without IDS. However, provisional cement contamination significantly reduced SBS regardless of the cleaning method applied, and none of the tested protocols fully restored the bond strength observed in uncontaminated IDS-treated dentin. SEM analysis revealed residual cement remnants and surface alterations after cleaning, even in specimens that appeared macroscopically clean. Within the limitations of this in vitro study, IDS enhances resin–dentin bonding when contamination is avoided; however, current mechanical and chemical cleaning methods are insufficient to completely recover bond strength compromised by provisional cement contamination, highlighting the importance of preventing contamination and preserving IDS layer integrity during indirect restorative procedures. Full article