Understanding O3 formation in petrochemical regions requires consideration of how abundant precursor emissions influence local photochemical characteristics. This study investigated ozone production characteristics at the Yeosu National Petrochemical Industrial Complex. We observed gaseous pollutants and Benzene, Toluene, Ethylbenzene, Xylene, Styrene (BTEXS) concentrations, calculated radical-based ozone production rates p(O3), and performed Framework for 0-D Atmospheric Modeling (F0AM) simulations. During the observation period, mean O3, NO, NO2, and CO concentrations were 54.32 ± 19.88, 2.99 ± 3.56, 17.42 ± 11.34, and 152.86 ± 90.78 ppb, respectively. Among BTEXS compounds, toluene showed the highest mean concentration, followed by benzene, m&p-xylene, ethylbenzene, styrene, and o-xylene. O3 exhibited clear daytime enhancement, while BTEXS compounds showed compound-specific temporal and diurnal patterns associated with industrial emissions and photochemical reactivity. Calculated p(O3) was positively associated with both observed and F0AM-simulated O3, with the stronger relationship for F0AM providing an internal consistency check between the simplified calculation and box-model results. Precursor reduction scenarios showed that simultaneous NOx and BTEXS reductions decreased p(O3). These results highlight the importance of coordinated control of NOx and reactive aromatic volatile organic compounds (VOCs) for mitigating industrial ozone formation.Implications: This study provides a monitoring- and modeling-based assessment of ozone production in a petrochemical industrial atmosphere, where aromatic VOCs and NOx jointly influence photochemical ozone formation. By combining observed BTEXS and gaseous pollutant data with radical-based p(O3) calculations and F0AM simulations, the results identify high-production conditions under which precursor reductions are most effective. The findings suggest that coordinated control of NOx and reactive aromatic VOCs, rather than single-precursor management, is necessary to reduce ozone formation in petrochemical industrial regions. This approach can support targeted emission-control strategies for industrial air-quality management.
The US Environmental Protection Agency (EPA) may set emissions standards according to a threshold for maximum exposure that accounts for a substantial safety margin if exposure to a substance is expected to operate according to a non-linear, threshold model. The consideration of health-based thresholds for hazardous air pollutants (HAPs) that are being considered for carcinogenicity is relatively novel and reflects the fact that EPA now recognizes that some HAPs (both carcinogens and non-carcinogens) can be either non-threshold or threshold pollutants, or both, depending on the health outcome of interest. If a threshold model is accepted for carcinogenicity, EPA may set a health-based emission limit (HBEL), in addition to existing technology-based requirements, using the estimated threshold, plus an ample margin of safety. EPA is currently considering thresholds for several substances, including hydrochloric acid (HCl). To demonstrate the type of analysis that might address this issue, we conducted a targeted literature review of the evidence regarding the carcinogenicity of HCl based on available epidemiologic and toxicological studies, including genotoxicity studies. We discuss when regulations could be based on threshold vs. non-threshold models, using HCl as a case study. We found no evidence to support the use of a linear, no-threshold model and limited, inconsistent evidence to suggest that HCl is likely to be carcinogenic or a DNA-reactive mutagen. The evidence summarized here is intended to aid EPA in its risk evaluation and clearly supports the setting of an HBEL for HCl and other chemicals where the biological mechanism supports the existence of a threshold.Implications: Section 112(d)(4) of the Clean Air Act permits EPA to consider health-based emission limits for hazardous air pollutants when the available scientific evidence supports the existence of a threshold for adverse effects and an ample margin of safety can be established. Using hydrochloric acid as a case study, this review integrates epidemiologic, toxicologic, and mechanistic evidence relevant to evaluating threshold versus non-threshold modes of action. The evidence is more consistent with threshold-mediated effects than with a direct mutagenic carcinogenic mechanism and may inform future scientific evaluations conducted under Section 112(d)(4).
This study used excess sludge from urban wastewater treatment plants as a raw material to prepare sludge-based activated carbon (SAC) via ZnCl2 activation and high-temperature carbonization. The structure of SAC was characterized using XRD, SEM, and FTIR, and the adsorption performance of SAC toward Cr(VI) in wastewater was systematically investigated. The results showed that, under the conditions of a ZnCl2 activator concentration of 1 mol/L, a carbonization temperature of 550°C, and a heating rate of 10 ℃/min, the prepared SAC had a maximum adsorption capacity of 57.90 mg/g for Cr(VI) in wastewater, and could achieve 100% removal of Cr(VI) at an initial concentration of 10 mg/L. The adsorption process conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model, indicating that chemical adsorption was the rate-controlling step, and Cr(VI) was mainly adsorbed in a uniform monolayer on the SAC surface. This study provides a feasible technical route for sludge resource utilization and Cr(VI) wastewater treatment.Implications:In this study, activated carbon was prepared using sludge as the raw material, realizing the reduction and resource utilization of sludge. This method not only solves the problems of land occupation and secondary pollution caused by sludge storage and landfilling, but also reduces the preparation cost of activated carbon, which conforms to the environmental protection policies for solid waste recycling.To address the pollution of highly toxic Cr(VI) in wastewater, the as-prepared sludge-based activated carbon shows excellent adsorption performance, which can efficiently remove Cr(VI) from aqueous solution and significantly reduce the biological toxicity and environmental risks of heavy metals.This work constructs a cyclic utilization pathway of "sludge disposal-functional carbon preparation-heavy metal wastewater treatment," providing an economically feasible technical scheme for the treatment of chromium-containing industrial wastewater. It has important theoretical value and practical application significance for promoting solid waste resource utilization, improving the water ecological environment and ensuring water environmental safety.
Filter-based optical techniques compare light transmission intensities between loaded (I) and unloaded (I0) filters as a measure of light-absorbing mass for subsequent estimations of equivalent black carbon (eBC). We analyzed 5,379 15 mm Teflon filters from the Household Air Pollution Intervention Network (HAPIN) trial to assess the influence that different methods of I0 estimations have on eBC measures. We compared eBC measurements using filter-specific I0 values (Method 1) to those using three other methods of I0 estimation: the lab blank scan from a given session (Method 2), the average of all pre-sample filter scans (Method 3), and the average of all lab blank filter scans (Method 4). We assessed the agreement between Method 1 and the alternative methods using Bland-Altman analysis. We also assessed the relationship between Method 1 and the alternative methods across the complete measurement range and after stratifying exposure data into quartiles according to Method 1 eBC exposures. The mean (SD) personal eBC exposure for Method 1 was 7.8 μg/m3 (5.9), and exposures ranged from 1.3 to 46.8 μg/m3. Compared to Method 1, eBC using Methods 2, 3, and 4 were higher by 0.7 μg/m3, 0.1 μg/m3, and 0.7 μg/m3, respectively. The performances of linear regression models between Method 1 and all other methods were moderate to strong (R2 range: 0.42-0.93) in the second, third, and fourth quartiles; however, the models in the first quartile (eBC range: 1.3-2.9 μg/m3) performed poorly (R2 = 0.25-0.26), with error approximately 25% of the mean. Our findings suggest that, in most instances, conventional methods for obtaining I0 values can be used to sufficiently characterize eBC; however, analyzing filters before sampling adds appreciably to the accuracy of eBC estimations in lower concentration settings.Implications: Filter-based optical techniques compare light transmission intensities between loaded (I) and unloaded (I0) filters as a measure of light-absorbing mass for subsequent estimations of equivalent black carbon (eBC). To assess the influence that different methods of I0 estimations have on eBC measures, we analyzed 5,379 15 mm Teflon filters from the Household Air Pollution Intervention Network (HAPIN) trial. Our findings suggest that, in most instances, conventional methods for obtaining I0 values can be used to sufficiently characterize eBC; however, analyzing filters before sampling adds appreciably to the accuracy of eBC estimations in lower concentration settings.
Although transitioning to electric mobility is critical, decarbonization pathways for mixed-powertrain ride-sourcing fleets, particularly those already dominated by hybrid electric vehicles, remain underexplored. This study assesses well-to-wheel emissions and carbon pricing implications for a regional ride-sourcing fleet through a policy-anchored scenario-simulation framework. Within this framework, a hybrid ARIMA-LSTM model is employed to forecast mileage demand as a key input, which is then integrated with time-varying emission factors and national electrification pathways to evaluate emission and carbon-fee outcomes across scenarios. Five scenarios were established, ranging from a baseline of 100% internal combustion engine vehicles to policy-driven targets of 30%, 60%, and 100% electric vehicles by 2030, 2035, and 2040. Results reveal a significant divergence: while tank-to-wheel emissions decrease by 33%, 62%, and 100% respectively, reductions are limited to 17%, 29%, and 44% when well-to-wheel emissions are taken into account. Furthermore, analysis confirmed that fleet electrification would effectively mitigate future expenditures for carbon fees. Regarding electricity emission factors, estimations showed that faster grid decarbonization leads to significantly greater cumulative reductions. This demonstrates that vehicle electrification alone is insufficient for deep decarbonization; its benefits are significantly enhanced only when combined with parallel grid decarbonization, producing a compounding reduction effect across the well-to-wheel boundary.Implications: This study demonstrates that for mixed-powertrain fleets, relying solely on tank-to-wheel metrics overstates the achievable decarbonization under full electrification, indicating a 100% reduction when the actual well-to-wheel reduction is only 44%. Consequently, policymakers must synchronize vehicle electrification mandates with accelerated grid decarbonization to bridge the gap between local zero-emission targets and actual lifecycle reductions. Furthermore, the analysis confirms that fleet electrification serves as a critical financial hedge against rising carbon prices. These insights provide stakeholders with a realistic framework for integrating transportation strategies with energy policy to ensure holistic long-term sustainability.
This study examines the feasibility of applying ground-based hyperspectral imaging to monitor methane (CH4) concentrations at landfills. The hyperspectral imaging system implemented in this study is an imaging Fourier transform spectrometer (IFTS) that operates in the long-wavelength infrared (LWIR) spectrum, between 750 and 1350 cm-1. The instrument produces a three-dimensional absolute intensity data cube, where the first two dimensions define the image plane and the third dimension corresponds to the wavenumber spectrum. The intensity spectrum of each pixel can be inverted using a spectroscopic model to infer air temperature, background temperature, and CH4 and H2O column densities. Additionally, the gas velocity near the surface can be visualized by tracking features in interference-corrected interferogram images. The findings show that this technique can image CH4 column densities from both diffuse and point sources within landfills, provided there is an adequate thermal contrast between the background surface and the air column between the background surface and the camera aperture. The capability to obtain images of CH4 column densities and velocimetry from the IFTS opens the potential for estimating CH4 emissions rates from landfills.IMPLICATIONThe ability to image methane is crucial for monitoring and studying landfill methane emissions, given their high spatial variability. Hyperspectral imaging of methane from landfills is often conducted via airborne or satellite-based imaging techniques, which are often associated with low spatial resolution (~30 m) and rely on reflective sunlight. Our manuscript presents methane field test results from active and closed landfills using ground-based hyperspectral imaging operating in the long-wavelength infrared spectrum, which enables higher spatial resolution (~7 cm) and demonstrates the capability to image methane using thermal radiation from the background surface. The manuscript also discusses the uncertainty associated with the operating conditions of the technology.
In this study, air pollutant emission factors have been developed for emerging fuels and technologies under representative cyclic operation in residential and commercial boilers. The cases explored include 20% biodiesel blends; 100% biodiesel; renewable diesel; and modulating-condensing ("Mod-Con") gas boilers with 100% utility natural gas and 20% hydrogen blends. Three appliances were evaluated: a residential retention-head liquid fuel-fired boiler with pressure atomization and a single firing rate; a residential Mod-Con boiler; and a commercial boiler with a two-stage pressure atomized liquid fuel burner. Measured pollutants included particulate matter (PM), carbon monoxide (CO), nitrogen oxides (NOx), methane (CH4), volatile organic compounds (VOCs), and hazardous air pollutants (HAPs). Particulates were measured using EPA Methods 5 and 202 to capture filterable and condensable particulates supplemented by real-time PM instrumentation. Results are compared with prior work using conventional fuels and technologies as well as emission factors commonly used in inventories. Findings highlight the importance of burner on-off operation in driving pollutant emissions associated with incomplete combustion; this behavior is not well captured by current emission factors, which are based primarily on steady-state operation and much larger applications.Implications: Residential and commercial boilers contribute substantially to building-sector emissions, but existing emission factors often reflect steady-state operation of larger systems rather than cycling in smaller appliances. This study develops new emission factors for emerging fuels, including renewable diesel, biodiesel blends, and natural gas/hydrogen mixtures, as well as a modern modulating, condensing gas boiler. Results show that burner cycling strongly affects incomplete-combustion pollutants and that condensable particulate matter can dominate total PM, especially in advanced gas systems. These findings support more realistic emissions inventories and regulatory assessments of fuel-switching and decarbonization strategies.
Advances in Earth observation (EO) remote sensing technologies have delivered a range of aerosol and trace gas pollution data with ever-improving spatial and temporal resolution, significantly benefitting assessments of global air quality (AQ). Furthermore, the application of data synthesis techniques incorporating satellite EO with other information sources has improved the availability of satellite-derived estimates of pollutant exposure at local to global scales. These data have been applied to address a diversity of use cases in AQ monitoring and public health, from long-term trend tracking, exposure assessment, and epidemiological analysis to short-term emissions identification and early warning. Successful application of satellite EO to address AQ and AQ-related health problems requires an alignment between (1) the technical capabilities of satellite data to provide relevant information, (2) a defined case for using this information to address a particular need, and (3) the human capacity, computational resources, operational plans, and policy and governance frameworks to implement a solution and take action, and to sustain the solution for as long as the need remains. Only when there is substantial alignment across all these factors can satellite EO information be effectively translated into public health benefits. This paper surveys applications of satellite EO to AQ assessment and AQ-related health management globally, synthesizing key commonalities into recommendations for how satellite EO can effectively support health needs. We also identify gaps in current satellite EO capabilities, use-case applications, and feasibility factors where future research and investment could reduce barriers to increased application of satellite EO to address pressing public health concerns related to AQ worldwide.Implications: This paper summarizes insights collected through the Group on Earth Observations (GEO) Health Community of Practice Air Quality and Respiratory Health Work Group on the current state and gaps in the use of satellite EO to support air quality and related health decision-making globally. We synthesize these insights into general recommendations for how satellite EO capabilities, use cases, and feasibility considerations can be aligned towards effective use of satellite EO data for air quality and related health effects. We also identify barriers and gaps in current capabilities, uses, and capacities, making recommendations for how these might be addressed.
This work investigates the catalytic performance of unmodified waste-to-energy (WtE) ash for nitrogen oxides (NOx) abatement via selective catalytic reduction. NOx conversions up to 44% were measured in a simulated flue gas (2,600 ppm NO, 9,700 ppm CO, 1.8% H2O). Pretreatment substantially enhanced NO conversion relative to the as-received ash, with H2 pretreatment yielding up to 91% conversion. Characterization revealed a low surface area (17.8 m2 g-1), SiO2-CaO-Al2O3 matrix, and trace Fe, Mn, and Cu. Temperature-programmed reduction and thermal analysis indicated redox-active, non-metallic species. Additional spectroscopic analysis indicates temperature-dependent evolution of surface species under reaction conditions, consistent with an oxygen-mediated redox contribution to NO reduction. However, the active intermediates and specific reaction pathway remain to be fully resolved. These findings demonstrate that WtE ash, an abundant industrial byproduct, can be repurposed as a low-cost, harsh-environment catalyst for NOx abatement.Implications: This study shows that municipal waste-to-energy ash can catalytically reduce NOx at temperatures relevant to real-world flue-gas conditions, offering a potential low-cost alternative to conventional SCR catalysts. Because the material is already generated at scale, its catalytic behavior presents a new opportunity for emissions control strategies that integrate waste-derived resources and support circular-economy objectives. These findings may inform future technology development, regulatory evaluations, and research into waste-based materials for air-pollution mitigation.
Our work provides new insights into the importance of aquatic waste, particularly that derived from crabs. The present study aimed to compare the phospholipid and fatty acid compositions of shell waste from two different crab species: the green crab (Carcinus aestuarii) and the blue crab (Portunus segnis). Both species exhibited low total lipid contents. Our findings revealed that C. aestuarii had a lower content of total lipid and proteins compared to P. segnis. Analysis of shell waste from both species identified four classes of phospholipids (PL): phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), and phosphatidylinositol (PI). In C. aestuarii, PC, PE and PI were the predominant components, whereas PE, PI and PS were the dominant phospholipid in P. segnis. However, significant change son PC and PS were recorded between C. aestuarii and P. segnis. Total fatty acid profile revealed that C.aestuarii shell waste had significant amount of saturated fatty acid (SFA) and PUFA n-3 mainly C18:0; docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), respectively. However, highest amount of monounsaturated fatty acid (MUFA) and PUFA n-6 principally C16:1 and arachidonic acid (ARA) were noted compared to C.aestuarii. Fatty acids profile analysis of phospholipid's fractions revealed for the first time a dominance of SFA, MUFA, followed by PUFA and PUFA (n-3) in all classes for both species. High quantities of the essential fatty acids EPA and DHA, exceeding 0.4 mg/g dw, were detected in all lipid classes of both species, highlighting the strong potential of these wastes as stability indicators in biofertilizer formulation and for integration into aquaculture diets.Implication: The shell residues have strong potential for valorization for applications in agriculture, aquaculture, as well as in the development of functional feed for crustaceans. These valorization strategies are fully in line with a sustainable approach to marine waste management, consistent with the principles of the circular bio-economy and green technologies.
Air pollution is a major public health concern, particularly for children who are more susceptible to its harmful respiratory effects. Makkah experiences elevated levels of air pollution due to the influx of religious visitors, vehicular emissions, and traffic during the annual Hajj. The resulting increase in air pollutants raises concerns about respiratory health risks among children, yet local research has focused little on this vulnerable group. This study investigated the association between air pollutants (PM10 and NO2) and pediatric admissions from acute lower respiratory infections (ALRI) among children aged 5-14 years in Makkah, Saudi Arabia, from January 2021 to December 2022. The study period overlapped with the COVID-19 pandemic, which was considered when interpreting the findings. Daily time-series log-linear Poisson regression models were used, adjusting for temporal trends using natural cubic splines, meteorological variables, and sociodemographic factors. Relative risks were estimated per interquartile range increase in pollutant concentrations across lag days 0-2. Hajj-specific associations were assessed using interaction terms for the Hajj and non-Hajj periods. Exposure to NO2 was significantly associated with an increased risk of same-day ALRI admissions in children during the Hajj events (RR = 1.033; 95% CI: 1.003-1.063 per IQR rise) but not outside the Hajj events. In contrast, PM10 effects were non-significant. The findings suggest that NO2, but not PM10, was associated with ALRI admissions during Hajj, highlighting the need for Hajj-focused traffic-emission control and child health protection strategies in Makkah.Implications: Increased NO2 levels during Hajj are associated with higher pediatric ALRI admissions, highlighting the need for targeted air quality management during mass gatherings. Strengthening emission controls, traffic regulation, and monitoring can reduce exposure and protect vulnerable children.
Although small businesses play an important role in generating employment opportunities and local economic development, their involvement in recycling programs has not been characterized in greater detail. This study explored the perceptions and willingness of selected small businesses in Gauteng province townships to reuse or recycle some of their waste materials. This study used a quantitative research approach to explore the perceptions and willingness of selected small businesses to reuse or recycle some of the waste they generate. The results showed that the perceptions about the contribution of recycling to environmental pollution reduction among small businesses in the study differed significantly across the townships (χ2 = 6.892, p = 0.003). On the other hand, most formal businesses significantly agreed with the potential benefits of waste recycling on environmental pollution reduction (χ2 = 16.118, p = 0.003), saving landfill space (χ2 = 11.610, p = 0.003), improving environmental quality (χ2 = 10.443, p = 0.005), and providing job opportunities (χ2 = 10.263, p = 0.036). However, regardless of their formality (χ2 = 2.957, p = 0.228) or location (χ2 = 9.463, p = 0.051), there was no statistically significant variation in the recycling practices of the small businesses in this study. Moreover, businesses' willingness to use recycling facilities if they were located nearby differed across townships (0.05 > p = 0.010) but was similar despite the formality of the enterprises. In conclusion, recycling perceptions and willingness of small businesses can vary significantly depending on whether they are formal or informal and across townships. As a result, relevant educational interventions should be uniquely developed to raise awareness about the need for waste minimization through recovery, re-use, and recycling among small businesses in the Gauteng province.Implications: Small, Medium, and Micro enterprises (SMMEs) play a crucial role in local economic development in South Africa. However, research on their environmental sustainability is scarce, despite their significant impacts on natural resources and contributions to pollution. Most waste management studies have focused on households and municipalities, leaving a gap in understanding SMMEs' waste management behaviors, particularly in townships.
The increasing generation of industrial and commercial waste (ICW) in urban regions undergoing industrial expansion poses significant challenges for landfill-based waste management systems. This study presents a comprehensive characterization of ICW generated in the Monterrey Metropolitan Area, MX, to support the assessment of its recycling and Waste-to-Energy (WtE) potential through thermal (incineration) and biological (anaerobic digestion) pathways. The study combines statistical evaluation of landfill-received ICW streams with the characterization of heterogeneous commercial waste and segregated industrial fractions to assess their variability, composition, and recovery potential. Daily ICW disposal during 2023-2024 was modeled using probability function fitting, complemented by physicochemical, energetic, elemental, and heavy metal analyses from four sampling campaigns conducted between November 2023 and March 2024. Heterogeneous ICW accounted for 310,782 t y-1, representing approximately 58% of the total landfill-disposed ICW, and consisted mainly of paper and cardboard (38.1%), plastics (22.8%), and organic waste (14.5%). Most recyclable fractions followed log-normal distributions, whereas wastepaper sludge and segregated food waste exhibited normal distributions associated with more stable generation patterns. The inorganic fraction showed an average lower heating value of 14.3 MJ kg-1 and chlorine contents below 0.2%, meeting Class 1 RDF quality criteria. Polymeric fractions such as LDPE and HDPE exhibited carbon contents above 60% and LHVs up to 40.8 MJ kg-1. Heavy metal concentrations were low, while the food fraction exhibited an average biochemical methane potential of 115.2 mL CH4 g VS-1. Overall, inorganic and organic ICW fractions could provide up to 217 and 2.7 GWh y-1 of recoverable energy, respectively, while recycling pathways could substitute nearly 1,500 t of virgin materials annually. These findings demonstrate that detailed ICW characterization supports the identification of priority fractions for recovery and the design of recycling and WtE systems in landfill-dependent waste management contexts.Implications: Addressing the lack of industrial and commercial waste (ICW) data in Latin America, this study presents a methodological framework combining sampling (2023-2024) and probabilistic modeling. Focusing on Monterrey, Mexico, where half a million tons of ICW are landfilled annually, the research provides key data on composition, contaminants, and energy potential. These findings support realistic scenarios for recycling, waste-to-energy valorization, logistical planning, and GHG quantification. This strategic information is vital to strengthen regional regulatory frameworks, guide policy decision-making, and drive public-private investments in infrastructure within landfill-dominated management systems.
Despite sustained estimated reductions in anthropogenic precursor emissions, ozone design values remain above the 2015 8-hour National Ambient Air Quality Standard in four large, urban nonattainment areas (NAAs) in the Intermountain Western U.S.: Phoenix-Mesa, Arizona; Las Vegas, Nevada; Wasatch Front, Utah; and Denver Metro/North Front Range, Colorado. We synthesize recent field campaigns, regulatory analyses, and observationally constrained modeling to summarize shared drivers of stalled progress and the region-specific mechanisms that modulate ozone accumulation. Across these areas, elevated background ozone, terrain-driven recirculation, and meteorological conditions favoring stagnation and vertical coupling all reduce the effectiveness of local emission controls. However, many important factors also differ by airshed: Phoenix is strongly influenced by monsoon-modulated photochemistry and boundary-layer dynamics; Las Vegas by frequent entrainment of ozone-rich layers from aloft and a high ozone "floor"; the Wasatch Front by corridor confinement, elevated background concentrations, and multi-day recirculation; and the Front Range by complex terrain flows interacting with spatially heterogeneous precursor sources, including strong within-NAA oil and gas emissions. Together, each of these case studies underscores the need for ozone management strategies tailored to each airshed's structural and dynamical constraints, supported by coordinated collaborative science.Implications: Despite decades of declining anthropogenic precursor emissions, four major Intermountain Western U.S. metropolitan areas (Phoenix, Las Vegas, Salt Lake City, and Denver) continue to exceed the 2015 ozone standard. This synthesis identifies factors, both shared and specific to each airshed, driving persistent nonattainment. Elevated background ozone, wildfire smoke, terrain driven recirculation, and vertical entrainment all limit the effectiveness of local controls, though dominant mechanisms differ by area. For lawmakers and regulators, these findings underscore the need for region specific strategies, better vertical and precursor monitoring, and improved attribution of controllable versus transported ozone to support sound, technically defensible regulatory decisions.
The accumulation of detectable amounts of radon progeny in the maternal-fetal placental barrier may be a risk factor for fetal development and lifelong disabilities. In this preliminary study, we analyzed the levels of alpha-emitting radon progeny Polonium-210 (210Po) (in Becquerel/kg) in the maternal-fetal placental barrier from placentas in Sao Paulo, SP, Brazil. Overall, there were higher levels of 210Po at the maternal portion of the placenta 1.45 (0.34) Bq/kg when compared to the fetal placental portion [1.08 (0.35) Bq/kg]. The presence of 210Po in the maternal-fetal placenta may indicate a potential risk of adverse pregnancy and fetal outcomes, including impaired placenta growth and fetus development potentially leading to lifelong disabilities. Future studies are warranted to identify the natural and anthropogenic sources of 210Po in urban areas and 210Po-related adverse pregnancy health outcomes.Implications: Our findings suggest that the presence of environmental 210Po in maternal and fetal placenta tissues may indicate a potential hazard risk of adverse pregnancy outcomes and fetal health. Future studies with a larger number of pregnant women should be able to identify more accurately the biological mechanisms of the exposures to natural and anthropogenic sources of 210Po, and help generate public health policies to mitigate it.
Air quality in Delhi has deteriorated significantly over the past decade, yet accurate high-resolution forecasting across multiple pollutants remains a major challenge due to heterogeneous monitoring networks, missing data, and complex spatial - temporal interactions. Motivated by the need for reliable early-warning systems, this study proposes DynLink-AQ, an end-to-end framework for multi-pollutant forecasting using data from 39 CPCB stations over 2009-2023. The system integrates rigorous data quality control and robust spatio-temporal imputation, followed by feature engineering enriched with meteorological drivers and temporal encodings. Unlike static distance-based station graphs, DynLink-AQ learns time-varying inter-station connectivity by inferring adaptive graph attention weights from station embeddings, spatial proximity, and temporal similarity, enabling event-driven and meteorology-linked coupling to be captured. Built upon this structure, the model alternates temporal attention blocks with spatial adaptive graph-attention layers to capture deep spatial - temporal dependencies. The framework supports multi-task prediction for 1-24-hour pollutant horizons with optional uncertainty quantification, and hyperparameters are tuned using the Enzyme Action Optimizer Algorithm (EAOA) under rolling-window training. Extensive walk-forward and spatial generalization experiments demonstrate strong predictive skill across pollutants, with ablation studies confirming the importance of dynamic connectivity learning and meteorological features. The study additionally provides GIS-ready outputs for seamless visualization and operational use in pollution management.Implications: DynLink-AQ enables operational, network-wide forecasting of PM2.5, PM10, NO2, and O3 across Delhi using Central Pollution Control Board monitoring data. By learning time-varying inter-station connectivity and combining spatial graph attention with temporal attention, the model improves 1-24h predictions and provides uncertainty bounds for risk-aware alerts. Agencies can use these forecasts to issue timely hotspot formation, alerts, and plan short-term mitigation (traffic control, construction restrictions, industrial scheduling) during unexpected times. The framework is transferable to other cities with dense station networks and can integrate meteorological drivers already available hourly.
Industrial solid waste generation in China remains a major environmental challenge. While the cap-and-trade carbon emissions trading system (ETS) is designed primarily to mitigate climate change through carbon pricing, its potential to affect the generation of industrial solid waste - a pervasive environmental pollutant and an important source of greenhouse gas emissions - remains a critical yet under-explored empirical question. This study bridges this gap by investigating the impact of China's carbon ETS on the generation of general (i.e., non-hazardous) industrial solid waste (GISW) and hazardous industrial solid waste (HISW). Using a provincial panel dataset for 31 mainland Chinese provinces from 2001 to 2020, including measures of HISW and GISW generation, ETS policy timing, and key socioeconomic, climate, and regulatory covariates, we employ a difference-in-differences approach to evaluate the policy effect. The results indicate that the carbon ETS significantly reduces the scale, intensity, and per-employee levels of both GISW and HISW. Compared to the non-ETS regions, on average, the ETS leads to an approximately 40% reduction in industrial solid waste generation in the policy-regulated regions. Further mechanism analysis reveals that the ETS promotes investment in industrial solid waste abatement, boosts R&D, and reduces energy use, which together improve resource efficiency and reduce process-related solid waste generation. These findings provide a plausible explanation for the observed effect of the ETS in reducing industrial solid waste. Our findings reveal that the carbon ETS can serve as a potent policy instrument for addressing a broader spectrum of industrial pollution beyond its primary carbon-cutting goal.Implications: This study reveals that the carbon ETS can serve as a potent policy instrument for addressing a broader spectrum of industrial pollution beyond its primary carbon-cutting goal. To strategically strengthen the identified pathways through which the ETS mitigates industrial solid waste, a complementary policy mix is essential. This should include measures to lower financing barriers for waste treatment upgrades, incentivize R&D and technological progress, and support energy efficiency projects alongside carbon trading.
Incineration remains a common method for healthcare waste disposal; however, concerns related to air pollutant emissions, limited resource recovery, and compatibility with circular economy goals have driven interest in alternative treatment technologies. Among thermochemical options, pyrolysis offers advantages over incineration by operating under oxygen-limited conditions, enabling conversion of waste into value-added products while potentially reducing the formation of regulated air pollutants. This review examines the state of pyrolytic valorization of healthcare waste and its potential role within sustainable waste management systems and circular economy. A brief bibliometric assessment indicates that although pyrolysis research has traditionally focused on biomass and municipal solid waste, studies addressing healthcare waste have increased steadily in recent years. Different categories of healthcare-related wastes, including hospital residues and medical plastics, are reviewed alongside applicable pyrolysis reactor technologies. The properties and potential uses of resulting products, including syngas, liquid fuels, waxes, and chemical feedstocks, are discussed in relation to environmental performance and resource recovery. Key challenges, such as feedstock heterogeneity, contaminant management, regulatory constraints, and process optimization, are identified. Overall, pyrolysis is presented as a complementary technology that can support circular economy objectives in healthcare waste management.Implications: Incineration remains widely used for healthcare waste disposal, but concerns regarding emissions, limited resource recovery, and circular economy compatibility have increased interest in pyrolysis. This review evaluates pyrolytic valorization of healthcare waste as a sustainable complementary technology to incineration. Different healthcare waste streams, reactor technologies, operating conditions, and resulting products, including syngas, liquid fuels, waxes, and chemical feedstocks, are discussed. Key challenges such as feedstock heterogeneity, contaminant management, regulatory limitations, and process optimization are highlighted. Essentially, pyrolysis demonstrates significant potential for resource recovery and sustainable healthcare waste management within circular economy frameworks.
