High Concentrations Of NO Research Articles

Higher population density is associated with worse air quality and related health outcomes in Tāmaki Makaurau.

To explore associations between population density, air pollution concentrations, and related health outcomes in Tāmaki Makaurau Auckland, Aotearoa New Zealand. Concentrations of nitrogen dioxide (NO2) and fine particulate matter (PM2.5)and associated health outcomes (premature mortality, cardiovascular and respiratory hospitalisations, and childhood asthma) were obtained from the Health and Air Pollution in New Zealand 2016 study. The possible mediating factors assessed were motor vehicle traffic, domestic fires, local industry, and green space. Higher population density was associated with higher concentrations of NO2 (β: 0.18, p < 0.01) and PM2.5 (β: 0.04, p < 0.01). Adverse health outcomes related to NO2 and respiratory hospitalisations attributed to PM2.5 exposure increased incrementally with the density of urban areas. The mediating factor with the strongest effect was motor vehicle traffic. Higher population density in Auckland is associated with worse air quality and related health outcomes. Motor vehicle traffic is the most important source of pollution and is highest in the most densely populated parts of the city. Housing intensification in Auckland will likely increase ill health from air pollution unless steps are taken to reduce exposure to emissions from motor vehicles.

Impact of Metro Construction Activities on Air Quality: A Case Study of Delhi Region in North India

The current study investigated the concerns about the possible effects of metro infrastructure's fast growth on the environment, particularly air quality. This study investigates how the building of metro lines in Delhi, India, affects the quality of the air at the selected locations in south and west parts of union territory of Delhi. Different air pollutants, including particulate matter (PM10, PM2.5), gaseous pollutants like nitrogen dioxide (NO2), and sulfur dioxide (SO2), were monitored. Air Quality Index (AQI) was also applied to the obtained data to convert the intricate data into single digits. The findings revealed that the values of PM10 and PM2.5 were beyond the National Ambient Air Quality Standards (NAAQS) threshold at the proximity of metro work zones due to construction activity. Moreover, higher NO2 concentrations were noted because of construction machinery operations and vehicle emissions. The study emphasizes the necessity of efficient mitigation solutions, such as green barriers, emission control plans, and dust suppression tactics, to reduce the negative environmental effects of metro development on Delhi's air quality. The results of this study can help urban planners and politicians to create sustainable development plans for transportation infrastructure that protect the environment and public health.

Enhancing Low-Concentration Electroreduction of NO to NH3 via Potential-Controlled Active Site-Intermediate Interactions.

Electronic defect states in catalysts are recognized as highly effective active sites for enhancing the low-concentration electroreduction of NO to NH3 (NORR). Their structures dynamically evolve with applied electrode potentials, allowing the active sites to adjust interactions with intermediates, thereby improving electrocatalytic performance. However, the dynamic changes in these interactions under applied potentials remain poorly understood, hindering the design of more diverse electrocatalytic systems. Herein, we developed a strategy that unitizes electrode potential to control the interactions between active sites and intermediates over oxygen vacancy-modified TiO2 (VO-TiO2-x) to enhance NORR performance. By combining state-of-the-art constant inner potential (CIP) DFT calculations with in situ (spectro)electrochemical measurements, we investigated how the electrode potential influences these interactions in NORR. The results clearly demonstrate that applying an external potential alters the spatial symmetry of degenerate orbitals of Ti3+ to facilitate the generation of key intermediates for NO-to-NH3 conversion. Therefore, the VO-TiO2-x catalyst exhibited superior NORR performance with a NH3 Faradaic efficiency up to 76.4 % and a high NH3 yield rate of 632.9 μg h-1 mgcat. -1 under 1.0 vol % NO atmosphere, which is competitive with those of previously reported works under higher NO concentration (above 10 vol %). Remarkably, the NORR process achieved a record-breaking NH3 yield of 2292.7 μg h-1 mgcat. -1 in a membrane electrode assembly (MEA) electrolyzer under the same conditions. This study opens a new avenue for enhancing electrocatalytic activity by adjusting operating conditions, thereby transcending the limitations of material design.

Enhancing Low‐Concentration Electroreduction of NO to NH3 via Potential‐Controlled Active Site‐Intermediate Interactions

AbstractElectronic defect states in catalysts are recognized as highly effective active sites for enhancing the low‐concentration electroreduction of NO to NH3 (NORR). Their structures dynamically evolve with applied electrode potentials, allowing the active sites to adjust interactions with intermediates, thereby improving electrocatalytic performance. However, the dynamic changes in these interactions under applied potentials remain poorly understood, hindering the design of more diverse electrocatalytic systems. Herein, we developed a strategy that unitizes electrode potential to control the interactions between active sites and intermediates over oxygen vacancy‐modified TiO2 (VO−TiO2−x) to enhance NORR performance. By combining state‐of‐the‐art constant inner potential (CIP) DFT calculations with in situ (spectro)electrochemical measurements, we investigated how the electrode potential influences these interactions in NORR. The results clearly demonstrate that applying an external potential alters the spatial symmetry of degenerate orbitals of Ti3+ to facilitate the generation of key intermediates for NO‐to‐NH3 conversion. Therefore, the VO−TiO2−x catalyst exhibited superior NORR performance with a NH3 Faradaic efficiency up to 76.4 % and a high NH3 yield rate of 632.9 μg h−1 mgcat.−1 under 1.0 vol % NO atmosphere, which is competitive with those of previously reported works under higher NO concentration (above 10 vol %). Remarkably, the NORR process achieved a record‐breaking NH3 yield of 2292.7 μg h−1 mgcat.−1 in a membrane electrode assembly (MEA) electrolyzer under the same conditions. This study opens a new avenue for enhancing electrocatalytic activity by adjusting operating conditions, thereby transcending the limitations of material design.

Cavity Ring-Down Spectroscopy Analysis of Radiocarbon from Nuclear Waste Materials.

Radiocarbon analysis of nuclear waste produced in nuclear facilities lacks fast, in situ detection methods. Moreover, the amount of radiocarbon desorbing from graphitic waste is not well known. In this study, we demonstrate the use of mid-infrared cavity ring-down spectroscopy combined with an automatic sample processing unit as a method to examine radiocarbon concentration in three types of nuclear waste: spent ion-exchange resin, graphite, and graphite outgassing in sealed storage crates. The solid samples were gasified, which allowed analyzing the effect of heating on the radiocarbon outgassing from the samples. The presented method also enabled examination of molecular speciation of the radiocarbon in the samples. The method performed well with the graphite and gaseous samples, but the analysis of the spent ion-exchange resin did not produce repeatable results due to high N2O concentrations. In the future, the presented method can be used in situ at nuclear facilities and expanded to a wider variety of sample materials than those presented here.

Indoor Air Quality in a Museum Storage Room: Conservation Issues Induced in Plastic Objects

This study focuses on assessing the indoor air quality in a storage room (SR) belonging to Museo Nazionale Scienza e Tecnologia Leonardo da Vinci in Milan (MUST), covering pollutants originating from outdoor sources and emissions from historical plastic objects made from cellulose acetate (CA), cellulose nitrate (CN), and urea–formaldehyde (UF) stored in metal cabinets. The concentrations of SO2 (sulphur dioxide), NO2 (nitrogen dioxide), NOx (nitrogen oxides), HONO (nitrous acid), HNO3 (nitric acid), O3 (ozone), NH3 (ammonia), CH3COOH (acetic acid), and HCOOH (formic acid) were determined. The concentrations of SO₂, O₃, and NOx measured inside the metal cabinets were consistently lower compared to the other sampling sites. This result was expected due to their reactivity and the lack of internal sources. The SR and metal cabinets showed similar concentrations of NO and NO2, except for CA, where a high NO concentration was detected. The interaction between the CA surfaces and NO2 altered the distribution of NO and NO2, leading to a significant increase in NO. The presence of HNO3 potentially led to the formation of ammonium nitrate, as confirmed by ER-FTIR measurements. High levels of HONO and HNO3 in CN and NH3 in the UF indicate object deterioration, while elevated concentrations of CH3COOH in CA and HCOOH in the SR suggest specific degradation pathways for cellulose acetate and other organic materials, respectively. These results could direct conservators towards the most appropriate practical actions.

First evaluation of the GEMS glyoxal products against TROPOMI and ground-based measurements

Abstract. The Geostationary Environment Monitoring Spectrometer (GEMS) on board the GEO-KOMPSAT-2B satellite is the first geostationary satellite launched to monitor the environment. GEMS conducts hourly measurements during the day over eastern and southeastern Asia. This work presents glyoxal (CHOCHO) vertical column densities (VCDs) retrieved from GEMS, with optimal settings for glyoxal retrieval based on sensitivity tests involving reference spectrum sampling and fitting window selection. We evaluated GEMS glyoxal VCDs by comparing them to the TROPOspheric Monitoring Instrument (TROPOMI) and multi-axis differential optical absorption spectroscopy (MAX-DOAS) ground-based observations. On average, GEMS and TROPOMI VCDs show a spatial correlation coefficient of 0.63, increasing to 0.87 for northeastern Asia. While GEMS and TROPOMI demonstrate similar monthly variations in the Indochinese Peninsula regions (R &gt; 0.67), variations differ in other areas. Specifically, GEMS VCDs are higher in the winter and either lower or comparable to TROPOMI and MAX-DOAS VCDs in the summer across northeastern Asia. We attributed the discrepancies in the monthly variation to a polluted reference spectrum and high NO2 concentrations. When we correct GEMS glyoxal VCDs as a function of NO2 SCDs, the monthly correlation coefficients substantially increase from 0.16–0.40 to 0.45–0.72 in high NO2 regions. When averaged hourly, GEMS and MAX-DOAS VCDs exhibit similar diurnal variations, especially at stations in Japan (Chiba, Kasuga, and Fukue).

Evaluating the Spatio-Temporal Distribution of Nitrogen Dioxide, Land Surface Temperature and NDVI in Nairobi City County

Abstract. Cities are becoming larger and it is estimated that by the year 2050, more than 6 billion people will be living in cities. As cities expand and grow, the quality of life and conditions will also transform. An integral part of environmental studies has been statistical analysis in modelling the spatial dynamics of land use changes. The research involved the use of satellite imagery to determine yearly averaged values of LST and NDVI from Landsat 8 OLI/TIR and monthly mean values of Nitrogen Dioxide (NO2) from Sentinel 5-Precursor (Sentinel-5P) across Nairobi City County. The datasets covered the period 2019, 2020, 2021, 2022 and 2023 and were analysed in Google Earth Engine. Results indicated that the yearly mean values in NO2 and LST in 2020 reduced by 2% and 12% respectively from 2019, while the mean NDVI value significantly increased by 28% in 2020 from 2019. NO2 has a negative correlation with LST in all years and a positive correlation with NDVI. Pearson correlation with population densities in constituencies in Nairobi in 2019 and 2023 indicate a negative correlation with NDVI and a positive correlation with NO2 and LST. Constituencies that have higher population densities tend to have lower vegetation densities and higher NO2 concentrations and temperature. Vegetation therefore plays a crucial role in air quality and that climatic factors such as precipitation and temperature influence the concentration of pollutants.

Assessment of exurban expansion on water quality in Rock Creek of the Yellowstone River in southcentral Montana, USA

Exurban expansion can degrade significantly stream water quality. This study was conducted on Rock Creek of the Clark’s Fork of the Yellowstone River in southcentral Montana, USA. The impact from recent exurban expansion was evaluated by a baseline study measuring total suspended solids (TSS), total phosphorus (TP), total nitrogen (TN) and nitrites (NO2) and nitrates (NO3) together. This was part of a larger study by Montana Department of Environmental Quality to assess water quality, identify sources of pollution and develop total maximum daily loads (TMDL). Water samples were measured for these analytes at nine (2022) and 11 (2023) locations with different land-uses over seven periods (both years). Seasonal spikes, corresponding to runoff (2022, late May), occurred in TSS, TP and TN. Data from 2023 showed similar but reduced levels occurring in June for TSS and TP. Total suspended solids, TP, NO2 and NO3 concentrations increased by location year over year, 2022 to 2023. The high relative concentrations of NO2 and NO3 in Rock Creek are primarily associated with exurban expansion, a significant threat to stream quality and wildlife habitat in Montana. The results will assist county planners in land use decisions.

IPCC Emission Factor Overestimates N2O Emissions from Agricultural Ditches.

Agricultural ditches emit disproportionate amounts of nitrous oxide (N2O), but their contributions to regional or global N2O emissions remain unclear due to limited data. The Intergovernmental Panel on Climate Change (IPCC) recommends using emission factors (EFs) to estimate indirect N2O emission, but the EF for ditches (EF5g) is categorized as groundwater, which potentially introduces a significant bias. This study conducted a regional-scale campaign in the North China Plain, one of the world's most intensive agricultural regions, and calculated the EF5g values from agricultural ditches by the concentration method (N2O-N/NO3--N). The results found that the regional-scale mean EF5g value (0.0028) was less than half of the IPCC default value (0.006), illustrating that the current IPCC methodology significantly overestimates N2O emissions from agricultural ditches. Despite the relatively small EF5g values, agricultural ditches exhibited a high mean N2O concentration (3.36 μg L-1) and a large regional emission (1.14 ± 0.86 Gg N2O-N yr-1), which is equal to 3.8 ± 2.9% of direct N2O emission from the croplands in the North China Plain. Since ditches are ubiquitous in agricultural regions and are likely to expand under climate change, refining EF5g is crucial to accurately assess their contribution to global N2O budgets.

Air pollution is associated with persistent peanut allergy in the first 10 years

The role of air pollution in eczema and food allergy development remains understudied. We aimed to assess whether exposure to air pollution is associated with eczema and food allergies in the first 10 years of life. HealthNuts recruited a population-based sample of 1-year-old infants who were followed up at ages 4, 6, and 10 years. Annual average fine particulate matter (particulate matter with diameter of 2.5 μm or less, or PM2.5) and nitrogen dioxide (NO2) exposures were assigned to geocoded residential addresses. Eczema was defined by parent report. Oral food challenges to peanut, egg, and sesame were used to measure food allergy. Multilevel logistic regression models were fitted, and estimates were reported as adjusted odds ratios. Those exposed to high concentration of NO2 (<10 ppb) at age 1 year had higher peanut allergy prevalence at ages 1 (adjusted odds ratio [95% confidence interval], 2.21 [1.40-3.48]) and 4 (2.29 [1.28-4.11]) years. High exposure to NO2 at 6 years old were associated with higher peanut allergy prevalence at age 6 (1.34 [1.00-1.82] per 2.7 ppb NO2 increase) years. Similarly, increased PM2.5 at age 1 year was associated with peanut allergy at ages 4, 6, and 10 years (respectively, 1.27 [1.01-1.60], 1.27 [1.01-1.56], and 1.46 [1.05-2.04] per 1.2 μg/m PM2.5 increase) years. We found that increased concentrations of NO2 or PM2.5 at age 1 year were associated with persistent peanut allergy at later ages. Little evidence of associations was observed with eczema or with egg allergy. Early-life exposure to PM2.5 and NO2 was associated with peanut allergy prevalence and persistence. Policies aiming at reducing air pollution could potentially reduce presence and persistence of peanut allergy.

Exposure to tropospheric ozone and NO2 in the ambient air of Tehran metropolis: Spatiotemporal distribution and inhalation health risk assessment

BackgroundAir pollution has emerged as a critical challenge in the 21st century, necessitating alert monitoring of key pollutants such as ozone and nitrogen dioxide (NO2)F. These pollutants are exacerbated by urbanization and industrialization, posing significant health risks, particularly in densely populated metropolitan areas. ObjectiveThe aim of this study was inhalation health risk assessment of NO2 and ozone in various scenarios and spatiotemporal Distribution Interpolation. MethodsData were collected from the Tehran Air Quality Control Center, encompassing 18 monitoring stations from March 2019 to February 2022. Health risk assessments (HRA) were performed for adult age groups across three different exposure scenarios (3, 8, and 12 h) And a sensitivity analysis was also conducted to determine the relative importance of each parameter in assessing the risks of each scenario. ResultsThe hazard index (HI) values for NO2 and ozone in all three scenarios were found to range from 0.24 to 1.56 and 0.04 to 0.49, respectively and body weight is a risk-lowering factor in sensitivity analyses. The interpolation results of ozone, NOx, and NO2 using the IDW approach from March 2019 to February 2022 showed that overall, the north and northeast of Tehran had the highest concentrations of NO2 and NOx, and the north and west had the highest concentrations of ozone. SignificanceThis study underscores the HRA with exposure to NO2 and ozone, particularly for individuals spending more than 8 h outdoors. Given Tehran's high population density and persistent air pollution, it is imperative to implement effective control policies to safeguard public health. The findings advocate for limiting outdoor activity to less than 8 h per day, especially for vulnerable occupational groups. Additionally, the study highlights the importance of considering body weight in health risk assessments.

Hybrid system for nitric oxide and hydrogen production

The device for nitric oxide inhalation therapy TIANOX has been put into use in clinical practice. It produces NO in nonequilibrium plasma of a diffusive spark discharge in the air at atmospheric pressure. There is a tendency to use a therapeutic gas mixture with high NO concentration for inhalation in the developing medical treatment methods. Nitric oxide transition into active compounds such as nitric dioxide, peroxynitrite, and nitrotyrosine can lead to oxidative stress. The use of hydrogen as an antioxidant that decreases the levels of hydroxyl radicals and peroxynitrite can protect cells from oxidative damage. Positive effect of the nitric oxide mixture and hydrogen is shown in the experiments with animals.The aim of the article is to describe development and performance the first hybrid system producing nitric oxide and hydrogen that was created in Federal State Unitary Enterprise “Russian Federal Nuclear Center – All-Russian Research Institute of Experimental Physics”. The system is based on the plasmochemical generator Tianox and the hydrogen generator, which is based on the electrolyzer with a solid polymeric electrolyte. It is fitted with H2, NO, and NO2 monitor and provides a continuous monitoring of concentrations of these gases and helps ensure safety of medical procedures by disconnecting NO and H2 generators at the moment when the gas concentrations exceed maximum levels (H2max, NOmax, NO2max).Conclusion. This hybrid system for nitrogen and hydrogen production passed the first study in human successfully. The preclinical studies also demonstrated its efficacy and safety.

Daily NO2 Simulation Research Based on Automatic Machine Learning Ensemble Models

To understand the spatial distribution of NO2 near the surface, we utilized measured data from NO2 monitoring stations and combined it with column concentration data from the Tropospheric Monitoring Instrument （TROPOMI）, taking the Yangtze River Delta region as the study area. We considered the impact of factors such as population, elevation, and meteorological conditions on NO2 levels. We used automated machine learning to select five machine-learning algorithms with high simulation accuracy, namely ET, RF, XGBoost, LightGBM, and Catboost, and then integrated these five algorithms using the Stacking model to simulate the daily NO2 concentration in the Yangtze River Delta region from March 2020 to February 2021. The results indicated that the RMAE and MAE values of the Stacking ensemble model were 7.078 and 5.270, respectively, which outperformed the single algorithms of ET, RF, XGBoost, LightGBM, and Catboost. The spatial distribution of high NO2 concentrations in the Yangtze River Delta region, consisting of three provinces and one municipality, exhibited a U-shaped pattern with the convergence point located at the intersection of the three provinces, extending towards the southwest. Notably, urban pollution was particularly significant in the urban agglomerations centered around Shanghai, Hangzhou, Nanjing, and Hefei. There were 27 cities that exceeded the national standard daily limit. Changzhou was the city with the most serious NO2 pollution, with the NO2 concentration exceeding the standard for 14 d, followed by Shanghai, with 13 d. In terms of seasonal variation, the order of severity was as follows： winter, autumn, spring, and summer, with the least NO2 pollution occurring on July 9th during the summer, and the most severe NO2 pollution was observed on December 23rd during the winter.

Visualizing Convergent Pressures on Arctic Development

A rapidly changing Arctic has impacted biophysical and human systems while creating new economic opportunities. Spatially identifying locations with development potential in this changing environment requires characterizing convergences in critical enabling/constraining factors occurring in a particular place. However, mapping techniques based on simple overlays of spatially heterogeneous data may result in visual clutter, compromising legibility, and increasing the likelihood of interpretation errors. To overcome these limitations, we introduce Pythia, a tool that combines geographic statistical analysis with a subtractive color model to enable bi- or tri-variate data analysis. Three case studies showcase this visualization tool. Case study 1 identifies locations where temperature and population are projected to increase by 2040. Case study 2 reveals locations with a significant presence of major roads and high NO2 concentrations but few hospitals and clinics. In case study 3, a combination of transportation infrastructure, protected areas, and travel and tourism infrastructure signals challenges for the future Alaskan tourism industry. Comparing these results allows for further geographic characterization of locations, aiding policymakers in identifying areas lacking resources and infrastructure, exploring possible futures, and supporting long-term strategic planning.

-temporal variability in fire events due to crop residue burning and their impact on atmospheric variables using ground and remote sensingdata in Punjab

We attempted monitoring and mapping of the active fire events in Punjab, during the wheat and rice harvesting period of 2017-2021 from the Visible Infrared Imaging Radiometer Suite (VIIRS) at 375 m aboard. The analysis showed that the highest fire counts were observed in the central region, followed by the south-west and thelowest in the north-east region of Punjab during all the years. Moreover, during the wheat season, highest fire counts were observed in 2019, being 2535, 11062 and 6212 in north-east, central and south-west regions, respectively. However, during rice, highest fire counts were observed in 2020 in the north-east being 2857 and in 2021 the central and south-west regions being 40960 and 30351 respectively. In line with the number of fire counts, the highest concentration of gases and particulate matter obtained from the Central Pollution Control Board (CPCB) was also observed in the central zone. During the wheat harvesting season, central zone experienced the highest concentration of PM2.5 and PM10 in May 2018 and that of SO2 and O3 in May 2019. Similarly, during the rice harvesting season, central zone also experienced the highest concentration of PM2.5 and PM10 during November 2017 and that of SO2 in 2018. However, the highest concentration of NO2 was observed in October 2018 and that of O3 in October 2020 in the central region. Analysis of the concentration of NO2 and SO2 obtained from the Soumi-NPP satellite also had similar results to CPCB. Such a high concentration of gases and particulate matter might be attributed to crop residue burning a significant positive correlation was observed between fire counts and concentration of particulate matter (PM2.5 and PM10). In view of the alarming deterioration of air quality, there is a dire need to check this practice in the region by providing incentives and viable alternatives to the farmers.

Numerical study on the effect of injection strategy on combustion and NO emission from different sources in a diesel/ammonia RCCI engine

Diesel/ammonia operation is one of the ways to efficiently utilize ammonia and reduce carbon emissions, however, the increase in fuel NO introduces serious emission problems. To explore the generation mechanisms of fuel NO and oxidant source NO, a multi-component diesel/ammonia chemical reaction mechanism was constructed in this study, and based on 3D CFD simulation and N-element tracking method, the combustion and different source NO emission characteristics of diesel/ammonia reactivity controlled compression ignition (RCCI) engine at low loads were investigated by pilot injection timing (SOI1) and pilot injection ratio (PIR). In addition, the effect of different first injection spray angle (SA1) and double injection spray angle (SAtotal) on the engine operation was investigated. The results showed that high PIR and delayed SOI1 enhanced the engine IMEP but led to high PRRmax. At a PIR of 15 %, total NO emissions increased as SOI1 advanced, and the trend was reversed when the PIR was higher than 15 %. Fuel NO was produced earlier than the oxidant source N∗O. In terms of 1 spatial distribution, high concentrations of both NO and N∗O were distributed in and around the secondary diesel fuel ignition location, and fuel NO began to be reduced where the oxidant source N∗O was rapidly formed. The reduction mechanism of NO in the cylinder was a multi-path reduction mechanism incorporating Thermal DeNOx, NO Reburning, and inverse reaction pathways for NO formation from the oxidant source. Appropriate reduction of the SAtotal can significantly reduce the total NO emission while maintaining no significant reduction in IMEP. When SAtotal was 82°, the total NO emission was only 16.3 % of the original spray angle and PRRmax was further reduced. After optimization, when a narrow SAtotal of 82°, SOI1 of −15° CA, and PIR of 35 % were used, the IMEP of the engine increased by 5.9 %, and the total NO emission was reduced by 86 %, while PRRmax did not exceed the PRR upper limit.

PM2.5 estimation and its relationship with NO2 and SO2 in China from 2016 to 2020

ABSTRACT The distribution of surface particulate matter (PM2.5) exhibits significant spatiotemporal patterns, especially with a spatial clustering effect. Therefore, resolving spatial characteristics is essential in the modeling process. This study proposes a space–time varying coefficients (STVC-LG) model by considering spatial effects from the perspective of eigenvector spatial filtering and incorporating spatial effects and temporal features into the LightGBM model to estimate ground PM2.5. A site-based cross-validation result of the estimated daily 1 km PM2.5 concentration in China from 2016 to 2020 shows that the proposed model offers high accuracy, an R2 of 0.88, and an RMSE of 12.21 μg/m3 (17% and 32% enhanced compared to the original LightGBM model). It uses a series of spatial eigenvectors to describe different spatial patterns. It then constructs spatial interaction terms by combining the eigenvectors and influencing variables, allowing the values of the variable to vary spatially with the eigenvectors. The obtained PM2.5, with a decreasing trend, had a clear distributional consistency with NO2 and SO2 according to the co-occurrence distribution maps, particularly in winter. In areas where high concentrations co-occur, both NO2 and SO2 concentrations are Granger-causing PM2.5 concentrations from a statistical perspective.

Nitrate, Nitrite, and Iodine Concentrations in Commercial Edible Algae: An Observational Study.

Edible algae are a natural source of nutrients, including iodine, and can also contain nitrogen in the form of nitrate (NO3-) and nitrite (NO2-) as they can fix nitrogen from seawater. This study aimed to analyse the NO3-, NO2-, and iodine concentrations in eighteen macroalgae and five microalgae species commercially available in the United Kingdom. NO3- and NO2- concentrations were measured using high-performance liquid chromatography (HPLC), and iodine was determined using inductively coupled plasma mass spectrometry (ICP-MS). NO3- and iodine concentrations in macroalgae (NO3-: 4050.13 ± 1925.01 mg/kg; iodine: 1925.01 ± 1455.80 mg/kg) were significantly higher than in microalgae species (NO3-: 55.73 ± 93.69 mg/kg; iodine: 17.61 ± 34.87 mg/kg; p < 0.001 for both). In the macroalgae group, nori had the highest NO3- (17,191.33 ± 980.89 mg/kg) and NO2- (3.64 ± 2.38 mg/kg) content, as well as the highest iodine content. Among microalgae, Dunaliella salina had the highest concentration of NO3- (223.00 ± 21.93 mg/kg) and iodine (79.97 ± 0.76 mg/kg), while Spirulina had the highest concentration of NO2- (7.02 ± 0.13 mg/kg). These results indicate that commercially available edible algae, particularly macroalgae species, could be a relevant dietary source of NO3- and iodine.

A Comparison of Regression Methods for Inferring Near‐Surface NO2 With Satellite Data

AbstractNitrogen dioxide (NO2) is an atmospheric pollutant emitted from anthropogenic and natural sources. Human exposure to high NO2 concentrations causes cardiovascular and respiratory illnesses. The Environmental Protection Agency operates ground monitors across the U.S. which take hourly measurements of NO2 concentrations, providing precise measurements for assessing human pollution exposure but with sparse spatial distribution. Satellite‐based instruments capture NO2 amounts through the atmospheric column with global coverage at regular spatial resolution, but do not directly measure surface NO2. This study compares regression methods using satellite NO2 data from the TROPospheric Ozone Monitoring Instrument (TROPOMI) to estimate annual surface NO2 concentrations in varying geographic and land use settings across the continental U.S. We then apply the best‐performing regression models to estimate surface NO2 at 0.01° by 0.01° resolution, and we term this estimate as quasi‐NO2 (qNO2). qNO2 agrees best with measurements at suburban sites (cross‐validation (CV) R2 = 0.72) and away from major roads (CV R2 = 0.75). Among U.S. regions, qNO2 agrees best with measurements in the Midwest (CV R2 = 0.89) and agrees least in the Southwest (CV R2 = 0.65). To account for the non‐Gaussian distribution of TROPOMI NO2, we apply data transforms, with the Anscombe transform yielding highest agreement across the continental U.S. (CV R2 = 0.77). The interpretability, minimal computational cost, and health relevance of qNO2 facilitates use of satellite data in a wide range of air quality applications.