Levels Of Nitrogen Oxides Research Articles

Simultaneous measurement of NO and NO2 by dual-channel cavity photoacoustic spectroscopy technique

The levels of nitric oxide (NO) and nitrogen oxide (NO2) are trace gases in the order of ppb, which are the main products of fossil fuel, anthropogenic combustion, natural lightning and microbial emissions, and are important for further analysis of air quality. Photoacoustic spectroscopy (PAS) technique, which is based on absorption at the wavelength of 403.65 nm, has been used for NO2 measurements. In this study, a dual-channel PAS system for NO2 and NOx detection is reported. The PAS method is capable of measuring species with good sensitivity and accuracy. The calibrated slopes of photoacoustic cavity A and B are 0.040 μv/ppb and 0.039 μv/ppb, respectively. And the detection limits of the developed PAS system for NO2 and NOx measurements are estimated to be about 1.47 ppb (3σ, 60 s) and 1.50 ppb (3σ, 60 s), respectively. In order to reduce the influence of local noise, the photoacoustic cavity with multiple buffer partitions is designed and the corresponding photoacoustic frequency of the photoacoustic pool is analyzed. The sound pressure value and resonance frequency of the photoacoustic pool gradually decrease with the increase of the number of buffer partitions, but the amplitude is small. The relationship between the gas absorption cross section, volume fraction, laser power and photoacoustic excitation signal is derived. After deducting the influence of local noise, the photoacoustic response gradients of dual-channel cavities are obtained, the linear fitting of the response gradient of both cavities is good, the correlation R2 is greater than 0.99, and the fitting slope is 0.040 and 0.039 respectively. The influence of O3 generated by photolysis of the mercury lamp is considered under different NO level conditions. An intercomparison between the system and a cavity ring-down system (CRDS) independently developed by our research group showed a good agreement for measuring the ambient atmosphere NO2 gas. The results of NO2 showed a linear correction factor (R2) of 0.943 in a slope of 0.944 ± 0.002, with an offset of (0.636 ± 0.021) ppb. The accuracy of NO2 measurement by the photoacoustic spectroscopy system was verified. In addition, the simultaneous measurement of NO and NO2 by dual-channel cavity photoacoustic spectroscopy technique was deployed. These observations indicate that NO2 and NO concentrations can be effectively observed with the dual-channel PAS instrument.

Modeling Ground Ozone Concentration Changes after Variations in Precursor Emissions and Assessing Their Benefits in the Kanto Region of Japan

Ozone (O3) is a pollutant of concern in urban areas because of its effects on health, crops, ecosystems, and materials. Despite efforts to meet the Japanese air quality standard for O3 in the Kanto region, the attainment percentage is close to zero. Considering that O3 formation is sensitive to emissions of volatile organic compounds (VOC) and nitrogen oxides (NOx), this study evaluated a range of reductions in the emissions of both precursors using a regional air quality model (ADMER-PRO) and estimated their benefits measured as the economic change due to O3 concentration differences between scenarios. The simulation period was set during the 2016 O3 season. The results showed that O3 concentrations could be reduced using two approaches: significant reduction in VOC levels combined with minor NOx level changes or significant NOx emission reduction. Significant reduction in NOx levels was the most effective strategy for a generalized decrease in the O3 levels in the Kanto region, and the benefit analysis revealed that the most significant economic impacts could be achieved by adopting the latter approach.

Multiple Fuel Injection Strategies for Compression Ignition Engines

Until the early 1990s, the predominant method of fuel delivery for compression ignition engines was the mechanical pump-line-nozzle system. These systems typically consisted of a cam-driven pump that would send pressurized fuel to the fuel injectors where injection timing was fixed according to the pressure needed to overcome the spring pressure of the injector needle. These configurations were robust; however, they were limited to a single fuel injection event per thermodynamic cycle and respectively low injection pressures of 200–300 bar. Due to their limited flexibility, a poorly mixed and highly stratified air fuel mixture would result in and produce elevated levels of both nitrogen oxides and particulate matter. The onset of stringent emissions standards caused the advancement of fuel injection technology and eventually led to the proliferation of high-pressure common rail electronic fuel injection systems. This system brought about two major advantages, the first being operation at fuel pressures up to 2500 bar. This allowed better atomization and fuel spray penetration that improves mixing and the degree of charge homogenization of the air fuel mixture. The second is that the electronic fuel injector allows for flexible and precise injection timing and quantity while allowing for multiple fuel injection events per thermodynamic cycle. To supply guidance in this area, this effort reviews the experimental history of multiple fuel injection strategies involving both diesel and biodiesel fuels through 2019. Summaries are supplied for each fuel highlighting literature consensus on the mechanisms that influence noise, performance, and emissions based on timing, amount, and type of fuel injected during multiple fuel injection strategies.

Long-term trend in surface ozone in Houston-Galveston-Brazoria: Sectoral contributions based on changes in volatile organic compounds

This study investigated the long-term variations in ambient levels of surface ozone, volatile organic compounds (VOCs), and nitrogen oxides (NOx) within the Houston-Galveston-Brazoria (HGB) region. Analysis of ozone levels revealed an overall reduction in the maximum daily 8-h average ozone (MDA8 O3) from 2000 to 2019 (April–October) with an average rate of ∼ −0.48 ppb/yr across HGB. With a few exceptions, the MDA8 O3 reduction rates were more pronounced for the monitoring sites closer to the Houston Ship Channel (HSC). Meanwhile, ambient levels of NOx and most VOC species (across the three representative sites as Houston Bayland Park, Haden Road, and Lynchburg Ferry) decreased significantly within the same investigation period, reflecting the impact of emission reductions. The positive matrix factorization (PMF) model applied to the mentioned sites identified regional background ozone, petrochemical emissions, engine combustion, natural gas/fuel evaporation, and solvent/painting/rubber industries as the major sources of MDA8 O3. The regional background ozone was the predominant source, accounting for 59–70% of MDA8 O3 across the three sites. Regarding the local anthropogenic emissions, natural gas/fuel evaporation was the largest contributor (19.5 ± 6.1%) to MDA8 O3 at Houston Bayland Park, whereas petrochemical facilities (10.9 ± 4.9%) and solvent/painting/rubber industries (18.1 ± 9.5%) were the largest factor at Haden Road and Lynchburg Ferry, respectively. Notable reductions were found in the contributions of petrochemical emissions, engine combustion, and natural gas/fuel evaporation to MDA8 O3 within 2000–2019, but an increasing trend was revealed in the role of solvent/painting/rubber industries on MDA8 O3 most probably due to the enhanced demand for their products. Results of this study corroborated the success of emission control policies in limiting ozone precursors and provided useful details for prioritizing emission reduction policies to further reduce ozone pollution in the HGB.

Abstract 1437: Ambient air pollution and risk of prostate cancer: The multiethnic cohort study

Abstract Previous epidemiological evidence on air pollution and prostate cancer risk is limited, with few studies examining the time varying effects of air-pollution, and primarily among whites in the US and Canada. To further our understanding on this topic, we assessed ambient air pollutants in relation to prostate cancer incidence in a large multi-ethnic population. We included 33,830 men aged 45 years or older at baseline (1993-1996) who resided in Southern California at enrollment in the Multiethnic Cohort (24.5% African American, 15.1% Japanese American, 48.4% Latino, 0.2% Native Hawaiian, and 11.8% White). Until 2016, with a median of 20 years of follow-up, 4,540 prostate cancer cases were identified by linkage to the California SEER cancer registry. Monthly exposures to particulate matter with aerodynamic diameter ≤ 10 μm (PM10) and nitrogen oxides (NOx) per participant were estimated by Kriging interpolation based on air-monitoring data and residential addresses. We used Cox proportional hazards models to estimate the association between time-varying air-pollutant levels and prostate cancer risk, using age in months as the time metric. We adjusted for neighborhood socioeconomic status (nSES) at baseline and current nSES at event, education, race/ethnicity, smoking pack years, BMI, diabetes status, asthma history, and family history of prostate cancer, using age at cohort entry as the strata variable. The average NOx and PM10 over the study period was 73.1 parts per billion (ppb) and 38.1 μg/m3 in prostate cancer cases, respectively, and 60.9 ppb and 35.5 μg/m3 in men without prostate cancer, respectively. Across racial/ethnic groups, African Americans had the highest average NOx levels (74.3ppb) and Latinos had the highest average PM10 levels (39.0 μg/m3) over the study period. In the overall population, NOx per 50 ppb was statistically significantly associated with an increased risk of prostate cancer [hazard ratio (HR)=1.12, 95% confidence interval (CI): 1.01-1.25] and PM10 per 10 μg/m3 was associated with a suggestive increased risk (HR=1.07, 95%CI: 0.99-1.16). In analysis by race/ethnicity, statistically significant positive associations with NOx (HR=1.25, 95%CI: 1.07-1.46) and PM10 (HR=1.21, 95%CI: 1.07-1.38) were detected among African American, but not consistently in other racial/ethnic groups. In a subset of 21,537 men with no residential moves over the follow-up period, we observed positive associations for both NOx and PM10 similar to those among all men. In conclusion, our results suggest that both NOx and PM10 are associated with an increased risk of prostate cancer. Analyses of other air pollutants in relation to prostate cancer risk and disease aggressiveness are ongoing. Citation Format: Anqi Wang, Chiu-chen Tseng, Heather Rose, Iona Cheng, Anna H. Wu, Christopher A. Haiman. Ambient air pollution and risk of prostate cancer: The multiethnic cohort study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1437.

An Evaluation of Risk Ratios on Physical and Mental Health Correlations due to Increases in Ambient Nitrogen Oxide (NOx) Concentrations

Nitrogen oxides (NOx) are gaseous pollutants contributing to pollution in their primary form and are also involved in reactions forming ground-level ozone and fine particulate matter. Thus, NOx is of great interest for targeted pollution reduction because of this cascade effect. Primary emissions originate from fossil fuel combustion making NOx a common outdoor and indoor air pollutant. Numerous studies documenting the observed physical health impacts of NOx were reviewed and, where available, were summarized using risk ratios. More recently, the literature has shifted to focus on the mental health implications of NOx exposure, and a review of the current literature found five main categories of mental health-related conditions with respect to NOx exposure: common mental health disorders, sleep, anxiety, depression, and suicide. All the physical and mental health effects with available risk ratios were organized in order of increasing risk. Mental health concerns emerged as those most influenced by NOx exposure, with physical health impacts, such as asthma, only beginning to surface as the fourth highest risk. Mental health conditions occupied seven of the top ten highest risk health ailments. The results summarized in this narrative review show that there are clear positive correlations between NOx and negative physical and mental health manifestations, thus strengthening the argument in support of the reduction in ambient NOx levels.

An environmental cost basis for regulating aviation NOx emissions

Combustion in aircraft engines results in the formation of nitrogen oxides (NOx) and carbon dioxide (CO2), among other species. NOx impacts air quality and is an indirect contributor to radiative forcing, while CO2 is a long-lived greenhouse gas. The International Civil Aviation Organization sets limits on NOx emissions from commercial aircraft, where for engines with a rated thrust greater than 89 kN the allowable NOx production per unit rated thrust is defined as a function of engine overall pressure ratio (OPR). This definition links the engine thermodynamic cycle, and implicitly fuel burn and CO2 emissions, to allowable NOx levels. These regulations have historically been evaluated and implemented with a focus on reducing adverse air quality impacts around airports, but the thermodynamic efficiency tradeoff with CO2 requires additional analysis to quantify net environmental impacts. This paper introduces a social cost basis for evaluating aviation NOx emissions regulations and quantifies the implied CO2 and NOx attributable air quality damage, climate damage, and fuel costs associated with the emissions standard. We show that higher overall pressure ratio engines operating at the current NOx regulatory limit are allowed more environmental damage per unit rated thrust than lower overall pressure ratio engines, resulting in variable social costs per unit thrust (i.e. fuel and environmental costs combined) across the engine design space. This is a consequence of the definition of the regulation today, where higher pressure ratio engines are allowed higher NOx emissions. Alternative regulation definitions are evaluated which consider the engine cycle and combustor together. Achieving constant social costs requires a regulatory limit where the increase in allowed NOx emissions tapers off at higher pressure ratios, corresponding to the diminishing marginal efficiency improvements due to increasing OPR in that region.

The Impact of COVID-19 Strict Lockdown on the Air Quality of Smart Cities of Rajasthan, India

Aim: The main focus of this study is to evaluate the air quality by comparing the concentration of particulate matter PM2.5, PM10, NO2, CO, SO2, and ozone of smart cities of Rajasthan before the lockdown and during the period of lockdown. Background: In India, the first case of the COVID-19 was reported on January 30th, 2020. Indian government declared strict lockdown, i.e., public health emergency in India on March 24th, 2020, which is implemented from March 25th, 2020, to April 14th, 2020, for 21 days. Objective: The objective of this study is to evaluate the air quality by comparing the levels of all parameters of air pollution during the COVID-19 lockdown period with values registered in the pre-lockdown period. Methods: Data were obtained from four automatic monitoring stations under the control of the Central Pollution Control Board, New Delhi (https://www.cpcb.nic.in/). Data regarding all the parameters were recorded as 24 hours average period. Results: CO levels showed the highest significant reduction in Udaipur (50.76%) followed by Jaipur (19.96%), Ajmer (17.11%), and Kota (5.51%) due to the ban on transport and driving. The levels of PM2.5, PM10, NO2, and SO2 were also decreased substantially for each smart city. Ozone concentrations were recorded greater than before due to decreased nitrogen oxides levels. Conclusion: This study can be useful considering our present role in environmental restoration or environmental destruction. It will also be helpful in updating our present plan toward the assurance and conservation of nature.

Ammonia injection failure diagnostic and correction in engine after-treatment system by NOx and NH3 emissions observation

To ensure that after-treatment systems (ATS) reduce emissions to the levels for which they were designed, it is essential that the ATS control can rely on the feedback signals from the sensors and actuators that are part of the system. Knowing that the amount of ammonia injected into the catalyst governs the Nitrogen oxides (NOx) reduction, this work addresses the impact of the ammonia injection failure in the Selective Catalytic Reduction (SCR) on the exhaust emissions and describes a model-based fault diagnosis strategy. The proposed approach is based on an artificial neural network (ANN) and a sensor signal analysis (SSA) model of the catalyst, as well as an observer to merge the models and accurately estimate the emissions. The proposed diagnostic strategy is based on the comparison of the observed NOx and ammonia (NH3) emissions of the actual system with those expected in the system without ammonia injection failure. Experimental results show that the proposed strategy can detect failures in ammonia injection above 10%. Once the degradation level is detected, a correction strategy is applied by increasing the ammonia injector opening time according to the estimated degradation to increase the injected ammonia up to levels similar to faultless conditions. When the injection failure was corrected, the proposed strategy was able to mitigate the impact on NOx emissions, reducing them by 23.33% and approaching the NOx levels without injection failure (5.35% increase).

48V EGR Pump System Development and Fuel Benefit Evaluation

Upcoming global emission regulations include considerable reduction in emission of nitrogen oxides (NOx) and greenhouse gases (GHGs) for vehicles with heavy-duty (HD) diesel application. These regulations will phase between 2024 and 2030 in the United States and the European Union. CARB Regulations include up to 90% reduction in NOx levels along with ∼25% reduction in CO2. One of the primary technologies used to reduce engine out NOx emission is the use of cooled exhaust gas recirculation (EGR). Research studies carried out across multiple domains by engine/vehicle original equipment manufacturers (OEMs) and others have identified air handling as one of the technologies to help meet next-generation regulations (Joshi, 2020; Dreisbach et al. 2021). This includes more efficient turbomachinery which helps improve engine efficiency and thus reduce GHGs. This has an adverse effect on driving EGR which affects engine out NOx. In this study, the development and performance impact of the EGR pump is investigated, which allows improved engine fuel efficiency without the corresponding penalty to engine out NOx. Computational fluid dynamics (CFD) is used to optimize the EGR pump design, which leads to reduction in fluid-borne noise of the pump, which is then evaluated for fuel benefits using a calibrated GT-POWER engine model.

Secondary organic aerosol formation from camphene oxidation: measurements and modeling

Abstract. While camphene is one of the dominant monoterpenes measured in biogenic and pyrogenic emission samples, oxidation of camphene has not been well-studied in environmental chambers and very little is known about its potential to form secondary organic aerosol (SOA). The lack of chamber-derived SOA data for camphene may lead to significant uncertainties in predictions of SOA from oxidation of monoterpenes using existing parameterizations when camphene is a significant contributor to total monoterpenes. Therefore, to advance the understanding of camphene oxidation and SOA formation and to improve representation of camphene in air quality models, a series of experiments was performed in the University of California Riverside environmental chamber to explore camphene SOA mass yields and properties across a range of chemical conditions at atmospherically relevant OH concentrations. The experimental results were compared with modeling simulations obtained using two chemically detailed box models: Statewide Air Pollution Research Center (SAPRC) and Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A). SOA parameterizations were derived from the chamber data using both the two-product and volatility basis set (VBS) approaches. Experiments performed with added nitrogen oxides (NOx) resulted in higher SOA mass yields (up to 64 %) than experiments performed without added NOx (up to 28 %). In addition, camphene SOA mass yields increased with SOA mass (Mo) at lower mass loadings, but a threshold was reached at higher mass loadings in which the SOA mass yields no longer increased with Mo. SAPRC modeling of the chamber studies suggested that the higher SOA mass yields at higher initial NOx levels were primarily due to higher production of peroxy radicals (RO2) and the generation of highly oxygenated organic molecules (HOMs) formed through unimolecular RO2 reactions. SAPRC predicted that in the presence of NOx, camphene RO2 reacts with NO and the resultant RO2 undergoes hydrogen (H)-shift isomerization reactions; as has been documented previously, such reactions rapidly add oxygen and lead to products with very low volatility (i.e., HOMs). The end products formed in the presence of NOx have significantly lower volatilities, and higher O : C ratios, than those formed by initial camphene RO2 reacting with hydroperoxyl radicals (HO2) or other RO2. Further analysis reveals the existence of an extreme NOx regime, wherein the SOA mass yield can be suppressed again due to high NO / HO2 ratios. Moreover, particle densities were found to decrease from 1.47 to 1.30 g cm−3 as [HC]0 / [NOx]0 increased and O : C decreased. The observed differences in SOA mass yields were largely explained by the gas-phase RO2 chemistry and the competition between RO2+ HO2, RO2+ NO, RO2+ RO2, and RO2 autoxidation reactions.

Experimental investigation of the achieving methods and the working characteristics of a near-zero NOx emission turbocharged direct-injection hydrogen engine

Hydrogen, as clean and renewable energy, is regarded as a promising fuel applied to internal combustion engines. The relatively high level of Nitrogen oxides (NOx) emissions is an important limiting factor to realize the application of hydrogen engine. Previous researches on the NOx emissions reduction were based on the naturally-aspired or supercharger hydrogen engine with medium load and efficiency. In this study, a 2.0 L turbocharged direct-injection engine is used to find the methods of achieving near-zero NOx emission (without any posttreatment equipment) with large power and high thermal efficiency. The effects of the coefficient of excess air (λ), the timing of the start of injection (SOI), and injection pressure on NOx emissions are investigated detailly with the engine speed range of 1000 rpm to 4000 rpm. The target of the NOx emission is set below 20 ppm according to the emission standards. A leaner combustion (λ = 3.29@ 3000 rpm) compared to λ = 2.62@ 2000 rpm is required to achieve near-zero emission. The utilization of the turbocharger and improved injection pressure increase the power and efficiency simultaneously. The maximum brake mean effective pressure (BMEP) can reach 13.3 bar@3000 rpm, and the maximum brake thermal efficiency (BTE) reaches 40.4% @2000 rpm with near-zero NOx emission. Various techniques, such as turbocharging, exhaust gas recirculation, and increased compression ratios, are also compared to qualify the trade-off relationships among the power, efficiency, and emission of the direct-injection hydrogen engine. These conclusions can be used to broaden the working boundary and optimize the fuel economy of turbocharged direct-injection hydrogen engines with near-zero NOx emission.

Wintertime haze and ozone at Dinosaur National Monument

ABSTRACT Dinosaur National Monument (DINO) is located near the northeastern edge of the Uinta Basin and often experiences elevated levels of wintertime ground-level ozone. Previous studies have shown that high ozone mixing ratios in the Uinta Basin are driven by elevated levels of volatile organic compounds (VOCs) and nitrogen oxides (NOx) from regional oil and gas development coupled with temperature inversions and enhanced photochemistry from persistent snow cover. Here, we show that persistent snow cover and temperature inversions, along with abundant ammonia, also lead to wintertime haze in this region. A study was conducted at DINO from November 2018 through May 2020 where ozone, speciated fine and coarse aerosols, inorganic gases, and VOCs were measured. Three National Ambient Air Quality Standards (NAAQS) ozone exceedances were observed in the first winter, and no exceedances were observed in the second winter. In contrast, elevated levels of particulate matter were observed both winters, with 24-h averaged particle light extinction exceeding 100 Mm−1. These haze events were dominated by ammonium nitrate, and particulate organics were highly correlated with ammonium nitrate. Ammonium nitrate formation was limited by nitric acid in winter. As such, reductions in regional NOx emissions should reduce haze levels and improve visibility at DINO in winter. Long-term measurements of particulate matter from nearby Vernal, Utah, suggest that visibility impairment is a persistent issue in the Uinta Basin in winter. From April through October 2019, relatively clean conditions occurred, with average particle extinction of ~10 Mm−1. During this period, ammonium nitrate concentrations were lower by more than an order of magnitude, and contributions from coarse mass and soil to haze levels increased. VOC markers indicated that the high levels of observed pollutants in winter were likely from local sources related to oil and gas extraction activities. Implications: Elevated ground-level ozone and haze levels were observed at Dinosaur National Monument in winter. Haze episodes were dominated by ammonium nitrate, with 24-h averaged particle light extinction exceeding 100 Mm−1, reducing visual range near the surface to ~35 km. Despite elevated ammonium nitrate concentrations, additional gas-phase ammonia was available, such that any increase in NOx emissions in the region is likely to lead to even greater haze levels.

The effects of hydrogen enriched natural gas under different engine loads in a diesel engine

Natural gas, which is among the alternative fuels, has become widespread in the transportation as it is both economical and environmentally friendly. While the use of natural gas is at a significant level in spark ignition engines, it has not yet been implemented in compression ignition engines (CI) as it worsens combustion due to ignition delay. In CI engines, however, the combustion properties of natural gas (NG) can be improved by adding hydrogen (H2) to NG. This is one of the methods applied to use natural gas in CI engines. In this experimental study, two different volumetric rates of NG and NG/H2 mixtures were added to the combustion air in a CI engine, and engine performance and emissions were examined under different engine loads. The experiments were performed at two different engine speeds, four different engine loads and no-load condition. An engine cylinder pressure of 59.16 bar, which is the closest value to the 59.39 bar obtained in the use of diesel fuel, was obtained at 1500 rpm for “Diesel + NG(500 g/h)” and 59.9 bar (highest values) was obtained for “Diesel + (500 g/h) [80%NG+20%H2]" at 1750 rpm. For “Diesel + NG(250 g/h)” (Mix1) and “Diesel + NG(500 g/h)” (Mix2), as the engine speed increases, at the point where the maximum in-cylinder pressure is obtained occurs further to the right from top dead center (TDC). With the addition of 500 g/h NG, an increase of 4.5% was achieved in the cylinder pressure at full load, while an increase of 6.5% was achieved in the case of using “Diesel + (500 g/h) [80%NG+20%H2]". Although the effect of the NG and NG/H2 mixtures on in-cylinder pressure was small, the fuel consumption and thermal efficiency improved. Substantial improvements in hydrocarbon (HC) emissions were observed with the use of “Diesel + (250 g/h)[80%NG+20%H2]”. Carbon dioxide (CO2) emissions decreased with speed increase, but no significant differences in terms of CO2 emissions were observed between the mixtures. There was a maximum difference of 15% between the diesel and the mixtures in CO2 emissions. Although there was a decrease in nitrogen oxide (NOx) levels with the increase in engine speed, the lowest NOx emissions of 447.6 ppmvol was observed in “Diesel + NG(250 g/h)” (Mix1) at 1750 rpm at maximum load.

Photochemical evolution of air in a tropical urban environment of India: A model-based study

The photochemical processes over tropical Indian region impact the atmospheric composition and air quality over local to global scales; nevertheless, studies on detailed atmospheric chemistry remain sparse in this region. In this study, we investigate the photochemical evolution of air in the downwind of a tropical semi-arid urban environment (Ahmedabad) in India using the Master Mechanism model. The 5-days long chemical evolution has been simulated for the winter conditions - when this region experiences strong ozone build up. Model environment has been set up by including the meteorological conditions, overhead ozone, and aerosol loading, etc. Nitrogen oxides (NOx), carbon monoxide (CO), ozone (O3), and several volatile organic compounds (VOCs) have been initialized in the model based on the wintertime observations. The model predicts large O3 production (∼115 ppbv) in the downwind regions, followed by a gradual decrease from the 3rd day onwards. Additionally, significant amounts of the secondary inorganics, e.g. nitric acid (∼17 ppbv), hydrogen peroxide (∼9 ppbv), and organics, e.g. ketones (∼11 ppbv), are also simulated. The noontime maximum levels of hydroxyl (OH) and hydroperoxyl (HO2) radicals are simulated to be 0.3 and 44 pptv, respectively. While the production of OH is dominated by the reaction of NO with HO2 on the first day, photolysis of O3 dominates subsequently with reduction in NOx levels. VOCs are the major OH sink during day 1, however contribution of CO is greater on further days. The air mass trajectory analysis suggests the outflow of ozone-rich air over the rural areas and the Arabian Sea, in agreement with measurements and a global model. Our study highlights the strong impact of the urban outflows on the regional atmospheric composition. The continuous measurements of VOCs and radicals are needed over tropical regions to complement the models and further improve the understanding of air chemistry.

Monitoring burn severity and air pollutants in wildfire events using remote sensing data: the case of Mersin wildfires in summer 2021

Remotely sensed data have been used to investigate air pollutants and matter toxicity, land cover changes and burn severity. The goal of this study is to analyze land and atmospheric data for wildfire events that occurred in Mersin Province between July 28 and August 3, 2021. We used a variety of open-access remotely sensed data sets (MODIS, Sentinel 2A and Sentinel 5P TROPOMI) from the pre-fire (20-27 July), fire (28 July – 3 August), and post-fire period (4-10 August). This comprehensive study's findings can be divided into two categories. The first group is the land cover output, which includes maps of the affected region's land surface temperature and burn severity, as well as comparisons of the two. The atmospheric output, which consists of trace gas column density maps (for carbon monoxide, formaldehyde, sulphur dioxide and ozone), is the second group. The quantitative results of these analyses indicate that high severity areas correspond to 16.536 hectares, and the maximum column number density reached to 0.071 mol/m2 for carbon monoxide, 0.0043 mol/m2 for formaldehyde, 0.00049 mol/m2 for sulphure dioxide and 0.137 mol/m2 for ozone. The burn severity is found to be highly correlated with land surface temperatures. Pollutant levels in the atmosphere were found to be rising during and after the wildfire. There has not been any evidence of a significant increase in air pollutants near urban areas. However, ozone concentrations rose significantly after the wildfire because the province's nitrogen oxide levels were high enough to produce ozone.

Rheumatoid arthritis chondrocytes produce increased levels of pro-inflammatory proteins

ObjectiveTo investigate whether articular chondrocytes from rheumatoid arthritis (RA) patients have acquired a proinflammatory phenotype. MethodArticular cartilage explants from RA patients and healthy controls (HC) were cultured with or without interleukin (IL)-1β for two weeks. Protein levels of cytokines and metalloproteinases (MMPs) in the supernatant were measured by LUMINEX, mRNA with qPCR and nitrogen oxide (NO) levels with Griess assay. ResultsWithin 24 ​h after culture, cartilage explants from RA spontaneously produced MMP-1 and MMP-13, and matrix components (aggrecan and collagen type IV) were released. In addition, the RA explants released higher levels of tumor necrosis factor, interferon-γ, IL-33, IL-18, vascular endothelial growth factor-A, IL-6 but not IL-8, and granulocyte-macrophage colony-stimulating factor (GM-CSF) as compared with HC. During two weeks of incubation the higher levels did not diminish. IL-1β stimulation further increased the levels of IL-6, IL-8 and GM-CSF, mainly in RA explants, and induced increased levels of NO in the supernatant from both HC and RA explants, as a result of chondrocyte activation. ConclusionsRA chondrocytes are activated with a proinflammatory profile involving the production of cytokines as well as MMP-1 and MMP-13, that can lead to release of matrix molecules after activation, which suggests that the chondrocytes have a proinflammatory phenotype and thereby an active role in the pathogenesis.

Performance of Waste Insulating Mineral Oil-Based Biodiesel in a Direct-Injection CI Engine

Mineral oil has been used as an insulating fluid in the power industry. However, surplus waste oil poses serious environmental threats because of disposal concerns. Waste to biofuel is an excellent way to deal with waste material from various sources. In this study, the trans-esterification method was utilised to convert the waste-insulating mineral oil into a quality bio-fuel. Waste-insulating transformer oil was converted to biodiesel, and it was tested according to ASTM standards. Four different blends of waste-insulating biodiesel with diesel in 25 per cent (WIOBD25), 50 per cent (WIOBD50), 75 per cent (WIOBD75), and 100 per cent fractions (WIOBD100), were used for performance testing in a direct injection compression ignition (DICI) engine. The combustion parameters such as BSFC, EGT, and BTE were evaluated with varying crank angles and constant engine speed. The waste-insulating biodiesel performance results are then compared with diesel fuel. BSFC increased as the biofuel mixture in diesel was raised, and the brake thermal efficiency (BTE) was significantly reduced compared to diesel for all WIOBD diesel mixtures. Due to the combustion process, a high pressure and heat release rate (HRR) were noticed inside the cylinder with the waste-insulating oil-derived biodiesel samples. WIOBD biodiesel blends produced lower levels of hydrocarbon, carbon monoxide, and smoke emissions than diesel fuel, but greater levels of nitrogen oxides (NOx) were produced than diesel fuel. In addition to lower emissions combined with improved engine performance, the WIOBD25 fuel blend has been found to be experimentally optimal for practical application. As a result, the test findings indicated that WIOBD biodiesel might be used as a substitute for conventional diesel fuel.

Air Quality Measurements in Kitchener, Ontario, Canada Using Multisensor Mini Monitoring Stations

The Region of Waterloo is the third fastest growing region in Southern Ontario in Canada with a population of 619,000 as of 2019. However, only one air quality monitoring station, located in a city park in Kitchener, Ontario, is currently being used to assess the air quality of the region. In September 2020, a network of AQMesh Multisensor Mini Monitoring Stations (pods) were installed near elementary schools in Kitchener located near different types of emission source. Data analysis using a custom-made long-distance scaling software showed that the levels of nitrogen oxides (NO and NO2), ground level ozone (O3), and fine particulate matter (PM2.5) were traffic related. These pollutants were used to calculate the Air Quality Health Index-Plus (AQHI+) at each location, highlighting the inability of the provincial air quality monitoring station to detect hotspot areas in the city. The case study presented here quantified the impact of the 2021 summer wildfires on the local air quality at a high time resolution (15-min). The findings in this article show that these multisensor pods are a viable alternative to expensive research-grade equipment. The results highlight the need for networks of local scale air quality measurements, particularly in fast-growing cities in Canada.

The Social and Natural Environment's Impact on SARS-CoV-2 Infections in the UK Biobank.

COVID-19 has caused a global pandemic with considerable impact. Studies have examined the influence of socioeconomic status and air pollution on COVID-19 risk but in low detail. This study seeks to further elucidate the nuances of socioeconomic status, as defined by the Index of Multiple Deprivation (IMD), air pollution, and their relationship. We examined the effect of IMD and air pollution on the likelihood of testing positive for SARS-CoV-2 among 66,732 UKB participants tested for SARS-CoV-2 from 16 March 2020 through 16 March 2021. Logistic regression was performed controlling for age, sex, ancestry and IMD or air pollution in the respective models. IMD and its sub-scores were significantly associated with increased risk of testing positive for SARS-CoV-2. All particulate matter less than 2.5 μm (PM2.5), nitrogen oxide (NOx), and nitrogen dioxide (NO2) levels were associated with increased likelihood of testing positive for SARS-CoV-2. Measures of green space and natural environment around participants’ homes were associated with reduced likelihood of SARS-CoV-2. Socioeconomic status and air pollution have independent effects on the risk of testing positive for SARS-CoV-2. Green space and natural environment space in the proximity of people’s homes may mediate the effect of air pollution on the risk of testing positive for SARS-CoV-2.