Ambient Air Exposure Research Articles

Evidencing Phase Transformations of Li6PS5Cl Argyrodite under Ambient Air and Dry Room Exposure.

All-solid-state electrolytes have been extensively studied for the last years in order to achieve high conductivities and improved safety among lithium-ion technologies. Sulfide electrolytes, such as argyrodites (Li6PS5X, X = Cl, Br, and I), succeed to show high performances despite their poor chemical stability. As a matter of fact, argyrodite reactivity to water is known as a common drawback for easy implementation and requires the use of dry room for cell preparation. The understanding of argyrodite degradation under ambient air exposure is a key for the development of stable electrolytes, coatings, and processes and has been incompletely explored until now. This study brings unreported elements of comprehension around the degradation mechanisms of Li6PS5Cl solid electrolyte using transmission electron microscopy (TEM) and complementary spectroscopic techniques.

Resistive switching suppression in metal/Nb:SrTiO3 Schottky contacts prepared by room-temperature pulsed laser deposition

Deepening the understanding of interface-type resistive switching (RS) in metal/oxide heterojunctions is a key step for the development of high-performance memristors and Schottky rectifiers. In this study, we address the role of metallization technique by fabricating prototypical metal/Nb-doped SrTiO3 (M/NSTO) Schottky contacts via pulsed laser deposition (PLD). Ultrathin Pt and Au electrodes are deposited by PLD onto single-crystal (001)-terminated NSTO substrates and interfacial transport is characterized by conventional macroscale methods and nanoscale Ballistic Electron Emission Microscopy. We show that PLD metallization gives Schottky contacts with highly reversible current-voltage characteristics under cyclic polarization. Room-temperature (RT) transport is governed by thermionic emission with Schottky barrier height ϕB(Pt/NSTO)∼0.71−0.75eV , ϕB(Au/NSTO)∼0.70−0.83eV and ideality factors as small as n(Pt/NSTO)∼1.1 and n(Au/NSTO)∼1.6 . RS remains almost completely suppressed upon imposing broad variations of the Nb doping and of the external stimuli (polarization bias, working temperature, ambient air exposure). At the nanoscale, we find that both systems display high spatial homogeneity of ϕB ( ⩽50meV ), which is only partially affected by the NSTO mixed termination ( |ϕB(M/SrO)−ϕB(M/TiO2)|<35meV ). Experimental evidences and theoretical arguments—based on a metal-insulator-semiconductor description of the M/NSTO—indicate that the PLD metallization mitigates interfacial layer effects responsible for RS. This occurs thanks to the reduction of the interfacial layer thickness and to the creation of an effective barrier against the permeation of ambient gas species affecting charge trapping and redox reactions. This description allows to rationalize interfacial aging effects, observed upon several-months-exposure to ambient air, in terms of a slow interfacial re-oxidation. Our work contributes to the fundamental understanding of interface-type RS and demonstrates that RT PLD offers a viable platform for the realization of robust, RS-free NSTO-based Schottky contacts.

Intermittent hypoxia increases lipid insulin resistance in healthy humans: A randomized crossover trial.

Sympathetic overactivity caused by chronic intermittent hypoxia is a hallmark of obstructive sleep apnea. A high sympathetic tone elicits increases in plasma free fatty acid and insulin. Our objective was to assess the impact of 14 nights of chronic intermittent hypoxia exposure on sympathetic activity, glucose control, lipid profile and subcutaneous fat tissue remodelling in non-obese healthy humans. In this prospective, double-blinded crossover study, 12 healthy subjects were randomized, among them only nine underwent the two phases of exposures of 14 nights chronic intermittent hypoxia versus air. Sympathetic activity was measured by peroneal microneurography (muscle sympathetic nerve activity) before and after each exposure. Fasting glucose, insulin, C-peptide and free fatty acid were assessed at rest and during a multisampling oral glucose tolerance test. We assessed histological remodelling, adrenergic receptors, lipolysis and lipogenesis genes expression and functional changes of the adipose tissue. Two weeks of exposure of chronic intermittent hypoxia versus ambient air significantly increased sympathetic activity (p = 0.04). Muscle sympathetic nerve activity increased from 24.5 [18.9; 26.8] before to 21.7 [13.8; 25.7] after ambient air exposure, and from 20.6 [17.4; 23.9] before to 28.0 [24.4; 31.5] bursts per min after exposure to chronic intermittent hypoxia. After chronic intermittent hypoxia, post-oral glucose tolerance test circulating free fatty acid area under the curve increased (p = 0.05) and free fatty acid sensitivity to insulin decreased (p = 0.028). In adipocyte tissue, intermittent hypoxia increased expression of lipolysis genes (adipocyte triglyceride lipase and hormone-sensitive lipase) and lipogenesis genes (fatty acid synthase; p < 0.05). In this unique experimental setting in healthy humans, chronic intermittent hypoxia induced high sympathetic tone, lipolysis and decreased free fatty acid sensitivity to insulin. This might participate in the trajectory to systemic insulin resistance and diabetes for patients with obstructive sleep apnea.

Room temperature excitonic coupling in self-assembled copper – Fullerene hybrid films exposed to ambient air

Analytically sound combination of organic and inorganic semiconductors in designing functional hybrid nanomaterials promises new advances in nanoscience and in creation of next-generation optoelectronic devices. In this work, we report on combining two contrasting semiconductors (inorganic and organic) possessing attractive optical and electronic properties, namely Cu2O (in form of small single-crystalline nanoparticles, NPs) and C60-fullerene (as a medium supporting the NP ensemble), which were formed within the well-controlled Cux(Oy)C60 hybrid films through self-assembling and ambient air exposure of the vapour-deposited Cu and C60 mixture. The controllability of the hybrid film nanostructure was established and verified through systematic study of the films using Rutherford backscattering spectrometry, transmission electron microscopy, X-ray diffraction, Raman spectrometry and spectroscopic ellipsometry. The remarkable coincidence of the optical absorption peaks around 3.5 eV, reported for the Wannier-Mott (WM) excitons in a Cu2O crystal and detected for the Frenkel (F) excitons in the pristine C60 film, allowed us to observe room temperature polaritons as a product of the F-WM excitonic strong coupling. Quite high coupling energy of the FWM hybrid exciton estimated for the Cux(Oy)C60 films in the x interval of 5 < x < 15 (from 390 meV to 610 meV) implies the mediated effect of nanocavity photons and quantum confinement effect, strongly enhancing the hybrid exciton coupling energy. The implemented study discloses the self-assembled Cux(Oy)C60 hybrid films as promising material for application in optoelectronics and nonlinear optics.

Accumulation and removal of Si impurities on β-Ga2O3 arising from ambient air exposure

Here, we report that a source of Si impurities commonly observed on (010) β-Ga2O3 is from exposure of the surface to air. Moreover, we find that a 15 min hydrofluoric acid (HF) (49%) treatment reduces the Si density by approximately 1 order of magnitude on (010) β-Ga2O3 surfaces. This reduction in Si is critical for the elimination of the often observed parasitic conducting channel, which negatively affects transport properties and lateral transistor performance. After the HF treatment, the sample must be immediately put under vacuum, for the Si fully returns within 10 min of additional air exposure. Finally, we demonstrate that performing a 30 min HF (49%) treatment on the substrate before growth has no deleterious effect on the structure or on the epitaxy surface after subsequent Ga2O3 growth.

The Formation of Residual Lithium Compounds on Ni‐Rich NCM Oxides: Their Impact on the Electrochemical Performance of Sulfide‐Based ASSBs

AbstractResidual lithium compounds (RLCs) are known to form on the surface of nickel‐rich LiNi1‐x‐yCoxMnyO2 (NCM) oxides during synthesis and storage. In this study, the impact of RLCs on cathode performance in sulfide‐based all‐solid‐state batteries (ASSBs) is investigated by employing practically relevant approaches to generate (or remove) RLCs on (or from) NCM single crystal particles. It is revealed that Li2CO3 is the predominant component in samples exposed to air. Surprisingly, heat treatment at high temperatures does not remove RLCs but increases the overall RLC content, accompanied by the partial transformation of existing RLCs into Li2O. These samples exhibit compromised electrochemical performance due to asymmetric overpotential increase during cell discharge. However, it is possible to recover performance through controlled ambient air storage which enables the conversion of existing Li2O into Li2CO3 and formation of fresh Li2CO3 on the surface. Notably, the beneficial effects are not replicated with pure CO2 or moisturized air storage, emphasizing the significance of storage conditions and reaction pathways for Li2CO3 formation. This study demonstrates that removal of Li2O residuals through the formation of Li2CO3 under controlled ambient air exposure proves to be advantageous for sulfide‐based ASSBs, thereby offering valuable guidance for the development of optimized NCM‐based ASSB systems.

Environmental Health Risk Analysis of Sulfur Dioxide (SO2) Inhalation Exposure in Ambient Air Among the Tirtonirmolo Community, Bantul.

Introduction: Sulfur dioxide (SO2) is one of the gases that can pollute the ambient air and cause respiratory irritation. This study aims to determine the characterization of health risk and risk management of sulfur dioxide (SO2) exposure to prevent health impact in the Tirtonirmolo community, Bantul. Methods: This study was a quantitative descriptive research with an Environmental Health Risk Analysis (EHRA) approach. The study subjects were the Tirtonirmolo community in Bantul, with a sample of 110 respondents. The sampling method uses purposive sampling. Results and Discussion: Most respondents are female (74%) with ages over 54 years (52%), and the majority work as housewives (44%). The description of EHRA variables consists of an inhalation rate of 0.83 m3/hour, exposure time of 22 hours/day, exposure frequency of 354 days/year, and exposure duration for real-time projections of 35 years and 30 years for lifetime projections. The SO2 measurement results did not exceed the national quality standard, with the highest concentration being on Madukismo Road, with a concentration of 11.72 μg/m3. The dose-response analysis uses data from the US-EPA, which is 0.026 mg/kg/day. The real-time average intake value is 0.0039 mg/kg/day, and the 30-year lifetime average intake value is 0.0033 mg/kg/day. Conclusion: All respondents from this study had an RQ value&lt;1, both in the RQ for real-time and lifetime. Risk management needs to reduce health risk by using masks when doing outdoor activities and installing Flue Gas Desulfurization (FGD) in factories that emit SO2 emissions.

A Fluorinated Phenethylammonium‐Based Spacer Cation Prompts the Spontaneous Formation of Gradient 2D/3D Perovskites for Efficient and Stable Solar Cells

Despite the prominent photovoltaic performance and broad application prospect of perovskite solar cells (PVSCs), a significant challenge for their commercialization is the stability issue. Herein, a fluorinated organic ammonium salt, 4‐trifluoromethyl phenethyl ammonium iodide (4FPAI), is utilized for the spontaneous formation of gradient 2D/3D perovskite which can be prepared by a simple one‐step spin‐coating process with low‐dimensional phases on the surface and high‐dimensional phases at the bottom. The introduction of 4FPAI leads to improved charge transport as well as reduced nonradiative recombination. The optimal 4FPAI‐based PVSC exhibits a power conversion efficiency (PCE) of 22.12% which is higher than that of the control PVSC without the 4FPAI treatment (20.87%). Meanwhile, the encapsulated 4FPAI‐based device remains at about 88% of its initial PCE under ambient air exposure for 80 days, demonstrating its improved moisture resistance compared to the reference device. This work provides an important strategy for fabricating high efficiency and long‐term stable 2D/3D PVSCs.

The Effect of Air Exposure on the Hydrogenation Properties of 2Mg-Fe Composite after Mechanical Alloying and Accumulative Roll Bonding (ARB)

In this study, we successfully obtained a 2Mg-Fe mixture through mechanical alloying (MA) and processed it via accumulative roll bonding (ARB) (MA+ARB). Our primary focus was to analyze the impact of ambient air exposure while also evaluating the processing route. Some powder samples were exposed to air for 12 months (stored in a glass desiccator with an average yearly temperature and relative humidity of ~27 °C and 50.5%) before undergoing ARB processing. The Mg samples obtained after ARB processing exhibited a (002)-type texture. Our results demonstrate that all samples, including those processed via ARB, could rapidly absorb hydrogen within a matter of minutes despite considerable differences in surface area between powders and rolled samples. Grain size reduction by MA and ARB processing and texturing may have influenced this behavior. ARB-processed samples reached approximately 60% (~1.8 wt.%) of their maximum acquired capacity within just 24 min compared to powders (~2.2 wt.%) stored for a year, which took 36 min. In addition, the desorption temperatures (~300 °C) were lower than those of MgH2 (~434 °C). The absorption and desorption kinetics remained fast, even after prolonged exposure to air. Although there were minor variations in capacities, our overall findings are promising since scalable techniques such as ARB have the potential to produce hydrogen storage materials that are both safe and cost-effective in a highly competitive market.

Nitrogen-containing malodorous gas pollutants emission characteristics and health risk assessment from an A/O wastewater treatment plant

Unpleasant odorous emitted from wastewater treatment plants (WWTPs) have been of great concern for many years, especially among local communities with high population density. Knowledge about characteristics of odorous gas release from WWTP can assist in developing gas pollution reduction technologies. This study investigated the emission and variation of NH3 and organic amines (CH3NH2, C2H6NH, and C3H9N) at the water-air interface and concentrations of ambient air exposure from different treatment units in a wastewater treatment plant in North China, which uses the anaerobic/oxic (A/O) treatment process. Results demonstrated that NH3 and C2H6NH emission fluxes had followed a descending order of aeration treatment units > non aeration treatment units. NH3 and C2H6NH achieved the highest release concentration throughout the whole wastewater treatment process, where 0.0023 g of NH3 and 0.0018 g of C2H6NH were emitted during the treatment of 1 m3 wastewater, while CH3NH2 and C3H9N had never been detected. The emission of NH3 and C2H6NH from biological aeration tanks account for 98 % and 95 % of the total discharge of wastewater treatment plant, respectively. The odor pollution of NH3 and C2H6NH in the ambient air of different treatment units of WWTP was the most serious in summer. At the sensory level, NH3 dominated the malodorous effect and its exposure concentration posed a certain non carcinogenic risk to workers in wastewater treatment plant.

Inverse Modeling of Formaldehyde Emissions and Assessment of Associated Cumulative Ambient Air Exposures at Fine Scale

Among air toxics, formaldehyde (HCHO) is an important contributor to urban cancer risk. Emissions of HCHO in the United States are systematically under-reported and may enhance atmospheric ozone and particulate matter, intensifying their impacts on human health. During the 2021 Michigan-Ontario Ozone Source Experiment (MOOSE), mobile real-time (~1 s frequency) measurements of ozone, nitrogen oxides, and organic compounds were conducted in an industrialized area in metropolitan Detroit. The measured concentrations were used to infer ground-level and elevated emissions of HCHO, CO, and NO from multiple sources at a fine scale (400 m horizontal resolution) based on the 4D variational data assimilation technique and the MicroFACT air quality model. Cumulative exposure to HCHO from multiple sources of both primary (directly emitted) and secondary (atmospherically formed) HCHO was then simulated assuming emissions inferred from inverse modeling. Model-inferred HCHO emissions from larger industrial facilities were greater than 1 US ton per year while corresponding emission ratios of HCHO to CO in combustion sources were roughly 2 to 5%. Moreover, simulated ambient HCHO concentrations depended significantly on wind direction relative to the largest sources. The model helped to explain the observed HCHO concentration gradient between monitoring stations at Dearborn and River Rouge in 2021.

58 Setting Targets for Particles in Outdoor Air: Advice from the Committee on the Medical Effects of Air Pollutants (Comeap)

Abstract The Environment Act (2021) requires the government to set at least one long-term air-quality target, as well as a target for fine particulate matter (PM2.5) air pollution. COMEAP provided independent expert advice to the Department for Environment, Food and Rural Affairs (Defra) to inform the development of targets to reduce both the annual average (mean) concentration of PM2.5 in ambient air and long term population exposures. COMEAP’s advice includes that: a focus on reducing long-term average concentrations of PM2.5 is appropriate evidence indicates that PM2.5 pollution can have harmful effects on people’s health at low concentrations reducing concentrations to, or below, the World Health Organization’s new Air Quality Guideline (5 µg/m3) would benefit public health available studies have not indicated a threshold of effect below which there is no harm reducing exposure of the whole population would achieve the greatest overall public health benefit some individuals or groups are more at risk, but it might be difficult to reflect this in a national targets framework the health benefits of reducing other pollutants, such as nitrogen dioxide and ozone, should not be overlooked. In response to Defra’s evidence report explaining the rationale for its proposed targets, COMEAP: recommended that Defra should consider roles in continuing to improve air quality, even where legally binding targets are met suggested that interim targets would be important to ensure early progress and maximise health benefits stressed the importance of considering inequalities noted that international engagement will be required

Air-sensitive amplified spontaneous emission in lecithin-capped CsPbBr3 nanocrystals thin films

Fully inorganic lead halide perovskite nanocrystals (NCs) are receiving great attention as active materials for photonic and optoelectronic devices. While the lack of long-term stability, due to their sensitivity to ambient air exposure, currently prevents their application to commercial devices, the presence of reversible environmental effects opens the way for possible applications of lead halide perovskites in resistive or optical sensors. In this work we investigate the Amplified Spontaneous Emission (ASE) properties and their dependence on the surrounding environment of lecithin-capped CsPbBr3 NCs thin films. We demonstrate low ASE threshold under nanosecond pumping, both in air and in vacuum, with emission intensity lower in air than in vacuum. We also show that the emission quenching induced by ambient air exposure, ascribed to moisture-induced surface solvation, is reversible and it is fully restored by a suited vacuum stint application. The ASE sensitivity is up to 6.5 larger than the spontaneous emission one, making lecithin-capped CsPbBr3 NCs thin films promising systems for the development of optical humidity sensors with high sensitivity.

Relative Risks of Cardiopulmonary and Lung Cancer Mortality by PM2.5 Exposure in Ambient Air of Delhi Particularly During Smog Episode

Background Delhi, the capital city of India has experienced the problem of the great smog during November since a long time. Adverse meteorological conditions, stubble burning, and the celebration of Diwali were considered as the major responsible factors for the smog episodes. This study was designed to identify the concentration and relative risks associated with the exposure of PM2.5 in ambient air of Delhi during the episodic events. Methods 24-h average ambient levels of PM2.5 were procured for the year 2015–2020. Relative risks of cardiopulmonary and lung cancer diseases associated with PM2.5 exposure have been estimated using a probabilistic approach of risk assessment. Findings The average relative risks (2015–2020) for lung cancer mortality (RR 2.15; 95% CI 2.13, 2.17., p < 0.001) were observed higher than cardiopulmonary mortality (RR 1.66; 95% CI 1.65, 1.67., p < 0.001). An attempt has been done to identify the effect of high exposure concentration on relative risks particularly during smog period. The estimated relative risks during November (2016–2018) for lung cancer mortality were ranged as 2.51–2.68 and cardiopulmonary mortality were ranged as 1.85–1.93. Conclusion Such high levels of associated relative risks during such episodes could be considered as an important additive hazard factor for overall mortality burden.

Short-Term Ambient Air Ozone Exposure and Components of Metabolic Syndrome in a Cohort of Mexican Obese Adolescents.

Ambient air pollution is a major global public health concern; little evidence exists about the effects of short-term exposure to ozone on components of metabolic syndrome in young obese adolescents. The inhalation of air pollutants, such as ozone, can participate in the development of oxidative stress, systemic inflammation, insulin resistance, endothelium dysfunction, and epigenetic modification. Metabolic alterations in blood in components of metabolic syndrome (MS) and short-term ambient air ozone exposure were determined and evaluated longitudinally in a cohort of 372 adolescents aged between 9 to 19 years old. We used longitudinal mixed-effects models to evaluate the association between ozone exposure and the risk of components of metabolic syndrome and its parameters separately, adjusted using important variables. We observed statistically significant associations between exposure to ozone in tertiles in different lag days and the parameters associated with MS, especially for triglycerides (20.20 mg/dL, 95% CI: 9.5, 30.9), HDL cholesterol (-2.56 mg/dL (95% CI: -5.06, -0.05), and systolic blood pressure (1.10 mmHg, 95% CI: 0.08, 2.2). This study supports the hypothesis that short-term ambient air exposure to ozone may increase the risk of some components of MS such as triglycerides, cholesterol, and blood pressure in the obese adolescent population.

Insight into the Surface Reconstruction-Induced Structure and Electrochemical Performance Evolution for Ni-Rich Cathodes with Postannealing after Washing.

Ni-rich layered LiNixCoyAlzO2 (NCA, x ≥ 0.8) oxides have attracted wide attention as cathode materials for lithium-ion batteries due to their higher energy density and lower cost. However, the increase in the capacity for Ni-rich cathodes can cause faster capacity decay and increase sensitivity to ambient air exposure during the storage process. Especially, the residual lithium on the surface of Ni-rich cathodes will cause severe flatulence during cycling which greatly reduces the safety performance of the battery. Washing is an effective method to reduce residual lithium, but it will seriously damage the surface phase structure of Ni-rich materials. Here, we introduce a designed method involving two steps, washing and high-temperature annealing, which can ingeniously modify the surface phase structure of Ni-rich cathodes. The results show that the residual lithium content can be significantly reduced. The thin NiO-like rock-salt phase formed on the surface of Ni-rich cathode annealed at 600 °C improves the diffusion kinetics of Li+, reduces the polarization, and improves the electrochemical performance of Ni-rich materials, while the thick spinel-like phase formed at 400 °C hinders the diffusion kinetics of Li+, significantly increases the polarization, and eventually leads to the structural degradation of Ni-rich materials. As a result, the discharge capacity of the cathode annealed at 600 °C still retains 174.48 mA h g-1 after 100 cycles, with a capacity retention of 92.04%, much larger than the cathode annealed at 400 °C, for which the discharge capacity drops to 107.77 mA h g-1, with a capacity retention of 65.78%.

Influence of air exposure on structural isomers of silver nanoparticles

Up to date, the influence of ambient air exposure on the energetics and stability of silver clusters has rarely been investigated and compared to clusters in vacuum. Silver clusters up to 3000 atoms in size, on an amorphous carbon film, have been exposed to ambient air and investigated by atomic-resolution imaging in the aberration-corrected Scanning Transmission Electron Microscope. Ordered structures comprise more than half the population, the rest are amorphous. Here, we show that the most common ordered isomer structures is the icosahedron. These results contrast with the published behaviour of silver clusters protected from atmospheric exposure, where the predominant ordered isomer is face-centred cubic. We propose that the formation of surface oxide or sulphide species resulting from air exposure can account for this deviation in stable isomer. This interpretation is consistent with density functional theory calculations based on silver nanoclusters, in the size range 147-201 atoms, on which methanethiol molecules are adsorbed. An understanding of the effects of ambient exposure on the atomic structure and therefore functional properties of nanoparticles is highly relevant to their real-world performance and applications.

Diacetyl - A Critical Safety Review of the Science Defining the Environmental Inhalation Hazards Association with Chronic Lung Disease

In the last two decades scrutiny of several retrospective occupational studies on performed by NIOSH in the early 2000’s on ambient indoor air exposures to the flavoring chemical diacetyl and more complex butter flavoring formulations has led to a reported association between diacetyl and severe irreversible lung disease, primarily bronchiolitis obliterans. A group of laboratory rodent studies, performed primarily by associated researchers, followed in the next two decades with the intent to determine a plausible physiological mechanism for bronchiole scarring applicable to the human respiratory tract. Recently, a renewed interest in diacetyl as a flavoring constituent of vaping liquids and marijuana and inhalation exposures has emerged. This paper reviews the universe of published literature to date in relation to whether diacetyl or butter flavors containing diacetyl causes occupational or environmental lung disease, more specifically BO (i.e., general causation) and whether specific levels of inhaled diacetyl or butter flavors containing diacetyl are associated with chronic lung disease.&#x0D; The review included numerous journal articles, government reports, etc. Based upon the evidence, while the literature reflects a statistical association between both diacetyl and butter flavoring diacetyl mixtures and lung disease, there is sufficient evidence to conclude that general causation between exposure to diacetyl concentrations measured in the ambient air environments studied to date and chronic lung disease does not exist.

Assessment of health risks for criteria air pollutants present in 11 non-attainment cities of Uttar Pradesh, India

Uttar Pradesh (UP), one of the most populous state of India is facing the highest mortality rate due to ambient air exposure. In this study, the Relative Risk (RR) and Excess Risk (ER) due to six criteria air pollutants namely PM10, PM2.5, SO2, NO2, O3, and CO have been estimated for 11 non-attainment cities (NAC) of this State. Results indicated that the estimated total ER was 2.62 times higher when calculated using WHO 2021 Air Quality standards (AQS) and compared with estimates using India’s CPCB 2009 AQS. Ghaziabad faces the highest ERs for both PM10 (6.20%) and PM2.5 (3.9%) as per WHO 2021 AQS. ER due to NO2 was observed highest for Kanpur. The ERs obtained for CO, SO2, and O3 were found negative mainly because the estimated pollutant concentration was observed less than AQS and therefore possess no health risks. The study concludes that the present AQS of India’s CPCB for air pollutants PM10, PM2.5, and NO2 are underestimating the excess health risks and need to be revised urgently for better action plans in saving lives.

Electronic structures and optical properties of (Ph4P)MX2 (M = Cu, Ag; X = Cl, Br)

In recent years, all inorganic copper(I) halides have emerged as an exciting new class of optical materials that demonstrate high-efficiency photoluminescence (PL) properties. Here, we report the synthesis and characterization of a series of hybrid copper(I) and silver(I) halides (Ph4P)MX2 (M ​= ​Cu, Ag; X ​= ​Cl, Br) containing tetraphenylphosphonium (Ph4P+) cation as the organic component. Addressing one of the shortcomings of all-inorganic copper(I) halides, inclusion of the bulky organic Ph4P+ cation improves the stability of the hybrid compounds; (Ph4P)MX2 show no sign of degradation upon long-term ambient air exposure. The compounds are found to exhibit unusually weak light emission properties for Cu(I) and Ag(I) halides. Our combined experimental and density-functional theory (DFT) studies attribute the contrasting optical properties of these compounds to their unique crystal and electronic structures. This work provides new materials design perspectives to explore low cost and low toxicity metal halides for light emission applications.