Continuous Air Research Articles

Variations in source contributions of particle number concentration under long-term emission control in winter of urban Beijing

Many studies revealed the rapid decline of atmospheric PM2.5 in Beijing due to the emission control measures. The variation of particle number concentration (PN) which has important influences on regional climate and human health, however, was rarely reported. This study measured the particle number size distributions (PNSD) in 3–700 nm in winter of Beijing during 2013–2019. It was found that PN decreased by 58% from 2013 to 2017, but increased by 29% from 2017 to 2019. By Positive matrix factorization (PMF) analysis, five source factors of PNSD were identified as Nucleation, Fresh traffic, Aged traffic + Diesel, Coal + biomass burning and Secondary. Overall, factors associated with primary emissions were found to decrease continuously. Coal + biomass burning dominated the reduction (65%) among the three primary sources during 2013–2017, which resulted from the great efforts on emission control of coal combustion and biomass burning. Fresh traffic and Aged traffic + Diesel decreased by 43% and 66%, respectively, from 2013 to 2019, as a result of the upgrade of the vehicle emission standards in Beijing-Tianjin-Hebei area. On the other hand, the contribution from Nucleation and Secondary decreased with the reduction of gaseous precursors in 2013–2017, but due to the increased intensity of new particle formation (NPF) and secondary oxidation, they increased by 56% and 70%, respectively, from 2017 to 2019, which led to the simultaneously increase of PN and particle volume concentration. This study indicated that NPF may play an important role in urban atmosphere under continuous air quality improvement.

Impact of the Coarse Indoor Non-radioactive Aerosols on the Background Radon Progenies' Compensation of a Continuous Air Monitor.

This paper addresses the problem of false positive alarm when using a continuous air monitor (CAM) in decommissioning sites of nuclear facilities. CAMs are used to measure airborne activity and play an important role in the radiation protection of workers likely to be exposed to radioactive aerosols. Monitors usually sample aerosols on a membrane filter. Radioactive particles sampled are detected through the alpha and beta decays that they emit. These latter ionizing particles are measured online by spectrometry thanks to a Passivated Implanted Planar Silicon detector (PIPS). Alpha and beta decays, in this context, come mainly from the natural radon progeny (218Po, 214Pb, and so on) and, in the case of radioactive contamination, also from artificial radionuclides such as 239Pu or 137Cs. The aim of the CAM is to alert the workers when the artificial airborne activity occurs, always considering the presence of a variable background due to the natural particulate airborne activity. The CAM-specific algorithm considers this background dynamically and continuously, often by using a constant parameter. However, non-radioactive aerosols are also sampled on the membrane filter. These latter make the discrimination more difficult as they lead to the deterioration of the alpha-energy spectrum. In this paper, the effect of coarse non-radioactive aerosols on the CAM response is highlighted with four aerosol size-distributions. The evolution of the background is characterized as a function of the aerosol mass sampled, with the example of a simple algorithm. Thus, in this paper, results show a positive correlation of the background with the aerosol mass sampled by the CAM. In addition, results highlight at least two different evolutionary trends according to the aerosol size distribution. An explanation of these evolutions is given by considering the penetration profile of the natural radioactive aerosols in the granular deposit above the CAM filter. The main consequence of these results is that the background could not be considered as proportional to radon progeny as it is currently used.

Modeling the effect of dual-core energy recovery ventilator unit on the energy use of houses in northern Canada

The use of single-core energy recovery ventilator (ERV) reduces the heating energy use in northern houses, but has the disadvantage of reducing the required outdoor air supplied to the house during the defrost operation by air recirculation, which might affect the indoor air quality. A dual-core ERV also reduces the heating energy use, but in addition supplies a continuous outdoor air flow rate in compliance with standards. This paper evaluates the advantage of using the dual-core ERV in northern houses. First, this paper presents new correlation-based models of supply air temperature and humidity after the ERV unit, based on laboratory-controlled experimental data. Second, the energy use for ventilation and heating, and ventilation rates are simulated with TRNSYS program for northern houses at three arctic locations. They are compared with Montreal conditions as reference. The single-core ERV unit significantly reduces heating energy use in arctic locations by about 27%, compared with the case without heat recovery, however the outdoor airflow rate during the defrost is smaller than minimum standard requirements by about 13% in Kuujjuaq (below Arctic Circle) and 24% in Resolute (above Arctic Circle). The dual-core ERV unit removes the frost while continuously supplying the minimum required outdoor air to the indoors, however at the cost of minor increase of the heating and fan energy use compared with the single-core ERV unit.

Short-Term Continuous Positive Air Pressure Treatment: Effects on Quality of Life and Sleep in Patients with Obstructive Sleep Apnea.

Background and Objectives: The aim of this study was to evaluate short-term continuous positive air pressure (CPAP) treatment for health-related quality of life (HRQL) in patients with obstructive sleep apnea. Materials and Methods: Our subjects were 18–65 years old, diagnosed with moderate-to-severe obstructive sleep apnea and treated with CPAP between January 2020 and June 2021 in Hospital of Lithuanian University of Health Sciences Kaunas clinics. All the patients completed the Epworth Sleepiness Scale (ESS), the 36-Item Short Form Health Survey (SF-36), the and Pittsburgh Sleep Quality Index (PSQI) before and after 3 months of treatment. Polysomnography was also repeated. Statistical analyses were performed using SPSS 27.0 software. The value of p < 0.05 was considered as statistically significant. Results: The active-treatment group comprised 17 subjects with a mean age of 51.9 ± 8.9 years. The total SF-36 questionnaire score improved from 499.8 ± 122.3 to 589.6 ± 124.7 (p = 0.012). The SF-36 role limitations due to emotional problems (p = 0.021), energy (fatigue) (p = 0.035), and general health (p = 0.042) domains score significantly improved after CPAP treatment for 3 months. The PSQI mean score at baseline was 12.6 ± 2.9 and in the post-treatment group, it was −5.5 ± 2.3 (p = 0.001). The ESS also changed significantly from a pretreatment mean score of 10.9 ± 5.7 to −5.3 ± 3.2 (p = 0.002) after 3 months. Conclusions: Improvement in HRQL is seen even after a short treatment period with CPAP. Questionnaires are a good tool to evaluate CPAP treatment efficacy.

A cost-effective method for producing spatially continuous high-resolution air temperature information in urban environments

Sustainable city planning requires detailed information on spatial temperature variations. Remotely sensed land surface temperature (LST) is known to differ substantially from air temperature (AT) causing misinterpretations of the ambient conditions. We demonstrate a reliable and cost-efficient method for AT modelling in urban environments using open data and few temperature observations. The study area is the city of Turku SW Finland, where we have a dense in situ AT observation network of 64 Onset Hobo temperature loggers as a reference. Landsat 8 thermal data from different seasons were used to extract pixel-based LST by employing MODIS and ASTER emissivity libraries and CORINE land cover classification. The LSTs were analysed against the in situ AT first with the correlation analysis. Except for December, the Pearson's correlation coefficients were statistically significant (0.449–0.654, p ≤ 0.001). Seasonally adjusted linear regression models were applied to predict spatially continuous air temperatures (ATp) based on the extracted LST. Our results demonstrate that it is possible to predict urban ATs reliably - within ca. half-a-degree accuracy (MAE 0.36–0.62 °C). The prediction works best in spring, summer and autumn. It improves the capacity to produce reliable high spatial resolution AT information even if in situ observations are sparse.

Development of a novel pneumatic positioning actuator equipped with new continuous air impulse generators

In this study, an innovative pneumatic positioning actuator is developed and tested. Furthermore, two novel mechanisms of crank-swinging lever and cam-follower that generate controlled air impulses are proposed, simulated in MSC.visualNastran software, and fabricated. The pneumatic actuator moves due to the recoil of an internally shot bullet. The bullet returns to its original place after one impact thanks to springs. The actuator and the base have a friction force that prevents hysteresis after each full forward movement. The recoil force is larger than the friction force, which causes the actuator to move. Meanwhile, since the spring force is smaller than the friction force, there is no movement during the return of the bullet. FLUENT and COMSOL software are employed to numerically study the proposed model and optimize the dimensions of the actuator. The problem consists of two components; solid mechanics and fluid-solid interface physics. The piston itself moves in a solid mechanic environment, and the air interaction and flow is related to laminar flow. Using the optimization part in Comsol, the parametric values of the proposed geometry are optimized. It is shown that the simulated device can provide repeatable displacements of 10 nm. The accuracy depends upon the magnitude of the air impact and the fabrication’s specifications and could decrease up to a few micrometers in each step. Repeating the steps gives a continuous stepped movement. Furthermore, the actuator moves in two directions using positive pressure or suction. The fabricated device can reach the positioning accuracy aimed in simulations.

Development of an in-situ continuous air monitor for the measurement of highly radioactive alpha-emitting particulates ([formula omitted]-aerosols) under high humidity environment

In the long-lasting decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), the dismantling of nuclear fuel debris (NFD) remaining in the damaged reactors is an unavoidable but significant issue with many technical difficulties. The dismantling is presumed to involve mechanical and/or thermal processing of NFD, generating significant concentrations of particulates containing α-radionuclides (α-aerosols) that pose significant health risk upon inhalation. In order to minimize the radiation exposure of workers with α-aerosols during the dismantling/decommissioning process at 1F, it is essential to monitor the concentration of α-aerosols at the point of initial generation, i.e. inside the primary containment vessels (PCV) of the damaged reactors. Toward this end, an in-situ monitoring system for α-aerosols (in-situ alpha air monitor: IAAM) was developed and its technical performance was investigated under the conditions expected for the actual environments at 1F. IAAM was confirmed to fulfill four technical requirements: (1) steady operation under high humidity, (2) operation without using filters, (3) capability of measuring high counting rates of α-radiation, and (4) selective measurement of α-radiation even under high radiation background with β/γ-rays. IAAM is capable of selectively measuring α-aerosols with a concentration of 3.2 × 102 Bq/cm 3 or higher without saturation under high humid environment (100%-relative humidity) and under high background with β/γ-radiation (up to 100 mSv/h of γ-radiation). These results demonstrate promising potential of IAAM to be utilized as a reliable monitoring system for α-aerosols during the dismantling of NFD, as well as the whole long-lasting decommissioning of 1F.

Effect of Large-Scale Paddy Rice Drying Process Using Hot Air Combined with Radio Frequency Heating on Milling and Cooking Qualities of Milled Rice.

The objectives of the study on a continuous flow hot air dryer combined with radio frequency heating at different temperatures (HA/RF) (38 °C, 42 °C, 46 °C, and 50 °C) in a large-scale process compared with conventional continuous flow hot air drying (HA) were (1) to investigate the drying characteristics, drying kinetics, and milling quality of the process and (2) to observe the cooking quality and compare the sensory differences of the cooked rice after treatment. The drying characteristics and moisture diffusivity showed that the higher the radio frequency (RF) heating temperature, the shorter the drying time. The specific energy consumption and energy cost decreased when the RF heating temperature increased. The optimal condition in terms of fissure percentage was HA/RF42. In addition, there were no significant differences in head rice yield and white rice color determination, amylose content, texture profiles, and pasting properties in all HA/RF treatments. In the triangle test, it was found that at least 6% of the population could perceive a difference between HA and HA/RF50. In conclusion, this study proposes the further development of the HA/RF drying process at low-temperature profiles and shows the great potential of RF technology for commercial drying in rice industry.

An Air-Stable High-Nickel Cathode with Reinforced Electrochemical Performance Enabled by Convertible Amorphous Li2 CO3 Modification.

High-nickel (Ni ≥ 90%) cathodes with high specific capacity hold great potential for next-generation lithium-ion batteries (LIBs). However, their practical application is restricted by the high interfacial reactivity under continuous air erosion and electrolyte assault. Herein, a stable high-nickel cathode is rationally designed via in situ induction of a dense amorphous Li2 CO3 on the particle surface by a preemptive atmosphere control. Among the residual lithium compounds, Li2 CO3 is the most thermodynamically stable one, so a dense Li2 CO3 coating layer can serve as a physical protection layer to isolate the cathode from contact with moist air. Furthermore, amorphous Li2 CO3 can be transformed into a robust F-rich cathode electrolyte interphase (CEI) during cycling, which reinforces the cathode's interfacial stability and improves the electrochemical performance. The assembled coin cell with this modified cathode delivers a high discharge capacity of 232.4mAhg-1 with a superior initial Coulombic efficiency (CE) of 95.1%, and considerable capacity retention of 90.4% after 100 cycles. Furthermore, no slurry gelation occurs during the large-scale electrode fabrication process. This work opens a valuable perspective on the evolution of amorphous Li2 CO3 in LIBs and provides guidance on protecting unstable high-capacity cathodes for energy-storage devices.

Autonomous Maneuver Decision Making of Dual-UAV Cooperative Air Combat Based on Deep Reinforcement Learning

Autonomous maneuver decision making is the core of intelligent warfare, which has become the main research direction to enable unmanned aerial vehicles (UAVs) to independently generate control commands and complete air combat tasks according to environmental situation information. In this paper, an autonomous maneuver decision making method is proposed for air combat by two cooperative UAVs, which is showcased by using the typical olive formation strategy as a practical example. First, a UAV situation assessment model based on the relative situation is proposed, which uses the real-time target and UAV location information to assess the current situation or threat. Second, the continuous air combat state space is discretized into a 13 dimensional space for dimension reduction and quantitative description, and 15 typical action commands instead of a continuous control space are designed to reduce the difficulty of UAV training. Third, a reward function is designed based on the situation assessment which includes the real-time gain due to maneuver and the final combat winning/losing gain. Fourth, an improved training data sampling strategy is proposed, which samples the data in the experience pool based on priority to accelerate the training convergence. Fifth, a hybrid autonomous maneuver decision strategy for dual-UAV olive formation air combat is proposed which realizes the UAV capability of obstacle avoidance, formation and confrontation. Finally, the air combat task of dual-UAV olive formation is simulated and the results show that the proposed method can help the UAVs defeat the enemy effectively and outperforms the deep Q network (DQN) method without priority sampling in terms of the convergence speed.

Continuous air purification by front flow photocatalytic reactor: Modelling of the influence of mass transfer step under simulated real conditions

In this work, a solution for the treatment of toxic gases based on a photocatalytic process using TiO2 coated on a cellulosic support, has been investigated. Here, cyclohexane was chosen as the reference for testing its removal efficiency via a continuous front flow reactor as type A anti-gas filters. The photocatalytic support was firstly characterized by EDX, to confirm its elemental composition. Then, the experiments were carried out, starting with a batch reactor in order to evaluate the degradation efficiency of the photocatalytic media, as well as the monitoring of the photocatalytic process which allowed the establishing of a carbon mass balance corresponding to the stoichiometric number of our target pollutant. The transition to a continuous treatment with a front flow reactor aims to highlight the influence of the input concentration (0.29–1.78 mM m−3) under different flow rates (12, 18 and 36 L min−1). The relative humidity effect was also investigated (from 5 to 90% of humidity) where an optimum rate was obtained around 35–45%. In addition, the mineralization rate was monitored. The major rates obtained were for a cyclohexane input concentration of 0.29 mM m−3 in wet condition (38%) at an air flow rate of 18 L min−1, where the CO2 selectivity reached 77% for an abatement of 62%. In order to understand the limiting steps of the photocatalytic process, a model considering the reactor geometry and the hydraulic flow was developed. The obtained results showed that the mass transfer must be considered in the photocatalytic process for a continuous treatment. The Langmuir-Hinshelwood bimolecular model was also developed to represent the influence of the humidity.

Metabolic Profile Correction in Patients with Obstructive Sleep Apnea Depends on the Duration of CPAP Therapy Sessions

Obstructive sleep apnea (OSA) is a common, heterogeneous chronic disease with sleep fragmentation, metabolic and cardiovascular disorders. Continuous Positive Air Pressure (CPAP) therapy is the primary treatment for patients with OSA. However, the effects of long-term CPAP therapy with night sessions &gt; 6 hours remain poorly understood. The aim of the study was to study the effects of different durations of night sessions of CPAP therapy on the “metabolic profile” of patients with severe OSA. Materials and methods. In a retrospective case-control study comparing two CPAP-therapy regimens by matching pairs from among patients with verified severe OSA (apnea-hypopnea index&gt; 30/h), arterial hypertension, obesity of I-II degrees according to the WHO classification (1997), signed informed consent, 2 groups of 18 people each were formed, comparable in age, anthropometric and somnographic indicators, using CPAP therapy 4-6 hours / night and more than 6 hours / night, respectively. Patients received CPAP therapy for a year, visits were carried out at 3, 6 and 12 months. The severity of sleep apnea was verified during nighttime computed somnography (CSG) on WatchPAT-200 hardware (ItamarMedical, Israel) with original software zzzPATTMSW ver. 5.1.77.7 (ItamarMedical, Israel) by registering the main respiratory polygraphic characteristics from 11.00 PM to 7:30 AM. The optimal therapeutic level of CPAP therapy was titrated at home using devices for automatic selection of therapeutic pressure (PR System One REMstar Auto CPAP Machine with A-Flex (Philips Respironics, USA)) within 7 days after the diagnostic study. To assess the compliance of OSA patients at 3-6-12 months of CPAP-therapy, we used the original compliance analysis program Encore Pro v.2.14 (Philips Respironics, USA). Results. With the initial comparability of the groups, by the 3rd month of therapy, patients with CPAP &gt; 6 h/night showed a statistically significant advantage over the patients with 4-6 h CPAP-therapy in ESS, neck circumference and testosterone. By the 6th month, statistically significant differences of BMI, VAI, leptin, oral glucose tolerance test, fasting insulin, HOMA-IR, lipid metabolism (HDL, LDL, triglycerides, Apo-B) appeared. By the 12th month of therapy, the CPAP group &gt; 6 h/night had a statistically significant advantage in waist circumference, fasting blood glucose and uric acid. Differences between groups at control points persisted throughout the observation period. Conclusions. Long-term home-based CPAP therapy with sessions &gt; 6 h/night has an advantage over therapy with sessions 4-6 h/night in achieving a rapid and pronounced improvement in metabolic profile and hormonal levels in patients with severe OSA.

Airborne Microorganism Inactivation by a UV-C LED and Ionizer-Based Continuous Sanitation Air (CSA) System in Train Environments.

Improving indoor air quality present in environments where people live is important to protect human health. This particularly applies to public transportation, where air quality may affect the health and safety of passengers, workers and staff. To provide better air quality, many buildings and transports are provided with heating, ventilation and air conditioning (HVAC) systems, which are always equipped with filters to retain the particulate present in the airflow, but they lack continuous air sanitization systems. In this study, a new UV-C LED and ionizer-based continuous sanitation air (CSA) system to be installed in a train HVAC was developed (international patent: N.PCT/IB2021/054194) and its sanitation efficacy against various microbial species (bacteria and fungi) was assessed. The device proved to be very effective at the microbial killing of aerodispersed microorganisms, both in its experimental configuration (ISO 15714:2019) and in a train setting. The installation of this CSA system on public transportation appears to be a promising solution to guarantee high microbiological air quality with a very low environmental impact due to its eco-friendly components.

RADON-222 CONCENTRATION IN AIR: A CASE STUDY OF AYEDUASE TOWNSHIP, KUMASI, GHANA

Objective: Radon levels in structures (interior environment) were measured in many dwellings and hostels in Ayeduase Township, Ashanti Region, Ghana. The purpose of this study was to quantify radon toxicity in the Ayeduase community, which houses approximately half of the students at Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, and to determine the risk levels for individuals (categorized as infants, children, and adults) living in the community's various suburbs.&#x0D; Materials and Methods: Households in Ayeduase had an average of four people per room. The radon in air concentration was measured with a continuous radon monitor using continuous active sampling approach. Multiple measurements were taken at tight space-time intervals over a period of 24 hours. The Continuous Radon Monitor was installed in dwelling rooms in zones where the monitor could record fresh air entering the room. The yearly effective dose was computed using the Mondal 3 Software.&#x0D; Results: The continuous sample air radon concentration in Ayeduase Township was found to be in the range of 8.510 0.05607 Bq/m3 to 11.100 0.6379 Bq/m3. The manually computed effective annual dose rate for indoor air radon was 0.3494 mSv/year to 0.4558 mSv/year for babies, 0.0683 mSv/year to 0.0891 mSv/year for children, and 0.0559 mSv/year to 0.0729 mSv/year for adults. The comparative results from the Mondal 3 Software showed that the effective annual dose rate for indoor air ranged from 0.32 mSv/year to 0.37 mSv/year, with an average of 0.36 mSv/year for infants, 0.11 mSv/year to 0.14 mSv/year, with an average of 0.12 mSv/year for children, and 0.084 mSv/year to 0.097 mSv/year, with an average of 0.94 mSv/year for adults.&#x0D; Conclusion: Ayeduase's radon toxicity profile in terms of air showed distinct features. The maximum value of indoor air radon concentration level determined was lower than the global average value of 40 Bq/m3 of indoor radon concentration level and also lower than the reference level of 100 Bq/m3. In Ayeduase, the estimated average effective dosage over a year for babies, children, and adults were lower than the 1.2 mSv/year indicated by ICRP Publication 126.&#x0D; Recommendation: Radon toxicity due to water and soil sources are required to access the total toxicity levels in the township. Reliable evaluation of the potential for human exposure to radon depends in part on the reliability of supporting analytical data from environmental samples and biological specimens is highly recommended, as well as, concentrations of radon in unpolluted atmospheres and in pristine surface waters are typically within the limits of current analytical methods.&#x0D;

Influence of Adaptive Gap Control Mechanism and Tool Electrodes on Machining Titanium (Ti-6Al-4V) Alloy in EDM Process.

Titanium alloy is widely used for orthodontic technology and easily machined using the EDM process. In the EDM process, the workpiece and tool electrode must be separated by a continuous air gap during the machining operation to generate discharge energy in this method. In the present study, an endeavor was made to analyze the effects of a servo feed air gap control and tool electrode in the EDM process. The developed mechanical setup consists of a linear action movement with zero backlash along the X-axis, which can be controlled up to 0.03 mm. It was observed that the suggested air gap control scheme can enhance the servo feed mechanism on a machining titanium alloy. A tungsten carbide electrode can enhance the surface measures owing to its ability to produce tiny craters with uniform distribution. Since it produces a little crater and has a higher melting point, a tungsten carbide electrode can create lesser surface roughness than a copper tool and brass tool electrode.

Geospatial Modelling for Estimation of PM2.5 Concentrations in Two Megacities in Peninsular India

Airborne particles finer than 2.5 microns (PM2.5) constitute a major public health risk in India. Therefore, extensive scientific studies must be conducted to assess the PM2.5 exposures of Indians and determine the “exposure-response function” specific to India. While Peninsular India includes three megacities with populations exceeding 10 million each, there are very few studies on air quality modelling in this region compared to North India. In this paper, the authors describe a Linear Mixed Effects (LME) model to estimate monthly-average PM2.5 concentrations at a spatial resolution of 1 km2 between 2016 and 2019 in the megacities of Bengaluru and Hyderabad with a total population of 23 million. This model is based on covariates such as aerosol optical depth (AOD), meteorological parameters, and Land-use-Land-cover (LULC) variables and is validated with extensive datasets from continuous and manual air quality monitoring stations through a 10-fold cross-validation process. The final LME model can explain more than 60 percent of the variation in the PM2.5 concentrations in Bengaluru and Hyderabad. This model is then used to predict the monthly-average grid-wise PM2.5 concentrations in more than 800 grids in each of these two cities to study the spatial and temporal patterns in PM2.5 concentrations between 2016 and 2019. These spatiotemporal maps of PM2.5 concentration are critical to overcoming the misclassification of exposure and will form a crucial input to much-needed PM exposure-response studies in these two megacities. This paper can serve as a useful framework for similar studies by showing the way to bridge the gaps in the current air quality monitoring network in Peninsular India.

A Deep Spatio-Temporal Learning Network for Continuous Citywide Air Quality Forecast Based on Dense Spatial-Maps

A Deep Spatio-Temporal Learning Network for Continuous Citywide Air Quality Forecast Based on Dense Spatial-Maps

Analysis of Air Pollution Data in India between 2015 and 2019

India suffers from among the worst air pollution in the world. In response, a large government effort to increase air quality monitoring is underway. We present the first comprehensive analysis of government air quality observations from 2015–2019 for PM10, PM2.5, SO2, NO2 and O3 from the Central Pollution Control Board (CPCB) Continuous Ambient Air Quality Monitoring (CAAQM) network and the manual National Air Quality Monitoring Program (NAMP), as well as PM2.5 from the US Air-Now network. We address inconsistencies and data gaps in datasets using a rigorous procedure to ensure data representativeness. We find particulate pollution dominates the pollution mix across India with virtually all sites in northern India (divided at 23.5°N) exceeding the annual average PM10 and PM2.5 residential national ambient air quality standards (NAAQS) by 150% and 100% respectively, and in southern India exceeding the PM10 standard by 50% and the PM2.5 standard by 40%. Annual average SO2, NO2 and MDA8 O3 generally meet the residential NAAQS across India. Northern India has (~10%–130%) higher concentrations of all pollutants than southern India, with only SO2 having similar concentrations. Although inter-annual variability exists, we found no significant trend of these pollutants over the five-year period. In the five cities with Air-Now PM2.5 measurements - Delhi, Kolkata, Mumbai, Hyderabad and Chennai, there is reasonable agreement with CPCB data. The PM2.5 CPCB CAAQM data compares well with satellite derived annual surface PM2.5 concentrations (Hammer et al., 2020), with the exception of the western desert region prior to 2018 when surface measurements exceeded satellite retrievals. Our reanalyzed dataset is useful for evaluation of Indian air quality from satellite data, atmospheric models, and low-cost sensors. Our dataset also provides a baseline to evaluate the future success of National Clean Air Programme as well as aids in assessment of existing and future air pollution mitigation policies.

A novel low-cost bubble continuous positive airway pressure device with pressure monitoring and controlling system for low resource settings

Background Currently bubble continuous positive airway pressure (bCPAP) is commonly used in low resource settings to treat respiratory distress. However, the accumulation of condensate in the patient's exhalation limb during operation could significantly increase pressure delivered to the body, which can lead to severe respiratory failure in the infant. The objective of this research was to develop a novel low-cost bCPAP device that can monitor and control the pressure delivered to infants. Methods When the neonate expires, the pressure sensor inside the expiratory limb measures the instant positive end-expiratory pressure. The microcontroller decides whether to turn the relay to switch the path of expiration between the two expiratory tubes connected to the valve outlets. This depends on the pressure reading and the cutoff pressure value inserted by the physician. Results The system was tested for accuracy, safety, cost, ease of use, and durability. The prototype was accurate in eight iterations at eight different depths of water that were made to monitor and control the pressure. It was safe and provided suitable pressure for the neonate, and the prototype was built in less than 193 USD. Conclusions The performance testing of the device demonstrated accurate and safe control and monitoring of continuous positive air pressure (CPAP) and oxygen levels with humidity levels safe for infants. The device provides humidified, blended, and pressurized gas for the patient. It allows physicians to easily monitor and control the accumulation of condensate in the exhalation limb of the CPAP machine accurately and safely.

Dramatically reducing the critical velocity of air cavity generation via biomimetic microstructure effects.

Control over the generation of air cavities in liquids is vitally important in numerous underwater marine systems, with behaviors ranging from largely reducing the fluid resistance to minimizing the energy consumption. However, reducing the critical velocity of air cavity generation simultaneously on both original and hydrophobic materials can be mutually exclusive. In strong contrast to the view that the surface wettability is what determines the critical velocity of air cavity entrainment, we report a facile method to dramatically reduce the critical velocity of air cavity generation by etching a kind of biomimetic microstructure on the sphere surface. It is worth noting that the generation of air cavities induced by the microstructure effect is almost independent of surface wettability; even for the hydrophilic spheres, the critical velocity of air cavity generation is reduced by over 86.3%. The physical mechanism is mainly related to the pinning of the moving contact line and the regulable transition of the wetting state from the Wenzel model to the Cassie-Baxter model at the solid-liquid-air interface. We also investigated the stability of the microstructured spheres to induce underwater air cavities and found that a continuous and robust air cavity could still be produced even after 1200 repeated impacts. This research provides a simple, economical and energy-efficient method for minimizing the critical velocity for generating air cavity entrainment to reduce hydrodynamic drag.