Main Air Research Articles

Short-term field research on air pollution within the boundaries of the large city in the Baltic region.

Air quality in urban and suburban areas is strongly affected by the level of local urbanization, climatic conditions and industrial activity. Monitoring the main air pollutants such as nitrogen oxides, carbon monoxide and particulate matter may help control the most polluted areas of the site and take measures to reduce pollution. Uncontrolled emissions from other chemical pollutants, including volatile organic compounds and odorous contamination sources like ammonia, may cause both a chronic human disease and damage to flora and fauna. The conducted field research is aimed at determining air pollution within the areas of the large city (residential territory, recreation territory and the areas close to intense transport streets) polluted with the gaseous pollutants of varying nature (CO, NO2, ozone, sulfur dioxide, VOC and NH3) as well as particulate matter in different seasons of the year. Studies on Vilnius district air quality were carried out in 17 urban locations (sites) and based on two-phase measurements. The first phase was initiated in 2016-2017 and the second one took place in 2019-2020. It was observed that in the areas close to intense transport streets, the concentration of pollutants can increase more than 3 times, thus reaching up to 36.0µg/m3 of PM10 (particulate matter) and up to 48.0µg/m3 of nitrogen dioxide. During the summer period, ammonia concentrations can increase up to 3 times, reaching up to 11.0µg/m3 from farming and/or industrial activities.

Characterization of PM2.5 in Coastal Urban Area, Northwest Morocco: Seasonal Variations, Elemental Composition and Source Apportionment

Sale, located along the Atlantic Ocean, is the third-largest city in Morocco. The Bouregreg river separates Sale from Rabat (Morocco’s capital city). This City is characterized by a high demographic density. Their main air pollution sources are traffic, ocean, potteries, fishing, domestic heating, and artisanal activities. Ambient PM2.5 particles were collected in an urban area of Sale City (Morocco) from July 2018 to July 2019. The sampling was carried out using a Dichotomous sampler and the Total X-Ray Fluorescence technique (TXRF) was used to evaluate the elemental composition of the collected filters. In this paper, chemical characterization, and source apportionment of PM2.5 were investigated. The results showed that the PM2.5 mass concentrations vary, during the sampling period, from 3.08 µg/m3 to 49.48 µg/m3 with an average of 17.30 µg/m3. The highest values were observed in winter while the lowest in summer. The influence of atmospheric transport scenarios on the levels of PM was carried out using air mass back-trajectories, using the HYSPLIT™ model. This study allowed identifying four main clusters arriving at our receptor site in Sale City: Iberian Coast (24%), Near Atlantic Ocean (33%), Local (28%), and Oceanic (15%). For seasonal variations of metal concentrations, K, Ca, V, Mn, Fe, Ni, Cu, Zn, As, Sr, Ba, and Pb exhibited their highest concentrations during winter while Ti and Cr, their highest concentrations were observed during Autumn. The Enrichment Factor (EF) analysis showed that Ti, Sr, Mn, K, Ca, and Ba are mainly originated from airborne dust with EF < 10, V, Cu, Cr have both natural and anthropogenic sources with 10 < EF < 100, while Ni, Zn, and Pb were mainly from anthropogenic source with EF > 100. Five factors were selected in Positive Matrix Factorization (PMF) model’s analysis: crustal contribution, road dust, brake wear, heavy oil combustion, and exhaust vehicle emissions. Their contributions to PM2.5 were 5%, 53.6%, 20.1%, 14.3% and 7%, respectively. Road dust and vehicle exhaust sources showed the highest contribution in winter; while soil dust, brake wear, and oil combustion sources contributed the most in summer. The present study could be considered as the first source apportionment study on PM2.5 fractions carried out in Sale City, Morocco.

Characteristics, mechanisms, and perceivability of combination tones in violins.

Combination tones (CTs) generated by the inner ear have been widely investigated in the past, starting from the famous Tartini's "third tone." Instead, much less attention has been dedicated to the CTs generated by musical instruments. In this paper, the CTs generated by a set of violins of different quality and age have been investigated when playing a selected set of dyads. CTs were found in all of the violins, and the strongest of them occurred at a frequency below the lower note of the dyad. Its amplitude was strongly dependent on violin and dyad played and was greatest in two old Italian violins and decreased down to a minimum in a factory-made violin. All of these findings are well explained by the boosting action of A0, the main air resonance of the violin that correlates well with the strongest CT. A listening test, performed using selected dyads and violins, showed that the differences between dyads with and without CTs were correctly recognized by a group of professional and amateur musicians, suggesting a possible musical significance of the main CT. The results investigating the possible source of violin nonlinearity are also described.

Proteksi Motor Berbasis Relay Ge Multilin pada Primary Air Fan di PT Indonesia Power

Abstract PT. Indonesia Power Suralaya PGU has an electricity capacity of 3400 MW. Motor Primary Air Fan as the main air supplier to the boiler. To keep the Primary Air Fan motor from being disturbed, it is protected and monitored with GE Multilin 269. The research method that the author uses is the online interview and observation method regarding the motor protection system with the head of the electrical division 5-7 PT. Indonesia Power with data analysis technique that is Miles & Huberman interactive model. GE Multilin 269 output relays (eg, TRIP, AUX) used to trip the motor must change state when control power is removed from the GE Multilin 269 relay. When the input data matches the database, an output is generated. The results of the study can be concluded that the output can be an analog signal as well as an action. The action here is in the form of relay outputs, namely: (1) breaker relay, (2) assistance relay, (3) delay relay and (4) service relay. When checking the motor setpoint page 1 to check and change all alarm trips on the primary air fan motor and setpoint page 3 to check the O/L curve set so that it displays the trip time from 1 second to 8 seconds.

Cytotoxicity of Particulate Matter PM10 Samples from Ouagadougou, Burkina Faso.

Particulate matter (PM) is one of the main air pollutants with 257,000 deaths per year in Africa. Studying their toxic mechanisms of action could provide a better understanding of their effects on the population health. The objective of this study was to describe the PM10 toxic mechanism of action collected in 3 districts of Ouagadougou. Once per month and per site between November 2015 and February 2016, PM10 was sampled for 24 hours using the MiniVol TAS (AirMetrics, Eugene, USA). The collected filters were then stored in Petri dishes at room temperature for in vitro toxicological studies using human pulmonary artery endothelial cells (HPAEC) at the Bordeaux INSERM-U1045 Cardio-thoracic Research Center. The three study districts were classified based on PM10 level (high, intermediate, and low, respectively, for districts 2, 3, and 4). PM10 induced a concentration-dependent decrease in cell viability. A significant decrease in cell viability was observed at 1 µg/cm2, 10 µg/cm2, and 25 µg/cm2 for, respectively, districts 2, 3, and 4. A significant increase in the production of reactive oxygen species (ROS) was observed at 10 µg/cm2 for district 2 versus 5 µg/cm2 and 1 µg/cm2 for districts 3 and 4, respectively. Finally, a significant production of IL-6 was recorded from 5 µg/cm2 for district 4 versus 10 µg/cm2 for districts 2 and 3. Consequently, Ouagadougou is subjected to PM10 pollution, which can induce a significant production of ROS and IL-6 to cause adverse effects on the health of the population.

A new perspective to satellite-based retrieval of ground-level air pollution: Simultaneous estimation of multiple pollutants based on physics-informed multi-task learning

Remote sensing of air pollution is essential for air quality management and health risk assessment. Many machine-learning-based retrieval models have been established for estimating various kinds of air pollutants. These methods mainly aimed to estimate a single pollutant (single-pollutant approach). However, different air pollutants interact with each other and are highly correlated. Building a unified model and conducting a joint retrieval of multiple pollutant can make a better use of these connections and improve the model efficiency. This study proposed a physics-informed multi-task deep neural network (phyMTDNN) for the joint retrieval of six main air pollutants, i.e., PM2.5, PM10, SO2, NO2, CO, and O3. The relationships among these pollutants were used to design the physics-informed network structure and loss function. Top-of-atmosphere reflectance which can generate retrieval results at ultrahigh resolution was used as model input. Experiments for mainland China in 2019 showed that the proposed model successfully achieved simultaneous estimation of six air pollutants, with the cross-validated R2 for the six pollutants varying from 0.72 to 0.90. The contrast experiments proved that physics-informed network structure contributed to the most of the model performance improvement. Compared to the single-pollutant approach, phyMTDNN ameliorated the model accuracy on traces gases retrieval. Furthermore, the modeling efficiency was largely improved in that a lot of repetitive work was avoided and modeling method was optimized. The proposed new multiple-pollutant retrieval frame can be applied to various fields for multi-variate retrieval or estimation.

Analysis of Microtopography Atmospheric Precipitable Water Vapour over the Northeastern Margin of the Qinghai–Tibet Plateau

The Liupan Mountain (LPM) area is located on the northeast margin of the Qinghai–Tibet Plateau, which is the western part of the second ladder of China’s terrain. It is also an intersection area of two air currents, which are caused by the combined action of the Qinghai–Tibet Plateau, the middle and lower levels of the westerly belt and the edge of the monsoon area. LPM is one of the main air water vapour transport pathways in Northwest China as well as a main water conservation area for nearly ten million people. Research on atmospheric precipitable water vapour (PWV) variation characteristics in LPM is beneficial for understanding the mechanisms of orographic precipitation and improving the effects of weather modification. Based on the data from 10 Global Navigation Satellite System Meteorology (GNSS/MET) stations for 6 years and the data of automatic weather stations in the LPM, the temporal and spatial variation characteristics of PWV in the LPM were analysed, and the differences in PWV in the 24 h before and after precipitation were compared in this study. The results showed that the hourly, monthly and seasonal variations in PWV displayed obvious patterns. PWV increased rapidly 10 h ahead of precipitation, while it decreased rapidly within 10 h after precipitation, which was slower than that before precipitation. In terms of spatial distribution, PWV was larger in the south than in the north and larger in the east than in the west. Although the precipitation on the LPM peak was the highest in the whole LPM area, its PWV was always the lowest, indicating that the PWV was obviously affected by the air temperature. This showed that under the same water vapour condition, precipitation was more likely to form in the area with low temperature, and the precipitation was larger, which also provided a train of thought for improving the method of artificial precipitation enhancement by using the condensation catalyst.

Arctic Development in Connection with the Northern Sea Route: A Review of Ecological Risks and Ways to Avoid Them

The unprecedented melting of Arctic ice provides new opportunities for shipping by decreasing the distance for commercial traffic between Asia and Europe by up to 40%. However, its development is associated with inevitable problems caused by the vulnerability of polar ecosystems. As research methods, we have chosen system and comparative analyses of open sources; national development strategies of the Russian Federation (primarily), China, Northern Europe, and the USA (partially); and scientific articles from the Scopus and Elibrary databases. As a result, we have identified the reasons for possible risk situations for the Arctic region’s sustainable development: mining on the shelf, oil and oil product spills during the transportation of goods and fishing activities, etc. Black carbon (soot) emitted from using marine diesel fuel is the main atmospheric air pollutant. In addition, actively developing infrastructure (ports and new industrial zones) also has a negative anthropogenic impact on the environment. Within the framework of an ecosystem approach, we studied ways to prevent risky situations when planning logistics routes using the Northern Sea Route. We concluded about the need to expand the icebreaker fleet. We proposed a conceptual model of the risk management system based on the monitoring of the key indicators’ system. We identified possible types of risks according to the place of their occurrence and according to the stages of the life cycle of such systems. Furthermore, we provided the steps of the risk management system and an example of the application of a “bow-tie” diagram—a qualitative method for assessing the risk of “collision”.

CFD Simulation into the Spread of Covid-19 in a Passenger Deck of a Sea Transportation Model

COVID-19 is a type of disease that emerged at the end of 2019 and can cause respiratory system disorders, ranging from mild symptoms such as flu to severe symptoms such as pneumonia. According to data released by WHO, in October 2020, the fatality rate caused by COVID-19 in Indonesia was 3.5%. Long-distance sea transportation with a large passenger capacity, in a countrylike Indonesia, has the potential to be one of the main locations for the spread of COVID-19 virus. To obtain the proper information, a numerical CFD RANSE based simulation is carried out on aneconomy-class passenger deck. The deck has a size of 14.1 meters x 15 meter together with maximum capacity of 206 passengers. The CFD simulation involves 3 main components, namely, air inlet, air outlet and mouth inlet, and k-epsilon turbulence modelling is used because it predicts well far from theboundaries. Finally, the simulation is expected to reflect the real situation of indoor transmission in a sea transportation vehicle in order to reduce the victims and provide a mitigation plan due to the spread of virus.

A rapid removal of xylene from air based on nano-activated carbon in the dynamic and static systems and compared to commercial activated carbon before determination by gas chromatography

As main air pollutants, volatile organic compounds (VOCs) must be paid special attention. In this study, the removal efficiency of xylene from the air was investigated by nano-activated carbons (NACs) as an efficient adsorbent and compared to commercial activated carbons (ACs). In the chamber, the xylene vapor in pure air was generated, stored in the airbag (5 Li), and moved to adsorbents. Then, the xylene vapor was absorbed on the NAC/AC adsorbents and desorbed from it by a heat accessory. The efficiency of xylene removal with NACs and ACs was investigated in the dynamic and static systems based on 100-700 mg L-1 of xylene, flow rates of 100 ml min-1, and 100 mg of adsorbent at a humidity of 32% (25°C). Xylene concentrations were determined by gas chromatography equipped with a flame ionization detector (GC-FID). In the batch system, the maximum absorption capacity for NACs and ACs was obtained at 205.2 mg g-1 and 116.8 mg g-1, respectively. The mean adsorption efficiency for NACs and ACs adsorbents was obtained at 98.5% and 76.55%, respectively. The RSD% for NACs ranged between 1.1-2.5% in optimized conditions. The characterizations of the NACs adsorbent showed that the particle-size range was between 35-100 nm.

Assessment of Lockdown Effectiveness during COVID-19 Pandemic Using Air Pollution Data in Armenia in March–June 2019 and 2020: A Cross-Sectional Study

Various methods used by different countries’ governments to control the spread of coronavirus disease 2019 (COVID-19), the cause of pandemic in 2020, affected air quality. The aim of this study was to evaluate the effects of lockdown in Armenia on the content of the main air pollutants—dust, SO2 and NO2. This was a cross-sectional study. We analyzed data on the concentrations of SO2, NO2 and dust from March to June, 2019 and the same period in 2020 as well as data on positive COVID-19 cases from Yerevan, Vanadzor and Hrazdan. In 2020, dust was found to be lower in Yerevan and in Hrazdan and higher in Vanadzor than in the same period in 2019. The same pattern was present for SO2 concentrations: in Yerevan and Hrazdan there was a decrease, and there was an increase in Vanadzor. The concentrations of NO2 increased in Yerevan and Hrazdan, with a slight decrease in Vanadzor. New cases of COVID-19 had a negative correlation with dust and a positive correlation with SO2. The strict quarantine measures were effective in containing the spread of COVID-19.

Three-Dimensional Landscape Pattern Characteristics of Land Function Zones and Their Influence on PM2.5 Based on LUR Model in the Central Urban Area of Nanchang City, China.

China’s rapid urbanization and industrialization process has triggered serious air pollution. As a main air pollutant, PM2.5 is affected not only by meteorological conditions, but also by land use in urban area. The impacts of urban landscape on PM2.5 become more complicated from a three-dimensional (3D) and land function zone point of view. Taking the urban area of Nanchang city, China, as a case and, on the basis of the identification of urban land function zones, this study firstly constructed a three-dimensional landscape index system to express the characteristics of 3D landscape pattern. Then, the land-use regression (LUR) model was applied to simulate PM2.5 distribution with high precision, and a geographically weighted regression model was established. The results are as follows: (1) the constructed 3D landscape indices could reflect the 3D characteristics of urban landscape, and the overall 3D landscape indices of different urban land function zones were significantly different; (2) the effects of 3D landscape spatial pattern on PM2.5 varied significantly with land function zone type; (3) the effects of 3D characteristics of landscapes on PM2.5 in different land function zones are expressed in different ways and exhibit a significant spatial heterogeneity. This study provides a new idea for reducing air pollution by optimizing the urban landscape pattern.

Study on Optimization of Tunnel Ventilation Flow Field in Long Tunnel Based on CFD Computer Simulation Technology

With the rapid development of tunnel construction, more and more long tunnels are being designed and built. In contrast to ordinary tunnels, long tunnels are characterized by large construction distances and difficult ventilation. In this study, gallery ventilation systems in the construction of long tunnels were studied. Combined with the CFD software FLUENT, a three-dimensional model of tunnel ventilation of a double tunnel was established, and a numerical simulation analysis of the ventilation flow field was carried out and optimized the flow field of gallery ventilation. We found that the main circulation air flow of gallery ventilation was formed by the jet fan, which was installed near the air flow-in tunnel. We also determined the main factors that affect the ventilation effect in gallery ventilation, including the wind wall formed by the high-speed airflow at the cross-aisle and found that the draft fan in front of the cross-aisle could eliminate the wind wall and improve the ventilation effect. The influence of the location and type of the draft fan on the elimination of air flow structure was studied, and the best fan layout scheme suitable for the site was determined. The ventilation scheme of the tunnel was optimized.

Unraveling the Drivers Controlling the Transient and Seasonal CO2 Dynamic in a Shallow Temperate Cave

Understanding the dynamics and spatial distribution of gases in the subterranean atmospheres is essential to increase the reliability of carbon balances in karst ecosystems or the paleoclimate reconstructions based on cave deposits. This scientific information is also very valuable for cave managers to ensure the safety of visitors and the conservation of the subterranean heritage. Through a comprehensive monitoring of the main air parameters in a shallow temperate cave, we decipher the physical drivers and mechanisms involved in the CO2 and radon exchange between the cave and the outer atmosphere, and how this process is triggered by the changes of local weather. Our results reveal that the biphasic infiltration (water plus air) in the network of penetrative structures from the overlying soil and host rock exercise remarkable control over the cave environment, delaying the thermal response of the cave air to the outer climate-driven changes and also the gaseous transfer between the cave atmosphere and the exterior. The cave location concerning the karstified outcrop determines that this subterranean site acts as a gas emitter during summer, which is contrary to what happens in many other caves. Prominent gas entrapment at a micro-local level is also registered in some upper galleries.

Environmental Impact Assessment of Production Plant during Construction Period

Based on the construction project of a manufacturing plant, the environmental impact assessment of possible environmental pollution during the construction period was carried out from the perspective of atmosphere, water, noise, and solid waste. The analysis of air pollution indicates that dust and motor vehicle exhaust are the main air pollution factors, of which dust emission is 33 t, and the daily emission of NOx, CO, and THC in tail gas is 5.35 kg, 3.7 kg, and 1.1 kg, respectively. The annual average wind speed of the area where the factory is located is 3.15 m/s, and the average wind speed in August is 2.50 m/s, which is 20.6% lower than the annual average. The annual average monthly precipitation is 59.5 mm, and the precipitation in July is 186.4 mm, which is 213.3% higher than the monthly average. Therefore, summer is the best time for construction. Meanwhile, in addition to taking road hardening measures to reduce emissions, dust can also be restrained through watering, and motor vehicle exhaust is reduced through reasonable operation. Water pollution analysis shows that the pH of groundwater in the factory is within the standard limit range (6.5-8.5), and the maximum standard index is less than 0.1, with a very high level of reaching the standard. Cleaning engineering machinery will produce wastewater containing petroleum substances and suspended solids. The amount of wastewater produced every day is 0.5 m3, which can be used for dust suppression. The daily amount of sewage during the construction period is 0.6 m3, which can be directly discharged to the pipe network without polluting local water sources. Noise pollution analysis shows that the minimum distance between day construction and night construction is 50 m and 281 m, respectively. Although there is large construction machinery in the construction area, the construction area itself is in the production area and there are other noise pollution sources around it, so there will not be obvious noise pollution during the construction period. The analysis of solid waste pollution indicates that the total amount of construction waste generated during the construction period is about 4.2 t, and the daily production of domestic waste is 21 kg. Part of various solid wastes is collected and treated in a centralized manner, while the rest can conducted with landfill treatment after part of them is recycled and utilized, without causing significant pollution to the local environment.

Analysis of Atmospheric Pollutants and Meteorological Factors on PM2.5 Concentration and Temporal Variations in Harbin

With rapid economic development, the problem of air pollution has become increasingly prominent. Countries have paid attention to PM2.5, one of the main air pollutants, and have gradually addressed this issue. Based on the 2015–2019 air quality data, meteorological data, and aerosol optical depth data from Harbin, China, this study investigated the relationship between PM2.5, a number of influencing factors, and their temporal changes using a machine-learning method. It can be seen from the analysis that the random forest model can predict PM2.5 concentration. In this model, the mean RH and AOD have a high impact on PM2.5 concentration, but there was negligent correlation with PM2.5. The results indicated that the level of PM2.5 pollution continuously decreased from 2015 to 2019, and there were significant seasonal differences in PM2.5 concentration and its variations. In 2019, due to the impact of heating and adverse meteorological conditions, PM2.5 pollution during the heating period increased significantly. This study provides theoretical and data support for the analysis of PM2.5 pollution in Harbin and formulation of air pollution control policies.

Relationship Between Intraoperative Electrocochleography Responses and Immediate Postoperative Bone Conduction Thresholds in Cochlear Implantation

To determine the relationship between intraoperative electrocochleography (ECochG) measurements and residual hearing preservation after cochlear implant (CI) surgery by comparing differences between preoperative and immediate postoperative bone conduction thresholds. Prospective cohort study. Tertiary academic referral center. Sixteen patients with preoperative residual hearing and measurable (no-vibrotactile) bone conduction thresholds at 250 and/or 500 Hz who underwent cochlear implantation. Intraoperative ECochG and air and bone conduction thresholds. Nine patients showed no significant drop (<30%) in ECochG amplitude during CI surgery with an average preoperative and immediate postoperative BC threshold of 46 and 39 dB HL, respectively, at 500 Hz. Seven patients with a decrease in ECochG amplitude of 30% or greater showed an average preoperative 500 Hz BC threshold of 32 dB HL and immediate postoperative threshold of 55 dB HL. Air and bone conduction thresholds measured approximately 1 month after CI surgery show delayed-onset of hearing loss across our study patients. A small decrease (<30%) in difference response or cochlear microphonics amplitude correlates with no significant changes in immediate postoperative residual hearing, whereas patients who show larger changes (≥30%) in difference response or cochlear microphonics amplitude during intraoperative ECochG measurements show significant deterioration in BC thresholds. This study reveals the necessity of prompt postoperative bone conduction measurement to isolate the intraoperative cochlear trauma that may be detected during intraoperative ECochG measurements. Although delayed postoperative audiometrics represent longer-term functional hearing, it includes the sum of all postoperative changes during the recovery period, including subacute changes after implantation that may occur days or weeks later. Measuring air and bone conduction thresholds immediately postoperatively will better isolate factors influencing intraoperative, early postoperative, and delayed postoperative hearing loss. This will ultimately help refine surgical technique, device design, and highlight the use of intraoperative ECochG in monitoring cochlear trauma during CI surgery.

Characterization of air pollutant emissions from construction machinery in Beijing and evaluation of the effectiveness of control measures based on information code registration data.

Non-road mobile machinery (NRMM), mainly construction machinery, has a high emission intensity of air pollutants, significantly impacting urban air quality. Most previous estimates of NRMM emissions have employed a top-down approach mainly based on estimates of energy consumption, leading to large uncertainties. This study uses the information code registration data specified in the latest regulations to establish a bottom-up method for emission accounting to more precisely identify the characteristics of air pollutant emissions from construction machinery in Beijing in 2020. Moreover, the study evaluates the effectiveness of the implementation of the corresponding control measures in conjunction with the current situation of pollution control of NRMM in Beijing. The results show the following: (1) Based on the information code registration data, there are 37,000-based fuel construction machines, with excavators accounting for the largest proportion (56%), loaders and forklifts also accounting for large proportions (19% and 15%, respectively), representing the main types of construction machinery. (2) Information code registration data better reflect the actual situation of construction machinery emissions than the top-down method; the emissions of the main air pollutants NOx, PM2.5, and VOCs amount to 12,000 tons, 600 tons, and 1000 tons, respectively, which are overestimated to some extent by the top-down method. (3) Loaders and excavators have a large contribution to emissions, accounting for 80-91% of these three pollutants emissions; there is a large quantity of machinery classified into the China III standard, accounting for 64-68% of these pollutants emissions; the designation of low emission zones banning the use of high-emission machinery plays a positive role in pollution reduction, but high-emission machinery is still used in these regions, which requires further attention. (4) In the future, the scope of these regions banning high-emission machinery and the types of controlled machinery should be further expanded, and the supervision and enforcement should be strengthened, Furthermore, the structural adjustment and energy conservation of construction machinery should be promoted, and measures such as electrification should be implemented for part of the light construction machinery to continue to reduce pollutant emissions.

Acute effects of exposure to fine particulate matter and ozone on lung function, inflammation and oxidative stress in healthy adults

Both fine particulate matter (PM2.5) and ozone (O3) may have adverse effects on human health. However, previous studies on the effects of air pollutants mainly have focused on susceptible population, and evidence on healthy young adults is limited. We aimed to examine the associations of the two main air pollutants (PM2.5 and O3) with lung function, inflammation and oxidative stress in healthy young adults. We recruited 30 healthy young adults for a longitudinal panel study in Beijing and implemented health examination seven times, including lung function (FEV1 and PEF) and biomarkers of inflammation and oxidative stress (i.e. C-reactive protein, CRP; interleukin-6, IL-6; malondialdehyde, MDA) from December 2019 to May 2021. Hourly ambient air pollutants data were obtained from the closest air quality monitoring station. Linear mixed-effect model was applied to explore the associations between air pollutants and lung function, inflammation and oxidative stress. We observed higher PM2.5 exposure was associated with decrement in lung function and increment in CRP and MDA. Each 10 μg/m3 increase in PM2.5 (lag 2 day) is associated with a 17.06 ml (95% CI: −31.53, −2.58) decrease in FEV1, 46.34 ml/s (95% CI: −76.41, −16.27) decrease in PEF and increments of 2.86% (95% CI: 1.47%, 4.27%) in CRP, 1.63% (95% CI: 0.14%, 3.14%) in MDA respectively. However, there is no significant association between ozone exposure and health indicators. The study suggested that short-term exposure to PM2.5 may decrease lung function and induce inflammation and oxidative stress in healthy adults, but there is no association between O3 and each outcome.

Gas-Solid Flow and High-Efficiency and Low-NO x Combustion of a Novel Arch-Fired Boiler with Swirl Burners: Impact of Over-Fire Air

ABSTRACT For a 300 MWe anthracite- and arch-fired boiler with biased-swirling-secondary-air (BSSA) technology, the distribution law of gas/solid two-phase velocity in the furnace is obtained with the help of a 1:10 cold modeling experiment bench, and the combustion and NO x formation characteristics in the furnace are revealed by numerical calculation. The results show that, with the increase of over-fire air rate, the reflux velocity in the reflux zone under the arch decreases continuously, and when the main air flow from the furnace arch reaches the staged air region from the vent air region, the position of particle flow in the primary air turn upward is advanced, and the utilization rate of the space in the lower furnace will decrease continuously. In the regions of vent air and staged air, when the over-fire air rate increases from 15% to 25%, the maximum vertical velocity decreases by approximately 2 times, and the downward depth of air flow from the furnace arch decreases significantly. When the over-fire air rate is increased from 10% to 25%, the thermal resistance between the primary air of the burner and the high-temperature flue gas in the furnace center increases, the ignition of the primary pulverized coal air flow is advanced, the flue gas temperature in the center of the lower furnace is decreased. As a result, with the increase of over-fire air rate, the combustible content of fly ash increases continuously. Especially, when the over-fire air rate increases from 20% to 25%, the combustible content of fly ash increases significantly. With the increase of the over-fire air rate, the high CO concentration region in the primary combustion zone expands, the reducing atmosphere is strengthened, the formation of NO x is effectively restrained, and the NO x emission concentration at the furnace outlet continues to decreases. In particular, when the over-fire air rate increases from 15% to 20%, the NO x emission concentration decreases greatly. After the swirling secondary air of the arch-fired boiler is biased, the setting of over-fire air rate is recommended to be 20%, and the NO x emission concentration and combustible content of fly ash are 694 mg/m3(O2 = 6%) and 7.32%, respectively. Compared with a traditional swirling arch-fired boiler, the combustible content of fly ash and NO x emission concentration are reduced by 46.8% and 34.1%, respectively.