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1.
Rev Med Suisse ; 17(749): 1515-1519, 2021 Sep 08.
Artigo em Francês | MEDLINE | ID: mdl-34495587

RESUMO

Inhaled medication is the cornerstone of medical treatment of COPD. The efficacy of these treatments depends on the optimal use of inhalation devices. This requires not only an impeccable inhalation technique, but above all the selection of an inhaler adapted to the patient. In this article, we describe the specificities of the different inhalation devices and some of the patient's characteristics to be taken into account when selecting an inhaler, in particular the presence of cognitive disorders, impaired dexterity or insufficient inspiratory force.


Assuntos
Doença Pulmonar Obstrutiva Crônica , Administração por Inalação , Aerossóis/uso terapêutico , Desenho de Equipamento , Humanos , Nebulizadores e Vaporizadores , Doença Pulmonar Obstrutiva Crônica/tratamento farmacológico
2.
J Hazard Mater ; 416: 125833, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492791

RESUMO

Aerosol emissions from wastewater treatment plants (WWTPs) have been associated with health reverberation but studies about characteristics of size-segregated aerosol particulate matter (PM) are scarce. In this study, the measurement of particulate number size distribution in the range of < 10 µm, and the collection of PM10-2.5, PM2.5-1.0 and PM1.0, were conducted from an aerobic moving bed biofilm reactor (MBBR) at a full-scale WWTP. MBBR aerosols showed a unimodal number size distribution, with the majority of particles (>94%) in the ultrafine size range (<100 nm). For toxic metal(loid)s or potential pathogens, significant differences were found within MBBR aerosols (PM10-2.5, PM2.5-1.0, and PM1.0), and also between MBBR aerosols and wastewater. Both wastewater and ambient air had important source contributions for MBBR aerosols. The compositions of toxic metal(loid)s in PM1.0, and the populations of potential bacterial or fungal pathogens in PM10-2.5 and PM2.5-1.0, were dominated by that from wastewater. Compared to PM10-2.5 and PM2.5-1.0, PM1.0 had the highest aerosolization potential for the toxic metal(loid)s of As, Cd, Co, Cr, Li, Mn, Ni, U, and Zn, and the genera of Acinetobacter, Pseudomonas and Fusarium. Due to the size-segregated specialty, targeted measures should be employed to reduce the health risks. CAPSULE: The compositions of toxic metal(loid)s in PM1.0, and the populations of potential pathogens in PM10-2.5 and PM2.5-1.0, were dominated by that from wastewater.


Assuntos
Biofilmes , Purificação da Água , Aerossóis/análise , Reatores Biológicos , Material Particulado
3.
Proc Natl Acad Sci U S A ; 118(37)2021 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-34465564

RESUMO

After the Spanish flu pandemic, it was apparent that airborne transmission was crucial to spreading virus contagion, and research responded by producing several fundamental works like the experiments of Duguid [J. P. Duguid, J. Hyg. 44, 6 (1946)] and the model of Wells [W. F. Wells, Am. J. Hyg. 20, 611-618 (1934)]. These seminal works have been pillars of past and current guidelines published by health organizations. However, in about one century, understanding of turbulent aerosol transport by jets and plumes has enormously progressed, and it is now time to use this body of developed knowledge. In this work, we use detailed experiments and accurate computationally intensive numerical simulations of droplet-laden turbulent puffs emitted during sneezes in a wide range of environmental conditions. We consider the same emission-number of drops, drop size distribution, and initial velocity-and we change environmental parameters such as temperature and humidity, and we observe strong variation in droplets' evaporation or condensation in accordance with their local temperature and humidity microenvironment. We assume that 3% of the initial droplet volume is made of nonvolatile matter. Our systematic analysis confirms that droplets' lifetime is always about one order of magnitude larger compared to previous predictions, in some cases up to 200 times. Finally, we have been able to produce original virus exposure maps, which can be a useful instrument for health scientists and practitioners to calibrate new guidelines to prevent short-range airborne disease transmission.


Assuntos
COVID-19/transmissão , Guias como Assunto , Aerossóis , Biologia Computacional , Simulação por Computador , Humanos , Exposição por Inalação , Medição de Risco , Espirro
4.
J Hazard Mater ; 416: 125856, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492805

RESUMO

Inhalation of aerosols such as pharmaceutical aerosols or virus aerosol uptake is of great concern to the human population. To elucidate the underlying aerosol dynamics, the deposition fractions (DFs) of aerosols in healthy and asthmatic human airways of generations 13-15 are predicted. The Navier-stokes equations governing the gaseous phase and the discrete phase model for particles' motion are solved using numerical methods. The main forces responsible for deposition are inertial impaction forces and complex secondary flow velocities. The curvatures and sinusoidal folds in the asthmatic geometry lead to the formation of complex secondary flows and hence higher DFs. The intensities of complex secondary flows are strongest at the generations affected by asthma. The DF in the healthy airways is 0%, and it ranges from 1.69% to 52.93% in the asthmatic ones. From this study, the effects of the pharmaceutical aerosol particle diameters in the treatment of asthma patients can be established, which is conducive to inhibiting the inflammation of asthma airways. Furthermore, with the recent development of COVID-19 which causes pneumonia, the predicted physics and effective simulation methods of bioaerosols delivery to asthma patients are vital to prevent the exacerbation of the chronic ailment and the epidemic.


Assuntos
Asma , COVID-19 , Aerossóis , Asma/tratamento farmacológico , Simulação por Computador , Humanos , Pulmão , Modelos Biológicos , Tamanho da Partícula , SARS-CoV-2
5.
Environ Monit Assess ; 193(10): 626, 2021 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-34482422

RESUMO

A simplified model has been devised to estimate the falling dynamics of severe acute respiratory syndrome corona-virus 2 (SARS-CoV-2)-laden droplets in an indoor environment. Our estimations were compared to existing literature data. The spread of SARS-CoV-2 is closely coupled to its falling dynamics as a function of respiratory droplet diameter (1 to 2000 µm) of an infected person and droplet evaporation. The falling time of SARS-CoV-2 with a respiratory droplet diameter of about 300 µm from a height of 1.7 m remained almost the same among the Newtonian lift equation, Stokes's law, and our simplified model derived from them so as to account for its evaporation. The evaporative demand peaked at midday which was ten times that at midnight. The evaporating droplets [Formula: see text] 6 µm lost their water content rapidly, making their lifetimes in the air shorter than their falling times. The droplets [Formula: see text] 6 µm were able to evaporate completely and remained in the air for about 5 min as droplet nuclei with SARS-CoV-2.


Assuntos
Aerossóis , Microbiologia do Ar , Monitoramento Ambiental , SARS-CoV-2 , Humanos , SARS-CoV-2/isolamento & purificação
6.
Artigo em Inglês | MEDLINE | ID: mdl-34501544

RESUMO

Aerosols generated during dental procedures are one of the most significant routes for infection transmission and are particularly relevant now in the context of COVID-19 pandemic. This study aimed to assess the effectiveness of an indoor air purifier on dental aerosol dispersion in dental offices. The spread and removal of aerosol particles generated from a specific dental operation in a dental office are quantified for a single dental activity in the area near the generation and corner of the office. The effects of the air purifier, door condition, and particle sizes on the spread and removal of particles were investigated. The results show that, in the worst-case scenario, it takes 95 min for 0.5-µm particles to settle and that it takes a shorter time for the larger particles. The air purifier expedited the removal time at least 6.3 times faster than the case with no air purifier in the generation zone. Our results also indicate that particles may be transported from the source to the rest of the room even when the particle concentrations in the generation zone dropped back to the background. Therefore, it is inaccurate to conclude that indoor purifiers help reduce the transmission of COVID-19. Dental offices still need other methods to reduce the transmission of viruses.


Assuntos
COVID-19 , Consultórios Odontológicos , Aerossóis , Humanos , Pandemias , SARS-CoV-2
7.
J Environ Sci (China) ; 108: 120-133, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34465426

RESUMO

Landfill sites are regarded as prominent sources of bioaerosols for the surrounding atmosphere. The present study focused on the emission of airborne bacteria and fungi in four seasons of a sanitary landfill site. The main species found in bioaerosols were assayed using high-throughput sequencing. The SourceTracker method was utilized to identify the sources of the bioaerosols present at the boundary of the landfill site. Furthermore, the health consequences of the exposure to bioaerosols were evaluated based on the average daily dose rates. Results showed that the concentrations of airborne bacteria in the operation area (OPA) and the leakage treatment area (LTA) were in the range of (4684 ± 477)-(10883 ± 1395) CFU/m3 and (3179 ± 453)-(9051 ± 738) CFU/m3, respectively. The average emission levels of fungal aerosols were 4026 CFU/m3 for OPA and 1295 CFU/m3 for LTA. The landfill site received the maximum bioaerosol load during summer and the minimum during winter. Approximately 41.39%- 86.24% of the airborne bacteria had a particle size of 1.1 to 4.7 µm, whereas 48.27%- 66.45% of the airborne fungi had a particle size of more than 4.7 µm. Bacillus sp., Brevibacillus sp., and Paenibacillus sp. were abundant in the bacterial population, whereas Penicillium sp. and Aspergillus sp. dominated the fungal population. Bioaerosols released from the working area and treatment of leachate were the two main sources that emerged in the surrounding air of the landfill site boundary. The exposure risks during summer and autumn were higher than those in spring and winter.


Assuntos
Microbiologia do Ar , Monitoramento Ambiental , Aerossóis/análise , Fungos , Medição de Risco , Estações do Ano , Instalações de Eliminação de Resíduos
8.
J Environ Sci (China) ; 108: 164-174, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34465430

RESUMO

Surface-active organic molecules (surfactants) may influence the ability of an aerosol particle to act as a cloud condensation nuclei by reducing its surface tension. One source of organic mass in aerosol particles, which may also contain surfactants, is bubble bursting on the sea surface. In order to directly compare these molecules in the ocean and aerosol particles, we developed a method using multiple solid phase extractions and high resolution mass spectrometry to characterize surface active organic molecules in both. This method has extraction efficiencies greater than 85%, 75%, and 60% for anionic, cationic, and nonionic surfactant standards, respectively. In this study, we demonstrate the presence of three ionic classes of surface active organics in atmospheric aerosol particles and estuarine water from Skidaway Island, GA. With this extraction method, organic molecules from both estuarine water and atmospheric aerosol particles significantly reduced surface tension of pure water (surface tension depression of ~ 18 mN/m) and had high ratios of hydrogen to carbon (H/C) and low ratios of oxygen to carbon (O/C), indicative of surfactants. While previous work has observed a larger fraction of anionic surface active organics in seawater and marine aerosol particles, here we show cationic surface active organics may make up a large fraction of the total surface active molecules in estuarine water (43%-47%).


Assuntos
Água do Mar , Tensoativos , Aerossóis , Espectrometria de Massas , Extração em Fase Sólida
9.
J Environ Sci (China) ; 108: 175-187, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34465431

RESUMO

The Coronavirus Disease 2019 (COVID-19) highlights the importance of understanding and controlling the spread of the coronavirus between persons. We experimentally and numerically investigated an advanced engineering and environmental method on controlling the transmission of airborne SARS-CoV-2-laden aerosols in the breathing microenvironment between two persons during interactive breathing process by combining the limited space air stability and a ventilation method. Experiments were carried out in a full-scale ventilated room with different limited space air stability conditions, i.e., stable condition, neutral condition and unstable condition. Two real humans were involved to conducted normal breathing process in the room and the exhaled carbon dioxide was used as the surrogate of infectious airborne SARS-CoV-2-laden aerosols from respiratory activities. A correspondent numerical model was established to visualize the temperature field and contaminated field in the test room. Results show that the performance of a ventilation system on removing infectious airborne SARS-CoV-2-laden aerosols from the interpersonal breathing microenvironment is dependent on the limited space air stability conditions. Appropriate ventilation method should be implemented based on an evaluation of the air condition. It is recommended that total volume ventilation methods are suitable for unstable and neutral conditions and local ventilation methods are preferable for stable conditions. This study provides an insight into the transmission of airborne SARS-CoV-2-laden aerosols between persons in ventilated rooms with different limited space air stability conditions. Useful guidance has been provided to cope with COVID-19 in limited spaces.


Assuntos
COVID-19 , SARS-CoV-2 , Aerossóis , Humanos
10.
Anal Chem ; 93(33): 11347-11356, 2021 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-34370455

RESUMO

For over 25 years, transmission electron microscopy (TEM) has provided a method for the study of aerosol particles with sizes from below the optical diffraction limit to several microns, resolving the particles as well as smaller features. The wide use of this technique to study aerosol particles has contributed important insights about environmental aerosol particle samples and model atmospheric systems. TEM produces an image that is a 2D projection of aerosol particles that have been impacted onto grids and, through associated techniques and spectroscopies, can contribute additional information such as the determination of elemental composition, crystal structure, and 3D particle structures. Soot, mineral dust, and organic/inorganic particles have all been analyzed using TEM and spectroscopic techniques. TEM, however, has limitations that are important to understand when interpreting data including the ability of the electron beam to damage and thereby change the structure and shape of particles, especially in the case of particles composed of organic compounds and salts. In this paper, we concentrate on the breadth of studies that have used TEM as the primary analysis technique. Another focus is on common issues with TEM and cryogenic-TEM. Insights for new users on best practices for fragile particles, that is, particles that are easily susceptible to damage from the electron beam, with this technique are discussed. Tips for readers on interpreting and evaluating the quality and accuracy of TEM data in the literature are also provided and explained.


Assuntos
Poluentes Atmosféricos , Material Particulado , Aerossóis/análise , Poluentes Atmosféricos/análise , Monitoramento Ambiental , Microscopia Eletrônica de Transmissão , Tamanho da Partícula , Material Particulado/análise
11.
Anal Chem ; 93(33): 11433-11441, 2021 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-34379402

RESUMO

Aerosols dispersed and transmitted through the air (e.g., particulate matter pollution and bioaerosols) are ubiquitous and one of the leading causes of adverse health effects and disease transmission. A variety of sampling methods (e.g., filters, cyclones, and impactors) have been developed to assess personal exposures. However, a gap still remains in the accessibility and ease-of-use of these technologies for people without experience or training in collecting airborne samples. Additionally, wet scrubbers (large non-portable industrial systems) utilize liquid sprays to remove aerosols from the air; the goal is to "scrub" (i.e., clean) the exhaust of industrial smokestacks, not collect the aerosols for analysis. Inspired by wet scrubbers, we developed a device fundamentally different from existing portable air samplers by using aerosolized microdroplets to capture aerosols in personal spaces (e.g., homes, offices, and schools). Our aerosol-sampling device is the size of a small teapot, can be operated without specialized training, and features a winding flow path in a supersaturated relative humidity environment, enabling droplet growth. The integrated open mesofluidic channels shuttle coalesced droplets to a collection chamber for subsequent sample analysis. Here, we present the experimental demonstration of aerosol capture in water droplets. An iterative study optimized the non-linear flow manipulating baffles and enabled an 83% retention of the aerosolized microdroplets in the confined volume of our device. As a proof-of-concept for aerosol capture into a liquid medium, 0.5-3 µm model particles were used to evaluate aerosol capture efficiency. Finally, we demonstrate that the device can capture and keep a bioaerosol (bacteriophage MS2) viable for downstream analysis.


Assuntos
Levivirus , Material Particulado , Aerossóis/análise , Microbiologia do Ar , Monitoramento Ambiental , Humanos , Tamanho da Partícula
12.
Science ; 373(6558)2021 08 27.
Artigo em Inglês | MEDLINE | ID: mdl-34446582

RESUMO

The COVID-19 pandemic has revealed critical knowledge gaps in our understanding of and a need to update the traditional view of transmission pathways for respiratory viruses. The long-standing definitions of droplet and airborne transmission do not account for the mechanisms by which virus-laden respiratory droplets and aerosols travel through the air and lead to infection. In this Review, we discuss current evidence regarding the transmission of respiratory viruses by aerosols-how they are generated, transported, and deposited, as well as the factors affecting the relative contributions of droplet-spray deposition versus aerosol inhalation as modes of transmission. Improved understanding of aerosol transmission brought about by studies of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection requires a reevaluation of the major transmission pathways for other respiratory viruses, which will allow better-informed controls to reduce airborne transmission.


Assuntos
Microbiologia do Ar , COVID-19/transmissão , Infecções Respiratórias/transmissão , SARS-CoV-2 , Viroses/transmissão , Fenômenos Fisiológicos Virais , Aerossóis , COVID-19/virologia , Transmissão de Doença Infecciosa , Humanos , Viabilidade Microbiana , Tamanho da Partícula , Sistema Respiratório/virologia , Infecções Respiratórias/virologia , SARS-CoV-2/isolamento & purificação , SARS-CoV-2/fisiologia , Carga Viral , Viroses/virologia , Vírus/isolamento & purificação
13.
Environ Sci Technol ; 55(17): 11557-11567, 2021 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-34431667

RESUMO

The lockdown due to COVID-19 created a rare opportunity to examine the nonlinear responses of secondary aerosols, which are formed through atmospheric oxidation of gaseous precursors, to intensive precursor emission reductions. Based on unique observational data sets from six supersites in eastern China during 2019-2021, we found that the lockdown caused considerable decreases (32-61%) in different secondary aerosol components in the study region because of similar-degree precursor reductions. However, due to insufficient combustion-related volatile organic compound (VOC) reduction, odd oxygen (Ox = O3 + NO2) concentration, an indicator of the extent of photochemical processing, showed little change and did not promote more decreases in secondary aerosols. We also found that the Chinese provinces and international cities that experienced reduced Ox during the lockdown usually gained a greater simultaneous PM2.5 decrease than other provinces and cities with an increased Ox. Therefore, we argue that strict VOC control in winter, which has been largely ignored so far, is critical in future policies to mitigate winter haze more efficiently by reducing Ox simultaneously.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , COVID-19 , Aerossóis/análise , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Poluição do Ar/prevenção & controle , China , Controle de Doenças Transmissíveis , Monitoramento Ambiental , Humanos , Oxigênio , Material Particulado/análise , SARS-CoV-2
14.
Nat Commun ; 12(1): 4985, 2021 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-34404778

RESUMO

Transmission of SARS-CoV-2 is driven by contact, fomite, and airborne transmission. The relative contribution of different transmission routes remains subject to debate. Here, we show Syrian hamsters are susceptible to SARS-CoV-2 infection through intranasal, aerosol and fomite exposure. Different routes of exposure present with distinct disease manifestations. Intranasal and aerosol inoculation causes severe respiratory pathology, higher virus loads and increased weight loss. In contrast, fomite exposure leads to milder disease manifestation characterized by an anti-inflammatory immune state and delayed shedding pattern. Whereas the overall magnitude of respiratory virus shedding is not linked to disease severity, the onset of shedding is. Early shedding is linked to an increase in disease severity. Airborne transmission is more efficient than fomite transmission and dependent on the direction of the airflow. Carefully characterized SARS-CoV-2 transmission models will be crucial to assess potential changes in transmission and pathogenic potential in the light of the ongoing SARS-CoV-2 evolution.


Assuntos
COVID-19/transmissão , Fômites , Administração Intranasal , Aerossóis , Animais , COVID-19/sangue , COVID-19/virologia , Citocinas/sangue , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Pulmão/virologia , Mesocricetus , Cavidade Nasal/virologia , Tamanho da Partícula , RNA Viral/genética , Sistema Respiratório/virologia , SARS-CoV-2/isolamento & purificação , Índice de Gravidade de Doença , Vacinação , Replicação Viral , Eliminação de Partículas Virais
15.
Sci Rep ; 11(1): 16051, 2021 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-34362974

RESUMO

With an increasing body of evidence that SARS-CoV-2 is an airborne pathogen, droplet character formed during speech, coughs, and sneezes are important. Larger droplets tend to fall faster and are less prone to drive the airborne transmission pathway. Alternatively, small droplets (aerosols) can remain suspended for long time periods. The small size of SARS-CoV-2 enables it to be encapsulated in these aerosols, thereby increasing the pathogen's ability to be transmitted via airborne paths. Droplet formation during human respiratory events relates to airspeed (speech, cough, sneeze), fluid properties of the saliva/mucus, and the fluid content itself. In this work, we study the fluidic drivers (fluid properties and content) and their influence on factors relating to transmissibility. We explore the relationship between saliva fluid properties and droplet airborne transmission paths. Interestingly, the natural human response appears to potentially work with these drivers to mitigate pathogen transmission. In this work, the saliva is varied using two approaches: (1) modifying the saliva with colloids that increase the viscosity/surface tension, and (2) stimulating the saliva content to increased/decreased levels. Through modern experimental and numerical flow diagnostic methods, the character, content, and exposure to droplets and aerosols are all evaluated. The results indicate that altering the saliva properties can significantly impact the droplet size distribution, the formation of aerosols, the trajectory of the bulk of the droplet plume, and the exposure (or transmissibility) to droplets. High-fidelity numerical methods used and verify that increased droplet size character enhances droplet fallout. In the context of natural saliva response, we find previous studies indicating natural human responses of increased saliva viscosity from stress and reduced saliva content from either stress or illness. These responses both favorably correspond to reduced transmissibility. Such a finding also relates to potential control methods, hence, we compared results to a surgical mask. In general, we find that saliva alteration can produce fewer and larger droplets with less content and aerosols. Such results indicate a novel approach to alter SARS-CoV-2's transmission path and may act as a way to control the COVID-19 pandemic, as well as influenza and the common cold.


Assuntos
COVID-19/transmissão , SARS-CoV-2/isolamento & purificação , Saliva/virologia , Aerossóis/química , Microbiologia do Ar , Coloides/química , Tosse , Humanos , Pandemias , Saliva/química , Espirro , Viscosidade
16.
J Environ Sci (China) ; 107: 1-13, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34412773

RESUMO

Atmospheric aerosols have effects on atmospheric radiation assessments, global climate change, local air quality and visibility. In particular, aerosols are more likely transformed and accumulated in winter. In this paper, we used the Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument to study the characteristics of aerosol type and contributions of PM2.5 chemical components to aerosol extinction (AE), vertical distribution of aerosols, and source. From December 30, 2018 to January 27, 2019, we conducted MAX-DOAS observations on Sanmenxia. The proportion of PM2.5 to PM10 was 69.48%-95.39%, indicating that the aerosol particles were mainly fine particles. By analyzing the ion data and modifying Interagency Monitoring of Protected Visual Environments (IMPROVE) method, we found that nitrate was the largest contributor to AE, accounting for 31.51%, 28.98%, and 27.95% of AE on heavily polluted, polluted, and clean days, respectively. NH4+, OC, and SO42- were also major contributors to AE. The near-surface aerosol extinction retrieved from MAX-DOAS measurement the PM2.5 and PM10 concentrations measured by an Unmanned Aerial Vehicle (UAV) have the same trend in vertical distribution. AE increased about 3 times from surface to 500 m. With the backward trajectory of the air mass during the haze, we also found that the continuous heavy pollution was mainly caused by transport of polluted air from the northeast, then followed by local industrial emissions and other sources of emissions under continuous and steady weather conditions.


Assuntos
Poluentes Atmosféricos , Aerossóis/análise , Poluentes Atmosféricos/análise , Monitoramento Ambiental , Material Particulado/análise , Análise Espectral
17.
J Environ Sci (China) ; 107: 138-149, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34412776

RESUMO

A rapid reaction occurs near the exhaust nozzle when vehicle emissions contact the air. Twenty diesel vehicles were studied using a new multipoint sampling system that is suitable for studying the exhaust plume near the exhaust nozzle. The variation characteristics of fine particle matter (PM2.5) and its components in diesel vehicle exhaust plumes were analyzed. The PM2.5 emissions gradually increased with increasing distance from the nozzle in the plume. Elemental carbon emissions remained basically unchanged, organic carbon and total carbon (TC) increased with increasing distance. The concentrations of SO42-, NO3- and NH4+ (SNA) directly emitted by the vehicles were very low but increased rapidly in the exhaust plume. The selective catalytic reduction (SCR) reduced 42.7% TC, 40% NO3- emissions, but increased 104% SO42- and 36% NH4+ emissions, respectively. In summary, the SCR reduced 29% primary PM2.5 emissions for the tested diesel vehicles. The NH4NO3 particle formation maybe more important in the plume, and there maybe other forms of formation of NH4+ (eg. NH4Cl). The generation of secondary organic carbon (SOC) plays a leading role in the generation of secondary PM2.5. The SCR enhanced the formation of SOC and SNA in the plume, but comprehensive analysis shows that the SCR more enhanced the SNA formation in the plume, which is mainly new particles formation process. The inconsistency between secondary organic aerosol (SOA) and primary organic aerosol definitions is one of the important reasons for the difference between SOA simulation and observation.


Assuntos
Material Particulado , Emissões de Veículos , Aerossóis/análise , Carbono , Simulação por Computador , Emissões de Veículos/análise
18.
J Environ Sci (China) ; 107: 49-64, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34412787

RESUMO

Lake Baikal is the biggest reservoir of fresh water with unique flora and fauna; presently it is negatively affected by climate change, water warming, industrial emissions, shipping, touristic activities, and Siberian forest fires. The assessment of air pollution - related Baikal's ecosystem damage is an unsolved problem. Ship, based expedition exploring the Baikal atmospheric aerosol loading, was performed over the lake area in July 2018. We combine the aerosol near - water and vertical distributions over the Lake Baikal basin with meteorological observations and air mass transportation simulations. Lidar sounding of aerosol fields in the troposphere assesses the atmospheric background in the pristine areas and the pollution during fire-affected periods. Aerosol optical properties (scattering and spectral absorption) converted to the particle number size, black carbon (BC) mass, and Absorption Angstrom Exponent (AAE) provide the inside into aerosol characterization. Transport of industrial emissions from Krasnoyarsk and Irkutsk regions, and wildfire plumes from Republic of Yakutia relates the pollution sources to the increased concentrations of fine particle numbers, PM10 and BC mass over Southern and Northern/Central Baikal, respectively. The highest PM10 and BC are associated to the harbor and touristic areas of intensive shipping and residential biomass burning. Deposition estimates applied to aerosol data exhibit the pollution fluxes to water surface over the whole Baikal area. AAE marks the impact of coal combustion, residential biomass burning, and wildfires indicating the high pollution level of the Lake Baikal ecological system .


Assuntos
Poluentes Atmosféricos , Incêndios Florestais , Aerossóis/análise , Poluentes Atmosféricos/análise , Ecossistema , Monitoramento Ambiental
19.
Huan Jing Ke Xue ; 42(9): 4116-4125, 2021 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-34414710

RESUMO

Organic carbon (OC), elemental carbon (EC), and PM2.5 concentration data obtained from Shanxi Super Station in Jiashan County of Jiaxing City, in the winter of 2018 and 2019, were analyzed to determine the variation and potential source areas of carbonaceous aerosols. The results show that OC concentrations in the winter of 2018 and 2019 were 6.90 µg·m-3 and 5.63 µg·m-3, respectively, while EC concentrations were 2.47 µg·m-3 and 1.57 µg·m-3, respectively. The concentrations of OC and EC in the winter of 2019 were lower than those in the winter of 2018, by approximately 18.4% and 36.4%, respectively. In 2018 and 2019, the concentrations of secondary organic carbon (SOC), calculated using the minimum R-squared (MRS) method, were 1.49 µg·m-3 and 1.97 µg·m-3, respectively, and the concentrations of primary organic carbon (POC) were 5.41 µg·m-3 and 3.66 µg·m-3, respectively. The proportion of POC in OC showed a downward trend, from 96.0% in December 2018 to 64.9% in February 2020, indicating a decrease of 31.1 percentage points. SOC showed an upward trend, increasing by 31.1 percentage points from 4.0% in December 2018 to 35.1% in February 2020. It is worth noting that with the increase in PM2.5 concentration, the concentration of OC and EC increased by 474.7% and 408.2%, respectively, although the proportion of OC in PM2.5 decreased from 18.8% to 12.3%. and the percentage of OC decreased from 5.8% to 3.3%. The contribution of POC to PM2.5 did not fluctuate, and only decreased significantly above 150 µg·m-3, while the contribution of SOC to PM2.5 first decreased and then increased. In Jiaxing, the potential sources of OC and EC were mainly southern Jiangsu, southeastern Anhui, local Jiaxing, and northern Zhejiang. In the winter of the contribution concentrations of OC and EC in the main potential source regions were approximately 2 µg·m-3 and 6 µg·m-3 lower, respectively, than in winter 2018. The range of high values in the potential source regions also decreased in 2019. Before the COVID-19 epidemic, it was affected by both motor vehicle exhaust emissions and coal burning. During the Spring Festival and home isolation, due to traffic control and other reasons, motor vehicle emissions were reduced, which leaving coal burning as the main contributor.


Assuntos
Poluentes Atmosféricos , COVID-19 , Aerossóis/análise , Poluentes Atmosféricos/análise , Monitoramento Ambiental , Humanos , Material Particulado/análise , SARS-CoV-2
20.
Huan Jing Ke Xue ; 42(9): 4104-4115, 2021 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-34414709

RESUMO

Based on hourly concentration data of PM10 and PM2.5 from 2017 to 2019 and wind speed and direction data at the corresponding times in Yangquan, an urban valley of the Taihang Mountains, the characteristics of air transport in a cross-valley urban area and their influence on aerosols in Yangquan were analyzed using the HYSPLIT model, cluster analysis, and the potential source contribution factor and concentration weight trajectory methods. The pollutant transport characteristics on the east and west sides of the Taihang Mountains were evaluated. The diurnal variation of the aerosols showed a single peak and single valley, with continuous improvements in aerosol concentration from evening to the morning of the next day. The maximum aerosol concentration occurs at 10:00-11:00 in winter and at 09:00 in other seasons, whereas the minimum value occurs at 15:00-16:00. The monthly mean aerosol concentration in Yangquan was highest in January and lowest in August, and PM10 was also high in March and April. The most frequent surface wind directions in Yangquan are easterly and westerly due to the topography of the cross valley. The average concentrations of aerosols were highest in the calm wind weather. Furthermore, the dust weather caused by the westerly wind in spring and autumn and the easterly transport in winter also causes an increase in aerosol concentration in Yangquan. The backward trajectories in combination with the pollution characteristics showed that 26.2% of the pollution trajectories are in spring, 36.4% are in autumn, and 33.7% are in winter, and that these are mainly distributed in the southwest and southeast of Yangquan and also in the northeast in winter. There was significant fine particle transport on both sides of the mountains, and the trajectories originating from or passing through the west side of the Taihang Mountains also transport coarse particles. As indicated by the pollution trajectory, the westerly air transport has an impact on PM10 in excess of the standard rate. The easterly transport has larger noise and mainly affects the exceedance rate of PM2.5. The main potential source areas of aerosol pollution in Yangquan differ in different seasons. The potential source areas are to the southwest and southeast of Yangquan in spring, the southwest and south of Yangquan in autumn, and the south and east of Yangquan in winter. The areas with high PSCF and CWT in PM2.5 were in the southeast region, but those for PM10 were in the southwest region. The area southeast of Shanxi and the border area north of Henan are the main source areas. Based on the influence of aerosol pollution transmission in Yangquan, the cross-valley urban area is affected simultaneously by the areas east and west of the Taihang Mountains, especially by PM2.5 transport from east to west.


Assuntos
Poluentes Atmosféricos , Aerossóis/análise , Poluentes Atmosféricos/análise , Poeira , Monitoramento Ambiental , Estações do Ano
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