Aerosol Concentrations Research Articles

Inhalable Fungi and Opportunistic Pathogens During Haze and Haze‐Dust Events From Winter to Springtime in One Typical Inland City of Northern China

AbstractFungal aerosols, as significant biocomponents of inhalable particulate matter, encompass a variety of allergens and pathogens. However, comprehensive knowledge regarding their composition, sources, and opportunistic pathogens present in severe air pollution remains limited. In this study, PM2.5 samples were collected from January to March 2018 in a northern Chinese city, during the winter heating and spring sandstorm seasons. The fungal community characteristics within three distinct haze and haze‐dust composite pollution were examined. The concentration of fungal aerosols was found to be significantly higher in dust samples. This was evidenced by a strong positive correlation with Ca2+, temperature, and wind speed (p < 0.05). Human and animal pathogens, such as Candida, were more prevalent in haze samples. Conversely, allergens and plant pathogens, like Alternaria, were found in higher concentration in dust samples. The primary ecological function shifted from being saprophytic to becoming human‐animal pathogenic or plant‐animal pathogenic. This shift was observed from non‐pollution, haze, to haze‐dust composite pollution. The dispersion of fungal aerosols was influenced by factors such as dust events and meteorological conditions, including increased temperature and wind speed. In the spring dust episodes, dust‐related pollutants, such as soil Ca2+ and PM10, accounted for 51.39% of the variation in the fungal community. This research explored the dynamics of fungal communities, potential pathogens, and factors influencing fungal communities in regional air pollution. The insights garnered from this research provide a robust foundation for subsequent human health exposure assessments.

Role of Fluid Dynamics in Infectious Disease Transmission: Insights from COVID-19 and Other Pathogens

The spread of infectious diseases such as COVID-19 depends on complex fluid dynamics interactions between pathogens and fluid phases, including individual droplets and multiphase clouds. Understanding these interactions is crucial for predicting and controlling disease spread. This applies to human and animal exhalations, such as coughs and sneezes, as well as bursting bubbles that create micron-sized droplets in various indoor and outdoor environments. By exploring case studies in this regard, this study examines the emerging field of fluid dynamics in disease transmission, focusing on multiphase flows, interfacial flows, turbulence, pathogens, human traffic, aerosol transmission, ventilation, and breathing microenvironments. These results indicate that increased ventilation rates and local ventilation methods can effectively reduce the concentration of SARS-CoV-2-laden aerosols in the immediate breathing spaces between individuals. In a displacement-ventilated room, both neutral and unstable conditions were more effective in removing breathed SARS-CoV-2-laden aerosols from the air, regardless of the presence of test subjects. However, stable conditions may increase the risk of infection in individuals living in confined spaces. Thus, the findings of this study are useful for providing practical guidance for managing the spread of airborne infections. HIGHLIGHTS Fluid dynamics affect the transmission of infectious diseases such as COVID-19 This study explored multiphase fluid flow, aerosol dispersion, and respiratory zones Increased ventilation and local methods reduce SARS-CoV-2 aerosol concentration Displacement ventilation eliminates SARS-CoV-2 aerosols under unstable conditions Cramped and damp living environments can increase the risk of transmission of infection GRAPHICAL ABSTRACT

Substantial Warming of the Atlantic Ocean in CMIP6 Models

Abstract The storage of anthropogenic heat in oceans is geographically inhomogeneous, leading to differential warming rates among major ocean basins with notable regional climate impacts. Our analyses of observation-based datasets show that the average warming rate of 0–2000-m Atlantic Ocean since 1960 is nearly threefold stronger than that of the Indo-Pacific Oceans. This feature is robustly captured by historical simulations of phase 6 of Coupled Model Intercomparison Project (CMIP6) and is projected to persist into the future. In CMIP6 simulations, the ocean heat uptake through surface heat fluxes plays a central role in shaping the interbasin warming contrasts. In addition to the slowdown of the Atlantic meridional overturning circulation as stressed in some existing studies, alterations of atmospheric conditions under greenhouse warming are also essential for the increased surface heat flux into the North Atlantic. Specifically, the reduced anthropogenic aerosol concentration in the North Atlantic since the 1980s has been favorable for the enhanced Atlantic Ocean heat uptake in CMIP6 models. Another previously overlooked factor is the geographic shape of the Atlantic Ocean which is relatively wide in midlatitudes and narrow in low latitudes, in contrast to that of the Indo-Pacific Oceans. Combined with the poleward migration of atmospheric circulations, which leads to the meridional pattern of surface heat uptake with broadly enhanced heat uptake in midlatitude oceans due to reduced surface wind speed and cloud cover, the geographic shape effect renders a higher basin-average heat uptake in the Atlantic.

Characteristics of new particle formation events occurred over the Yellow Sea in Springtime from 2019 to 2022

Characteristics of atmospheric new particle formation (NPF) events were investigated using the data obtained from the ship measurement campaign named Yellow Sea Air Quality (YES-AQ) over the Yellow Sea during the springtime from 2019 to 2022. NPF events occurred 15 times for the valid 128 observation days for the four-year period, and the average and standard deviation formation rate (FR) and growth rate (GR) of the NPF events were 2.38 ± 1.53 cm−3 s−1 and 4.11 ± 2.81 nm h−1, respectively. The FR and GR were close to those in urban regions, implying the unique characteristics of the Yellow Sea. Owing to the NPF events, the number concentrations of total aerosols and nucleation mode particles increased by approximately 7850 and 6002 cm−3, respectively, and those of cloud condensation nuclei at 0.2% and 0.6% supersaturation increased by about 1269 and 3269 cm−3, respectively. The NPF events mostly occurred under the meteorological conditions of low temperature and relative humidity as well as high solar radiation and wind speed. These meteorological conditions appeared predominantly when the air mass originated from the continent north of the Korean Peninsula. The current analyses based on the data measured repeatedly during a specific period each year, which were not well conducted in other maritime NPF studies, highlight the reliability of the presented characteristics of NPF events over the Yellow Sea.

Flipping of temperature and precipitation trends over the Indian subcontinent due to diametrically opposing influence of GHGs and aerosols

Despite significant development in the Earth system models (ESMs) and releases of several coupled model intercomparison projects (CMIPs), the evolving patterns of Indian summer monsoon rainfall and its future trajectory is still uncertain, with low confidence in its direction. This could be because of differential impacts from increasing greenhouse gas (GHG) and aerosol concentrations. We found that the observed pre-2000 (1951–2000) declining monsoon was likely attributed to the increasing aerosol concentrations. On the contrary, the reported revival of post-2000 monsoon rainfall is due to GHG dominance. These are spatiotemporally consistent with individual CMIP Phase 6 (CMIP6) ESM simulations with GHG and aerosols separately. Similar results were obtained for temperature in India, which showed no to low warming signal in pre-2000 due to aerosol-driven cooling. The dominance of GHG impacts has increased India’s warming trend in post-2000. This research highlights a notable trend in temperature and precipitation across the Indian subcontinent during the past two decades, emphasizing the dynamic character of climate change explained by contrasting anthropogenic influences, including GHGs and aerosols.

Widespread 2013-2020 decreases and reduction challenges of organic aerosol in China

High concentrations of organic aerosol (OA) occur in Asian countries, leading to great health burdens. Clean air actions have resulted in significant emission reductions of air pollutants in China. However, long-term nation-wide trends in OA and their causes remain unknown. Here, we present both observational and model evidence demonstrating widespread decreases with a greater reduction in primary OA than in secondary OA (SOA) in China during the period of 2013 to 2020. Most of the decline is attributed to reduced residential fuel burning while the interannual variability in SOA may have been driven by meteorological variations. We find contrasting effects of reducing NOx and SO2 on SOA production which may have led to slight overall increases in SOA. Our findings highlight the importance of clean energy replacements in multiple sectors on achieving air-quality targets because of high OA precursor emissions and fluctuating chemical and meteorological conditions.

The Cloud Indicator: A novel algorithm for automatic detection and classification of clouds using airborne in situ observations

Airborne in situ observations of aerosols and clouds provide relevant data sets crucial to improving the understanding of cloud microphysical processes and reducing uncertainties connected to future climate predictions. However, the selection and classification of cloud sequences in such data sets can be very time-consuming if done manually, and criteria used by the community are numerous and prone to misclassification, especially when coarse aerosol particles (> 1 μm diameter) are present.In this study, we present the Cloud Indicator, a novel algorithm that automatically detects and classifies measurement periods inside clouds. The Cloud Indicator was developed using data from three international airborne field campaigns, including ATom (Atmospheric Tomography; 2016–2018), A-LIFE (Absorbing aerosol layers in a changing climate: aging, lifetime and dynamics; 2017), and FIREX-AQ (Fire Influence on Regional to Global Environments Experiment and Air Quality; 2019). The algorithm utilizes size distribution measurements, combined with measurements of relative humidity and temperature, to automatically detect flight sequences in clouds and classify the cloud type. As an additional criterion for the Cloud Indicator, we established the cloud-aerosol volume factor fCA to ensure a precise and robust distinction between clouds and aerosol layers such as mineral dust or biomass burning thereby reducing misclassifications. The Cloud Indicator algorithm was developed with data from a second-generation Cloud, Aerosol, and Precipitation Spectrometer (CAPS) which was calibrated with a novel calibration procedure – introduced in this study - that results in a refractive index independent calibration and works also in the field. However, the Cloud Indicator algorithm is not restricted specifically to the CAPS and thus allows its application to a variety of in situ instruments that measure coarse aerosol and cloud particle size.Case studies from ATom and A-LIFE demonstrate the ability of the Cloud Indicator to precisely screen (airborne) in situ data sets for clouds. The algorithm separates the data set into cloud-free periods, Aerosol-Cloud Transition Regime (ACTR), liquid clouds, clouds in the Mixed-Phase Temperature Regime (MPTR), and cirrus clouds. The unique ability of the Cloud Indicator to successfully differentiate between layers of enhanced coarse-mode aerosol concentrations and clouds is demonstrated by measurements in a complex mixture of clouds embedded into a mineral dust layer during the A-LIFE. The empirically derived parameter thresholds of the Cloud Indicator are in good agreement with values in the literature.

Assessment of Particulate Matter Concentrations in Aerosols from Selected Location of Kastina, Batagarawa, Kaita and Jibia Local Government Areas of Katsina State, Nigeria

Assessment of Particulate Matter Concentrations in Aerosols from Selected Location of Kastina, Batagarawa, Kaita and Jibia Local Government Areas of Katsina State, Nigeria

A numerical framework for the analysis of indoor air quality in a classroom

This paper presents a framework for applying Computational Fluid Dynamics (CFD) to study indoor air quality in a classroom environment by analysing the transport and extent of human-generated aerosol and carbon dioxide (CO2) accumulation. A methodology is outlined for identifying the appropriate amounts of exhaled aerosol and CO2 needed as boundary conditions for human breathing in CFD simulations, which is validated with in situ measurements obtained within a stale air classroom environment at matched conditions. This is crucial for quantifying the exhaled CO2 and aerosols from occupants, which is essential for designing ventilation settings that promote a healthy indoor environment. Good agreement is observed between the CFD and experiments for CO2 and aerosol concentration within the size range of 0.7-1μm. Further, we explore the impact of individual heat sources and breathing momentum flux on air stratification and aerosol dispersion. The analysis reveals that the thermal plume generated by each occupant and the momentum created from breathing are the characteristics of airflow in a stale air environment. This paper demonstrates the ability of the developed numerical model to reproduce realistic exhaled aerosol and CO2 in indoor ventilation settings, serving as a benchmark for investigating indoor air quality in the built environment.

Characteristics of Atmospheric Ice Nucleation during Spring: A Case Study on Huangshan

Atmospheric ice nucleation particles (INPs) play a crucial role in influencing cloud formation and microphysical properties, which in turn impact precipitation and Earth’s radiation budget. However, the influence of anthropogenic activities on the properties and concentrations of INPs remains an area of significant uncertainty. This study investigated the physical and chemical characteristics of atmospheric ice nucleation particles in Huangshan, China during the May Day labor holiday period (spanning 8 days, from April 27th to May 5th). INP concentrations were measured at temperatures from −17 °C to −26 °C and relative humidities (RHw) from 95% to 101%. Average INP concentrations reached 13.7 L−1 at −26 °C and 101% RH, 137 times higher than at −17 °C and 95% RH. INP concentrations showed exponential increases with decreasing temperature and exponential increases with increasing RH. Concentration fluctuations were observed over time, with a peak of ~30 L−1 (t = −26 °C, RHw = 101%) around the start and end of the holiday period. Aerosol number concentrations were monitored simultaneously. The peak in aerosols larger than 0.5 μm aligned with the peak in INP concentrations, suggesting a link between aerosol levels and INPs. Chemical composition analysis using SEM–EDX revealed the distinct elemental makeup of INPs based on the activation temperature. INPs active at warmer temperatures contained N, Na, and Cl, indicating possible biomass and sea salt origins, while those active at colder temperatures contained crustal elements like Al and Ca.

Developing a climatological simplification of aerosols to enter the cloud microphysics of a global climate model

Abstract. Aerosol particles influence cloud formation and properties. Hence climate models that aim for a physical representation of the climate system include aerosol modules. In order to represent more and more processes and aerosol species, their representation has grown increasingly detailed. However, depending on one's modelling purpose, the increased model complexity may not be beneficial, for example because it hinders understanding of model behaviour. Hence we develop a simplification in the form of a climatology of aerosol concentrations. In one approach, the climatology prescribes properties important for cloud droplet and ice crystal formation, the gateways for aerosols to enter the model cloud microphysics scheme. Another approach prescribes aerosol mass and number concentrations in general. Both climatologies are derived from full ECHAM-HAM simulations and can serve to replace the HAM aerosol module and thus drastically simplify the aerosol treatment. The first simplification reduces computational model time by roughly 65 %. However, the naive mean climatological treatment needs improvement to give results that are satisfyingly close to the full model. We find that mean cloud condensation nuclei (CCN) concentrations yield an underestimation of cloud droplet number concentration (CDNC) in the Southern Ocean, which we can reduce by allowing only CCN at cloud base (which have experienced hygroscopic growth in these conditions) to enter the climatology. This highlights the value of the simplification approach in pointing to unexpected model behaviour and providing a new perspective for its study and model development.

Aerosol uncertainties in tropical precipitation changes for the mid-Pliocene warm period

Abstract. The mid-Pliocene Warm Period (mPWP, 3.3–3.0 Ma) was characterised by an atmospheric CO2 concentration exceeding 400 ppmv with minor changes in continental and orbital configurations. Simulations of this past climate state have improved with newer models but still show some substantial differences from proxy reconstructions. There is little information about atmospheric aerosol concentrations during the Pliocene, but previous work suggests that it could have been quite different from the modern period. Here we apply idealised aerosol scenario experiments to examine the importance of aerosol forcing on mPWP tropical precipitation and the possibility of aerosol uncertainty explaining the mismatch between reconstructions and simulations. The absence of industrial pollutants leads to further warming, especially in the Northern Hemisphere. The Intertropical Convergence Zone (ITCZ) becomes narrower and stronger and shifts northward after removal of anthropogenic aerosols. Though not affecting the location of monsoon domain boundary, removal of anthropogenic aerosol alters the amount of rainfall within the domain, increasing summer rain rate over eastern and southern Asia and western Africa. This work demonstrates that uncertainty in aerosol forcing could be the dominant driver in tropical precipitation changes during the mid-Pliocene: causing larger impacts than the changes in topography and greenhouse gases.

Impact of air quality model settings for the evaluation of emission reduction strategies to curb air pollution

For air quality management, while numerical tools are mainly evaluated to assess their performances on absolute concentrations, this study assesses the impact of their settings on the robustness of model responses to emission reduction strategies for the main criteria pollutants. The effect of the spatial resolution and chemistry schemes is investigated. We show that whereas the spatial resolution is not a crucial setting (except for NO2), the chemistry scheme has more impact, particularly when assessing hourly values of the absolute potential of concentrations. The analysis of model responses under the various configurations triggered an analysis of the impact of using online models, like WRF-chem or WRF-CHIMERE, which accounts for the impact of aerosol concentrations on meteorology. This study informs the air quality modeling community on what extent some model settings can affect the expected model responses to emission changes. We suggest to not activate online effects when analyzing the effect of an emission reduction strategy to avoid any confusion in the interpretation of results even if an online simulation should represent better the reality.

Ventilation improvement for effective protection of healthcare workers in negative pressure airborne infectious isolation room from viral aerosols

A negative pressure airborne infectious isolation room (AIIR) is the primary healthcare air contamination control system used for the treatment of severe respiratory infectious patients. Effects of the ventilation system configuration and conditions on airflow pattern, aerosol distribution and ventilation performance were investigated using computational fluid dynamics (CFD). The field measurement by SARS-CoV-2 environmental surface test was also conducted. The cycle threshold values from transcription polymerase chain reaction (RT-PCR) method showed inverse relation to the simulated number of particles trapped on the surfaces indicating a good agreement. Modification of the present AIIR to have alignment between air inlet and outlet where the aspect ratio of the air outlet, Width (W): Height (H) = 1:1 (Improved case: IC#1) showed a 78 % reduction of aerosol concentration in healthcare workers (HCWs) zones. Aerosol concentrations were increased when the openings of the air outlet were enlarged. Addition of air outlet led to large swirling air, resulting in more aerosols being trapped and suspended in the air. Results suggested that AIIR with alignment air inlet on the ceiling and air outlet at the wall over the patient's head with W:H = 1:1 be the most suitable configuration to maximize the ventilation performance and minimize exposure risk to aerosolized viral infection for HCWs. Air change rate plays a more important role than the differential pressure on the removal efficiency. The differential pressure value should be at least −2.5 Pa and the air supply rate 12 ACH for effective protection of HCWs in the negative pressure AIIR.

Life Cycle Evolution of Mixing in Shallow Cumulus Clouds

AbstractUnderstanding how entrainment and mixing shape the cloud droplet size distribution (DSD) is crucial for understanding the optical properties and precipitation efficiency of clouds. Different mixing scenarios, mainly homogeneous and inhomogeneous, shape the DSD in a distinct way and alter the cloud's impact on climate. However, the prevalence of these mixing scenarios and how they vary in space and time is still uncertain, as underlying processes are commonly unresolved by conventional numerical models. To overcome this challenge, we employ the L3 model, which considers supersaturation fluctuations and turbulent mixing down to the finest relevant lengthscales, making it possible to represent different mixing scenarios realistically. We investigate the spatial and temporal evolution of mixing scenarios over the life cycle of shallow cumulus clouds for varying boundary layer humidities and aerosol concentrations. Our findings suggest homogeneous mixing is generally predominant in cumulus clouds, while different mixing scenarios occur concurrently in the same cloud. Notably, inhomogeneous mixing increases over the cloud life cycle across all analyzed cases. The mean and standard deviation of supersaturation are found to be the most capable indicators of this evolution, providing a comprehensive insight into the characteristics of mixing scenarios. Finally, we show inhomogeneous mixing is more prevalent in drier boundary layers and for higher aerosol concentrations, underscoring the need for a more comprehensive investigation of how these mixing dynamics evolve in a changing climate.

Assessment of Occupational Exposure to Inhalable Aerosols in an Instant Powdered Food Manufacturing Plant in Norway

BackgroundIn the food manufacturing industry, exposure to inhalable aerosols contributes to respiratory illnesses such as occupational asthma and rhinitis. However, there is a lack of comprehensive exposure assessment studies. This study evaluated occupational exposure to inhalable aerosols in an instant powdered food manufacturing plant during work operations involving dried food and powders. MethodsIn total, 50 workers from an instant powdered food manufacturing plant were recruited. Personal inhalable aerosol exposure measurements were taken for both full-shift and task-based activities. The concentrations of inhalable aerosols were analyzed to identify any variation within and across departments, as well as between seasons, handedness, and sex. ResultsIn total, 134 personal air samples were collected, and the particulate mass was determined gravimetrically. The concentrations of inhalable aerosols ranged from 0.1 to 27 mg/m3 for full-shift exposure measurements and 3.1 to 73 mg/m3 for task-based measurements. Statistically significant differences in mean aerosol concentrations were found across departments (A:B p < 0.001, A:C p < 0.05, B:C p < 0.001) and between seasons (p < 0.001). ConclusionThis study revealed high exposure to inhalable aerosols among workers, particularly those involved in manual weighing, mixing, and adding powders. The significant differences between departments highlight the specific activities contributing to increased inhalable aerosol concentrations. Seasonal variations were also evident, with autumn showing higher concentrations of inhalable aerosols in all departments compared with summer. These findings emphasize the importance of understanding the distribution of aerosol concentrations across different work tasks and departments, particularly during different seasons.

Shallow- and deep-convection characteristics in the greater Houston, Texas, area using cell tracking methodology

Abstract. The convective lifecycle, from initiation to maturity and dissipation, is driven by a combination of kinematic, thermodynamic, microphysical, and radiative processes that are strongly coupled and variable in time and space. Weather radars have been traditionally used to provide various convective-cloud characteristics. Here, we analyzed climatological convective-cell radar characteristics to obtain and assess the diurnal cycles of three convective-cell types – shallow, modest deep, and vigorous deep convective cells – that formed in the greater Houston area, using the National Weather Service radar from Houston, Texas, and a multi-cell identification and tracking algorithm. The examined dataset spans 4 years (2018–2021) and covers the warm-season months (June to September) in those years. The analysis showed clear diurnal cycles in cell initiation (CI) consistent with the sea breeze circulation and showed diurnal and normalized lifetime relationships in cell evolution parameters (e.g., maximum reflectivity, echo-top height, Geostationary Operational Environmental Satellite-16 (GOES-16) channel 13 brightness temperature, and the height of maximum reflectivity). The cell evolution is well represented by relationships between (1) the height and value of the maximum radar reflectivity, (2) the minimum GOES-16 channel 13 brightness temperature and the maximum vertically integrated liquid, (3) the maximum reflectivity and columnar-average reflectivity, and (4) the echo-top ascent rate and cell lifetime. The relationships presented herein help to identify the cell lifecycle stages such as early shallow convection, vigorous vertical development, anvil development, and convective core dissipation. GOES-16 Aerosol Optical Depth values are also used as a proxy for cell initiation aerosol concentrations to investigate any potential relationships between initiation location and aerosol concentration. Overall, no significant relationships between initiation location and aerosol concentration were found for the three cell types investigated, but there are some minor differences in the pre-CI aerosol optical depth for vigorous deep convective cells.

Biomass Burning Greatly Enhances the Concentration of Fine Carbonaceous Aerosols at an Urban Area in Upper Northern Thailand: Evidence From the Radiocarbon‐Based Source Apportionment on Size‐Resolved Aerosols

AbstractTo study the role of biomass burning (BB) in air pollution at upper‐northern Thailand, the source apportionment of size‐resolved carbonaceous aerosols from Chiang Mai was carried out based on the radiocarbon (14C) analysis. The fraction of modern carbon (F14C) was generally decreased with particle size increasing and with the highest and lowest values of 0.90 ± 0.04 and 0.61 ± 0.04, respectively. Elemental carbon, regardless of emission sources, and BB‐derived organic carbon (OCbb) showed unimodal size distribution patterns with peaks at 0.43–0.65 μm. Fossil‐fuel derived‐OC (OCf) displayed a bimodal mode with the major peak at 2.1–10 μm, and the minor one at 0.43–0.65 μm. The biogenic secondary organic aerosols (BSOA) showed a typical fine‐mode unimodal size distribution pattern during the high BB (HBB) season, and a bimodal mode during the low BB season. The BSOA concentration increased by 189% ± 80% due to the interaction with open BB plums during HBB season, which was quantified by a 14C‐involved random forest model. Besides, the concentration of biogenic primary organic aerosols also showed a significant increment during the HBB season, especially in sub‐microns. Our results highlight the critical importance of controlling open fires to reduce air pollutants and the potential exposure risk.

Aerosol impacts on the East Asian winter monsoon: Insights from TaiESM1 and CMIP6 simulations

AbstractThe East Asian winter monsoon (EAWM) is an important climate pattern in Southeast Asia. This study delved into the aerosol effects on the EAWM by analysing simulations conducted with the Taiwan Earth System Model version 1 (TaiESM1) model, part of the Coupled Model Intercomparison Project Phase 6 (CMIP6). Our assessment, validated against observational and reanalysis data, revealed that TaiESM1 effectively replicates the robust circulation of the EAWM and aerosol concentrations, placing its performance above average level among CMIP6 models. Notably, the simulated global mean aerosol optical thickness exhibited an approximately 20% increase from 1850 to 2014. The increased aerosols corresponded to a weakened Aleutian Low and an intensified Siberian High, leading to a weakened EAWM in the lower atmosphere over extratropical areas. In addition, the cooling across the Northern Hemisphere might affect enhanced northerly winds at approximately 10°N, which are situated in the southern part of the EAWM. An analysis of the near‐surface temperature budget indicated that the aerosol‐induced cooling in East China and India was primarily driven by changes in shortwave and longwave radiation fluxes, albeit slightly offset by sensible heat and latent heat fluxes. Furthermore, our study also reveals that while the mechanisms through which anthropogenic aerosols affect the northern portion of the EAWM vary across most CMIP6 models, their impacts on the tropical region remain consistent.

Construction and Investigation of a Filtration Efficiency Test System for High-Efficiency Filter Materials Based on Mass Concentration

Protection from nuclear biochemical aerosol and air pollution pays attention to aerosol mass concentration. The concentration of upstream aerosol of the commonly used filtration efficiency detection device for high-efficiency filter materials is low, making it insufficient for detecting the filtration efficiency of high-efficiency filter materials. This study designed and built a set of filtration efficiency detection devices for high-efficiency filter materials based on mass concentration. By adjusting the oil bath temperature, injection pressure, the degree of spiral-separator separation, as well as the number and size of nozzles, we investigated the effects of each condition on the concentration and particle size distribution of aerosol generation. As a result, the oil mist generator of the device can stably generate high-concentration aerosol with a mass concentration of up to 1587.9 mg/m3 and a number concentration of up to 107–108 P/cm3. The high-concentration aerosol generated can meet the E11–U15 filter material performance requirements.