Concentration Of Aerosol Particles Research Articles

Complex Assessment of Atmospheric Air Quality in the City of Gelendzhik

The atmospheric air quality is determined by the concentrations of some gaseous pollutants and mass concentrations of aerosol particles of different sizes. A wide range of atmospheric pollutants in both gaseous and aerosol phases was studied in the vicinity of Gelendzhik in July 2009, simultaneously at several land sites, in the water area of the bay, and at altitudes of up to 2200m. No such complex experiments were carried out in that region before. The following characteristics of the atmospheric aerosol (3 nm–32 μm in size) were studied: elemental composition of particles (23 chemical elements) and concentrations of polyaromatic hydrocarbons (14 compounds), unsaturated hydrocarbons, total protein, biotoxins, and culturable microorganisms. The concentration fields of different air pollutants and the complex air pollution index were constructed using mathematical models of pollutant propagation and data on the hydrometeorological conditions during the period of measurements. The sources of aerosols in the region were detected from the study of the chemical composition of airborne particles. The results allowed us to estimate air pollutants and to calculate the complex air pollution index for the Gelendzhik area. The daily average concentrations of all the pollutants were compared to the daily average maximum permissible concentrations. All these concentrations were less than daily average maximum permissible concentrations. The complex air pollution index did not exceed 1. Hence, the air in the vicinity of Gelendzhik did not contain any significant pollutants in the period under study.

Assessment of air pollution in exercise centers and health risks

Background: In recent years, Tehran has faced major problems with air pollution for many reasons, and this issue has become a critical point in most of the days. However, less attention has been paid to the indoor air pollutants in exercise centers and their possible health effects. In this research, it was tried to briefly describe the characteristics and chemical composition of the aerosols present in the exercise centers of Tehran. Methods: Sampling was carried out by a high volume sampler with a value of 1.5 m3/min. Fiberglass filters were used to sample aerosol particles. The samples were then studied by scanning electron micrograph (SEM) method. Results: The results showed that average concentration of aerosol particles in the indoor and outdoor sports halls was 125 and 162 μg/m3, respectively. Therefore, there was a minor difference in the aerosols concentration inside and outside the sports venues during the competition period and in the presence of athletes. Also, chemical composition and morphology of the aerosol particles showed that there was a minor difference between the atmospheric particles inside and outside the exercise centers. Major elements found in the PM2.5 aerosol were Si, O, C, Mg, Ca, Mn and K. In general, common major crustal elements found in the atmospheric particles over all the sites were Si, Al, and Fe. Conclusion: It seems that many citizens of the polluted cities exercise indoor because of causes other than outdoor air pollution such as lack of time or appropriate facilities. Thus, it is necessary for all students, athletes, people and other health workers involved in sports and exercise medicine to know briefly about indoor air pollutants and its possible health effects on athletes who exercise in these environments. Keywords: Air pollution, Athletes, Aerosols, Outdoor

Influence of intensified air pollution on the sunny diffuse radiation fraction in China

In recent years, air pollution has been getting increasingly serious in China—A cause of great concern for the government and general public. Research on air pollution has focused mainly on the environmental and climatic effects, such as the increasing number of haze days, reduction in visibility, human health impacts, suppression of global warming, extension of cloud life, restriction of light precipitation, and weakening of the East Asian monsoon. In fact, the exacerbation of air pollution might also affect the radiation balance of the surface-atmosphere system, with subsequent direct impacts in areas of socioeconomic concern like agricultural production. However, domestically, research in this area is currently lacking. Accordingly, the present study, based mainly on the sunny diffuse radiation fraction (SDRF—defined as the diffuse solar radiation divided by the total solar radiation in conditions of sunny weather) at 47 stations over China, combined with CO2 emissions data, aerosol optical depth (AOD) and sunshine duration data, analyzes the spatiotemporal variation of SDRF in China and the possible determining factors. The results provide a reference and basis for the accurate assessment of terrestrial ecosystem productivity and its carbon budget. Analysis of the SDRF distribution reveals clear regional characteristics in China, with relatively larger values distributed mainly in the Sichuan Basin and Central China. However, the values of SDRF in Yunnan, Xinjiang, Tibet and Northeast China are small. The majority of stations show an obvious upward trend in SDRF, especially in Eastern China, where the upward trend is more significant than in other regions. Therefore, after removal of the effects of cloud, aerosols should be considered a factor with important influence on the SDRF during the past 50 years. Analysis of the characteristics in each region shows that the increase in SDRF is more obvious in North China, East China and Central China than in South China, Northeast China, Northwest China and Southwest China. This indicates that, in regions where air pollution is more serious, the decline in SDRF is more significant. Sunshine duration in sunny weather is highly correlated with SDRF, with the correlation coefficient in East China, Central China and North China often exceeding −0.8 (statistically significant at the 99.9% confidence level). This result implies that an increase in the concentration of aerosol particles in the air has a significant impact on sunshine duration and SDRF over China.

Status and future of numerical atmospheric aerosol prediction with a focus on data requirements

Abstract. Numerical prediction of aerosol particle properties has become an important activity at many research and operational weather centers. This development is due to growing interest from a diverse set of stakeholders, such as air quality regulatory bodies, aviation and military authorities, solar energy plant managers, climate services providers, and health professionals. Owing to the complexity of atmospheric aerosol processes and their sensitivity to the underlying meteorological conditions, the prediction of aerosol particle concentrations and properties in the numerical weather prediction (NWP) framework faces a number of challenges. The modeling of numerous aerosol-related parameters increases computational expense. Errors in aerosol prediction concern all processes involved in the aerosol life cycle including (a) errors on the source terms (for both anthropogenic and natural emissions), (b) errors directly dependent on the meteorology (e.g., mixing, transport, scavenging by precipitation), and (c) errors related to aerosol chemistry (e.g., nucleation, gas–aerosol partitioning, chemical transformation and growth, hygroscopicity). Finally, there are fundamental uncertainties and significant processing overhead in the diverse observations used for verification and assimilation within these systems. Indeed, a significant component of aerosol forecast development consists in streamlining aerosol-related observations and reducing the most important errors through model development and data assimilation. Aerosol particle observations from satellite- and ground-based platforms have been crucial to guide model development of the recent years and have been made more readily available for model evaluation and assimilation. However, for the sustainability of the aerosol particle prediction activities around the globe, it is crucial that quality aerosol observations continue to be made available from different platforms (space, near surface, and aircraft) and freely shared. This paper reviews current requirements for aerosol observations in the context of the operational activities carried out at various global and regional centers. While some of the requirements are equally applicable to aerosol–climate, the focus here is on global operational prediction of aerosol properties such as mass concentrations and optical parameters. It is also recognized that the term “requirements” is loosely used here given the diversity in global aerosol observing systems and that utilized data are typically not from operational sources. Most operational models are based on bulk schemes that do not predict the size distribution of the aerosol particles. Others are based on a mix of “bin” and bulk schemes with limited capability of simulating the size information. However the next generation of aerosol operational models will output both mass and number density concentration to provide a more complete description of the aerosol population. A brief overview of the state of the art is provided with an introduction on the importance of aerosol prediction activities. The criteria on which the requirements for aerosol observations are based are also outlined. Assimilation and evaluation aspects are discussed from the perspective of the user requirements.

Preliminary Development of a Real-Time Respirator Seal Integrity Monitor With Low-Cost Particle Sensor

In many industrial environments, properly fit and functioning respirators are required to reduce individual's exposure to particulate matter. Respirator fits are evaluated prior to use by the Occupational Health and Safety (OSHA) fit testing protocol. However, this testing cannot ensure that the seal is maintained during actual use. The OSHA fit testing equipment and laboratory grade aerosol monitors are both too expensive and bulky to be deployed in workplace environments. In this effort, a low cost portable device, the respirator seal integrity monitor (ReSIM) was developed to monitor the aerosol particle concentrations inside a wearer's respirator mask, alerting the wearer when seal breaches allow aerosol particles to enter the mask. Multiple low-cost particle sensors were tested, with the Shinyei PPD60PV-T2 sensor being selected. The PPD60PV-T2 sensor can detect particles of 0.5 μm and above. These large particles cannot penetrate a properly fit respirator in quantity; thus, their detection points to a compromised seal. ReSIM utilizes an air pump to consistently draw in-mask air into the sensor without allowing external air to be pulled into the mask. ReSIM aggregates all particle detection events over 30-s intervals and determines the percentage of time during, which particles are detected, identifying spikes in particle detection corresponding to seal failures. The newly-developed ReSIM system was tested with polystyrene latex spheres, salt, and combustion aerosols under different flow conditions including cyclic breathing at 30 and 85 L/min. Results obtained while testing under cyclic breathing conditions showed 96.9% accuracy in identifying intervals with leaks versus intervals without leaks.

Characterization of the Spatial and Temporal Dispersion Differences Between Exhaled E-Cigarette Mist and Cigarette Smoke.

IntroductionThere are fundamental differences between electronic cigarettes (e-cigarettes) and conventional cigarette product categories with regards to potential environmental exposures, notably that e-cigarettes do not contain tobacco or generate side-stream emissions. Here we assess the spatial and temporal patterns of exhaled e-cigarette aerosol at a bystander’s position, and compare it with conventional cigarette smoke emissions.MethodsSmokers were asked to use e-cigarettes or smoke conventional cigarettes in a room-simulating chamber. Volunteers used the products at different distances from a heated mannequin, representing a bystander, and under different room ventilation rates. Aerosol particle concentrations and size distributions at the bystander’s position were measured.ResultsFor both product categories, the particle concentrations registered following each puff were in the same order of magnitude. However, for e-cigarettes the particle concentration returned rapidly to background values within seconds; for conventional cigarettes it increased with successive puffs, returning to background levels after 30–45 minutes. Unlike for the e-cigarette devices tested, such temporal variation was dependent on the room ventilation rate. Particle size measurements showed that exhaled e-cigarette particles were smaller than those emitted during smoking conventional cigarettes and evaporated almost immediately after exhalation, thus affecting the removal of particles through evaporation rather than displacement by ventilation.ConclusionsSignificant differences between emissions from the tested e- and conventional cigarettes are reported. Exhaled e-cigarette particles are liquid droplets evaporating rapidly; conventional cigarette smoke particles are far more stable and linger.Implications• Several factors potentially influencing particle behavior after exhalation of e-cigarette aerosols or emitted during smoking conventional cigarettes were studied.• Differences in particle size between those exhaled following use of e-cigarettes and those emitted during smoking of conventional cigarettes were observed.• E-cigarette particle concentrations decreased rapidly following exhalation due to evaporation.• The removal of particles following smoking conventional cigarettes was much slower and was dependent on the room ventilation rate.

Simulation of aerosol distribution in hyperbolic resonator

Dynamics of the distribution of aerosol particles in acoustic field inside a hyperbolic plane resonator is numerically studied. The exact value of the first resonant frequency, as well as the amplification of gas velocity amplitude are found. The existence of acoustic flow in the form of four Rayleigh and four Schlichting vortices is revealed at first resonant frequency. Dynamics of the initially uniformly distributed particles and their drift at the first resonant frequency is simulated. Five zones of attraction of aerosol particles (acoustic traps) are observed. The influence of entrainment coefficient of particles on their distribution is analyzed. • At first resonant frequency in hyperbolic resonator the Schlichting and Rayleigh vortices are formed. • Maximum acoustic streaming velocity is reached between Schlichting and Rayleigh vortices. • Five zones of increased concentration of aerosol particles (acoustic traps) arise in hyperbolic resonator. • The concentration of aerosol particles in traps is affected by the entrainment coefficient. • For the case of maximal eigen drift of particles the borders of all traps are the clearest.

Aerosol Component of the Atmosphere of Saturn: Comparison of the Vertical Structure Characteristics in Latitudinal Belts

The altitude dependences of the aerosol and gas scattering components of the effective optical depth in the latitudinal belts of Saturn’s Northern Hemisphere have been obtained from the reflectance spectra in the methane absorption bands at λ = 727 and 619 nm measured in 2015. Zonal characteristics of the vertical structure of the cloud cover of Saturn have been estimated. In the latitudinal belts, the aerosol, the relative concentration of which monotonically decreases with depth in the atmosphere, was found, and no signs of substantial cloud clusterings and rarefactions were observed. The largest and smallest aerosol amounts were determined at the latitudes of 49° N and 80° N, respectively. The altitude levels where the sizes of aerosol particles or their nature may change were revealed. We failed to determine the atmospheric level where the relative concentration of aerosol particles is largest; however, the character of the obtained dependences suggests that such a level is probably in the higher layers of the atmosphere of the giant planet.

Aerosol characteristics and particle production in the upper troposphere over the Amazon Basin

Abstract. Airborne observations over the Amazon Basin showed high aerosol particle concentrations in the upper troposphere (UT) between 8 and 15 km altitude, with number densities (normalized to standard temperature and pressure) often exceeding those in the planetary boundary layer (PBL) by 1 or 2 orders of magnitude. The measurements were made during the German–Brazilian cooperative aircraft campaign ACRIDICON–CHUVA, where ACRIDICON stands for Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems and CHUVA is the acronym for Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modeling and to the GPM (global precipitation measurement), on the German High Altitude and Long Range Research Aircraft (HALO). The campaign took place in September–October 2014, with the objective of studying tropical deep convective clouds over the Amazon rainforest and their interactions with atmospheric trace gases, aerosol particles, and atmospheric radiation. Aerosol enhancements were observed consistently on all flights during which the UT was probed, using several aerosol metrics, including condensation nuclei (CN) and cloud condensation nuclei (CCN) number concentrations and chemical species mass concentrations. The UT particles differed sharply in their chemical composition and size distribution from those in the PBL, ruling out convective transport of combustion-derived particles from the boundary layer (BL) as a source. The air in the immediate outflow of deep convective clouds was depleted of aerosol particles, whereas strongly enhanced number concentrations of small particles (< 90 nm diameter) were found in UT regions that had experienced outflow from deep convection in the preceding 5–72 h. We also found elevated concentrations of larger (> 90 nm) particles in the UT, which consisted mostly of organic matter and nitrate and were very effective CCN. Our findings suggest a conceptual model, where production of new aerosol particles takes place in the continental UT from biogenic volatile organic material brought up by deep convection and converted to condensable species in the UT. Subsequently, downward mixing and transport of upper tropospheric aerosol can be a source of particles to the PBL, where they increase in size by the condensation of biogenic volatile organic compound (BVOC) oxidation products. This may be an important source of aerosol particles for the Amazonian PBL, where aerosol nucleation and new particle formation have not been observed. We propose that this may have been the dominant process supplying secondary aerosol particles in the pristine atmosphere, making clouds the dominant control of both removal and production of atmospheric particles.

Drivers of Seasonal Variability in Marine Boundary Layer Aerosol Number Concentration Investigated Using a Steady State Approach

AbstractMarine boundary layer (MBL) aerosol particles affect the climate through their interaction with MBL clouds. Although both MBL clouds and aerosol particles have pronounced seasonal cycles, the factors controlling seasonal variability of MBL aerosol particle concentration are not well constrained. In this paper an aerosol budget is constructed representing the effects of wet deposition, free‐tropospheric entrainment, primary surface sources, and advection on the MBL accumulation mode aerosol number concentration (Na). These terms are then parameterized, and by assuming that on seasonal time scales Na is in steady state, the budget equation is rearranged to form a diagnostic equation for Na based on observable variables. Using data primarily collected in the subtropical northeast Pacific during the MAGIC campaign (Marine ARM (Atmospheric Radiation Measurement) GPCI (GCSS Pacific Cross‐Section Intercomparison) Investigation of Clouds), estimates of both mean summer and winter Na concentrations are made using the simplified steady state model and seasonal mean observed variables. These are found to match well with the observed Na. To attribute the modeled difference between summer and winter aerosol concentrations to individual observed variables (e.g., precipitation rate and free‐tropospheric aerosol number concentration), a local sensitivity analysis is combined with the seasonal difference in observed variables. This analysis shows that despite wintertime precipitation frequency being lower than summer, the higher winter precipitation rate accounted for approximately 60% of the modeled seasonal difference in Na, which emphasizes the importance of marine stratocumulus precipitation in determining MBL aerosol concentrations on longer time scales.

The role of cavitation in submicron aerosol dispersion

Here we discuss the problem of atomizing submicron aerosols by special design atomizers enabling the cavitation regime. The formation of submicron aerosol was studied using an impulse atomizer model powered by a high-energy material and an atomizer model with a special spray nozzle generating countercurrent flows. For these atomizers, the role played by cavitation in producing submicron liquid aerosols is demonstrated herein. A mathematical model is also suggested to describe the aerosol cloud genesis. The cavitation development critical pressure, outflow velocity, and the resulting droplet sizes were evaluated. The aerosol particle size and concentration were experimentally measured by optical methods. The measured disperse parameters of aerosols during the origination and propagation of the aerosol cloud resulted from the cavitation-assisted atomization of liquids are reported: the intrinsic particle diameter of water aerosol is 10…30 μm depending on the features of the atomizer designs and their operating regimes.

Pilot-Scale Production and Application of Microparticulated Plant Proteins

New Carbon Dioxide Assisted Spray Nebulisation Drying (CASND) technology has been used to produce microparticulated protein concentrates for human nutrition from alternative plant sources - hemp and canola seed filtration cakes. Alkali extraction was used to extract the proteins from the filtration cakes. The protein solutions after the alkali extractions were dried with the CASND demonstrator ATOMIZER. Aerosol particle size distribution and concentration in the draying chamber were determined by two different on-line aerosol spectrometers SMPS (Scaning Mobility Particle Sizer) and APS (Aerodynamic Particle Sizer). The protein powders were in form of hollow spheres with average particle diameter about 600 nm. The particles were characterized by the SEM method. The functional properties of the microparticulated protein concentrates were compared with the same protein concentrates dried by the convenctional spray drying process. The protein microparticulatin resulted in improved foaming and emulsifying properties and formation of long-term stable water dispersions. Gluten-free baguettes were prepared with the microparticulated protein concentrates as only protein source and evaluated by sensory analysis.

Temporal Variation of Atmospheric Static Electric Field and Air Ions and their Relationships to Pollution in Shanghai

ABSTRACT Atmospheric electric field (EF) and air ions were measured in Shanghai from December 2014 to December 2015 to examine the influence of particulate pollutants. Fair-weather EF exhibits a diurnal variation of multi-modal oscillations in spring, summer, and autumn. Linear correlation analyses show that the local meteorological conditions of relative humidity, temperature, pressure and wind affect atmospheric electric field, with wind direction exhibiting the highest correlation coefficient. Atmospheric EF is significantly higher in the west compared with that in the east, as the air mass from inland areas carries more polluted aerosols. Air ion concentrations are generally higher in the daytime than at night and correlate with meteorological factors. Atmospheric EF undergoes a substantial fluctuation in polluted periods, but remains flat under clean conditions. Overall, in areas with pollution, the atmospheric EF gradually increases with increased pollution or increased particle loading (e.g., PM2.5), a useful indicator of air pollution. The concentration of PM2.5 is positively correlated with the atmospheric electric field under polluted conditions, because as the concentration of aerosol particles declines, the concentrations of small ions and the atmospheric conductivity decrease accordingly, thus causing an increase in the electric field. Overall, aerosol particles, air ions, and their interactions in the presence of various meteorological parameters can have local effects on the atmospheric electric field.

Sea spray aerosol chemical composition: elemental and molecular mimics for laboratory studies of heterogeneous and multiphase reactions.

Sea spray aerosol particles (SSA), formed through wave breaking at the ocean surface, contribute to natural aerosol particle concentrations in remote regions of Earth's atmosphere, and alter the direct and indirect effects of aerosol particles on Earth's radiation budget. In addition, sea spray aerosol serves as suspended surface area that can catalyze trace gas reactions. It has been shown repeatedly that sea spray aerosol is heavily enriched in organic material compared to the surface ocean. The selective enrichment of organic material complicates the selection of representative molecular mimics of SSA for laboratory or computational studies. In this review, we first provide a short introduction to SSA formation processes and discuss chemical transformations of SSA that occur in polluted coastal regions and remote pristine air. We then focus on existing literature of the chemical composition of nascent SSA generated in controlled laboratory experiments and field investigations. We combine the evidence on the chemical properties of nascent SSA with literature measurements of SSA water uptake to assess SSA molecular composition and liquid water content. Efforts to speciate SSA organic material into molecular classes and specific molecules have led to the identification of saccharides, alkanes, free fatty acids, anionic surfactants, dicarboxylic acids, amino acids, proteinaceous matter, and other large macromolecules. However to date, less than 25% of the organic mass of nascent SSA has been quantified at a molecular level. As discussed here, quantitative measurements of size resolved elemental ratios, combined with determinations of water uptake properties, provides unique insight on the concentration of ions within SSA as a function of particle size, pointing to a controlling role for relative humidity and the hygroscopicity of SSA organic material at small particle diameters.

Predicting atmospheric particle formation days by Bayesian classification of the time series features

Atmospheric new-particle formation (NPF) is an important source of climatically relevant atmospheric aerosol particles. NPF can be directly observed by monitoring the time-evolution of ambient aerosol particle size distributions. From the measured distribution data, it is relatively straightforward to determine whether NPF took place or not on a given day. Due to the noisiness of the real-world ambient data, currently the most reliable way to classify measurement days into NPF event/non-event days is a manual visualization method. However, manual labor, with long multi-year time series, is extremely time-consuming and human subjectivity poses challenges for comparing the results of different data sets. These complications call for an automated classification process. This article presents a Bayesian neural network (BNN) classifier to classify event/non-event days of NPF using a manually generated database at the SMEAR II station in Hyytiälä, Finland. For the classification, a set of informative features are extracted exploiting the properties of multi-modal log normal distribution fitted to the aerosol particle concentration database and the properties of the time series representation of the data at different scales. The proposed method has a classification accuracy of 84.2 % for determining event/non-event days. In particular, the BNN method successfully predicts all event days when the growth and formation rate can be determined with a good confidence level (often labeled as class Ia days). Most misclassified days (with an accuracy of 75 %) are the event days of class II, where the determination of growth and formation rate are much more uncertain. Nevertheless, the results reported in this article using the new machine learning-based approach points towards the potential of these methods and suggest further exploration in this direction.

Concentration and size distribution of biological particles in school classrooms

Fungal and bacterial aerosol particles concentrations are measured in a school classrooms at two different floors using the 6-stage Andersen impactor as a bioaersol sampler. The average bacterial concentration is higher than the average fungal concentration. The concentrations were 957 and 955 cfu/m3 for bacterial particles at first and second floors, respectively while the fungal particles concentrations were 146 and 235 cfu/m3 at first and second floors, respectively. Most of the biological particles were concentrated at the size range of respirable particles (< 5 µm ) that can penetrate into the alveoli and may cause lung diseases. The human activity is a main factor for the production of microbiological particles. Environmental factors play also a role on the fungal growth. Bacterial concentration is almost twice the guide value of WHO while the fungal concentration is underestimation.

Deposition of micrometer-sized aerosol particles in neonatal nasal airway replicas

ABSTRACTThe nasal aerosol filtration properties of infants 0–3 months old have been quantified through in vitro measurements. Computed tomography (CT) scan data was obtained of seven individuals with ages of 5–79 days. Nasal airway replicas based on these images were manufactured using rapid prototyping. Deposition in the replicas was measured using an electrical low pressure impactor (ELPI) to measure the concentration of aerosol particles in the inertial regime. Comparing the difference in concentration when sampling through the model versus sampling through a blank line gave the deposition fraction. Deposition was measured for particles with aerodynamic diameters between 0.53 and 5.54 μm. Nonlinear least squares curve fitting was performed to collapse intersubject variability and represent the data with a single curve. To achieve satisfactory intersubject variability collapse, a non-dimensional pressure drop, the Euler number (Eu), was required in addition to the Reynolds number (Re) and the particle S...

Review: The Use of Real-Time Fluorescence Instrumentation to Monitor Ambient Primary Biological Aerosol Particles (PBAP)

Primary biological aerosol particles (PBAP) encompass many particle types that are derived from several biological kingdoms. These aerosol particles can be composed of both whole living units such as pollen, bacteria, and fungi, as well as from mechanically formed particles, such as plant debris. They constitute a significant proportion of the overall atmospheric particle load and have been linked with adverse health issues and climatic effects on the environment. Traditional methods for their analysis have focused on the direct capture of PBAP before subsequent laboratory analysis. These analysis types have generally relied on direct optical microscopy or incubation on agar plates, followed by time-consuming microbiological investigation. In an effort to address some of these deficits, real-time fluorescence monitors have come to prominence in the analysis of PBAP. These instruments offer significant advantages over traditional methods, including the measurement of concentrations, as well as the potential to simultaneously identify individual analyte particles in real-time. Due to the automated nature of these measurements, large data sets can be collected and analyzed with relative ease. This review seeks to highlight and discuss the extensive literature pertaining to the most commonly used commercially available real-time fluorescence monitors (WIBS, UV-APS and BioScout). It discusses the instruments operating principles, their limitations and advantages, and the various environments in which they have been deployed. The review provides a detailed examination of the ambient fluorescent aerosol particle concentration profiles that are obtained by these studies, along with the various strategies adopted by researchers to analyze the substantial data sets the instruments generate. Finally, a brief reflection is presented on the role that future instrumentation may provide in revolutionizing this area of atmospheric research.

The Attenuation of Free Space Optical Communication under Dusty Conditions in Lahore

FSO (free space optical) communication is one of the most advanced modes of wireless communication. FSO is a line of sight communication which is used to convey data from an optical transmitter to an optical receiver through atmosphere. FSO offers higher data rates but fading level due to atmospheric effects (like sand, dust, fog, rain, snow etc.) are higher than RF (radio frequency) technology. The atmosphere affects the laser beam passing through it. The atmospheric turbulence and scattering results in the degradation of the signal. In this research paper is focused and analyzes the variations in the visibility and attenuation with respect to the concentration of aerosol particles (suspended elemental particles) is done. This research work is conducted and dust model is designed in the atmosphere of urban area of Lahore city. The model deals the effect of the size of the dust particles on the visibility of FSO link and suggests a formula for the calculation of attenuation generated in the link.

Determination of black carbon and nanoparticles along glaciers in the Spitsbergen (Svalbard) region exploiting a mobile platform

An innovative approach to characterize concentration of atmospheric aerosol particles and air mass layering along the elevation profile of glaciers is presented for the first time and validated, exploiting low weight and fast response sensors deployed on a snowmobile. Two micro-Aethalometers for black carbon measurements and a miniature Diffusion Size Classifier (miniDisc) for total aerosol concentration (airborne particles) in the 14–260 nm range were used. Test experiments were conducted in the Arctic (Svalbard) in Spring (2016). Three glaciers in the Spitsbergen region were considered for this exploratory study, the Austre Brøggerbreen, the Edithbreen and the Kongsvegen. The Austre Brøggerbreen and Edithbreen were considered as test sites to setup the experiment, to optimize the sampling strategy and to identify some basic experimental artefacts. Kongsvegen glacier was chosen for the main case study, extending from the Kongsfjorden coast to roughly 700 m above sea level for a total length of ca. 25 km and with a nearly constant elevation gradient. The obtained results were rather consistent for the three glaciers and show an increase of nanoparticles with altitude. Black carbon concentration show stationary to decreasing trends going from the bottom to the top of the glaciers. These observations indicate a very active secondary aerosol formation at the highest elevations, responsible for the increase concentration of ultrafine particles at the glacier top. On the other side, black carbon shows higher levels at the lower altitudes of the glacier. This is indicative that in absence of a long-range transport as demonstrated by calculated back trajectories, black carbon might have accumulated due to the effect of katabatic winds flow along the glacier profile. The results obtained were compared and are largely consistent with the observations from concurrent soundings with a tethered balloon experiment conducted in the nearby site of Ny-Ålesund. The proposed experimental design opens new perspectives for future experiments, which may be of relevance for the understanding of black carbon and dry dust deposition on the glacier surface, which may impact the melting of ice and snow. The investigations also contribute to better understanding of the transport and surface exchange processes acting within the atmospheric layer over glacier surface.