Measured Particle Number Research Articles

International comparison CCQM-K150: particle number concentration (100 to 20 000 cm-3) and particle charge concentration (0.15 to 3 fC cm-3)

Main textThis report presents the results of CCQM-K150, a key comparison between nine National Measurement Institutes (NMIs) which tested the capability of the NMIs to measure particle number concentration (in the range of 100 to 20 000 cm-3) using condensation particle counters (CPCs), and particle charge concentration (in the range of 0.15 to 3 fC cm-3) using aerosol electrometers (AEs).Measurements of aerosol particle number concentration are needed to demonstrate compliance to vehicle emission legislation and are becoming increasingly important in other areas such as ambient air and workplace monitoring. The measurements are typically carried out using condensation particle counters, which are calibrated using either reference CPCs or reference AEs.An analogous report is available for the CCQM-P189 comparison. CCQM-P189 was identical to and used the same experimental data as CCQM-K150 with one exception: data from TROPOS, which is not an NMI or Designated Institute (DI), were only included in CCQM-P189.CCQM-K150 was an amount-of-substance Track C comparison.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

International comparison CCQM-P189: particle number concentration (100 to 20 000 cm-3) and particle charge concentration (0.15 to 3 fC cm-3)

Main textThis report presents the results of CCQM-P189, a pilot comparison between 10 laboratories which tested the participants’ capability to measure particle number concentration (in the range of 100 to 20 000 cm-3) using condensation particle counters (CPCs), and particle charge concentration (in the range of 0.15 to 3 fC cm-3) using aerosol electrometers (AEs).Measurements of aerosol particle number concentration are needed to demonstrate compliance to vehicle emission legislation and are becoming increasingly important in other areas such as ambient air and workplace monitoring. The measurements are typically carried out using condensation particle counters, which are calibrated using either reference CPCs or reference AEs.An analogous report is available for the CCQM-K150 comparison. CCQM-K150 was identical to, and used the same experimental data as CCQM-P189 with one exception: data from TROPOS, which is not a National Measurement Institute (NMI) or Designated Institute (DI), were only included in CCQM-P189.CCQM-P189 was an amount-of-substance Track C comparison.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Investigating the Effect of Volatiles on Sub-23 nm Particle Number Measurements for a Downsized GDI Engine with a Catalytic Stripper and Digital Filtering

Recent efforts of both researchers and regulators regarding particulate emissions have focused on the contribution and presence of sub-23 nm particulates. Despite being previously excluded from emissions legislation with the particle measurement programme (PMP), the latest regulatory proposals suggest lowering the cut-off sizes for counting efficiencies and the use of catalytic strippers to include solid particles in this size range. This work investigated particulate emissions of a 1.0 L gasoline direct injection (GDI) engine using a differential mobility spectrometer (DMS) in combination with a catalytic stripper. Direct comparison of measurements taken with and without the catalytic stripper reveals that the catalytic stripper noticeably reduced variability in sub-23 nm particle concentration measurements. A significant portion of particles in this size regime remained (58–92%), suggesting a non-volatile nature for these particles. Digital filtering functions for imposing defined counting efficiencies were assessed with datasets acquired with the catalytic stripper; i.e., particle size distributions (PSDs) with removed volatiles. An updated filtering function for counting efficiency thresholds of d65 = 10 nm and d90 = 15 nm showed an increase in particulate numbers between 1.5% and up to 11.2%, compared to the closest previous digital filtering function. However, this increase is highly dependent on the underlying PSD. For a matrix of operating conditions (1250 to 2250 rpm and fast-idle to 40 Nm brake torque), the highest emissions occurred at fast-idle 1250 rpm with 1.93 × 108 #/cm3 using the updated filtering function and catalytic stripper. This setup showed an increase in particulate number of +27% to +390% over the test matrix when compared to DMS measurements without the catalytic stripper and applied counting efficiency thresholds of d50 = 23 nm and d90 = 41.

The Role of Portable Air Purifiers and Effective Ventilation in Improving Indoor Air Quality in University Classrooms.

In this study we investigated the effectiveness of air purifiers and in-line filters in ventilation systems working simultaneously inside various classrooms at the University of Southern California (USC) main campus. We conducted real-time measurements of particle mass (PM), particle number (PN), and carbon dioxide (CO2) concentrations in nine classrooms from September 2021 to January 2022. The measurement campaign was carried out with different configurations of the purifier (i.e., different flow rates) while the ventilation system was continuously working. Our results showed that the ventilation systems in the classrooms were adequate in providing sufficient outdoor air to dilute indoor CO2 concentrations due to the high air exchange rates (2.63-8.63 h-1). The particle penetration coefficients (P) of the investigated classrooms were very low for PM (<0.2) and PN (<0.1), with the exception of one classroom, corroborating the effectiveness of in-line filters in the ventilation systems. Additionally, the results showed that the efficiency of the air purifier exceeded 95% in capturing ultrafine and coarse particles and ranged between 82-88% for particles in the accumulation range (0.3-2 µm). The findings of this study underline the effectiveness of air purifiers and ventilation systems equipped with efficient in-line filters in substantially reducing indoor air pollution.

Assessment of the exposure to PM2.5 in different Lebanese microenvironments at different temporal scales.

The weak potential of using the sole outdoor concentrations to represent personal exposure to PM2.5 is confirmed by the literature; therefore, it is important to account for a person’s movements over time when estimating the short-term personal air pollution exposure within different microenvironments (MEs). This study is an example of applying an assessment method of the exposure to PM2.5 in different microenvironments at different temporal scales. A low-cost particle counter (the Dylos 1700) was used; its performance was validated in comparison with equivalent instruments such the SidePak AM520 Personal Aerosol Monitor (R2 = 0.89). This validation also provided a function to convert measured particle number concentrations (PNCs) into calculated particle mass concentrations. The 150 profiles that was collected on a minute-by-minute basis regarding PM2.5 concentration from December 2018 to May 2021 highlight the influence of individual activities and contextual factors on the air quality, so that Lebanon’s annual PM2.5 mean (24.2 µg⁄m3) is 142% higher than the World Health Organization (WHO) annual mean guideline (10 µg⁄m3). Winter is the most polluted period due to the increased application of space heating devices. Additionally, the occurrence of dusty winds during the spring period leads to the elevated levels of dispersed PM2.5. Simultaneously, the rural zones are more polluted than urban ones due to the usage of more traditional heating equipment, in addition to the usage of chemical products like pesticides and fertilizers in agricultural activities in such areas. Furthermore, the (outdoor–indoor–transport) MEs indicate that the transport and indoor MEs have similar levels of suspended fine particulates, while outdoor MEs are less polluted. Studies based on the personal exposure to PM2.5 were generally applied on specific and limited places such as schools, workplaces, or residences. The study aims to shed light on the modern method in an attempt to estimate the personal exposure to PM2.5 and to inspire similar studies to achieve the maximum efficiency.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10661-022-10607-6.

Particle Number Emission from Vehicles of Various Drives in the RDE Tests

In this study, the authors assessed the road emissions of several passenger cars using specialised instrumentation, of the PEMS type, to measure particle number emissions in real traffic conditions. The tests were performed on a RDE test route developed and compliant with EU guidelines. The results of the tests were discussed in terms of the direct (created in the internal combustion engine) emission of particulate matter in various road conditions. Additionally, an index was determined that characterizes the number of particles according to their diameter in relation to the content of particles in the air. A characteristic of combustion engines (gasoline, diesel) is that during a cold start of the engine, the concentration of the number of particles with diameters around 100 nm increases more than 200 times (for hybrids—300 times). On this basis, it can be concluded that particle emissions with diameters smaller than 23 nm are significant in motor vehicles powered by combustion engines, regardless of whether they are conventional or hybrid vehicles. The share of particles with diameters less than 5 nm is 66% (for diesel engines) and 40% (for gasoline engines) of all the particles.

Towards tailpipe sub-23 nm solid particle number measurements for heavy-duty vehicles regulations

A heavy-duty engine is type-approved in engine dynamometers, while its in-service conformity is controlled on the road. In the first case, laboratory particle number systems (LABS) sample from a full dilution tunnel or a proportional partial flow dilution system (PFDS). In the second case portable emissions measurements systems (PEMS) measure directly from the tailpipe. Permitting in the regulation LABS sampling directly from the tailpipe would simplify testing and would improve their comparability with PEMS. In this study PEMS and LABS, both sampling from the tailpipe and measuring solid particles >10 nm, were compared with references systems (i.e. LABS from PFDS). One compressed natural gas (CNG) engine, and three diesel engines, all Euro VI step E, with or without urea injection, and with or without crankcase ventilation connected to the tailpipe, challenged the systems with different emission levels and particle sizes and properties. The results showed that the differences of the LABS to the references were in most cases within ±25%, with a few exceptions. The PEMS were within ±50%. There was no or small effect on the differences from engine technology, urea injection or crankcase ventilation. The inclusion of sub-23 nm particles increased 100% to 250% the particle number emissions. The urea injection increased the >10 nm emissions 300–600% (2–5 × 1010 p/kWh). Connecting the crankcase ventilation to the tailpipe further increased the >10 nm particle number emissions 340–560% (1.4–2.5 × 1011 p/kWh), bringing the >10 nm levels of the engines to approximately half of the current particle number limit, applicable to particles >23 nm.

Investigation of aluminum dust cloud dispersion characteristics in an explosion hazard testing device using laser-based particle and flow diagnostics

Monitoring the dust cloud dispersion process inside testing equipment like the MIKE3 minimum ignition energy device is useful for assessing the ignitability characteristics of different dust materials. However, it is difficult to comprehensively capture the relevant micro-scale particle properties and macro-scale flow behavior of a dust cloud dispersion using a single measurement method. Thus, the objective of this work is to combine two complementary laser diagnostic techniques to obtain quantitative particle and flow properties from dust clouds in the MIKE3 glass tube. For this experiment, thirty repeated runs for each method were conducted using small (15-mg) aluminum powder samples. No ignition electrodes are included in the test geometry to establish a baseline flow configuration for the glass tube, although measurements are still made at the characteristic time delay and location of ignition tests. The first technique, digital in-line holography (DIH) is used for three-dimensional micro-scale particle diagnostics, yielding particle number (n = 78 ± 20), size (D̅ = 18.9 ± 0.6 µm), and three-component velocity (v̅x = 0.05 ± 0.05 m/s, v̅y = 0.60 ± 0.09 m/s, v̅z = − 0.07 ± 0.16 m/s) measurements. The second laser diagnostic technique, particle image velocimetry (PIV), is used for macro-scale flow diagnostics, yielding two-dimensional flow velocity and vorticity vector field measurements. Particle sizes are observed to follow a lognormal distribution (μ = 2.89, σ = 0.31), and a discrepancy between in-situ and ex-situ sizing results is identified for particle sizes larger than ~55 µm. Two-dimensional particle velocities follow a Weibull distribution (θ = 0.86, β = 2.12), and reasonable agreement is found between the DIH and PIV velocity measurements.

Characterization of Annual Average Traffic-Related Air Pollution Concentrations in the Greater Seattle Area from a Year-Long Mobile Monitoring Campaign.

Growing evidence links traffic-related air pollution (TRAP) to adverse health effects. We designed an innovative and extensive mobile monitoring campaign to characterize TRAP exposure levels for the Adult Changes in Thought (ACT) study, a Seattle-based cohort. The campaign measured particle number concentration (PNC) to capture ultrafine particles (UFP), black carbon (BC), nitrogen dioxide (NO2), fine particulate matter (PM2.5), and carbon dioxide (CO2) at 309 roadside sites within a large, 1200 land km2 (463 mi2) area representative of the cohort. We collected about 29 two-minute measurements at each site during all seasons, days of the week, and most times of the day over a 1-year period. Validation showed good agreement between our BC, NO2, and PM2.5 measurements and monitoring agency sites (R2 = 0.68-0.73). Universal kriging-partial least squares models of annual average pollutant concentrations had cross-validated mean square error-based R2 (and root mean square error) values of 0.77 (1177 pt/cm3) for PNC, 0.60 (102 ng/m3) for BC, 0.77 (1.3 ppb) for NO2, 0.70 (0.3 μg/m3) for PM2.5, and 0.51 (4.2 ppm) for CO2. Overall, we found that the design of this extensive campaign captured the spatial pollutant variations well and these were explained by sensible land use features, including those related to traffic.

Particle Number Measurement and Its Numerical Simulation of the Airborne Particle Counter by ‘Post-Collection-Check’

The measurement results of the light-scattering airborne particle counter can effectively evaluate the concentration of airborne particles in the clean environment and confined space, and the accuracy improvement of the calibration measurement results has attracted more and more attention. This paper introduces the ‘post-collection-check’ way of the airborne particle concentration measurement method of the OPC (Optical Particle Counter), based on FESEM (Field Emission Scanning Electron Microscopy) and AAO (Anodic Aluminum Oxide) template, the probability distribution of the collected PSL (Polystyrene Latex) particles on the surface of AAO template, and the pressure parameters of AAO template under the different particle over current areas are both simulated. The numerical simulation results will help to improve the accuracy of the inference statistics of the collected PSL particle number on the membrane filter, and to give guidance on the optimal design of the PSL particle collection tube and the membrane filter, in order to provide an important reference for further improving the OPC particle concentration calibration and traceability method based on statistical theory.

Sub-23 nm Particle Emissions from China-6 GDI Vehicle: Impacts of Drive Cycle and Ambient Temperature

Both the EU and China are evaluating the feasibility of lowering the detection limit of particle number (PN) measurement to 10 nm in future legislations, making it necessary to better understand the sub-23 nm particle emission characteristics from state-of-the-art vehicles. In this study, solid PN emissions with a diameter larger than 10 nm and 23 nm (known as SPN10 and SPN23) were compared over the WLTC, RTS95, and a so-called “worst-case” real driving emission (RDE) cycle (highly dynamic/0 °C) using two certification-level particle number counters (PNCs) employing evaporation tube (ET) and catalytic stripper (CS) as volatile particle remover (VPR). The results show that SPN10 emissions were 31.7%, 27.8%, and 15.2% higher than SPN23 over the WLTC, RTS95, and laboratory RDE cycles. Sub-23 nm particles were almost not identified within the engine cold-start phase and tended to be a hot-running pollutant favored by aggressive driving styles (frequent accelerations and high engine loads), fuel-cut during decelerations, and long idles. Lower testing temperature delayed the light-off of catalyst and, therefore, significantly reduced the formation of sub-23 nm particles within the engine warm-up stage. Lowering the detection limit to 10 nm is deemed to provide more public health protection since it will guide manufacturers to pay more attention to vehicle hot-running emissions.

A precise nanoparticle quantification approach using microfluidics and single-particle tracking

Due to the limited available amounts of components, especially of low water-soluble drugs, formulation development is often impeded by a careful characterization. The use of small batch sizes might solve this problem but requires also adequate analytics. Concentration of nanoparticulate formulations lack straightforward evaluation techniques. In this work, a precise and straight-forward method is established to individually count nanoparticles. A microfluidic chip with known dimensions was used to visualize single particles flowing through the channel (single-particle tracking (SPT)). A sequence of 10,000 images was analyzed to determine the mean particle concentration. The proposed method is independent of the particular flow rate through the microfluidic chip as long as there is no particle overlap and a continuous exchange of particles. Monodisperse Rhodamine B labeled poly (methyl methacrylate) (PMMA) nanoparticles (267.03 ± 9.79 nm) were used as a model and reference particle system for the evaluation process of SPT allowing for a gravimetric determination based on density analysis using analytical ultracentrifugation (AUC) and gas pycnometry. The SPT method was evaluated and compared to other techniques used for concentration measurement. Both approaches (SPT and gravimetry) provide very similar and comparable results indicating the applicability of this novel quantification approach. In contrast, multi angle dynamic light scattering (MADLS) could not yield a precision as good as SPT (number density rel. standard deviation SD nSPT = 11.67%; SD nMADLS = 49.45%). Finally, the measured particle number concentrations can be realized in low concentration ranges (0.8249 μg mL−1 – 0.08249 μg mL−1) not accessible for MADLS (0.08249 mg mL−1 – 0.008249 mg mL−1) and gravimetric analysis.

Management of Atherogenic Dyslipidemia in a Patient with LDL Discordance

<h3>Lead Author's Financial Disclosures</h3> Nothing to disclose. <h3>Study Funding</h3> None. <h3>Background/Synopsis</h3> We review a case of a 43-year-old male referred for optimal management of dyslipidemia and cardiovascular risk reduction. This is intended to highlight key features in diagnosis and management of atherogenic dyslipidemia in the setting of metabolic syndrome. <h3>Objective/Purpose</h3> To review a clinical scenario involving LDL discordance in a patient with atherogenic dyslipidemia and its impact on management. <h3>Methods</h3> Clinical management done at tertiary care lipid program. Advanced lipid testing including LDL particle number and size is ordered through Quest Diagnostics. <h3>Results</h3> A 43-year-old nonsmoker male with metabolic syndrome and recently diagnosed insulin dependent type 2 diabetes mellitus was referred to the lipid clinic for further evaluation. With subclinical atherosclerosis noted with calcium score of 6.6 at age 43 (50-75th percentile) and above-average carotid intimal medial thickness, he was treated with rosuvastatin 20 mg daily. Subsequently, he had a good response of ∼50% LDL reduction with LDL-c of 75 mg/dL. At this point, while most clinicians as well as guideline directed approach may suggest a sufficient management of his dyslipidemia, the advent of advanced lipid testing contrasts this dogma otherwise. LDL discordance noted based on higher-than-expected particle number strongly warrants further aggressive LDL lowering for optimal cardiovascular risk reduction in the setting of metabolic syndrome. <h3>Conclusions</h3> While calculated LDL cholesterol has been well established as a primary target of treatment to reduce cardiovascular risk, in patients with hypertriglyceridemia or metabolic syndrome, this may underestimate the true burden of atherogenic, cholesterol-carrying lipoproteins. Measurements of apoB or LDL particle number by NMR may more closely quantify the atherogenic lipoprotein load and thus prove to be better indices of cardiovascular disease risk than calculated LDL cholesterol or non-HDL cholesterol in such a population. In our clinical case, the patient may not be adequately treated based on a calculated LDL of 75 mg/dL on high intensity statin, however, an advanced lipid panel revealing LDL discordance suggests intensification and more aggressive LDL lowering for optimal cardiovascular risk reduction.

Realistic operation of two residential cordwood-fired outdoor hydronic heater appliances—Part 2: Particle number and size

ABSTRACT The use of wood as a fuel for home heating is a concern from an environmental health and safety perspective as biomass combustion appliances emit high concentrations of particulate matter. Wood burning significantly contributes to wintertime particulate matter concentrations in many states in the northern United States. Of particular concern are outdoor wood-fired hydronic heaters. These devices are concerning as they tend to have very large combustion chambers and typical use patterns can result in long periods of low output, which result in an increased particulate matter emission rate relative to high heat output operating conditions. In this study, the performance of two hydronic heaters operating under different combustion conditions, including four different heat output categories approximately corresponding to categories I–IV denoted in Environmental Protection Agency Method 28 Outdoor Wood-fired Hydronic Heaters, and during start-up and reloading events were investigated. Measurements of flue gas particulate number concentration and size for particles with aerodynamic diameters between 0.006 and 10 µm were made using a dilution sampling system. The measured particle number concentration in the flue gas was between 0.71 and 420 million particles per cubic centimeter and was dependent on fuel loading and heat output. For each hydronic heater tested, the highest average particle concentration was found at the beginning of each test during the cold-start condition. Additionally, the majority of the particles had aerodynamic diameters less than 0.100 µm (particles of this size made up between 64% and 97% of all particles) and less than 1% of all particles had aerodynamic diameters greater than 1 µm for all phases. For particles in the accumulation mode, between 0.100 and 1 µm, the mean particle diameter was dependent on fuel loading and heat output. Implications: In this work, we provide information on the particle number concentration and particle size of emissions from outdoor cord- wood-fired hydronic heaters. Wood-fired hydronic heater data is sparsely available compared to wood stove data. Thus, additionaldata from this source help to inform the work of modelers and policy makers interested in hydronic heaters. The test method used in this work is also novel, as it is more inclusive of real-world use cases than the current certification method. Our data helps to validate the test method and allows for comparisons between real-world use case scenarios, and idealized test cases.

Sewage sludge and wood sawdust co-firing: Gaseous emissions and particulate matter size distribution

Sewage sludge (SS) is an inevitable by-product of wastewater treatment and its disposal is a continuing challenge for sustainable development and environmental management. Co-firing dried SS and wood sawdust (WS) seems to be a feasible SS disposal method. In the presented work, composite pellets made at 100% WS/0% SS, 95/5, 90/10, 85/15 and 80/20 ratios were combusted in a 25-kW grate-fired boiler and the effects of SS on the emissions and particulate matter (PM) size distributions were studied. An online stack analyzer was used to measure gaseous emission values and the PM concentrations were determined by three different principles. HT-DLPI+ was deployed to measure the particle mass distribution of particles between 13 nm and 50 μm and a SMPS-3080 with a CPC-3775 by TSI was used to measure particle number concentrations between 19 and 1000 nm. The results reveal that with increasing SS content in the pellets, the NOx and SO2 emissions increased, while the CO emissions significantly decreased. PM emissions also showed a strong correlation with the amount of SS in the pellets. SS addition increased the mass median diameter, nonetheless the contribution of particles over 0.6 μm in aerodynamic diameter was found to be insignificant in all cases.

Evaluation of Measurement Procedures for Solid Particle Number (SPN) Measurements during the Periodic Technical Inspection (PTI) of Vehicles.

Periodic technical inspection (PTI) of vehicles guarantees safety and environmental compliance during their lifetime. Particulate matter emissions of diesel vehicles are controlled with opacity measurements. After the introduction of diesel particulate filters (DPFs), particulate matter emissions have drastically decreased and the sensitivity of the opacity method is questioned. Several countries have already or are planning to introduce a solid particle number (SPN) method at their PTI that will either substitute or complement opacity measurements. However, there are differences in the measurement procedures and the limit values. In this study, we compared the different approaches and investigated topics which are still not well defined, such as the uncertainty of the SPN-PTI instruments, repeatability of the procedures, impact of the DPF fill state, and the correlation between type-approval SPN emissions and SPN concentrations during PTI tests. Finally, we compared the SPN-PTI instruments with the opacity meters. Our results showed that SPN-PTI measurements can detect tampered and defective DPFs. We also made suggestions on the measurement procedures and the concentration limit.

Reproducibility of the 10-nm Solid Particle Number Methodology for Light-Duty Vehicles Exhaust Measurements

Many countries worldwide have introduced a limit for solid particles larger than 23 nm for the type approval of vehicles before their circulation in the market. However, for some vehicles, in particular for port fuel injection engines (gasoline and gas engines) a high fraction of particles resides below 23 nm. For this reason, a methodology for counting solid particles larger than 10 nm was developed in the Particle Measurement Programme (PMP) group of the United Nations Economic Commission for Europe (UNECE). There are no studies assessing the reproducibility of the new methodology across different laboratories. In this study we compared the reproducibility of the new 10 nm methodology to the current 23 nm methodology. A light-duty gasoline direct injection vehicle and two reference solid particle number measurement systems were circulated in seven European and two Asian laboratories which were also measuring with their own systems fulfilling the current 23 nm methodology. The hot and cold start emission of the vehicle covered a range of 1 to 15 × 1012 #/km with the ratio of sub-23 nm particles to the &gt;23 nm emissions being 10–50%. In most cases the differences between the three measurement systems were ±10%. In general, the reproducibility of the new methodology was at the same levels (around 14%) as with the current methodology (on average 17%).

The Application of maximum entropy technique to determine number concentration and size distribution in pneumatic transport

Based on laser-diffraction technique, the maximum entropy technique is applied to measure particle number concentration and size distribution in pneumatic transport. The information of particle number concentration and size distribution can be obtained simultaneously without distort the fluid and the particle trajectories. Detailed information about the distribution of the particle size and concentration in gas-solid two-phase flows near sand-bed surface are obtained in a large-scale wind tunnel test system. The experimental result shows that particle number concentration increases linearly with the increase of the wind speed. The mean particle size decreases exponentially with height (H > 3 cm), but almost unchanged for H < 3 cm. The weakly relationship of fluctuating velocity and particle-size dispersion is deduced from the underlying mechanism of equilibrium transport. This illustrates that transportation close to the mobile bed has selectivity for particle size.

Aerosol optical properties calculated from size distributions, filter samples and absorption photometer data at Dome C, Antarctica, and their relationships with seasonal cycles of sources

Abstract. Optical properties of surface aerosols at Dome C, Antarctica, in 2007–2013 and their potential source areas are presented. Scattering coefficients (σsp) were calculated from measured particle number size distributions with a Mie code and from filter samples using mass scattering efficiencies. Absorption coefficients (σap) were determined with a three-wavelength Particle Soot Absorption Photometer (PSAP) and corrected for scattering by using two different algorithms. The scattering coefficients were also compared with σsp measured with a nephelometer at the South Pole Station (SPO). The minimum σap was observed in the austral autumn and the maximum in the austral spring, similar to other Antarctic sites. The darkest aerosol, i.e., the lowest single-scattering albedo ωo≈0.91, was observed in September and October and the highest ωo≈0.99 in February and March. The uncertainty of the absorption Ångström exponent αap is high. The lowest αap monthly medians were observed in March and the highest in August–October. The equivalent black carbon (eBC) mass concentrations were compared with eBC measured at three other Antarctic sites: the SPO and two coastal sites, Neumayer and Syowa. The maximum monthly median eBC concentrations are almost the same (∼3±1 ng m−3) at all these sites in October–November. This suggests that there is no significant difference in eBC concentrations between the coastal and plateau sites. The seasonal cycle of the eBC mass fraction exhibits a minimum f(eBC) ≈0.1 % in February–March and a maximum ∼4 %–5 % in August–October. Source areas were calculated using 50 d FLEXPART footprints. The highest eBC concentrations and the lowest ωo were associated with air masses coming from South America, Australia and Africa. Vertical simulations that take BC particle removal processes into account show that there would be essentially no BC particles arriving at Dome C from north of latitude 10∘ S at altitudes &lt;1600 m. The main biomass-burning regions Africa, Australia and Brazil are more to the south, and their smoke plumes have been observed at higher altitudes than that, so they can get transported to Antarctica. The seasonal cycle of BC emissions from wildfires and agricultural burning and other fires in South America, Africa and Australia was calculated from data downloaded from the Global Fire Emissions Database (GFED). The maximum total emissions were in August–September, but the peak of monthly average eBC concentrations is observed 2–3 months later in November, not only at Dome C, but also at the SPO and the coastal stations. The air-mass residence-time-weighted BC emissions from South America are approximately an order of magnitude larger than from Africa and Oceania, suggesting that South American BC emissions are the largest contributors to eBC at Dome C. At Dome C the maximum and minimum scattering coefficients were observed in austral summer and winter, respectively. At the SPO σsp was similar to that observed at Dome C in the austral summer, but there was a large difference in winter, suggesting that in winter the SPO is more influenced by sea-spray emissions than Dome C. The seasonal cycles of σsp at Dome C and at the SPO were compared with the seasonal cycles of secondary and primary marine aerosol emissions. The σsp measured at the SPO correlated much better with the sea-spray aerosol emission fluxes in the Southern Ocean than σsp at Dome C. The seasonal cycles of biogenic secondary aerosols were estimated from monthly average phytoplankton biomass concentrations obtained from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite sensor data. The analysis suggests that a large fraction of the biogenic scattering aerosol observed at Dome C has been formed in the polar zone, but it may take a month for the aerosol to be formed, be grown and get transported from the sea level to Dome C.

Estimation of the Seasonal Inhaled Deposited Dose of Particulate Matter in the Respiratory System of Urban Individuals Living in an Eastern Mediterranean City.

In this study, we present an estimation for the inhaled deposited dose rate in adult males and females during common exposure scenarios to urban background aerosols in an Eastern Mediterranean city (Amman, Jordan) based on a one-year database of measured particle number size distribution. The dose rates show seasonal variations reflecting the physical characteristics (i.e., modal structure) of the particle number size distribution. An additional factor was the varying deposition fraction (DF) for different regions and different human activities (exercising versus resting). The total dose rate was 3 × 109–65 × 109 particles/h (PM2.5 and PM10 doses 1–22 µg/h and 9–210 µg/h; respectively) depending on the gender, activity, and season. Based on the particle number metrics, the inhaled deposited dose in the head, Tracheobronchial, and alveolar were 7–16%, 16–28%, and 56–76%; respectively. Based on the PM2.5 metric, the corresponding dose rate was 9–41%,13–19%; and 46–72% respectively. As for the PM10 metric, they were 25–75%, 7–35%, and 15–55%; respectively.