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Palembang has sustained heavy haze pollution events that are related to decrease public health quality. Because ground-based PM2.5 observation in the city has some limitations, such as spatial and temporal coverages. Thus, in this study, we applied the potential of using the surface mass concentration PM2.5 data acquired by the MERRA-2 satellite to predict daytime and night-time PM2.5 levels during heavy haze events in Palembang City. Results of the study revealed that the highest PM2.5 level was about 160 µg/m3 at 02:00 (night-time), while the lowest PM2.5 level was about 50 µg/m3 at 14:00 (daytime). Spatiotemporal variation of PM2.5 over the study area showed that more than half of the area showed PM2.5 above 90 µg/m3 at night. Stable wind conditions (2 m/s) and air temperature (29°C), and relative humidity (74%) in the study area have contributed to particulate matter accumulation. The study concluded that PM2.5 acquired by the MERRA-2 satellite could provide a new reliable source for assessing severe air pollution events. [ABSTRACT FROM AUTHOR]

Organic carbon (OC), elemental carbon (EC), and 90 organic compounds (36 polycyclic aromatic hydrocarbons [PAHs], 25 n-alkane homologues, 17 hopanes, and 12 steranes) were concurrently quantified in atmospheric particulate matter of PM2.5 and PM10. The 24-hr PM samples were collected using Harvard Impactors at a suburban site in Doha, Qatar, from May to December 2015. The mass concentrations (mean ± standard deviation) of PM2.5 and PM10 were 40 ± 15 and 145 ± 70 µg m−3, respectively, exceeding the World Health Organization (WHO) air quality guidelines. Coarse particles comprised 70% of PM10. Total carbonaceous contents accounted for 14% of PM2.5 and 10% of PM10 particulate mass. The major fraction (90%) of EC was associated with the PM2.5. In contrast, 70% of OC content was found in the PM2.5-10 fraction. The secondary OC accounted for 60-68% of the total OC in both PM fractions, indicating photochemical conversions of organics are much active in the area due to higher air temperatures and solar radiations. Among the studied compounds, n-alkanes were the most abundant group, followed by PAHs, hopanes, and steranes. n-Alkanes from C25 to C35 prevailed with a predominance of odd carbon numbered congeners (C27-C31). High-molecular-weight PAHs (5-6 rings) also prevailed, within their class, with benzo[b + j]fluoranthene (Bb + jF) being the dominant member. PAHs were mainly (80%) associated with the PM2.5 fraction. Local vehicular and fugitive emissions were predominant during low-speed southeasterly winds from urban areas, while remote petrogenic/biogenic emissions were particularly significant under prevailing northwesterly wind conditions. Implications: An unprecedented study in Qatar established concentration profiles of EC, OC, and 90 organic compounds in PM2.5 and PM10. Multiple tracer organic compounds for each source can be used for convincing source apportionment. Particle concentrations exceeded WHO air quality guidelines for 82-96% of the time, revealing a severe problem of atmospheric PM in Doha. Dominance of EC and PAHs in fine particles signifies contributions from combustion sources. Dependence of pollutants concentrations on wind speed and direction suggests their significant temporal and spatial variability, indicating opportunities for improving the air quality by identifying sources of airborne contaminants. [ABSTRACT FROM AUTHOR]

The objective of this study is to investigate the particle effective density of aerosol measurements in a railway tunnel environment. Effective density can serve as a parameter when comparing and calibrating different aerosol measurements. It can also be used as a proxy parameter reflecting the source of particles. Effective density was determined using two different methods. Method one defined it by the ratio of mass concentration to apparent volume size distribution. Method two relied on a comparison of aerodynamic and mobility diameter size distribution measurements. The aerodynamic size range for method one was 0.006-10 µm, and for method two, it was 10-660 nm. Using the first method, a diurnal average value of about 1.87 g/cm3 was observed for the measurements with tapered element oscillating microbalance (TEOM) in tandem with aerodynamic particle sizer + scanning mobility particle sizer (SMPS), and 1.2 g/cm3 for the combination of TEOM with electrical low pressure impactor plus (ELPI+) in the presence of traffic. With method two, the effective density was 1.45 g/cm3 estimated from the size distribution measurements with ELPI + and fast mobility particle sizer (FMPS), and 1.35 g/cm3 from ELPI + in tandem with SMPS. With both calculation methods, the effective density varied for conditions with and without traffic, indicating different sources of particles. The proportion of particles with small sizes (10-660 nm) had a significant effect on the value of the effective density when no traffic was operating. The responses of different instruments to the railway particle measurements were also compared. Copyright © 2018 The Authors. Published with license by Taylor & Francis Group, LLC [ABSTRACT FROM AUTHOR]

Spectrophotometric methods developed previously to quantify the major functional groups present in oxidized organic aerosol were modified for use with sample masses typical of those collected from ambient air. In these methods, carbonyl, hydroxyl, carboxyl, and ester groups are reacted with derivatizing agents that are specific to each functional group to form strongly light absorbing derivatives, a colored peroxide solution is formed through redox chemistry, and nitrates have an inherently strong absorbance. As described here, improved detection limits are made possible by measuring absorbance using a spectrophotometer that requires only a few microliters of solution for analysis, instead of the five milliliter volume required previously when using a standard cuvette. Use of this so-called NanoPhotometer allows comparable absorbances to be obtained with much less mass by concentrating samples by more than two orders of magnitude relative to previous methods. Detection limits are approximately 0.03, 0.02, 0.3, 1, 1, and 0.07 nmoles for carbonyl, hydroxyl, carboxyl, ester, peroxide, and nitrate groups, which correspond to approximately 0.8, 0.6, 10, 40, 50, and 5 ng of each functional group. In practice, depending on the composition of functional groups, the mass required for complete analysis of moderately oxidized organic aerosol is ∼10–100 µg. The new microscale methods were shown to provide good linearity, precision, and accuracy by comparing results from the analysis of standards and aerosol formed from reaction of α-pinene and O3with results obtained using the previously developed macroscale methods. The evaluation demonstrates that the microscale methods can be used to quantify these six functional groups at low organic aerosol mass concentrations. Copyright © 2016 American Association for Aerosol Research [ABSTRACT FROM PUBLISHER]

Airflow around an eight-passenger-car subway train running in the underground tunnel at a cruise speed of 70 km/h was numerically simulated, and the trajectories of the particles that were assumed to be re-suspended from the ground or generated at the contact points between the wheels and rails were predicted. In addition, field experiments were conducted to measure airflow velocity and PM10mass concentration under a T-car (trailer car without a driving cab) during the running of a subway train in straight sections of the underground tunnel of the Seoul Subway Line 5. The numerically predicted airflow velocities agreed well with the experimental data with the error of less than 30%, and the predicted particle distribution showed a similar tendency to the experimental results. The airflow under the T-car was predicted to be relatively uniform compared to the airflow under other passenger cars. Both numerical results and experimental data signified that a lot of particles could drift under the T-car by showing a higher particle concentration in the central area of the space under the T-car than in the edge area. As a result, the space underneath the T-car is anticipated to be a good place for installing a dust-removal system. © 2016 American Association for Aerosol Research [ABSTRACT FROM PUBLISHER]

Low-cost sensors are effective for measuring the mass concentration of ambient aerosols and second-hand smoke in homes, but their use at concentrations relevant to occupational settings has not been demonstrated. We measured the concentrations of four aerosols (salt, Arizona road dust, welding fume, and diesel exhaust) with three types of low-cost sensors (a DC1700 from Dylos and two commodity sensors from Sharp), an aerosol photometer, and reference instruments at concentrations up to 6500 µg/m3. Raw output was used to assess sensor precision and develop equations to compute mass concentrations. EPA and NIOSH protocols were used to assess the mass concentrations estimated with low-cost sensors compared to reference instruments. The detection efficiency of the DC1700 ranged from 0.04% at 0.1 µm to 108% at 5 µm, as expected, although misclassification of fine and coarse particles was observed. The raw output of the DC1700 had higher precision (lower coefficient of variation, CV = 7.4%) than that of the two sharp devices (CV = 25% and 17%), a finding attributed to differences in manufacturer calibration. Aerosol type strongly influenced sensor response, indicating the need for on-site calibration to convert sensor output to mass concentration. Once calibrated, however, the mass concentration estimated with low-cost sensors was highly correlated with that of reference instruments (R2= 0.99). These results suggest that the DC1700 and Sharp sensors are useful in estimating aerosol mass concentration for aerosols at concentrations relevant to the workplace. © 2016 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

In many European cities mass concentrations of PM10(particles less than 10 μm in size) are still exceeding air quality standards as set by the European Commission in 1999. As a consequence, many cities introduced low emission zones (LEZs) to improve air quality and to meet the limit values. In Germany currently 48 LEZs are in operation. By means of dispersion modeling, PM10concentrations were estimated to decrease up to 10%. Analysis of PM10levels conducted for Cologne, Berlin, and Munich some time after the LEZs were introduced showed reduction of PM10mass concentration in the estimated range. The PM10particle fraction is, however, composed of particles with varying toxicity, of which diesel soot is highly health relevant. An evaluation of air quality data conducted in Berlin showed that in 2010 traffic-related soot concentrations measured along major roads decreased by 52% compared to 2007. Diesel particle emissions in Berlin were reduced in 2012 by 63% compared to a business-as-usual scenario (reference year 2007). A strong reduction of the traffic-related particle fraction of PM2.5was also reported for Munich. Therefore, it is likely that the effects of LEZs are considerably more significant to human health than was anticipated when only considering the reduction of PM10mass concentrations.Implications: The implementation of low emission zones in German cities might result in a reduction of PM10 levels concentrations by up to 10%. However, it is difficult to show a reduction of PM10 annual averages in this order of magnitude as meteorology has a large impact on the year-to-year variation of PM mass concentrations. Monitoring of other PM metrics such as black smoke (BS) or elemental carbon (EC) might be a better strategy for evaluating LEZs effects. The benefit of low emission zones on human health is far greater than is presently visible from routine measurements of PM10. [ABSTRACT FROM AUTHOR]

In studies of coarse particulate matter (PM10-2.5), mass concentrations are often estimated through the subtraction of PM2.5from collocated PM10tapered element oscillating microbalance (TEOM) measurements. Though all field instruments have yet to be updated, the Filter Dynamic Measurement System (FDMS) was introduced to account for the loss of semivolatile material from heated TEOM filters. To assess errors in PM10-2.5estimation when using the possible combinations of PM10and PM2.5TEOM units with and without FDMS, data from three monitoring sites of the Colorado Coarse Rural–Urban Sources and Health (CCRUSH) study were used to simulate four possible subtraction methods for estimating PM10-2.5mass concentrations. Assuming all mass is accounted for using collocated TEOMs with FDMS, the three other subtraction methods were assessed for biases in absolute mass concentration, temporal variability, spatial correlation, and homogeneity. Results show collocated units without FDMS closely estimate actual PM10-2.5mass and spatial characteristics due to the very low semivolatile PM10-2.5concentrations in Colorado. Estimation using either a PM2.5or PM10monitor without FDMS introduced absolute biases of 2.4 µg/m3(25%) to –2.3 µg/m3(–24%), respectively. Such errors are directly related to the unmeasured semivolatile mass and alter measures of spatiotemporal variability and homogeneity, all of which have implications for the regulatory and epidemiology communities concerned about PM10-2.5. Two monitoring sites operated by the state of Colorado were considered for inclusion in the CCRUSH acute health effects study, but concentrations were biased due to sampling with an FDMS-equipped PM2.5TEOM and PM10TEOM not corrected for semivolatile mass loss. A regression-based model was developed for removing the error in these measurements by estimating the semivolatile concentration of PM2.5from total PM2.5concentrations. By estimating nonvolatile PM2.5concentrations from this relationship, PM10-2.5was calculated as the difference between nonvolatile PM10and PM2.5concentrations. Implications:Errors in the estimation of PM10-2.5 concentrations using subtraction methods were shown to be related to the unmeasured semivolatile mass when using certain combinations of TEOM instruments. For the northeastern Colorado region, the absolute bias associated with this error significantly affects mean and 95th percentile values, which would affect assessment of compliance if PM10-2.5 is regulated in the future. Estimating PM10-2.5 mass concentrations using nonvolatile mass concentrations from collocated PM10 and PM2.5 TEOM monitors closely estimates the total PM10-2.5 mass concentrations. A corrective model that removes the described error was developed and applied to data from two sites in Denver. Supplemental Materials:Supplemental materials are available for this paper. Go to the publisher's online edition of theJournal of the Air & Waste Management Association. [ABSTRACT FROM PUBLISHER]

Surface area in addition to mass concentration is increasingly being emphasized as an important metric representing potential adverse health effects from exposure to inhaled particles. Lung-deposited surface area (SA) concentrations for a variety of aerosols: coal, biomass, cigarette, incense, candle, and TiO2 were measured using an AeroTrak 9000 (TSI Incorporated) and compared with those calculated from number size distributions from a scanning mobility particle sizer (SMPS). Three methodologies to compute the SA concentrations using the International Commission on Radiological Protection's (ICRP) Lung Deposition model and an SMPS were compared. The first method calculated the SA from SMPS size distributions, while the second method used lognormal size distribution functions. A third method generated a closed-form equation using the method of moments. All calculated SMPS SA data against which the measured SA data were compared were gen-erated using the first method only; however, the SA concentrations calculated from each of the three methods demonstrated strong correlations with each other. Overall, results between measured and calculated lung-deposited SA indicated strong positive linear associations (R² 0.78 - >0.99), moderately dependent on the type of aerosol. In all cases, the measured SA concentrations slightly underestimated those calculated from the SMPS data, with the ex-ception of coal combustion particles. Although some dependency on aerosol material exists, the instrument measuring lung-deposited SA demonstrated consistent reliability across a range of concentra-tions for a range of materials. For optimal results however, applying a correction factor (CF) before taking the instrument to the field is recommended. [ABSTRACT FROM AUTHOR]

Copyright 2013 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]