PM10 Values Research Articles

PM LEVELS IN SELECTED URBAN MICROENVIRONMENTS NEAR THE COPER SMELTER COMPLEX, BOR, SERBIA

Background: Numerous epidemiological studies have associated exposure to PM in the outdoor environment to adverse health effects. Nowadays, the attention is paid to indoor air pollution, since people spend most of time in the indoor for which there is gap of PM data. Aims: The Municipality of Bor has been the major centre for mining and processing of copper and other precious metals, assumed as hot spot with the main source of air pollution of SO2 and toxic metals and metalloids in PM. However, annual values of outdoor PM in Bor town have been reported for several years as one of the lowest in Serbia. Our study is aimed to determine the level PM in selected indoor microenvironments as hospital, kindergarten, etc. Methods: In the real-time PM10 and PM2.5 were monitored in the outdoor air with the GRIMM EDM180 while in the indoor with Turnkey OSIRIS Model 2315. For calculation calibration factors at each location during the first week of campaign a 24-h samples were collected concurrently with reference gravimetric samplers for both PM fractions. Campaigns for microenvironments were conducted in duration of 240 days covering heating and non-heating period during work-shifts days in period of 2009-2012. Results:Mean PM10 levels at Hospital and Kindergarten surpassing the EU yearly air quality standard of 40 µg/m3. The number of days that exceed the daily limit value for ambient PM10 level was calculated equal to 52% and 63% respectively. Furthermore, the measured indoor PM10 concentrations were higher than the outdoor ones at both sites. At the both microenvironment during heating period, mean daily concentrations of PM2.5 were greater than 25 µg/m3. Conclusions: Correlation coefficient between 0.33 and 0.62 show influence of outdoor to indoor PM. Mean I/O ratios were found to vary depending on the indoor activities and the outdoor concentration levels. Further research should be carried out in order to fully confirm these findings and identify sources of indoor PM.

STABILITY OF AIR POLLUTION MODELS OVER TIME: EVALUATION OF POLLUMAP MODELS FOR THE SWISS COHORT STUDY, SAPALDIA

Background: In epidemiological studies investigating long term effects of air pollution, Gaussian dispersion and land-use regression modeling are generally used. Their applications typically assume stable spatial air pollution patterns over time. This assumption, however, must be examined. The SAPALDIA (Swiss Study on Air Pollution and Lung and Heart Diseases in Adults) cohort study completed its third health survey in 2010/11 and needs to update individual air pollution exposure histories of study participants since the last survey in 2001/3. Aims: We aim to evaluate the temporal stability of the PolluMap Gaussian dispersion model (2000 and 2010) predictions of PM10 and NO2 against empirical data from fixed site monitoring stations and to interpolate the models for intermediate years. Methods: First, the temporal stability of the PolluMap models over a 10-year period is evaluated by comparing model predictions with annually averaged measurements from fixed site monitoring stations. Second, statistical models of year-to-year changes in spatial air pollution patterns, mainly driven by annual variations in meteorology are derived based on measurements from fixed monitoring stations. In combination with the PolluMap models they will be used to build high resolution spatial models for each of the intermediate years. Results: Unlike dispersion model predictions, measured PM10 and NO2 levels showed slight decreases from 2000 to 2010 (22.0±5.0 to 21.1±5.4 micrg/m3 and 25.3±11.2 to 24.2±9.6 micrg/m3, respectively). For all sites and both years combined, high correlations were obtained for PM10 (R2= 0.53, N=51) and NO2 (R2=0.72, N=103). Models seem to overestimate at high altitude locations and underestimate at traffic sites. Conclusion: The good agreement between modeled and measured values of PM10 and NO2 in 2000 and 2010 holds promise for a successful temporal interpolation of these models.

Prevention potential of daily deaths in Switzerland between 2001 and 2010 under a realistic air pollution abatement scenario

Background: Obtaining risk estimates of the association between daily mortality and PM10 on time-series data is highly informative for local policy makers. Translating this information into the health prevention potential that could have been achieved in the past can help policy-makers better understand the impications of the times-series findings. Aims: We estimated the mortality prevention potential that would have resulted from lower daily PM10 levels between 2001 to 2010 in Switzerland for a realistic air pollution abatement scenario, which assumed a constant reduction of daily PM10-levels by 20%. Methods: The prevention potential of deaths over the study period was obtained by subtracting from the daily predicted cases given by a Poisson regression model the hypothesized new cases that would have occurred under this same predictive model if the daily values of PM10 were according to the hypothesized abatement scenario. Poisson regression models were fitted with spline functions of calendar time, polynomial functions of meteorological variables and influenza frequency, and indicator variables for different days of the week and holidays. To evaluate potential latency in effects, PM10 levels in the regression model were introduced with both a 7 and a 28-day lag. Results: Considering a 7-day lag effect of PM10, we estimated that 1493 (95% CI = 735 to 2251) deaths, 0.34% of all deaths, could have been avoided in Switzerland if daily PM10 levels had been 20% lower between 2001 and 2010. When the lag effect was extended to 28 days, the corresponding preventable number were 2857 (95% CI = 1674 to 4040), corresponding to 0.66% of all deaths. Conclusion: Even small abatement strategies can result in improved public health. The prevention potential was three times larger with a 28-day lag than with a 7-day lag suggesting a potential latency of the PM10 effects over several weeks.

Association between annually locality-level exposure to PM10 and adult-onset asthma with factors related to lifestyle; extended Cox proportional hazard model

Background:A number of studies have shown PM10 is associated with asthma in adults. However, most of those conducted either without or with few factors related to lifestyle. Aims:We estimated associations between annually locality-level PM10 and adult-onset asthma with factors indicating individual lifestyles including smoking, body mass index, basic livelihood security recipient, yearly income level, moderate physical activity and educational level. Methods:We employed 2008 Korean Community Health Survey providing individual information including physician diagnosed asthma. To determine subjects’ individual exposure, annual PM10 values as community level were extracted from Annual Report of Ambient Air Quality in Korea. Applied to risk of asthma, extended Cox proportional hazards model were used in retrospective way. All subjects were thought as if they began being in follow-up simultaneously. PM exposure, age and smoking were treated as time-dependent variable. Sex and the lifestyle factors were also considered in the model. Results:The risk of PM10 was 0.992 (95% CI: 0.981-1.003) in men and 1.001 (0.992-1.011) in women while both that of age and smoking (daily average cigarettes per year) showed a statistically significant association with greater asthma onsets. BMI was positively associated in women (1.105, 1.084-1.125); however, it was negatively associated in men (0.965, 0.940-0.992). Those who received basic livelihood security service were found being in significantly higher risk of being the asthmatics. Higher yearly income level was significantly associated to lower asthma incidence. Moderate physical activity didn’t have effect on the incidence. Educational level decreased the risk of adults onset asthma among men (P for trend=0.0184). Conclusions:Although our results are not statistically significant in association of PM10 with asthma-onset in adult, we suggest a couple of lifestyle factors can affect in this association. Our study results may not avoid a bias from measurement error on the estimation of the PM10 exposure level.

Major ions in PM2.5 and PM10 released from buses: The use of diesel/biodiesel fuels under real conditions

Currently, in Brazil, it is mandatory to use the fuel blend of 95% petro diesel and 5% biodiesel (B5) for heavy-duty vehicles. However, there is a lack of information about the emissions profile of major ions from the combustion of this blend under real conditions. In this study, aerosol samples were collected at an underground bus terminal in Salvador, Brazil between April and May 2010. PM2.5 and PM10 high volume samplers were used to collect particulate matter (PM) in parallel during daytime and nighttime. Ion chromatography technique was used to determine low-molecular weight carboxylate and water-soluble inorganic ions. The results showed that the mean mass concentrations for the PM2.5 were 201±56μgm−3 during the daytime and 47±24μgm−3 at nighttime. The PM10 mass concentrations were 309±99μgm−3 and 78±47μgm−3, respectively. The mean concentrations for the total carboxylate anions in PM2.5 were 139±33ngm−3 during the day and 60±18ngm−3 at night. The corresponding values for PM10 were 180±44ngm−3 during the day and 93±15ngm−3 at night. Monocarboxylate anions (propionate, acetate and formate) were the most abundant, followed by ketocarboxylate anions (pyruvate), while the dicarboxylate anions (oxalate and malonate) were the least abundant. Mg2+ was the most important cation and NO3- the main anionic species in PM2.5, while Na+ and SO42- were the most abundant cation and anion in PM10 during the day and at night. The main sources were found to be fuel combustion and gas-to-particle conversion for PM2.5 whereas they were fuel combustion and soil resuspension for PM10. We explain some of our results considering chemical reactions occurred during fuel combustion until formation of carboxylate anions at the bus terminal. Certainly, such an approach used in this study would provide information on the atmospheric transformations of engine exhausts, vehicular emissions, and their contribution to general air pollution in Brazilian cities what would, in turn, contribute to other cities around the world.

Air Pollution: A Case Study on Suspended Air Particulate Matter at Aman Perdana, Klang, Selangor, Malaysia

This paper was aimed to determine the level of particulate matter that satisfies the requirements of Malaysia Ambient Air Quality Guidelines (MAAQG) and World Health Organization (WHO), which includes the tracing of the concentration of heavy metal in dust samples. The study of ambient air quality was conducted at Aman Perdana, Klang, Selangor, Malaysia where the sampling of each size of the PM10, PM2.5 and PM1 was conducted within three days in order to determine the concentration levels. However, the sampling of PM10 was conducted over a period of five months to determine the concentration pattern. The dust sampling was conducted to trace and determine the concentration of heavy metal in the dust. Element of heavy metal was chosen based on the first batch sample screening namely Aluminium, Arsenic, Calcium, Cadmium, Chromium, Iron, Potassium, Magnesium, Nickel, Lead and Zinc. Methodically, the dust samplings, filter digestion and tracing heavy metal were determined by using the Real Time Aerosol Monitoring System (E-Sampler), Milestone Microwave Laboratory System (ETHOS Touch Control) and Inductively Coupled Plasma Optical Emission Spectroscopy (Perkin Elmer Optima 7300 DV) respectively. The values of PM10, PM2.5 and PM1 are within the ranges of 55µg/m³ and 25µg/m³, 42µg/m³ and 20µg/m³, and 42µg/m³ and 20µg/m³ inclusive, respectively. The analysis, which reflects the important step forward in the evaluation of environmental quality, reveals that on average, concentration of the three types of aerodynamic sizes is below the permissible limit of MAAQG, however, several data exceeded the maximum allowable limit of the World Health Organization (WHO, 2005), for examples, Calcium was recorded with higher concentration of 86ppm and the lowest is Zinc 0.5ppm.

Temporal distribution of fine particulates (PM2.5, PM10), potentially toxic metals, PAHs and Metal-bound carcinogenic risk in the population of Lucknow City, India

Ubiquitous fine particulates can readily be bound to toxic metals and polycyclic aromatic hydrocarbons and are considered to be a great threat to human health. The purpose of this study was to assess the magnitude of air pollution risks to public health by determining four crucial parameters- inhalable particulates, metals in particulates and PAHs which are associated with PM10 in the air environment of Lucknow, India during 2007–09. The values of PM10 and PM2.5 ranged between 102.3–240.5 and 28.0–196.9 μg/m3 whilst the average PM10 was 1.7 times and PM2.5 was 1.5 times higher than their respective NAAQS of 100 and 60 μg/m3 respectively. The estimated relative death rate and hospital admissions for each increase in the PM10 levels of 10 μg/m3 ranged from 1.5–8% and from 3.9–8.0% (as per APHEA2 1990) respectively in persons > 65 yrs. Among the locations; AQS-1, AQS-2, and AQS-3 (with diversified activities and heavy traffic) recorded higher concentrations of both the particulate fractions than the AQS-4 (residential area with low traffic). The average concentrations of Fe, Pb, Ni, Cu, Cr, Cd in PM10 were 219.4, 40.6, 35.1, 27.3, 22.2 and 16.2 ng/m3 and that in PM2.5 were 54.3, 33.9, 38.5, 29.4, 8.4, and 1.17 ng/m3 respectively. Regression analysis revealed that correlation of metals with PM2.5 was stronger than PM10. The ratio of metals adsorbed on surface of particles (PM2.5:PM10) reveals that PM2.5 has more affinity for Ni, Cu and Pb and PM10 for Cd, Fe and Cr. Health risk due to carcinogenic metals bound to respirable particulates was predicted by estimating excess cancer risk (ECR). The highest ECR value was estimated for Cr, 266.70 × 10−6, which was associated with PM10 and 100.92 × 10−6 which was associated with PM2.5, whereas lead has the lowest ECR value. Amongst PAHs, benzo(a)pyrene (51.96±19.71 ng/m3) was maximum in PM10 samples. Maximum concentrations of PM10, PM2.5, metals and PAHs were detected during winter, and the lowest was during monsoon. The higher prevalence of diseases among the population may be due to high concentration of particulates coated with toxic metals and PAHs present in air environment.

Examining Urban Heat Island Relations to Land Use and Air Pollution: Multiple Endmember Spectral Mixture Analysis for Thermal Remote Sensing

This paper proposes an integration of Spectral Mixture Analysis and Endmember Remote Sensing Indices to derive land surface temperature (LST), to identify urban heat islands (UHI) and to investigate their relationships to land use/land cover (LULC) and air-pollution in Tabriz city, Iran. LST values are assessed from ASTER remotely sensed thermal images to appraise the intensity of UHIs through a statistical approach. The results indicate that LST is highly influenced by LULC and that UHIs are closely linked to LST and LULC. As expected, LST is sensitive to vegetation and moisture and low temperatures are found in water bodies and vegetated areas. High temperatures are related to construction zones and industrial sites which are not necessarily located in the city centre. While the results demonstrate a high correlation between UHIs and air-pollution spatial analysis discloses a different pattern: when correlating identified UHI zones with air pollution the market area of Tabriz city reveals the highest measured PM values.

Atmospheric PM10 particle concentration measurements at central and peripheral urban sites in Athens and Thessaloniki, Greece

The analysis of the PM10 particle measurements at the two major urban areas of Greece, Athens and Thessaloniki, showed that the mean monthly PM10 concentrations at the central urban stations, are on the average about twice as high than the corresponding ones at the examined peripheral stations. The distribution of the daily PM10 values shows significant violations of the EU air quality standards, especially in the central urban stations. At the peripheral stations comparable distributions of PM10 concentration values are found. The highest PM10 hourly values are recorded at the central urban stations during the cold semester of the year and during the morning hours. The scatter-plot diagrams of the central urban daily PM10 mean values versus the peripheral stations show important influence of the regional aerosol episodes on the measured PM10 concentrations in the urban areas of Athens and Thessaloniki, which is stronger in Athens and during the warm semester of the year. The PM10 diurnal variation pattern are quite similar with the corresponding variations observed for primary urban pollutants, like the morning and the evening peaks, but also at the peripheral stations exhibit a broad mid-day peak indicating elevated rural background PM10 levels. Additional daily measurements at the rural station of Aliartos in Central Greece give PM10 average values around 30 μg m-3, comparable to the corresponding average PM10 values of the peripheral stations in Athens and Thessaloniki. Such high rural background PM10 daily mean values could lead to average annual values higher than the corresponding EU PM10 standard (40 μg m-3) and should be taken into account in the formulation of the local pollution abatement strategies as they represent about the half of the average PM10 levels measured at the central urban stations of both examined urban areas.

Overview of the Temporal Variation of PM10 Mass Concentrations in the two Major Cities in Greece: Athens and Thessaloniki

Literature reports have indicated that Particulate Matter (PM) concentrations in the atmosphere over the major urban centres of Greece are high compared to other European cities of the same size. The great majority of these reports are based on measurements that have been conducted over a limited amount of time. This study provides an overview of the temporal variation that shows the trends of PM10 concentrations in the two major urban centres of Greece (Athens and Thessaloniki) during the last decade (i.e., from 2001 to 2010). Annual average PM10 concentrations at the urban monitoring stations in Athens range from 32.3 to 62.5 μg m-3, and at the suburban stations from 21.5 to 62.9 μg m-3. In Thessaloniki the respective values range from 41.7 to 70.8 μg m-3 for the urban stations, and from 23.4 to 51.5 μg m-3 for the suburban. The highest and the lowest monthly average PM10 concentrations at the urban stations in Athens are observed during the autumn/winter and the summer months, respectively. For the suburban stations the highest values are observed during the spring and the lowest during the winter. In Thessaloniki, autumn exhibits the highest and summer the lowest PM10 values both for the urban and the suburban stations.

An application of theoretical probability distributions, to the study of PM10 and PM2.5 time series in Athens, Greece

Probability density functions (pdf) have been used in the analysis of the distribution of pollutant data, for examining the frequency of high concentration events. There have been very few studies on the concentration distribution of PM in urban areas. The distribution of PM concentrations has an impact on human health effects and the setting of PM regulations. Eight probability distribution functions were fitted to measured concentrations of PM10 and PM2.5 in order to determine the shape of the concentration distribution. The “goodness-of-fit” of the probability density functions, to the data, was evaluated, using various statistical indices (including Chi-square and Kolmogorov-Smirnov tests). The evaluation was conducted for two separate years and the results indicated that the Pearson type VI pdf provided a better fit to the measured data. Other functions exhibiting high accuracy of fit were the inverse Gaussian, the lognormal and Pearson type V. The possibility to use probability density functions for predicting the daily high concentration percentiles to less than everyday sampling scenarios is also shown. The differences in the distribution of concentrations under these scenarios are important for regulatory compliance. When trying to detect the high concentrations there is significant possibility of missing the events and thus, underestimating the number of exceedances occurred. Significant deviations from actual daily measurements of PM10 and PM2.5 concentration percentiles were observed, when infrequent sampling scenarios were examined. The differences were higher for the 1-in- 6 sampling schedules and reached 2.8% for mean PM10 and 8% for PM2.5 while for the maximum concentrations the respective differences were 21.3% and 31.9%. Differences between the frequency distributions of everyday and non-everyday sampled concentrations were observed, while lognormal and inverse Gaussian functions provided a better approximation of the upper percentiles. Fitting infrequent data on continuous probability functions for the improvement of the approximation to the real statistical values provided good results regarding the 90th percentile, which corresponds to the E.U. provision of 35 annual exceedances of 24-h limit PM10 values. In the case of the extreme 98th and 99th percentiles, the method provided satisfactory results for both the PM10 infrequent sampling scenarios.

Urban Air Pollution by Nanoparticles in Ostrava Region

Air pollution harms human health and the environment. Ostrava's agglomeration and its immediate vicinity suffer regular exceeding of air pollution limits due to its geomorphologic location and present heavy industry. Maximum exceedances of air quality standards and especially PM10 which 24 hour limit value is in EU 50μg.m-3, must not be exceeded more than 35 days per year. This limit is being still often exceeded. In the year 2011 such as situation occurred 126 times. It is very important then for identify sources of air pollution to find out maximum information about air borne dust, like size distribution, chemical composition of individual size fractions, morphology of particulate matter together with other parameters like meteorological conditions, year season etc. Our measurement started two years ago. We focus on the critical situation when there are values of PM10 over a long period above the limit. In winter season it is so called inversion. By default, during the campaign it is measured size distribution of air born dust in range 5.6 nm −560nm by FMPS and using the sampler NanoId are collected samples in range 1nm – 35μm in 12 size fractions for chemical analysis and morphological observations. This contribution deals with results of size distributions only.

Atmospheric particulate matter in Nigerian megacities

The paucity of data on air pollution indices in Nigeria prompted us to commence a national screening exercise regarding particulate matter loads. Six potential megacities (Aba, Abuja, Lagos, Kano, Maiduguri, and Port-Harcourt) representing the six geographical zones in Nigeria were chosen for the study. Sampling was achieved using a ‘Gent’ stacked filter unit sampler capable of collecting fractions of particulate matter with sizes of <10-μm and <2.5-μm simultaneously. The mean values for PM10 are 550, 35, 87, 340, 246 and 130 μg m−3 while for PM2.5 the mean values are 100, 14, 25, 67, 20 and 30 μg m−3 respectively for Aba, Abuja, Lagos, Kano, Maiduguri, and Port-Harcourt. Except for Abuja, the daily PM10 mass loads exceeded the World Health Organization (WHO) guidelines daily limit where as the PM2.5 values were within the WHO guideline limit. Their correlation matrix result indicates that some PM2.5 fractions mass fractions were strongly correlated than the PM10 fractions probably due to their long range transport potentials. Further work is in progress to determine the elemental profiles of both particulate fractions collected.

THE LARGE-SCALE MAGNETIC FIELDS OF THIN ACCRETION DISKS

Large scale magnetic field threading an accretion disk is a key ingredient in the jet formation model. The most attractive scenario for the origin of such a large scale field is the advection of the field by the gas in the accretion disk from the interstellar medium or a companion star. However, it is realized that outward diffusion of the accreted field is fast compared to the inward accretion velocity in a geometrically thin accretion disk if the value of the Prandtl number Pm is around unity. In this work, we revisit this problem considering the angular momentum of the disk is removed predominantly by the magnetically driven outflows. The radial velocity of the disk is significantly increased due to the presence of the outflows. Using a simplified model for the vertical disk structure, we find that even moderately weak fields can cause sufficient angular momentum loss via a magnetic wind to balance outward diffusion. There are two equilibrium points, one at low field strengths corresponding to a plasma-beta at the midplane of order several hundred, and one for strong accreted fields, beta~1. We surmise that the first is relevant for the accretion of weak, possibly external, fields through the outer parts of the disk, while the latter one could explain the tendency, observed in full 3D numerical simulations, of strong flux bundles at the centers of disk to stay confined in spite of strong MRI turbulence surrounding them.

The fine and coarse particulate matter at four major Mediterranean cities: local and regional sources

Particulate air pollution is associated with adverse health effects to the population exposed. The aim of this paper is the identification of local and regional sources, affecting PM10 and PM2.5 levels in four large cities of southern Europe, namely: Lisbon, Madrid, Marseille, and Rome. Air pollution data from seven sampling sites of the European Union network were used. These stations were selected due to their ability of monitoring PM2.5 concentrations and providing reliable series of data. Each station’s background was also taken into account. Pearson correlation coefficients and primal component analysis components were extracted separately for cold and warm periods in order to define the relationships among particle matters (PMs) and gaseous pollutants (CO, NO2, SO2, and O3) and evaluate the contributions of local sources. Possible seasonal variations of PM2.5/PM10 ratio daily values were also used as markers of PM sources, influencing particulate size distribution. Particle emissions were primarily attributed to traffic and secondarily to natural sources. Minimum daily values of PM2.5/PM10 ratio were observed during warm periods, particularly at suburban stations with rural background, due to dust resuspension and also due to the increase of biogenic coarse PM (pollen, dust, etc.). Hybrid Single-Particle Lagrangian Integrated Trajectory Model trajectory model was used in order to compute the 4-day backward trajectories of the air masses that affected the four cities which are under study during days with recorded PM10 exceedances, within a 5-year period (2003–2007), at 300, 750, and 1,500 m above ground level (AGL). The trajectories were then divided to clusters with a K-means analysis. In all four cities, the influence of slow-moving air masses was associated with a large fraction of PM10 exceedances and with high average and maximum daily mean PM10 concentrations, principally at the 300 m AGL analysis. As far the issue of the increased PM10 concentrations, the results were weaker in Marseille and particularly in Rome, probably due to their greater distance from Northwest Africa, in comparison to Madrid and Lisbon. Dust intrusions from the Sahara desert and transportation of Mediterranean/Atlantic sea spray, were characterized as primary regional sources of exogenous PM10 in all four cities. Continental trajectories from the industrialized northern Italy affected PM10 levels particularly in Marseille and Rome, due to their more eastern geographical position.

Particulate matter concentrations, physical characteristics and elemental composition in the Milan underground transport system

An extensive measurement campaign was conducted in the Milan subway system in order to investigate PM10 concentrations, to determine its physical and elemental composition, its origins, and to attempt to quantify source contributions. The Milan subway system includes three lines and stations typically consist of two underground levels: an intermediate floor (mezzanine) where the turnstiles for accessing the platform are located, and a platform level, one floor down. Measurements were performed in two stations for each line, and both microenvironments (platform and mezzanine) were investigated in all cases. PM10 samples were collected at all twelve sites over three daily periods for nine consecutive days at each site. Particle number concentrations were also measured with Optical Particle Counters (OPC) and size-number distributions were determined. X-ray fluorescence analysis was also performed on the samples to determine element concentrations. The results indicate PM sources related with train operations as the dominant impact on particulate concentrations. Average weekday PM10 concentrations between 105 and 283 μg m−3 were observed at the platform level, while average ambient concentrations of 36 μg m−3 were observed. Fe, Ba, Sb, Mn and Cu were found to be significantly enriched. Metal particles, occurring mostly in the range of diameters between 1 and 5 μm, and therefore likely originating from mechanical processes, account for most of the PM10 mass at the platform level. Wheel, brake and track wear are found to contribute 40–73% of total PM10 mass and electric cable wear (Cu and Zn oxides) 2%–3%. Concentrations measured on the mezzanine levels are intermediate between those found in ambient air and on the platform level, with average daytime PM10 values ranging from 50 to 80 μg m−3. The situation observed on the mezzanine can well be described through an appropriate mixing of ambient and platform level air. A decreasing, albeit still significant, impact from internal sources is observed, with particulate from wheel, brake and track wear contributing an average of 2–25%, and electric cable wear 0.5–1.2%, to total PM10 mass.

When Air Quality Becomes Deleterious—A Case Study for Kigali, Rwanda

Rwanda is a landlocked republic in Equatorial Africa. The capital Kigali (1°57'S, 30°04'E) can be mentioned as a typical African city due to its rising population and the rising rate of motorization. Different pollutants produced e.g. by a highusage rate of mopeds or open fireplaces burning wood for cooking and household chores could be detected. Climatological parameters as well as air pollutants were measured within the urban area. Additionally, highly frequented spatial and temporal mobile measurements of particulate matter were taken during different dry seasons regarding different conditions. These values indicated an urban heat island, which tended to rise for the last four decades. A temporary phenomenon for the air pollution indicators is visible during clear and calm weather situations, e.g. the distinctive relief caused an accumulation within small valleys called “Marais” in the night time. Unfortunately, these are the favourite places for living and agriculture. So there is no infrequence in values of PM10 > 1.000 μg·m-3. The origin of the different airborne particles was verified by using a scanning electron microscope and it could be mentioned that most particles were from the combustion of biomass and traffic.

DEVELOPMENT OF A GARLIC BULB SEPARATOR: 2. GRADING UNIT

Grading unit is the second operation in garlic bulb separator; with a separated clove grading is necessary to further processing. A grading and cleaning unit was added to garlic bulb separator. The grading unit was developed through consecutive stages of design, fabrication and evaluation. Some physical and mechanical properties (dimensions, mass, volume, static coefficient of friction and terminal velocity) of garlic bulb that are pertinent to the mechanical processing were measured and considered in design stage of grading unit. The developed unit was evaluated at four levels of crank speed (CS) (200, 225, 250 and 275 rpm), four levels of feeding rate (FR) (233, 266, 326 and 353 kg h-1) and three levels of sieve angle (SA) (5, 10 and 20 deg.). The Evaluation was based on the following parameters: grading efficiency (GE), machine capacity (Pm), consumed energy (CE) and cost. The results recommend operating the machine at combinations of CS =225→250 rpm, SA =5→20 degrees at different FR to maximize GE value of 86.9 % - 97.8%. The grading unit capacity increased to about 2.7 times and the grading cost decreased to about 93 % comparing with manual method. The obtained results were used to introduce empirical equations to predict the values of Pm, GE and CE as a function of CS, FR and SA.

Turbulent magnetic field amplification from the smallest to the largest magnetic Prandtl numbers

The small-scale dynamo provides a highly efficient mechanism for the conversion of turbulent into magnetic energy. In astrophysical environments, such turbulence often occurs at high Mach numbers, implying steep slopes in the turbulent spectra. It is thus a central question whether the small-scale dynamo can amplify magnetic fields in the interstellar or intergalactic media, where such Mach numbers occur. To address this long-standing issue, we employ the Kazantsev model for turbulent magnetic field amplification, systematically exploring the effect of different turbulent slopes, as expected for Kolmogorov, Burgers, the Larson laws and results derived from numerical simulations. With the framework employed here, we give the first solution encompassing the complete range of magnetic Prandtl numbers, including Pm ≪ 1, Pm ∼ 1 and Pm ≫ 1. We derive scaling laws of the growth rate as a function of hydrodynamic and magnetic Reynolds number for Pm ≪ 1 and Pm ≫ 1 for all types of turbulence. A central result concerns the regime of Pm ∼ 1, where the magnetic field amplification rate increases rapidly as a function of Pm. This phenomenon occurs for all types of turbulence we have explored. We further find that the dynamo growth rate can be decreased by a few orders of magnitude for turbulence spectra steeper than Kolmogorov. We calculate the critical magnetic Reynolds number Rmc for magnetic field amplification, which is highest for the Burgers case. As expected, our calculation shows a linear behaviour of the amplification rate close to the threshold proportional to (Rm − Rmc). On the basis of the Kazantsev model, we therefore expect the existence of the small-scale dynamo for a given value of Pm as long as the magnetic Reynolds number is above the critical threshold.

Analysis of Particulate matter (PM10and PM2.5) concentration in Khorramabad city

Aims: In this study, the concentration of PM10 and PM2.5 in eight station of Khorramabad city was analyzed. Materials and Methods: For this study, the data were taken from April 2010 to March 2011. The eight sampling point were chosen in account to Khorramabad maps. During this period, 240 daily PM samples including coarse particle (PM 10 ) and fine particle (PM 2.5 ) were collected. A two-part sampler was used to collect samples of PM. According to one-way ANOVA, multiple comparisons Scheffe, the obtained data were analyzed and then compared with the Environment protection organization standard rates. Khorramabad Results: The results revealed that during measuring the maximum concentration of PM 10 and PM 2.5 was respectively 120.9 and 101.09 μ/m 3 at Shamshirabad station. There was a significant difference between the mean values of PM 10 concentration (μg/m 3 ) in the seasons of summer. In addition, the mean concentrations of PM 10 in warmer months exceeded to the maximum permissible concentration. Conclusions: Year comparison of PM 10 and PM 2.5 concentration with standard were revealed particle matter concentration in summer season was higher than standard. Although total mean of particle matter was less than standard concentration.