scholarly journals Indoor / outdoor PM levels and EC surrogate, at typical microenvironments in the Athens area

2013 ◽  
Vol 12 (1) ◽  
pp. 12-19 ◽  
Keyword(s):  
Absorption Coefficient ◽  
Ambient Air ◽  
Ambient Atmosphere ◽  
Large Contribution ◽  
Outdoor Concentration ◽  
Measured Absorption ◽  
Athens Area ◽  
Very High ◽  
Concentration Levels ◽  
Indoor And Outdoor

The aim of the present work was to characterize particulate matter (PM) and elemental carbon (EC) indoor and outdoor concentration levels in the Athens area and to examine the contribution of ambient air to the observed indoor levels. 24-hr simultaneous indoor and outdoor PM10 and PM2.5 measurements were conducted at a central (CR) and a suburban (SR) residence, and at an office in the commercial centre of Athens (CO), during cold and warm period of 2006. The absorption coefficient (α) was measured on the collected filters, as a surrogate for EC concentration levels. Ambient PM levels were very high at both central sites and significant at SR (mean 24-hr PM10: 87.4, 50.3 and 87.3 μg m-3 and PM2.5: 50.7, 20.2 and 42.8 μg m-3 at CR, SR and CO). The measured absorption coefficient values were very high at CR and CO for both size fractions. Indoor PM concentration and absorption coefficient values were lower than the respective outdoor ones, but still significant at the two central sites. Very good correlations were observed between indoor and outdoor data (especially for absorption coefficient values), indicating a large contribution of the ambient atmosphere to the indoor levels, more pronounced in finer particles.

31. Indoor and Outdoor Concentration Levels of Airborne Fungi in Cincinnati Area Homes: Pilot Study

2005 ◽  
Author(s):  
T. Lee ◽  
D. Martuzevicius ◽  
C. Crawford ◽  
A. Adhikari ◽  
T. Reponen ◽  
...  
Keyword(s):  
Pilot Study ◽  
Airborne Fungi ◽  
Outdoor Concentration ◽  
Concentration Levels ◽  
Indoor And Outdoor

Comparison of the Structural, Optical and Thermoelectrical Properties of Ca Silicide Films with Variable Composition on Si Substrates

2018 ◽  
Vol 386 ◽  
pp. 3-8 ◽  
Author(s):  
Nikolay G. Galkin ◽  
Konstantin N. Galkin ◽  
Igor M. Chernev ◽  
Dmitrii L'vovich Goroshko ◽  
Evgeniy Anatolievich Chusovitin ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Seebeck Coefficient ◽  
Substrate Temperature ◽  
Annealing Temperature ◽  
Silicon Substrates ◽  
Constant Density ◽  
Large Contribution ◽  
Si Substrates ◽  
Growth Structure ◽  
Very High

The growth, structure, optical, electrical and thermoelectric properties of calcium silicides of various compositions on silicon substrates with (100) and (111) orientations were experimentally studied. It was found that when the atoms of Ca and Si are co-deposited on atomically clean silicon, the basis phases in the composition of the formed films depends on the substrate temperature and the annealing temperature: Ca2Si (TSi = 20°C, Tann = 330°C), CaSi (TSi = 190-320°C, Tann = 330°C) and CaSi2 (TSi = 500°C). It was established that the Ca2Si phase is a direct-gap semiconductor with a band gap of 0.82±0.02 eV, large contribution of defect levels to the absorption coefficient at energies 0.25 - 0.50 eV and huge transmission up 90% in the far IR region. In CaSi-based films the high transmission (30-40%) up to 25 μm was observed, which corresponds to a semimetal with a constant density of states near the Fermi level. It was found that CaSi-based films have the maximum Seebeck coefficient and the power factor (up to 430 μV/K and up to 1.14 × 10-6 W/(K2m), respectively) at 330K. CaSi2 films with CaSi2 lattice stretching and epitaxial ordering relative to the Si (100) substrate exhibit semimetal properties, with very high conductivity and light transparency (up 12%) in the photon energy range 0.06 - 0.65 eV.

scholarly journals Indoor and outdoor PM concenctration at a residential environment, in the Athens area

2013 ◽  
Vol 10 (2) ◽  
pp. 201-208
Keyword(s):  
Population Exposure ◽  
Air Exchange Rate ◽  
Diurnal Cycles ◽  
Indoor Sources ◽  
Limit Value ◽  
Pm10 And Pm2.5 ◽  
Outdoor Concentration ◽  
Highly Correlated ◽  
Concentration Levels ◽  
Indoor And Outdoor

The aim of the present work was to study exposure to PM in the indoor and outdoor microenvironment of a typical residence in the center of Athens. Simultaneous indoor and outdoor measurements of PM10 and PM2.5 were conducted, by the use of gravimetric and continuous samples, during October and November 2006. Moreover, air exchange rate was monitored continuously during the entire measurement period. The indoor and outdoor concentration levels were significant for both size fractions. Mean daily PM10 outdoor concentrations exceeded the E.U. 24-hr limit value for 84 % of the measured days, while the respective PM2.5 concentrations exceeded the 24-hr limit value set by the C.A.F.E. working group for 69 % of the measured days. PM10 and PM2.5 concentrations exhibited increased short-term variability with high peak concentrations during morning and afternoon/night rush hours. Indoor concentration levels seem to be mainly affected by PM of outdoor origin, since the calculated indoor-to-outdoor concentrations ratios (I/O) were much lower than 1.00 during all days and indoor and outdoor concentrations were highly correlated. This finding was also supported by the pattern of their diurnal cycles, which followed the outdoor ones, with a delay of approximately 1 hr. The results indicate increased PM concentration levels in the center of Athens, even in indoor microenvironments with no significant indoor sources and emphasize the need for a more extensive investigation of the Athens population exposure, for the protection of public health.

scholarly journals Determination of Glycol Ethers in Ambient Air by Adsorption Sampling and Thermal Desorption with GC/MS Analysis: Performance Evaluation and Field Application

2012 ◽  
Vol 9 (2) ◽  
pp. 970-979
Author(s):  
Young-Kyo Seo ◽  
Sung-Ok Baek
Keyword(s):  
Thermal Desorption ◽  
Analytical Method ◽  
Ambient Air ◽  
Industrial Area ◽  
Field Application ◽  
Ambient Atmosphere ◽  
Glycol Ethers ◽  
Ms Analysis ◽  
Sampling Campaign

Some of glycol ethers, such as 2-methoxyethanol (2-ME) and 2-ethoxyethanol (2-EE) are known to be toxic and classified as hazardous air pollutants in USA, Japan and Germany. In Korea, however, there has been no study conducted so far for these compounds in ambient air. In addition, no clear methodologies for the measurement of glycol ethers have been yet established. We carried out this study to evaluate a sampling and analytical method for the determination of glycol ethers, in ambient air samples collected in specific industrial areas of South Korea. To measure glycol ethers, adsorption sampling and thermal desorption with GC/MS analysis were used in this study. The analytical method showed good repeatability, linearity and sensitivity. The lower detection limits were estimated to be approximately 0.3∼0.5 ppb. Based on storage tests, it was suggested that samples should be analyzed within two weeks. It was also demonstrated that this method can be used for the simultaneous measurement of glycol ethers and other aromatic VOCs such as benzene, toluene, and xylenes. Field sampling campaign was carried out at 2 sites, located in a large industrial area, from October 2006 to June 2007, and a total of 480 samples were collected seasonally. Among them, 2-ME was not detected from any samples, while 2-EE and 2-Ethyloxyethylacetate (2-EEA) were found in 7 and 70 samples, respectively. The measured concentrations of 2-EE and 2-EEA for samples were ranged from 0.7-2.5 ppb and from 0.5-10.5 ppb, respectively. To our knowledge, this is the first measurement report for glycol ethers in the ambient atmosphere not only in Korea but also the rest of the world.

scholarly journals Regional Scale Impact of the COVID-19 Lockdown on Air Quality: Gaseous Pollutants in the Po Valley, Northern Italy

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 264 ◽  
Author(s):  
Giovanni Lonati ◽  
Federico Riva
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Regional Scale ◽  
High Volume ◽  
Ambient Air ◽  
Northern Italy ◽  
Traffic Emissions ◽  
Gaseous Pollutants ◽  
Po Valley ◽  
Concentration Levels

The impact of the reduced atmospheric emissions due to the COVID-19 lockdown on ambient air quality in the Po Valley of Northern Italy was assessed for gaseous pollutants (NO2, benzene, ammonia) based on data collected at the monitoring stations distributed all over the area. Concentration data for each month of the first semester of 2020 were compared with those of the previous six years, on monthly, daily, and hourly bases, so that pre, during, and post-lockdown conditions of air quality could be separately analyzed. The results show that, as in many other areas worldwide, the Po Valley experienced better air quality during 2020 spring months for NO2 and benzene. In agreement with the reductions of nitrogen oxides and benzene emissions from road traffic, estimated to be −35% compared to the regional average, the monthly mean concentration levels for 2020 showed reductions in the −40% to −35% range compared with the previous years, but with higher reductions, close to −50%, at high-volume-traffic sites in urban areas. Conversely, NH3 ambient concentration levels, almost entirely due the emissions of the agricultural sector, did not show any relevant change, even at high-volume-traffic sites in urban areas. These results point out the important role of traffic emissions in NO2 and benzene ambient levels in the Po Valley, and confirm that this region is a rather homogeneous air basin with urban area hot-spots, the contributions of which add up to a relatively high regional background concentration level. Additionally, the relatively slow response of the air quality levels to the sudden decrease of the emissions due to the lockdown shows that this region is characterized by a weak exchange of the air masses that favors both the build-up of atmospheric pollutants and the development of secondary formation processes. Thus, air quality control strategies should aim for structural interventions intended to reduce traffic emissions at the regional scale and not only in the largest urban areas.

Mechanical and optical behaviors: strain synergy effects in high temperature phase oxide of lead

2021 ◽  
Author(s):  
Qidong Kang ◽  
Fei Yang ◽  
Xinyu Zhang ◽  
Ziyu Hu
Keyword(s):  
High Temperature ◽  
Absorption Coefficient ◽  
Bulk Material ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Synergy Effects ◽  
High Absorption Coefficient ◽  
Very High ◽  
High Absorption

Since lead has a very high absorption coefficient μ, that the radiations from within the bulk material do not penetrate the layers. While, the oxygen and water (O2 and H2O)...

scholarly journals Direct Calculation of Thermodynamic Wet-Bulb Temperature as a Function of Pressure and Elevation

2013 ◽  
Vol 30 (8) ◽  
pp. 1757-1765 ◽  
Author(s):  
Sayed-Hossein Sadeghi ◽  
Troy R. Peters ◽  
Douglas R. Cobos ◽  
Henry W. Loescher ◽  
Colin S. Campbell
Keyword(s):  
Air Temperature ◽  
Mean Absolute Error ◽  
Direct Calculation ◽  
Ambient Air ◽  
Absolute Error ◽  
Mean Square ◽  
Air Temperatures ◽  
Order Polynomial ◽  
The Mean ◽  
Very High

Abstract A simple analytical method was developed for directly calculating the thermodynamic wet-bulb temperature from air temperature and the vapor pressure (or relative humidity) at elevations up to 4500 m above MSL was developed. This methodology was based on the fact that the wet-bulb temperature can be closely approximated by a second-order polynomial in both the positive and negative ranges in ambient air temperature. The method in this study builds upon this understanding and provides results for the negative range of air temperatures (−17° to 0°C), so that the maximum observed error in this area is equal to or smaller than −0.17°C. For temperatures ≥0°C, wet-bulb temperature accuracy was ±0.65°C, and larger errors corresponded to very high temperatures (Ta ≥ 39°C) and/or very high or low relative humidities (5% < RH < 10% or RH > 98%). The mean absolute error and the root-mean-square error were 0.15° and 0.2°C, respectively.

scholarly journals Evaluating the measurement interference of wet rotating-denuder–ion chromatography in measuring atmospheric HONO in a highly polluted area

2019 ◽  
Vol 12 (12) ◽  
pp. 6737-6748 ◽  
Author(s):  
Zheng Xu ◽  
Yuliang Liu ◽  
Wei Nie ◽  
Peng Sun ◽  
Xuguang Chi ◽  
...  
Keyword(s):  
Ion Chromatography ◽  
Atmospheric Chemistry ◽  
Eastern China ◽  
Ambient Air ◽  
Absorption Efficiency ◽  
Water Soluble ◽  
East China ◽  
Oh Radicals ◽  
Ambient Atmosphere ◽  
High Concentrations

Abstract. Due to the important contribution of nitrous acid (HONO) to OH radicals in the atmosphere, various technologies have been developed to measure HONO. Among them, wet-denuder–ion-chromatography (WD/IC) is a widely used measurement method. Here, we found interferences with HONO measurements by WD/IC based on a comparison study of concurrent observations of HONO concentrations using a WD/IC instrument (Monitor for AeRosols and Gases in ambient Air, MARGA) and long-path absorption photometer (LOPAP) at the Station for Observing Regional Processes of the Earth System (SORPES) in eastern China. The measurement deviation of the HONO concentration with the MARGA instrument, as a typical instrument for WD/IC, is affected by two factors. One is the change in denuder pH influenced by acidic and alkaline gases in the ambient atmosphere, which can affect the absorption efficiency of HONO by the wet denuder to underestimate the HONO concentration by up to 200 % at the lowest pH. The other is the reaction of NO2 oxidizing SO2 to form HONO in the denuder solution to overestimate the HONO concentration, which can be increased by to 400 % in denuder solutions with the highest pH values due to ambient NH3. These processes are in particularly important in polluted east China, which suffers from high concentrations of SO2, NH3, and NO2. The overestimation induced by the reaction of NO2 and SO2 is expected to be of growing importance with the potentially increased denuder pH due to the decrease in SO2. We further established a method to correct the HONO data measured by a WD/IC instrument such as the MARGA. In case a large amount WD/IC-technique-based instruments are deployed with the main target of monitoring the water-soluble composition of PM2.5, our study can help to obtain a long-term multi-sites database of HONO to assess the role of HONO in atmospheric chemistry and air pollution in east China.

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