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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Concentrações de amônia na atmosfera na cidade de São Paulo e sua relação com a poluição veicular / Atmospheric ammonia concentrations in São Paulo city and its relation to vehicle pollution

Silva, Silmara Regina da 07 October 2015 (has links)
Este trabalho teve o objetivo de verificar a existência de correlação entre as concentrações de amônia no município de São Paulo e as concentrações dos poluentes regulamentados associados à emissão veicular. Foi testada a correlação estatística entre as concentrações de amônia e os seguintes parâmetros: fumaça, partículas inaláveis finas, monóxido de carbono, dióxido, monóxido e óxidos de nitrogênio; temperatura e umidade relativa do ar. Os dados utilizados foram fornecidos pela CETESB e medidos na Estação Pinheiros no período de abril/12 a setembro/13. Os resultados obtidos nas análises foram que as concentrações diárias de amônia variaram de 1,3 g/m³ (limite de detecção do método) a 40,0 g/m³, sendo que a média aritmética das concentrações desse período foi de 14,3 g/m³ ± 9,5 g/m³ e a mediana de 14,1 g/m³. Esse valor de média é muito próximo às encontradas em Santiago, Roma, Cidade do México, Pequim e Xian, e os maiores valores diários de amônia foram observados entre novembro/2012 e fevereiro/2013 e as concentrações médias por dia da semana apontaram uma variação entre 12,1 g/m³ a 19,0 g/m³, sendo que a maior média foi observada no domingo. Na comparação com os poluentes atmosféricos, foram observadas algumas tendências de comportamento semelhantes em determinados períodos, porém as correlações foram muito fracas. Com relação aos parâmetros meteorológicos, observou-se que quando ocorreu a máxima de temperatura, o valor de concentração de amônia também foi elevado, porém nos dias em que as concentrações de amônia foram mais altas, as máximas de temperatura não foram as mais elevadas. A correlação encontrada entre a amônia e temperatura foi muito fraca e nos dias com os maiores percentuais de umidade relativa do ar apresentaram valores baixos de concentração de amônia. Não foi possível identificar correlação significante entre concentrações de amônia em relação aos demais poluentes atmosféricos de influência veicular e aos parâmetros meteorológicos temperatura e umidade relativa do ar. Portanto, para o período estudado, as emissões veiculares não influenciaram as concentrações de amônia presentes na região de estudo. Assim, sugere-se o prosseguimento do monitoramento de amônia no ar e estudos posteriores, tendo em vista o aumento de veículos com catalisadores veiculares que podem ocasionar emissão de amônia. / The general objective of this study was to verify the existence of correlation between the ammonia concentrations in São Paulo city and the concentrations of regulated pollutants associated with vehicle emissions. The concentration of air pollutants: black smoke, fine particulate matter, carbon monoxide and nitrogen dioxide, monoxide and oxides; temperature and relative humidity were statistically tested. CETESB measured the pollutants data at Pinheiros Station from April/12 to September/13. The daily ammonia concentrations ranged from 1.3 g/m³ (method detection limit) to 40.0 g/m³ and the average concentrations of this period was 14.3 g/m³ ± 9.5 g/m³ and the median 14.1 g/m³. This average value is very close to those found in Santiago, Rome, Mexico City, Beijing and Xi\'an, the largest daily ammonia values were observed between November/2012 and February/2013, and the average concentrations by day of week pointed a variation between 12.1 to 19.0 g/m³. The highest average was observed on Sunday. In the comparison between the atmospheric pollutants and air temperature and humidity some similar trends behavior were observed in certain periods, but the correlations were very weak. It was not possible to identify a significant correlation between ammonia concentration with air pollutants vehicular influence and meteorological parameters temperature and relative humidity. Therefore, for the period studied, vehicle emissions did not affect the concentrations of ammonia present in the study area. It is suggested to continue the monitoring of ammonia in the air and further studies due to the increase of vehicles equipped with catalysts, which can cause emission of ammonia.
42

Indoor and Outdoor Air Pollution in Relation to Allergy and Asthma in Taiyuan, China

Zhao, Zhuohui January 2006 (has links)
<p>The aim was to study the prevalence of asthma, eczema, allergy and respiratory symptoms among pupils in Shanxi province, China, in relation to home and school environment and outdoor air pollution. In one study there was a low prevalence of self-reported asthma, eczema and pollen or pet allergy among pupils (9-20y). Rural childhood and consumption of fruit and fish were negatively associated with asthma or allergy, while current urban residency and consumption of hamburgers tended to be risk factors. In another study in junior high school pupils, similar low prevalence of asthma and allergy was found. Compared with pupils at the same age in Uppsala, Sweden, asthma and allergy were less common while daytime attacks of breathlessness were more common in Chinese pupils. Parental asthma or allergy was a predictor of asthma symptoms. Factors in the home environment such as new floor, new furniture and ETS exposure were risk factors for asthma symptoms. Crowdedness, dust amount, CO<sub>2</sub>, temperature and air humidity were negatively associated with respiratory symptoms. Microbial chemical components like muramic acid and ergosterol, markers for bacteria and fungi, were negatively associated with wheeze or daytime attacks of breathlessness. The associations with endotoxin varied depending on the length of 3-hydroxy fatty acids of the lippopolysaccharides (LPS). Among outdoor air pollutants, SO<sub>2</sub> and formaldehyde were positively associated with asthma symptoms or respiratory infections. In addition, indoor SO<sub>2</sub>, NO<sub>2</sub> and formaldehyde were positively associated with asthma symptoms and respiratory infections. In conclusion, rural childhood and dietary factors can be protective for asthma and allergy. ETS and chemical emissions from new material at home can be risk factors for asthmatic symptoms. In the school environment, factors of indoor origin seemed to be generally protective for respirator symptoms while factors of outdoor origin seemed to be risk factors.</p>
43

Indoor and Outdoor Air Pollution in Relation to Allergy and Asthma in Taiyuan, China

Zhao, Zhuohui January 2006 (has links)
The aim was to study the prevalence of asthma, eczema, allergy and respiratory symptoms among pupils in Shanxi province, China, in relation to home and school environment and outdoor air pollution. In one study there was a low prevalence of self-reported asthma, eczema and pollen or pet allergy among pupils (9-20y). Rural childhood and consumption of fruit and fish were negatively associated with asthma or allergy, while current urban residency and consumption of hamburgers tended to be risk factors. In another study in junior high school pupils, similar low prevalence of asthma and allergy was found. Compared with pupils at the same age in Uppsala, Sweden, asthma and allergy were less common while daytime attacks of breathlessness were more common in Chinese pupils. Parental asthma or allergy was a predictor of asthma symptoms. Factors in the home environment such as new floor, new furniture and ETS exposure were risk factors for asthma symptoms. Crowdedness, dust amount, CO2, temperature and air humidity were negatively associated with respiratory symptoms. Microbial chemical components like muramic acid and ergosterol, markers for bacteria and fungi, were negatively associated with wheeze or daytime attacks of breathlessness. The associations with endotoxin varied depending on the length of 3-hydroxy fatty acids of the lippopolysaccharides (LPS). Among outdoor air pollutants, SO2 and formaldehyde were positively associated with asthma symptoms or respiratory infections. In addition, indoor SO2, NO2 and formaldehyde were positively associated with asthma symptoms and respiratory infections. In conclusion, rural childhood and dietary factors can be protective for asthma and allergy. ETS and chemical emissions from new material at home can be risk factors for asthmatic symptoms. In the school environment, factors of indoor origin seemed to be generally protective for respirator symptoms while factors of outdoor origin seemed to be risk factors.
44

Correlation Analysis for the Influence of Air Pollutants and Meteorological Factors on Low Atmospheric Visibility in the Taipei Basin

Li, Jian-jhang 07 September 2007 (has links)
This study aims to investigate the influence of air pollutant concentration and meteorological factors on the atmospheric visibility in Taipei basin. First of all, we collected air quality data measured by ambient air quality monitoring stations of EPA (Environmental Protection Administration) and the meteorological factors monitored by Tamsui and Taipei meteorological stations separately, based on the range of three observation directions. We then analyzed the data by PCA (principal component analysis) to determine the main effective factors on atmospheric visibility under low visibility condition. In order to comprehend the spatial and temporal distribution of atmospheric visibility, we collected the atmospheric visibility data from Taipei meteorological observation stations for the past twenty-two years (1984~2005), it showed that the atmospheric visibility increased gradually. The seasonal variation of visibility was also observed, the best season was autumn (10.7 km) and the worst season was spring (7.5 km). Furthermore, according to the monthly statistical results, the visibility trends in the Taipei Basin can be separated into three typical periods: low visibility period (January to May), transitional period (June to September), high visibility period (October to December). The average atmospheric visibilities observed at the Tamsui, Songshan, and Sindian directions were 10.66 km , 9.54 km and 8.44 km, respectively. In general, the visibility at the Tamsui direction was slightly higher than those from other two directions. The results showed that atmospheric visibility was influenced not only by air pollutant levels and meteorological factors, but also affected by local topography of Taipei Basin. This study revealed that the atmospheric visibility data led on the Tamsui, Songshan observation directions is better. Four intensive observations of atmospheric visibility were conducted during March 28~April 1, July 4~8, September 19~23, and November 14~18 in the year of 2006, respectively. The results showed that the atmospheric visibilities at Tamsui direction were generally higher than other two directions. The visibilities observed in the afternoon were generally higher than those in the morning. Results obtained from the principle component analysis showed that the atmospheric visibility in the Taipei Basin were mainly influenced by PM10, NOx and CO, that mobile sources was the main cause of low visibility in the Taipei Basin. In addition, Tamsui region were affected by PM10 and SO2 more than Songshan and Sindian regions, which was influenced by neighboring industrial and the power plants. In the meteorological factors, wind speed and temperature have more influence on atmospheric visibility, however, the relationship between atmospheric visibility and relative humidity was somehow irregular. The analysis of the spatial distribution of air pollutants showed that low visibilities can not be caused only by high air pollutant concentration within the region, it may caused by the rise of air pollutant concentration in the transition region.
45

Assessment of the Emission Rate and Distribution of Volatile Organic Compounts in the Sewege System in A Metropolitan City

Li, Chia-yu 23 June 2010 (has links)
This work is study 71 kinds of volatile organic compounds (VOCs) in the sewer system of a metropolitan city during dry/wet weather. The VOCs contains alkanes, alkenes and alkynes, aromatics, chlorinated organics, sulfides, ketones and ethers. The purpose of this work estimated the emission rates of VOCs and cancer risk within 12 kinds of hazardous air pollutants (HAPs) will be part of the investigation 26 HAPs by using risk assessment. TVOCs (concentrations of total VOCs) in dry weather was higher than that in wet weather for both sewer systems. The concentration distributions of dominant were KB7 (C3) in the A (B) sewer system. This system collected sewage from harbor and industrial park. During dry and wet weather, the most common VOCs were chlorinated organics and alkanes in the A sewer system, respectively. The main contribution were chloroethene and isopentane; the most common VOCs were aromatics in the B sewer system. The main contribution was m / p-Xylene. This results show that the most emission rates of TVOCs is C3 (13,834.79 mg/hr) during dry weather and KB2 (1875.25 mg/hr) during wet weather. The emission rates of K1
46

Spatial and Temporal Characteristics of Volatile Organic Compounds and Ozone Formation Potential in Industrial Park

Lin, Jia-shiang 23 June 2011 (has links)
This study measured Ambient concentrations of air pollutants and Volatile Organic Compounds (VOCs) in industrial park in Kaohsiung City. The spatial distribution was investigated during different time periods and seasons. The ozone formation potential (OFP) of VOCs species were evaluated based on the maximum incremental reactivity (MIR). Also, this study using factor analysis to estimate the polluted source. The season distribution of air pollutants showed concentration in spring higher than summer, owing to air activities of summer are acute include wet precipitation, photochemical reaction, and convection. The time period distribution showed the results which NOx and O3 concentration occurred peaks at 7:00 − 8:00, 18:00 − 19:00 and 13:00 − 16:00, respectively. The reason is photochemical reaction, lead to concentration trend with time of NOx inversely to O3. The concentration trend with time of CO and PM10 similar to NOx. The polluted sources were estimated mobile. By the way, O3 is proportional to temperature, but it is Inversely proportional to humility. The seasons distribution of VOCs showed most abundant species included 2-butanone, toluene, and n-pentane in spring, while included toluene, acetone, m,p-xylene, and methyl methacrylate in summer. According to percent composition, most abundant categories in spring and summer were both aromatics, ketones, and alkanes. The TVOC concentration was spring (164.6 £gg/m3) higher than summer (116.4 £gg/m3). The time periods distribution of VOCs showed most abundant categories included aromatics and ketones in morning and evening, while included aromatics and alkanes in night. The TVOC concentration of evening (163.2 ¡Ó 62.7 £gg/m3) was highest, followed by night (159.9 ¡Ó 87.4 £gg/m3), Lowest was morning (98.4 ¡Ó 32.3 £gg/m3). Results showed alkanes and alkenes own higher concentration in night, ketones and esters in evening, and aromatics in evening and night. The reason is related with sunshine, inversion layer, and lower wind speed. By the way, TVOC is proportional to temperature. In spring, the OFP was 566.0 £gg-O3/m3, OFP/TVOC was 3.44. In summer the OFP was 629.3 £gg-O3/m3, OFP/TVOC was 5.41. It was worth mentioning highest OFP categories in spring and summer was both aromatics (332.2 £gg-O3/m3, 380.3 £gg-O3/m3), and highest OFP species was toluene (138.8 £gg-O3/m3) and methyl methacrylate (171.7 £gg-O3/m3) , respectively. The results from factor analyses showed the predominant source included mobile polluted source, petrol evaporation, related electronic industry, metallurgy industry, refinery, and architectural coatings escape in spring. The predominant source included mobile polluted source, petrol evaporation, plastic industry, steel industry, and related electronic industry in summer.
47

Investigations of Three Dimensional Air Flow and Pollutants Dispersion in Traffic Tunnels

Chung, Chung-Yi 04 July 2002 (has links)
ABSTRACT Three-dimensional modeling on the aerodynamics of airflow and diffusion of air pollutants in a longitudinal-ventilated traffic tunnel was carried out. The model takes ventilation fans, traffic flow rate, speed, emission factor and piston effect of moving vehicles into consideration. Turbulent flow and dispersion of gaseous pollutants in road tunnels were solved numerically using the finite volume method. Traffic emissions were accordingly modeled as banded line sources along the tunnel floor. The effects of fan ventilation, roughness and piston effect of moving vehicles on the air flow and pollutant dilution are examined. Concentrations of gaseous pollutants CO, NOX, SO2 and THC (total hydrocarbons) at three axial locations in the tunnel, together with traffic flow rate, traffic speed and types of vehicle were measured. Case study was conducted on the Cross-Harbor Tunnel and the Chungcheng Tunnel in which on-site measurements of traffic flow were also conducted concurrently to provide traffic emission data to the tunnel environment for numerical simulation and comparisons. The aim of this study was to understand the spatial variation of air pollutants generated by traffic emissions and evaluation of ventilation performance and piston effect of moving vehicles on dilution of air pollutants in these tunnels. The results show that the major emission sources of CO are passenger cars and motorcycles, while major emission sources of NOx are trucks. Pollutants convect downstream with the wind generated either by longitudinal ventilation fans and/or moving vehicles, thus causing increasing pollutants concentrations with increasing downstream distance. The piston effect of moving vehicle alone can provide 64% ~ 85% increase of wind speed in Chungchen Tunnel and 13% ~ 20% in Cross-Harbor Tunnel. When all fans are on, showing 185% ~ 328% and 120% ~ 182% increases in Chungchen Tunnel and Cross-Harbor Tunnel, respectively. The piston effect of moving vehicle alone can provide 14% ~ 32% dilution of air pollutants in the Chungcheng Tunnel. The piston effect of moving vehicles is compounded with ventilation fans, showing a 47% ~ 66% dilution effect when all fans are on. For the Cross-Harbor Tunnel, the piston effect of moving vehicle alone can provide 9% ~ 23% dilution of air pollutants and 36% ~ 74% dilution effect when all fans are on. The results reveal that cross-sectional concentrations are non-uniformly distributed and that concentrations rise with downstream distance. When all fans were turned off, wind speed in tunnels would be considered as constant, and gaseous pollutants concentration agree with linearly alone the tunnel.
48

Temporal and Spatial Variation of Gaseous Air Pollutants Monitored at Inland and Offshore Sites in Kao-Ping Area

Su, Ming-min 11 September 2007 (has links)
Air quality was influenced by many factors, in South Taiwan, air pollutants transportation caused by monsoon or sea-land breeze that may caused high air pollution events. Air pollutant generated by human activity on daytime, then transported and accumulated at sea region by land breeze during the nighttime. Unfortunately, air pollutants that accumulated over sea on night may transport back to land by sea breeze on daytime. Besides, monsoon may carry air pollutants from other regions to South Taiwan and caused high air quality event. Till now, air quality influenced by sea-land breeze and monsoon were not verified in South Taiwan. This study investigated the temporal variation and spatial distribution of air pollutants in the atmosphere around the coastal region of South Taiwan. Ambient air pollutants were simultaneously monitored both inland and offshore. Inland monitoring was conducted at two sites associated with fourteen national air quality monitoring stations, while offshore monitoring was conducted at two sites both in an island and on the boat. A protocol of ambient air quality monitoring was conducted for forty-eight hours. Gaseous air pollutants (i.e. CO, SO2, NOX, THC, and O3) were continuously monitored instrumentally. Data obtained from both inland and offshore monitoring were applied to plot the concentration contour by a software SURFER. Hourly variation of air pollutant concentrations was further used to study the influences of sea-land breezes on the transportation of air pollutants around the coastal region of South Taiwan for different seasons. In August and November, 2006 and May, 2007, sea-land breeze was observed during sampling period and sea breeze arise from 9:00 A.M. to 24:00 P.M. The average wind velocity was 1~4 m/s during the sampling period. In January and March, 2007, prevail wind direction was north direction and northeast direction (270o~30o), that was influenced by northeast monsoon during the sampling period. The average wind velocity was 2~4 m/s. The results showed that distribution of air pollutants, including O3, NOX, THC, and CO influenced by sea-land breezes, particularly for ozone. Air pollutants transported to sea region during the nighttime, and transported back at daytime. This phenomenon cause air pollutants accumulated between Kao-Ping and sea region. In general, NOX generated by transportation and industrial process, thus high concentration of NOX appeared during traffic congestion period and at industry region, mainly Kaohsiung city and Linyuang industrial region. However, sea-land breeze effect upon transportation of air pollutants wasn¡¦t obvious for SO2. High SO2 concentration appeared at Linyuang industrial region and Siaogang at daytime, and transported to region along the coast. During northeastern monsoon season, northeast winds obstructed by Central Mountain Range cause air pollutants accumulated at Kao-Ping region. High NOX concentration appeared at Kaohsiung City and Linyuang industrial region. SO2 accumulated at Siaogang and Linyuang during the nighttime might be caused by high atmospheric pressure system and blew air pollutants to Linbian. CO was accumulated at Siaogang at daytime and transported to Donggang, while THC was accumulated at Donggang whole day.
49

The effectiveness of ventilated sanders in controlling inhalable dusts during scuff sanding on military aircraft /

Patel, Kalpesh B., January 2001 (has links) (PDF)
Thesis--University of Oklahoma. / Includes bibliographical references (leaves 45-46).
50

Assessment of the performance of 3m 3500 organic vapor monitors over extended sampling durations.

Brennan, Christopher. Stock, Thomas H. Burau, Keith D. Whitehead, Lawrence William. January 2009 (has links)
Source: Masters Abstracts International, Volume: 47-06, page: 3475. Adviser: Thomas H. Stock. Includes bibliographical references.

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