The environmental effects of the CNG bus program on metropolitan air quality in Korea

This study aims to analyze the effectiveness of the compressed natural gas (CNG) bus program on air quality in seven metropolitan cities in Korea. Two hundred and fifty-nine cases from monthly panel data covering June 2005 to June 2008 were analyzed. Natural and sociological characteristics in each city were included as control variables. The Chinese Air Pollution Index was also considered based on previous studies demonstrating that air quality in Korea is adversely affected by transboundary pollution from China. The relationship between five air pollutants (SO₂, NO₂, O₃, CO, and PM₁₀) and the CNG bus ratio was analyzed by panel data analysis. The key findings are as follows. CO and PM₁₀ significantly decrease with an increase in the CNG bus ratio. On the other hand, SO₂ and NO₂ demonstrate no statistically significant relationship with CNG bus ratio, while O₃ appears to have a slightly positive relationship. In addition, the results indicate that air pollution from China contributes to the increase in PM₁₀ and O₃ in Korea approximately at the threshold of 100 in Chinese Air Pollution Index. Even though introducing CNG buses can reduce the level of PM₁₀, it might be also increased due to the pollutants from China.     

Evaluation of a year-long dispersion modelling of PM10 using the mesoscale model TAPM for Christchurch, New Zealand

This paper examines the utility of The Air Pollution Model (TAPM; version 2) in simulating meteorology and dispersion of PM(10) for 1999 over the coastal city of Christchurch, New Zealand. Christchurch usually experiences severe degradation in air quality during austral winter. The formation of a nocturnal inversion layer and the emissions of particulate matter (PM(10)) mainly from solid fuel home heating appliances lead to severe smog episodes on an average of 30 nights during winter. The complex local topography surrounding the city in combination with influences from the urban areas can produce complicated boundary layer winds during quiescent weather. Simulated PM(10) data are used for construction of annual exposure maps for the urban areas in order to assess the health impact of air pollutants due to chronic exposure (presented in an accompanying paper). Meteorology and PM(10) dispersion results are statistically compared with the only permanent air pollution monitoring station available in order to evaluate the model's performance. Statistical measures such as the Index of Agreement (IOA) between modelled and measured data indicate that the model performs well. IOA is greater than 0.6 for meteorological variables, and various calculated skill scores place confidence in the model's performance. However, TAPM has a tendency to overestimate surface wind speed over urban areas during stagnant nocturnal conditions, resulting in quick flushing of pollutants.     

Particulate air pollution in urban areas of Shanghai, China: health-based economic assessment

Urban air quality is becoming a serious public health concern in China. To obtain the quantitative result of the impact of particulate air pollution on human health and the subsequent economic costs in Shanghai, we used epidemiology-based exposure-response functions to calculate the attributable number of cases due to particulate air pollution in urban areas of Shanghai in 2001, and then we estimated the corresponding economic costs of the health damage based on unit values of the health outcomes. It was estimated that the total economic cost of health impacts due to particulate air pollution in urban areas of Shanghai in 2001 was approximately 625.40 million US dollars, accounting for 1.03% of gross domestic product of the city. The results suggest that the impact of particulate air pollution on human health could be substantial in urban Shanghai, whether in physical and economic terms.     

Amenity,accessibility and housing values in metropolitan USA: A study of Salt Lake County,Utah

Negative amenities, such as air pollutions, have plagued many rapidly growing cities. However, researchers have not comprehensively examined their effects on housing values and on the local economy. These effects may be spatially auto-correlated with accessibility factors, differ in how they are dispersed over space and time, and have sizable localized effects. In this study, we use the assessed property value data and hedonic pricing models to examine consumers' underlying preferences for various amenities and accessibility factors in Salt Lake County, with a particular focus on air pollutions and forest coverage. Three models are used to address the problem of special and temporal heterogeneity. Results from ordinary least squares (OLS) regression show that single-family home values are affected not only by structural attributes, but also by urban amenities and accessibility factors such as air pollution, forest coverage, quality of public schools, and commuting cost. After controlling the covariates in spatial lag regression (SLR), we find that air pollutions and the lack of forest coverage have a significant and detrimental effect on housing values over time. Finally, results from geographically weighted regression (GWR) indicate that spatial heterogeneity is evident and that the forest coverage has more positive influences in the east side of Salt Lake County, while the negative effect of air pollutions is less pronounced on housing values in the southeast. However, air pollutions and forest cover matter irrespective of the method used.     

Interaction patterns of major air pollutants in Hong Kong territory

Air pollution in a metropolitan city like Hong Kong is a major obstacle to improve air quality and living environment due to the high population density and the vehicle emission increases. The high air pollutant levels impose harm to the human health and impair the city image. The characteristic analysis of air pollutants is very important and necessary to pollutant monitoring, forecasting and controlling. In this study, the interaction patterns of principle air pollutants, e.g. nitrogen dioxide (NO(2)), nitric oxide (NO), nitric oxides (NO(x)) and ozone (O(3)), a secondary pollutant, are investigated based on the measured database in four selected areas, which covers two urban types (i.e. residential area, mixed residential/commercial/industrial area) in Hong Kong, during the period of 1999-2001. The study involves analyzing the chemical and physical properties, the characteristics of air pollutants and the factors affecting such interactions using statistical method. The results reveal several routines in urban air pollutants' variations, interaction and trends from macro aspect.     

城市空气输送通道的布置与节约城市建设用地关系的研究

在污染源一定的条件下,城市的风(风向和风速)对城市的空气更新起着重要的作用。论述了微风条件下城市街道峡谷中的大气污染浓度变化与路面温度、街道空间结构及风等的关系。提出城市应规划顺风向的城市交通干道作为城市排气通道,其宽度、空间结构、绿化种植及路面铺装等均应以街谷内大气污染浓度快速降低为原则设置。城市应另外开辟以城市绿地为主的鲜风通道以供新鲜空气进入城市进行空气更新,并探讨了鲜风通道的布置原理和宽度计算方法;比较了不同布置形态的城市所需鲜风通道的宽度和面积的差异,得出合理的城市规划布局可以有效节省鲜风通道面积的结论。     

城市干道绿化的几个问题

城市干道已成为城市主要污染源之一。本文在论述街道空间结构及风对干道污染的影响机理的基础上，对现今城市干道绿化存在的几个问题进行了探讨；提出了干道绿化应充分考虑影响干道污染的因素，并与人工雨系统结合的建议。     

基于交通因素的日常生活圈环境健康出行 适老化研究——以南京市中心城区为例

15min生活圈能够提升老年人群健康安全的生活质量。老年人群与城市绿地的连接既依赖道路体系，又面临空气污染隐患。基于大数据与ArcGIS平台，从绿地可达性视角展开对南京市中心城区“绿-居-人”体系的空间分布研究。从健康出行视角综合判断绿地规划、可达便利与老年人群的呼吸健康。研究发现如下。1)老城区中50岁及以上的人口占比(4.23%)高于新城区(2.86%),1997年及之前的老旧小区面积占比高达64%。2)老城区有67%的居住区在绿地15min步行范围内，是新城区的2倍多。以老城区为中心向外辐射，绿地对老年人群的服务效能逐级降低。3)老城区绿地受到的道路空气污染压力约为新城区的2倍。可达性高的绿地，所受道路污染源影响也更大。主干道对绿地空气污染压力的源头供给占40%，对绿地可达性的支持达33%。提倡为老年人群出行构建健康绿色路网，满足绿地15min可达和低空气污染。研究成果对城市更新中统筹绿地、路网、居住区布局，优化生活圈适老化环境具有一定借鉴价值。     

多尺度时空PM 2.5 分布特征、影响要素、方法演进的综述及 城市规划展望

精细化治理空气污染正成为改善城 市品质的重点方向,对城市多尺度PM 2.5 时 空格局与影响要素的梳理有助于从研究和 实践层面加强规划设计对公共健康的积极 影响。本文从全国、城市、社区层面较全面 地阐述了不同时空尺度下PM 2.5 的时空格局 特征,总结了土地格局、交通网络、建成环 境、蓝绿空间等不同影响因素与城市空气中 PM 2.5 的相互关联耦合作用。同时,本文分析了不同的研究方法在精细化污染治理中的应用,指出人工智能方法在高精度尺度下的时空复 杂特征融合分析中的优势。最后,结合现有的城市PM 2.5 治理经验,对精细化目标下分时分区 的城市规划提出展望：基于提升精确度的新技术方法,优化城市空间结构,构建精细化分时 分区管理策略。     

基于分形理论和空间句法的城市形态演变研究——以福州市为例

结合GIS技术,该文提出综合分形理论和空间句法,对不断演变的城市空间形态进行定量分析和对比研究:通过计算不同时期城市建设用地分维数,对城市空间外部形态特征和拓展方式进行分析;利用空间句法解构城市空间网络,分析其内部结构的演进规律;最后,以福州市为例进行实例论证。