The influence of neighborhood traffic density on the respiratory health of elementary schoolchildren

Background

Several studies have found that living near major roadways is associated with an increase in respiratory illness but few studies have measured the volume and type of traffic.

Objective

We investigated the relation between traffic volume and respiratory health of 2328 children 9 to 11 years old in the city of Windsor, Canada.

Methods

We identified the roadways within a 200 meter radius of the child's neighborhood using the latitude and longitude of the residential postal code. Traffic exposure was defined as the sum of the annual volume of vehicles on all of these roadways. Volume was calculated using sensors to detect passing vehicles (simple traffic counts), and by counts and direction of traffic at intersections (turning movement counts). Ventilatory lung function was measured by spirometry and airway inflammation by exhaled nitric oxide (eNO).

Results

The odds ratio between an interquartile increase in truck turning movement counts and chest congestion was 1.20 (1.06-1.35). The percentage of predicted FVC declined 0.68%, (95% CI 1.32, 0.03) for an interquartile increase in simple traffic counts (33,787 vehicles daily). Among those with self-reported asthma, effect sizes were larger. Percentage predicted FEV₁ declined 1.84% (95% CI 0.07, 3.61) associated with an interquartile range increase in turning movement counts. No statistically significant change was detected between traffic measures and exhaled nitric oxide.

Conclusions

Our findings provide further support for the hypothesis that neighborhood exposure to traffic-related air pollution increases respiratory symptoms and reduces ventilatory function in children, especially those with self-reported asthma.     

Fog as a Fresh-Water Resource: Overview and Perspectives

The collection of fog water is a simple and sustainable technology to obtain fresh water for afforestation, gardening, and as a drinking water source for human and animal consumption. In regions where fresh water is sparse and fog frequently occurs, it is feasible to set up a passive mesh system for fog water collection. The mesh is directly exposed to the atmosphere, and the foggy air is pushed through the mesh by the wind. Fog droplets are deposited on the mesh, combine to form larger droplets, and run down passing into a storage tank. Fog water collection rates vary dramatically from site to site but yearly averages from 3 to 10 l m⁻² of mesh per day are typical of operational projects. The scope of this article is to review fog collection projects worldwide, to analyze factors of success, and to evaluate the prospects of this technology.     

国家湿地公园时空格局特征

采用标准差椭圆、点模式分析、统计分析等方法,运用ArcGIS可视化技术,从时间和空间视角分析国家湿地公园的空间格局特征,并探究其与城市的区位关系。研究表明：（1）国家湿地公园在时间序列上分为试点起步阶段、发展与成长阶段和规范发展阶段,各地发展不均衡,“质”的发展不同步于“量”,正式国家湿地公园处于规范发展的起步时期;（2）多尺度空间研究表明正式国家湿地公园空间以聚集分布形态为主,随机分布为辅,整体呈东北—西南分布格局,形成2个高密度热点区和3个中密度次热点区;（3）从城市尺度看,正式国家湿地公园呈现较大空间异质性,具有偏向城市规划区内或靠近城市规划区分布的特征;（4）正式国家湿地公园呈现为人口格局主导特征,响应了胡焕庸线的指导意义。     

CFD-based simulation of dense gas dispersion in presence of obstacles

Quantification of spatial and temporal concentration profiles of vapor clouds resulting from accidental loss of containment of toxic and/or flammable substances is of great importance as correct prediction of spatial and temporal profiles can not only help in designing mitigation/prevention equipment such as gas detection alarms and shutdown procedures but also help decide on modifications that may help prevent any escalation of the event.The most commonly used models - SLAB (Ermak, 1990), HEGADAS (Colenbrander, 1980), DEGADIS (Spicer & Havens, 1989), HGSYSTEM (Witlox & McFarlane, 1994), PHAST (DNV, 2007), ALOHA (EPA & NOAA, 2007), SCIPUFF (Sykes, Parker, Henn, & Chowdhury, 2007), TRACE (SAFER Systems, 2009), etc. - for simulation of dense gas dispersion consider the dispersion over a flat featureless plain and are unable to consider the effect of presence of obstacles in the path of dispersing medium. In this context, computational fluid dynamics (CFD) has been recognized as a potent tool for realistic estimation of consequence of accidental loss of containment because of its ability to take into account the effect of complex terrain and obstacles present in the path of dispersing fluid.The key to a successful application of CFD in dispersion simulation lies in the accuracy with which the effect of turbulence generated due to the presence of obstacles is assessed. Hence a correct choice of the most appropriate turbulence model is crucial to a successful implementation of CFD in the modeling and simulation of dispersion of toxic and/or flammable substances.In this paper an attempt has been made to employ CFD in the assessment of heavy gas dispersion in presence of obstacles. For this purpose several turbulence models were studied for simulating the experiments conducted earlier by Health and Safety Executive, (HSE) U.K. at Thorney Island, USA (Lees, 2005). From the various experiments done at that time, the findings of Trial 26 have been used by us to see which turbulence model enables the best fit of the CFD simulation with the actual findings. It is found that the realizable k-? model was the most apt and enabled the closest prediction of the actual findings in terms of spatial and temporal concentration profiles. It was also able to capture the phenomenon of gravity slumping associated with dense gas dispersion.     

安全标志的标准化生产使用及检验标准

就国内企业在安全标志的选材、制作、检验使用中存在的一些问题,提出了一些针对性较强同时具备可操作性的措施和方法,以便于生产企业和使用单位进一步规范其制作和使用安全标志的标准,使安全标志真正成为为企业传递安全信息的载体.     

标准加入法在原子吸收光度法中的应用

介绍了原子吸收光度法中的光谱干扰和非光谱干扰，指出标准加入法和分析校准曲线法是消除和减少某些干扰最简单、快速的校准方法。在标准加入法中，当分析曲线呈线性时，表明分析结果可信，当分析曲线不呈线性，表明方法灵敏度随质量浓度变化而变化，分析结果的准确性有问题。以改变基体的质量浓度和在同一质量浓度的基体溶液中加入不同量的标准两个实验可以验证标准加入法在原子吸收光度法中的适用性。     

氮氧化物减排博弈行为研究

针对我国氮氧化物减排的严峻形势,文章借鉴瑞典氮氧化物减排的税收返还制度,运用进化博弈的理论和方法,建立了政府与企业关于氮氧化物减排的进化博弈模型,并进行了求解分析。结果表明:策略(减排,税收返还制度)和策略(减排,标准减排制度)都可以是稳定均衡策略,即无论政府采取税收返还制度还是标准减排制度,只要对惩罚系数、税率等参数进行调整都能迫使企业进行氮氧化物减排。但通过模拟可知税收返还制度对企业的激励作用更大,可以促使企业长期持续的进行氮氧化物减排。     

催化分光加入标准法测定复杂基体水样中痕量汞的研究

采用催化分光标准加入法测定复杂组分水样中痕量Hg^2＋，线性范围为3．0×10^-3mg／L-8．0×10^-2mg／L，加标回收率为96．7％～103％，相对标准偏差为0．2％。该方法设备简单，操作简便可行，灵敏度、准确度高。     

劳动安全卫生标准体系编制探讨

阐述了劳动安全卫生标准体系研究的目的与意义,分析比较了劳动安全卫生标准分类的几种可能方案,着重讨论并提出整个劳动安全卫生标准体系的层次结构方框图。     

Plant phenology in Germany over the 20th century

Analysis of observational phenological data has indicated that the length of the vegetation period (VP), here defined as the time between leaf onset and leaf colouring (LC), has increased in the last decades in the northern latitudes mainly due to an advancement of bud burst. Analysing the patterns of spring phenology over the last century (1880–1999) in Southern Germany showed that the strong advancement of spring phases, especially in the decade before 1999, is not a singular event in the course of the 20th century. Similar trends were also observed in earlier decades. Distinct periods of varying trend direction for important spring phases could be distinguished. Marked differences in trend direction between early and late spring phases were detected, which can be explained by different trends in March and April mean temperatures. The advancement of spring phenology in recent decades is part of the multi-decadal fluctuations over the 20th century that vary with the species and the relevant seasonal temperatures. However, for all Natural Regions in Germany, spring phases were advanced by about 5–20 days on average between 1951 and 1999, LC was delayed between 1951 and 1984, but advanced after 1984 for all considered tree species and the length of the VP increased between 1951 and 1999 for all considered tree species by an average of 10 days throughout Germany.