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1.
The objective of this study was to identify spatial variability in exposure to outdoor traffic-related air pollution with specific emphasis on comparing exposure estimates for working females and males across a metropolitan area. A spatial exposure simulation model was used to estimate annual average exposure to traffic-related nitrogen dioxide for males and females reporting regular work in census tracts other than that of their residence, in Vancouver, British Columbia. The model produced estimates of annual average exposure in six microenvironments (home indoor, work indoor, other indoor, outdoor, in-vehicle to work, and in-vehicle other) using time-activity patterns and work flow data, for males and females in each of 382 census tracts. This allowed for the identification of spatial variations in exposure estimates for each gender, due to mobility within the study region. Indoor sources of nitrogen dioxide were not included in the simulation. No significant differences in estimated total exposure were found between working females and males in general. Small but observable spatial differences, however, were found between working females and males at the 90th percentile of the exposure distributions associated specifically with the work indoor microenvironment. These were highest in suburban areas (+3 μ g/m3 for females, relative to total exposures in the range of 26 to 37 μ g/m3 annual average hourly nitrogen dioxide). These results identify specific geographic locations in the study area where personal monitoring studies might be warranted and suggest that the inclusion of workplace locations in multivariate modeling could be useful to further understand differences in estimated exposures.  相似文献   
2.
中国人发砷背景值及其区域分布特征   总被引:10,自引:0,他引:10  
本文作者在全国不同自然地理类型区选择100余县近200个采样点,采样点在远离城镇的非污染地区,采集当地居民发样1313份,用氢化物原子荧光法测定砷含量。测定数据进行计算机统计,结果表明,中国人发中砷含量在0.004-9.999μg/g之间,中位值为0.56μg/g,算术平均值为0.927±1.213μg/g,几何平均值为0.571μg/g。性别和年龄差别不明显。皮尔逊(Pelson)x2法和W检验法检验结果表明,在同一自然地理区,人发砷含量呈对数正态分布。中国人发砷的地理分布呈南方高,北方低,自北而南逐渐递增的规律。人发砷的几何均值在北方中温带地区为0.2-0.4μg/g之间,到暖温带升高到0.4-0.6μg/g,至北亚热带则达到0.767μg/g,而到中亚热带以南则高达1μg/g以上。在同一自然地理带内,东西间差异不明显,青藏地区亦属发砷低含量区(几何均值0.267μg/g)。并依此对我国划分慢性砷中毒区的人发指标进行了讨论。  相似文献   
3.
目的:观察化脓灸联合胸腺五肽注射液治疗稳定期慢性阻塞性肺疾病(COPD)的临床疗效。方法:将稳定期COPD患者80 例随机分为治疗组和对照组,每组各40 例。2组均给予基础治疗,对照组加用胸腺五肽注射液治疗,治疗组在对照组治疗的基础上联合化脓灸治疗,治疗3个月后比较2组中医证候疗效,肺功能[第1秒用力呼气容积(FEV1)、用力肺活量(FVC)、FEV1/FVC],血气分析指标[动脉血氧分压(PaO2)、二氧化碳分压(PaCO2)]变化,以及疗程结束后随访1年的急性加重人均次数。结果:中医证候疗效总有效率治疗组为92.50%(37/40),对照组为62.50%(25/40),组间比较,差异有统计学意义(P<0.01);2组FEV1、FVC、FEV1/FVC、PaO22、PaCO2治疗前后组内组间比较及治疗后组间比较,差异均有统计学意义(P<0.01或P<0.05);随访1年急性发作人均次数2组组间比较,差异有统计学意义(P<0.05)。结论:化脓灸联合胸腺五肽注射液治疗COPD,能缓解中医症状,改善肺功能及血气分析指标,减少急性发作次数,值得临床推广应用。  相似文献   
4.
林琳  严程棋  杨莹  范艺馨  吴箐 《热带地理》2020,40(6):993-1003
基于广州13个社区问卷调查数据,运用多元线性回归模型探讨老年人“旁路”就医距离特征及其影响因素,结果发现:1)广州老年人小病及慢性病旁路就医距离以1 km为“就地—旁路”临界点,以5 km为“近旁路—远旁路”临界点,形成核心—边缘旁路就医圈层;2)男性老年人比女性老年人旁路就医距离更远;3)居住社区类型是影响旁路就医距离的关键因素,医疗级配不均对旁路就医距离远近影响较大,也是城乡社区老年人旁路就医距离差异化的重要原因;4)对社区越满意的老年人更倾向选择社区内就地就医。倾向特征、使能资源和医疗需求共同影响老年人旁路就医行为的距离远近,进而影响老年人健康公平结果。  相似文献   
5.
目的:结合多普勒超声心动图对比分析胸部CT平扫在慢性阻塞性肺病(COPD)合并肺动脉高压(PAH)分级上的诊断价值。方法:回顾性分析100例经多普勒超声心动图检查确诊、分级的COPD合并PAH患者的胸部CT平扫资料,测量CT所示的主肺动脉直径、右肺动脉直径及左肺动脉直径,并与30例未发生PAH的COPD患者的上述胸部CT平扫资料对比,分析它们与PAH分级的关系,并进行统计学分析。结果:100例COPD并PAH患者中,经超声心动图确诊为轻度PAH 57人,中度PAH 27例,重度PAH 16例。上述三组PAH患者CT上所测量的主肺动脉直径,方差分析得出三者间的差别有统计学意义,两两比较发现:轻度组PAH的主肺动脉直径与中度组PAH的主肺动脉直径有统计学差异(P=0.017);轻度组PAH的主肺动脉直径与重度组PAH的主肺动脉直径有统计学差异(P=0.000);中度组PAH的主肺动脉直径与重度组PAH的主肺动脉直径有统计学差异(P=0.031);轻度组PAH的主肺动脉直径中度组PAH的主肺动脉直径重度组PAH的主肺动脉直径。轻度PAH的主肺动脉直径约为29.71 mm±3.57 mm,最佳诊断阈值是29.11 mm;中度PAH的主肺动脉直径约为31.77 mm±3.44 mm,最佳诊断阈值是30.53 mm;重度PAH的主肺动脉直径约为34.28 mm±4.14 mm,最佳诊断阈值是32.00 mm。结论:胸部CT平扫通过测量主肺动脉直径对COPD并PAH的分级具有一定的诊断价值。  相似文献   
6.
用四氯化碳导致小鼠肝损伤,各组每日灌胃不同剂量螺旋藻,检测了饲养45d的小鼠血清的ALT活力、肝组织的SOD活力和MDA含量,分别建立ALT、SOD活力以及MDA含量随剂量(C)变化的函数,求出各项临界参数值,并对参数的生物学意义进行解释,以观察螺旋藻对肝损伤小鼠肝组织中SOD活力和MDA的影响.实验结果显示:螺旋藻能提高小鼠SOD的活力并降低其MDA含量,进一步验证了螺旋藻可提高肝损伤小鼠肝组织的抗氧化能力,分析结果还显示螺旋藻对肝组织抗氧化能力的提高既具有一定的量效累积性,也存在量效局限性.  相似文献   
7.
本研究采用静水实验法,在水温21℃、盐度30、pH8.10条件下,分析了水体氨氮对海月水母(Aurelia coerulea)螅状体以及碟状体的急性毒性作用,并且探讨了慢性氨氮胁迫对海月水母螅状体无性生殖的影响。急性毒性实验结果显示,氨氮毒性效应与浓度和胁迫时间呈正相关,氨氮对螅状体24、48、72、96h半致死浓度分别为225.60、164.26、62.67和25.44mg/L,氨氮对碟状体24、48、72、96h半致死浓度分别为49.96、31.53、24.54和21.43mg/L,螅状体与碟状体的总氨氮安全浓度分别为2.54和2.14mg/L,非离子氨安全浓度分别为0.13和0.11mg/L。慢性氨氮毒性实验显示,实验组螅状体产生的子代螅状体数少于对照组,而随着胁迫时间延长,螅状体繁殖子体的速率恢复至对照组水平。研究结果表明,氨氮对海月水母具有毒性作用,富营养化水体中氨氮含量升高不是海月水母暴发的直接原因;此外,海月水母螅状体可能具有一定的适应慢性氨氮胁迫的自我调节能力。  相似文献   
8.
目的:探讨糜烂性胃炎(CEG)中年人群不同中医健康状态、幽门螺杆菌(Hp)感染情况及胃镜下不同表现之间的关系。方法:选取78 例CEG患者,对患者的一般资料、中医健康状态、Hp感染情况以及胃镜下表现进行采集,将资料进行整理归纳,并进一步统计分析。结果:78 例患者中,已病态的病性要素为痰者有35 例,为湿者有29 例,为气虚者有14 例。不同中医健康状态已病要素间患者糜烂形态比较,差异有统计学意义(P<0.05),发生平坦型糜烂者气虚要素占比最高(100%),发生隆起型糜烂者痰要素占比最高(25.7%)。不同中医健康状态已病要素间患者在年龄、性别及Hp感染率间比较,差异无统计学意义(P>0.05)。结论:CEG患者不同中医健康状态与胃镜下糜烂形态间存在一定相关性,可为糜烂性胃炎人群的健康状态辨识提供证据,为临床治疗及用药选择提供依据。  相似文献   
9.
It is widely recognized that high supplies of fine sediment, largely sand, can negatively impact the aquatic habitat quality of gravel‐bed rivers, but effects of the style of input (chronic vs. pulsed) have not been examined quantitatively. We hypothesize that a continuous (i.e. chronic) supply of sand will be more detrimental to the quality of aquatic habitat than an instantaneous sand pulse equal to the integrated volume of the chronic supply. We investigate this issue by applying a two‐dimensional numerical model to a 1 km long reach of prime salmonid spawning habitat in central Idaho. Results show that in both supply scenarios, sand moves through the study reach as bed load, and that both the movement and depth of sand on the streambed mirrors the hydrograph of this snowmelt‐dominated river. Predictions indicate greater and more persistent mortality of salmonid embryos under chronic supplies than pulse inputs, supporting our hypothesis. However, predicted mortality varies both with salmonid species and location of spawning. We found that the greatest impacts occur closer to the location of the sand input under both supply scenarios. Results also suggest that reach‐scale morphology may modulate the impact of sand loads, and that under conditions of high sand loading climate‐related increases in flow magnitude could increase embryo mortality through sand deposition, rather than streambed scour. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
10.
In the decades since dramatic reductions in acid emissions and subsequent deposition in North America and Europe, the vast majority of research on aquatic chemical recovery has focused on trends in acid–base concentrations during baseflow conditions. Missing from such assessments is consideration of higher flow periods, when flow paths and chemical concentrations change and episodic acidification may occur. Stream samples collected weekly and bi‐hourly during high‐flow storm events from 1992 to 2015 at three watersheds representing a gradient in response to acid deposition in the south‐eastern United States were used to evaluate temporal trends in acid anions, base cations, acid neutralizing capacity (ANC), and pH for each of five distinct flow exceedance regimes, as well as trends in concentration–discharge (C–Q) relationships. For the most well‐buffered watershed (mean ANC = 220 μeq L?1), ANC and pH increased at a similar rate for baseflow and storm flow conditions. Decreases in sulfate controlled ANC trends at higher flows, whereas smaller sulfate decreases in combination with base cation increases resulted in similar ANC improvements for low‐flow periods. For the most acid sensitive watershed (mean ANC = 10 μeq L?1), no trends in ANC or pH were observed for the lowest flows (>90% flow exceedance), whereas reductions in sulfate resulted in significant increases in ANC during higher flow conditions. At all sites, greater rates of sulfate decline during high‐flow, as compared with low‐flow, conditions are likely a result of a reduced capacity of near surface soils to adsorb and retain sulfur in these non‐glaciated watersheds. Overall, consistent increases in pH (~0.01–0.02 pH units year?1) during higher flow conditions (<10% flow exceedance) in contrast to the variable trends observed during lower flows (>50% flow exceedance) illustrate that episodic acidification is recovering at an equal or greater rate than chronic acidification in these watersheds.  相似文献   
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