School of Population Health M431, The University of Western Australia, Crawley WA 6009, Australia.
Int J Health Geogr. 2009 Nov 24;8:63. doi: 10.1186/1476-072X-8-63.
There is increasing evidence that residential proximity to roadways is associated with an elevated risk of asthma exacerbation. However, there is no consensus on the distance at which these health effects diminishes to background levels. Therefore the optimal, clinically relevant measure of exposure remains uncertain. Using four spatially defined exposure metrics, we evaluated the association between residential proximity to roadways and emergency department (ED) presentation for asthma in Perth, Western Australia.
The study population consisted of 1809 children aged between 0 and 19 years who had presented at an ED between 2002 and 2006 and were resident in a south-west metropolitan area of Perth traversed by major motorways. We used a 1:2 matched case-control study with gastroenteritis and upper limb injury as the control conditions. To estimate exposure to traffic emissions, we used 4 contrasting methods and 2 independently derived sources of traffic data (video-monitored traffic counts and those obtained from the state government road authority). The following estimates of traffic exposure were compared: (1) a point pattern method, (2) a distance-weighted traffic exposure method, (3) a simple distance method and (4) a road length method.
Risk estimates were sensitive to socio-economic gradients and the type of exposure method that was applied. Unexpectedly, a range of apparent protective effects were observed for some exposure metrics. The kernel density measure demonstrated more than a 2-fold (OR 2.51, 95% CI 2.00 - 3.15) increased risk of asthma ED presentation for the high exposure group compared to the low exposure group.
We assessed exposure using traffic data from 2 independent sources and compared the results of 4 different exposure metric types. The results indicate that traffic congestion may be one of the most important aspects of traffic-related exposures, despite being overlooked in many studies on the exacerbation of asthma.
越来越多的证据表明，居住场所与道路的接近程度与哮喘恶化的风险增加有关。然而，对于这些健康影响降低到背景水平的距离，目前尚无共识。因此，最佳的、临床相关的暴露测量方法仍然不确定。本研究使用四种空间定义的暴露指标，评估了西澳大利亚州珀斯市，居住场所与道路的接近程度与因哮喘而到急诊室（ED）就诊的关系。
研究人群由 1809 名年龄在 0 至 19 岁之间的儿童组成，他们在 2002 年至 2006 年间在 ED 就诊，居住在珀斯市西南部的一个大都市地区，该地区有主要的高速公路穿过。我们采用了 1:2 的病例对照研究，以肠胃炎和上肢损伤为对照条件。为了估计交通排放的暴露，我们使用了 4 种不同的方法和 2 种独立的交通数据来源（视频监测的交通流量和从州政府道路管理局获得的数据）。比较了以下交通暴露的估计值：（1）点模式法，（2）距离加权交通暴露法，（3）简单距离法和（4）道路长度法。
风险估计值对社会经济梯度和应用的暴露方法类型敏感。出乎意料的是，对于某些暴露指标，观察到了一系列明显的保护作用。核密度测量法表明，高暴露组与低暴露组相比，哮喘 ED 就诊的风险增加了两倍以上（OR 2.51，95% CI 2.00-3.15）。
我们使用来自两个独立来源的交通数据来评估暴露情况，并比较了四种不同暴露指标类型的结果。结果表明，交通拥堵可能是与交通相关的暴露的最重要方面之一，尽管在许多哮喘恶化的研究中都被忽视了。
