School of Public Health and Family Medicine, University of Cape Town, Observatory 7925, Cape Town, South Africa.
Environ Health. 2009 Sep 25;8:45. doi: 10.1186/1476-069X-8-45.
Community concern about asthma prompted an epidemiological study of children living near a petrochemical refinery in Cape Town, South Africa. Because of resource constraints and the complexity of refinery emissions, neither direct environmental measurements nor modelling of airborne pollutants was possible. Instead a meteorologically derived exposure metric was calculated with the refinery as the putative point source. The study aimed to determine whether (1) asthma symptom prevalences were elevated compared to comparable areas in Cape Town and (2) whether there was an association between asthma symptom prevalences and the derived exposure metric.
A cross-sectional study was carried out of all consenting school children aged 11 to 14 years attending schools in a defined area, utilizing the International Study of Asthma and Allergy in Childhood (ISAAC) written and video questionnaires. Information was collected on potential confounders, e.g. parental history of atopic disease, active and passive smoking by the participant, birth order, number of children in the home and distance from a major road. The exposure metric combined residential distance of each child from the refinery with a wind vector in the form of wind speed, wind direction and proportion of the year blown.
A total of 2,361 children from 17 schools met the criteria for inclusion. In multivariate analysis, meteorologically estimated exposure (MEE), but not simple distance from the refinery, was positively associated with having to take an inhaler to school [odds ratio per interquartile range (OR) 1.22, 95% confidence interval (CI) 1.06-1.40], and with a number of video elicited asthma symptoms, including recent waking with wheezing (OR 1.33, 95% CI 1.06-1.66) and frequent wheezing at rest (OR 1.27, 95% CI 1.05 - 1.54). Symptom prevalences were higher than in other areas of the city, with frequent waking with wheezing being in great excess (OR 8.92, 95% CI 4.79-16.63).
The results support the hypothesis of an increased prevalence of asthma symptoms among children in the area as a result of refinery emissions and provide a substantive basis for community concern. The methodology also provides a low cost means of testing hypotheses about point source pollutant effects on surrounding populations of children.
社区对哮喘的关注促使南非开普敦的一项关于居住在石化炼油厂附近儿童的流行病学研究。由于资源限制和炼油厂排放的复杂性，既不能直接进行环境测量，也不能对空气污染物进行建模。相反，使用气象衍生的暴露指标来计算炼油厂作为假定的点源。该研究旨在确定（1）哮喘症状的患病率是否高于开普敦可比地区，以及（2）哮喘症状的患病率与衍生的暴露指标之间是否存在关联。
对在指定区域内就读的所有同意的 11 至 14 岁学校儿童进行了一项横断面研究，利用国际儿童哮喘和过敏研究（ISAAC）的书面和视频问卷。收集了潜在混杂因素的信息，例如父母的特应性疾病史、参与者的主动和被动吸烟、出生顺序、家中的儿童人数以及与主要道路的距离。暴露指标将每个孩子与炼油厂的距离与风速、风向和一年中风的比例等风向矢量相结合。
共有 17 所学校的 2361 名儿童符合纳入标准。在多变量分析中，气象估计暴露（MEE）而不是与炼油厂的简单距离，与上学时需要吸入器呈正相关[每四分位间距（OR）1.22，95%置信区间（CI）1.06-1.40]，并且与一些视频诱发的哮喘症状呈正相关，包括最近因哮喘而醒来（OR 1.33，95%CI 1.06-1.66）和经常在休息时哮喘（OR 1.27，95%CI 1.05-1.54）。症状的患病率高于城市的其他地区，经常因哮喘而醒来的情况更是严重超标（OR 8.92，95%CI 4.79-16.63）。
研究结果支持了这样一种假设，即由于炼油厂排放，该地区儿童哮喘症状的患病率增加，并为社区的关注提供了实质性的依据。该方法还为测试关于周围儿童人群的点源污染物影响的假设提供了一种低成本的方法。
