Stieb D M, Beveridge R C, Brook J R, Smith-Doiron M, Burnett R T, Dales R E, Beaulieu S, Judek S, Mamedov A
Environmental Health Directorate, Health Canada, Ottawa, ON.
J Expo Anal Environ Epidemiol. 2000 Sep-Oct;10(5):461-77. doi: 10.1038/sj.jea.7500112.
Existing studies of the association between air pollution, aeroallergens and emergency department (ED) visits have generally examined the effects of a few pollutants or aeroallergens on individual conditions such as asthma or chronic obstructive pulmonary disease. In this study, we considered a wide variety of respiratory and cardiac conditions and an extensive set of pollutants and aeroallergens, and utilized prospectively collected information on possible effect modifiers which would not normally be available from purely administrative data. The association between air pollution, aeroallergens and cardiorespiratory ED visits (n = 19,821) was examined for the period 1992 to 1996 using generalized additive models. ED visit, air pollution and aeroallergen time series were prefiltered using LOESS smoothers to minimize temporal confounding, and a parsimonious model was constructed to control for confounding by weather and day of week. Multipollutant and multi-aeroallergen models were constructed using stepwise procedures and sensitivity analyses were conducted by season, diagnosis, and selected individual characteristics or effect modifiers. In single-pollutant models, positive effects of all pollutants but NO2 and COH were observed on asthma visits, and positive effects on all respiratory diagnosis groups were observed for O3, SO2, PM10, PM2.5, and SO4(2-). Among cardiac conditions, only dysrhythmia visits were positively associated with all measures of particulate matter. In the final year-round multipollutant models, a 20.9% increase in cardiac ED visits was attributed to the combination of O3 (16.0%, 95% CI 2.8-30.9) and SO2 (4.9%, 95%CI 1.7-8.2) at the mean concentration of each pollutant. In the final multipollutant model for respiratory visits, O3 accounted for 3.9% of visits (95% CI 0.8-7.2), and SO2 for 3.7% (95% CI 1.5-6.0), whereas a weak, negative association was observed with NO2. In multi-aeroallergen models of warm season asthma ED visits, Ascomycetes, Alternaria and small round fungal spores accounted for 4.5% (95% CI 1.8-7.4), 4.7% (95% CI 1.0-8.6) and 3.0% (95% CI 0.8-5.1), respectively, of visits at their mean concentrations, and these effects were not sensitive to adjustment for air pollution effects. In conclusion, we observed a significant influence of the air pollution mix on cardiac and respiratory ED visits. Although in single-pollutant models, positive associations were noted between ED visits and some measures of particulate matter, in multipollutant models, pollutant gases, particularly ozone, exhibited more consistent effects. Aeroallergens were also significantly associated with warm season asthma ED visits.
现有关于空气污染、空气过敏原与急诊科就诊之间关联的研究，通常考察了少数几种污染物或空气过敏原对诸如哮喘或慢性阻塞性肺疾病等个体病症的影响。在本研究中，我们考虑了多种呼吸道和心脏疾病，以及一系列广泛的污染物和空气过敏原，并利用前瞻性收集的有关可能的效应修饰因素的信息，而这些信息通常无法从单纯的行政数据中获取。我们使用广义相加模型，对1992年至1996年期间空气污染、空气过敏原与心肺急诊科就诊（n = 19,821）之间的关联进行了研究。急诊科就诊、空气污染和空气过敏原时间序列使用局部加权回归散点平滑法（LOESS）进行预滤波，以尽量减少时间混杂因素，并构建了一个简约模型来控制天气和星期几造成的混杂。使用逐步程序构建多污染物和多空气过敏原模型，并按季节、诊断以及选定的个体特征或效应修饰因素进行敏感性分析。在单污染物模型中，除二氧化氮和一氧化碳外，所有污染物对哮喘就诊均有正向影响，而臭氧、二氧化硫、可吸入颗粒物（PM10）、细颗粒物（PM2.5）和硫酸根离子（SO4(2-)）对所有呼吸道诊断组均有正向影响。在心脏疾病中，只有心律失常就诊与所有颗粒物指标呈正相关。在最后的全年多污染物模型中，在每种污染物的平均浓度下，心脏急诊科就诊增加20.9%归因于臭氧（16.0%，95%置信区间2.8 - 30.9）和二氧化硫（4.9%，95%置信区间1.7 - 8.2）的共同作用。在最后的呼吸道就诊多污染物模型中，臭氧占就诊病例的3.9%（95%置信区间0.8 - 7.2），二氧化硫占3.7%（95%置信区间1.5 - 6.0），而与二氧化氮呈微弱的负相关。在暖季哮喘急诊科就诊的多空气过敏原模型中，子囊菌纲、链格孢属和小圆形真菌孢子在其平均浓度下分别占就诊病例的4.5%（95%置信区间1.8 - 7.4）、4.7%（95%置信区间1.0 - 8.6）和3.0%（95%置信区间0.8 - 5.1），并且这些效应不受空气污染效应调整的影响。总之，我们观察到空气污染组合对心脏和呼吸道急诊科就诊有显著影响。虽然在单污染物模型中，急诊科就诊与某些颗粒物指标之间存在正相关，但在多污染物模型中，污染气体，特别是臭氧，表现出更一致的效应。空气过敏原也与暖季哮喘急诊科就诊显著相关。
