Koenig J Q, Covert D S, Hanley Q S, van Belle G, Pierson W E
Department of Environmental Health, University of Washington, Seattle 98195.
Am Rev Respir Dis. 1990 Feb;141(2):377-80. doi: 10.1164/ajrccm/141.2.377.
The objective of this study was to test whether prior exposure to a low concentration of ozone (120 ppb) would condition airways in asthmatic subjects to respond to a subthreshold concentration of sulfur dioxide (100 ppb). Eight male and five female subjects 12 to 18 yr of age participated. They all had allergic asthma and exercise-induced bronchospasm. Subjects were exposed to three test atmosphere sequences during intermittent moderate exercise (a 45-min exposure to one pollutant followed by a 15-min exposure to the second pollutant). The sequences were: air followed by 100 ppb SO2, 120 ppb O3 followed by 120 ppb O3, and 120 ppb O3 followed by 100 ppb SO2. The pulmonary function measurements assessed were FEV1, total respiratory resistance (RT), and maximal flow (Vmax50). Air-SO2 and O3-O3 exposures did not cause significant changes in pulmonary function. On the other hand, exposure to 100 ppb SO2 after a 45-min exposure to 120 ppb O3 caused a significant (8%) decrease in FEV1 (p = 0.046), a significant (19%) increase in RT (p = 0.048), and a significant (15%) decrease in Vmax50 (p = 0.008). It is concluded that prior O3 exposure increased bronchial hyperresponsiveness in these subjects such that they responded to an ordinarily subthreshold concentration of SO2. These data suggest that assessment of pulmonary changes to single pollutant challenges overlooks the interactive effects of common coexisting or sequentially occurring air pollutants.
本研究的目的是测试先前暴露于低浓度臭氧（120 ppb）是否会使哮喘患者的气道产生条件反应，以应对低于阈值浓度的二氧化硫（100 ppb）。12至18岁的8名男性和5名女性受试者参与了研究。他们均患有过敏性哮喘和运动诱发的支气管痉挛。在间歇性中等强度运动期间，受试者暴露于三种测试大气序列中（先45分钟暴露于一种污染物，随后15分钟暴露于第二种污染物）。序列如下：空气后接100 ppb SO₂、120 ppb O₃后接120 ppb O₃、120 ppb O₃后接100 ppb SO₂。评估的肺功能指标为第一秒用力呼气容积（FEV₁）、总呼吸阻力（RT）和最大流量（Vmax50）。空气 - SO₂和O₃ - O₃暴露未导致肺功能发生显著变化。另一方面，在45分钟暴露于120 ppb O₃后再暴露于100 ppb SO₂，导致FEV₁显著下降（8%，p = 0.046），RT显著增加（19%，p = 0.048），Vmax50显著下降（15%，p = 0.008）。得出的结论是，先前的O₃暴露增加了这些受试者的支气管高反应性，使其对通常低于阈值浓度的SO₂产生反应。这些数据表明，对单一污染物挑战引起的肺部变化进行评估忽略了常见共存或相继出现的空气污染物的交互作用。
