Avol E L, Linn W S, Shamoo D A, Anderson K R, Peng R C, Hackney J D
Environmental Health Service, Rancho Los Amigos Medical Center, Downey, California 90242.
Am Rev Respir Dis. 1990 Aug;142(2):343-8. doi: 10.1164/ajrccm/142.2.343.
Thirty-two asthmatic volunteers 8 to 16 yr of age, recruited through local schools and private physicians, were exposed in a chamber to clean air (control condition) and to sulfuric acid aerosol at a "low" concentration (46 +/- 11 micrograms/m3; mean +/- SD) and at a "high" concentration (127 +/- 21 micrograms/m3). Acid aerosols had mass median aerodynamic diameters near 0.5 microns with geometric standard deviations near 1.9. Temperature was 21 degrees C, and relative humidity was near 50%. Subjects were exposed with unencumbered oronasal breathing for 30 min at rest plus 10 min at moderate exercise (ventilation rate approximately 20 L/min/m2 of body surface). A subgroup (21 subjects) were exposed similarly to clean air and to "high" acid (134 +/- 20 micrograms/m3) with 100% oral breathing. Increased symptoms and bronchoconstriction were found after exercise under all exposure conditions. For the group, symptom and lung function responses were not statistically different during control and during acid exposures with unencumbered breathing or with oral breathing. By contrast, other investigators have reported statistically significant lung function disturbances in groups of young asthmatics exposed similarly with oral breathing. A minority of our subjects showed possibly meaningful excess bronchoconstriction with "high" acid exposure relative to control with both routes of breathing. This could be the result of chance, or it could suggest the existence of an acid-sensitive subpopulation of young asthmatics.
通过当地学校和私人医生招募了32名8至16岁的哮喘志愿者，他们在一个舱室内暴露于清洁空气（对照条件）以及“低”浓度（46±11微克/立方米；平均值±标准差）和“高”浓度（127±21微克/立方米）的硫酸气溶胶中。酸性气溶胶的质量中值空气动力学直径接近0.5微米，几何标准差接近1.9。温度为21摄氏度，相对湿度接近50%。受试者在休息时以不受限制的口鼻呼吸暴露30分钟，然后在适度运动（通气率约为20升/分钟/平方米体表面积）时暴露10分钟。一个亚组（21名受试者）以同样的方式暴露于清洁空气和“高”酸性环境（134±20微克/立方米）中，采用100%经口呼吸。在所有暴露条件下运动后均发现症状加重和支气管收缩。对于该组，在对照期间以及在不受限制的呼吸或经口呼吸的酸性暴露期间，症状和肺功能反应在统计学上没有差异。相比之下，其他研究人员报告称，在采用经口呼吸进行类似暴露的年轻哮喘患者组中，存在统计学上显著的肺功能障碍。我们的少数受试者在两种呼吸方式下，相对于对照，在“高”酸性暴露时显示出可能有意义的过度支气管收缩。这可能是偶然结果，也可能表明存在对酸敏感的年轻哮喘亚群。
