Leduc D, Fally S, De Vuyst P, Wollast R, Yernault J C
Chest Department, Erasme University Hospital, Brussels, Belgium.
Environ Res. 1995 Nov;71(2):89-98. doi: 10.1006/enrs.1995.1070.
Naturally occurring fogs in industrialized cities are contaminated by acidic air pollutants. In Brussels, Belgium, the pH of polluted fogwater may be as low as 3 with osmolarity as low as 30 mOsm. In order to explore short-term respiratory effects of a realistic acid-polluted fog, we collected samples of acid fog in Brussels, Belgium, which is a densely populated and industrialized city, we defined characteristics of this fog and exposed asthmatic volunteers at rest through a face mask to fogs with physical and chemical characteristics similar to those of natural fogs assessed in this urban area. Fogwater was sampled using a screen collector where droplets are collected by inertial impaction and chemical content of fogwater was assessed by measurement of conductivity, pH, visible colorimetry, high pressure liquid chromatography, and atomic absorption spectrophotometry over a period of one year. The fogwater composition was dominated by NH4+ and SO4- ions. First we evaluated the possible effect of fog acidity alone. For this purpose 14 subjects with asthma were exposed at rest for 1 hr [mass median aerodynamic diameter to a large-particle (MMAD), 9 microns] aerosol with H2SO4 concentration of 500 micrograms/m3 (pH 2.5) and osmolarity of 300 mOsm. We did not observe significant change in pulmonary function or bronchial responsiveness to metacholine. In the second part of the work, 10 asthmatic subjects were exposed to acid fog (MMAD, 7 microns) containing sulfate and ammonium ions (major ions recovered in naturally occurring fogs) with pH 3.5 and osmolarity 30 mOsm. Again, pulmonary function and bronchial reactivity were not modified after inhalation of this fog. It was concluded that short-term exposure to acid fog reproducing acidity and hypoosmolarity of natural polluted fogs does not induce bronchoconstriction and does not change bronchial responsiveness in asthmatics.
工业化城市中自然形成的雾被酸性空气污染物污染。在比利时布鲁塞尔，受污染雾水的pH值可能低至3，渗透压低至30毫渗摩尔。为了探究现实中酸污染雾对呼吸的短期影响，我们在比利时布鲁塞尔收集了酸雾样本，布鲁塞尔是一个人口密集的工业化城市，我们确定了这种雾的特征，并让哮喘志愿者通过面罩在休息状态下接触具有与该城市地区评估的自然雾相似物理和化学特征的雾。使用筛网收集器对雾水进行采样，通过惯性碰撞收集液滴，并在一年的时间里通过测量电导率、pH值、可见比色法、高压液相色谱法和原子吸收分光光度法评估雾水的化学含量。雾水成分以铵根离子和硫酸根离子为主。首先，我们单独评估了雾酸度的可能影响。为此，让14名哮喘患者在休息状态下暴露1小时 [质量中位空气动力学直径 (MMAD)，9微米] 于硫酸浓度为500微克/立方米（pH值2.5）、渗透压为300毫渗摩尔的大颗粒气溶胶中。我们未观察到肺功能或对乙酰甲胆碱的支气管反应性有显著变化。在研究的第二部分，让10名哮喘患者暴露于pH值为3.5、渗透压为30毫渗摩尔且含有硫酸根和铵根离子（天然雾中回收的主要离子）的酸雾（MMAD，7微米）中。同样，吸入这种雾后肺功能和支气管反应性未发生改变。研究得出结论，短期暴露于模拟自然污染雾酸度和低渗透压的酸雾不会诱发哮喘患者的支气管收缩，也不会改变其支气管反应性。
