Delfino R J, Zeiger R S, Seltzer J M, Street D H
Epidemiology Division, Department of Medicine, University of California, Irvine, CA 92697 USA.
Environ Health Perspect. 1998 Nov;106(11):751-61. doi: 10.1289/ehp.98106751.
Experimental research in humans and animals points to the importance of adverse respiratory effects from short-term particle exposures and to the importance of proinflammatory effects of air pollutants, particularly O(subscript)3. However, particle averaging time has not been subjected to direct scientific evaluation, and there is a lack of epidemiological research examining both this issue and whether modification of air pollutant effects occurs with differences in asthma severity and anti-inflammatory medication use. The present study examined the relationship of adverse asthma symptoms (bothersome or interfered with daily activities or sleep) to O(3) and particles (less than or equal to)10 micrometer (PM10) in a Southern California community in the air inversion zone (1200-2100 ft) with high O(3) and low PM (R = 0.3). A panel of 25 asthmatics 9-17 years of age were followed daily, August through October 1995 (n = 1,759 person-days excluding one subject without symptoms). Exposures included stationary outdoor hourly PM10 (highest 24-hr mean, 54 microgram/m(3), versus median of 1-hr maximums, 56 microgram/m(3) and O(3) (mean of 1-hr maximums, 90 ppb, 5 days (greater than or equal to)120 ppb). Longitudinal regression analyses utilized the generalized estimating equations (GEE) model controlling for autocorrelation, day of week, outdoor fungi, and weather. Asthma symptoms were significantly associated with both outdoor O(3) and PM(10) in single pollutant- and co-regressions, with 1-hr and 8-hr maximum PM(10) having larger effects than the 24-hr mean. Subgroup analyses showed effects of current day PM(10) maximums were strongest in 10 more frequently symptomatic (MS) children: the odds ratios (ORs) for adverse symptoms from 90th percentile increases were 2.24 [95% confidence interval (CI), 1.46-3.46] for 1-hr PM10 (47 microgram/m(3); 1.82 (CI, 1.18-2.81) for 8-hr PM10 (36 microgram/m(3); and 1.50 (CI, 0.80-2.80) for 24-hr PM10 (25 microgram/m(3). Subgroup analyses also showed the effect of current day O(subscript)3 was strongest in 14 less frequently symptomatic (LS) children: the ORs were 2.15 (CI, 1.04-4.44) for 1-hr O(3) (58 ppb) and 1.92 (CI, 0.97-3.80) for 8-hr O(3) (46 ppb). Effects of 24-hr PM10 were seen in both groups, particularly with 5-day moving averages (ORs were 1.95 for MS and 4. 03 for LS; p(less than or equal to)0.05). The largest effects were in 7 LS children not on anti-inflammatory medications [5-day, 8-hr PM10, 9.66 (CI, 2.80-33.21); current day, 1-hr O(3), 4.14 (CI, 1.71-11.85)]. Results suggest that examination of short-term particle excursions, medication use, and symptom severity in longitudinal studies of asthma yields sensitive measures of adverse respiratory effects of air pollution.
针对人类和动物的实验研究表明，短期接触颗粒物会产生不良呼吸影响，空气污染物尤其是臭氧（O₃）具有促炎作用，这两者都很重要。然而，颗粒物平均时间尚未经过直接的科学评估，而且缺乏流行病学研究来考察这一问题以及空气污染影响是否会因哮喘严重程度和抗炎药物使用情况的不同而有所改变。本研究在南加州空气逆温层（海拔1200 - 2100英尺）一个臭氧含量高、颗粒物（PM）含量低（R = 0.3）的社区，考察了不良哮喘症状（令人烦恼或干扰日常活动或睡眠）与臭氧（O₃）和粒径小于或等于10微米的颗粒物（PM10）之间的关系。1995年8月至10月，对一组25名9至17岁的哮喘患者进行了每日跟踪（排除一名无症状受试者后，共1759人日）。暴露因素包括固定室外每小时的PM10（最高24小时均值，54微克/立方米，而1小时最大值的中位数为56微克/立方米）和臭氧（O₃）（1小时最大值的均值，90 ppb，5天中≥120 ppb）。纵向回归分析采用广义估计方程（GEE）模型，对自相关、星期几、室外真菌和天气进行了控制。在单污染物回归和共回归中，哮喘症状与室外臭氧（O₃）和PM10均显著相关，1小时和8小时的PM10最大值的影响大于24小时均值。亚组分析显示，当日PM10最大值对10名症状出现更频繁（MS）的儿童影响最强：第90百分位数增加导致不良症状的比值比（OR），1小时PM10（47微克/立方米）为2.24 [95%置信区间（CI），1.46 - 3.46]；8小时PM10（36微克/立方米）为1.82（CI，1.18 - 2.81）；24小时PM10（25微克/立方米）为1.50（CI，0.80 - 2.80）。亚组分析还显示，当日臭氧（O₃）对14名症状出现不那么频繁（LS）的儿童影响最强：1小时臭氧（O₃）（58 ppb）的OR为2.15（CI，1.04 - 4.44），8小时臭氧（O₃）（46 ppb）的OR为1.92（CI，0.97 - 3.80）。两组中均观察到24小时PM10的影响，尤其是5天移动平均值（MS组的OR为1.95，LS组为4.03；p≤0.05）。影响最大的是7名未使用抗炎药物的LS儿童[5天，8小时PM10，9.66（CI，2.80 - 33.21）；当日，1小时臭氧（O₃），4.14（CI，1.71 - 11.85）]。结果表明，在哮喘纵向研究中考察短期颗粒物波动、药物使用和症状严重程度，可得出空气污染对呼吸产生不良影响的敏感指标。
