Shamoo D A, Linn W S, Peng R C, Solomon J C, Webb T L, Hackney J D, Gong H
Rancho Los Amigos Medical Center, Downey, CA 90242, USA.
J Expo Anal Environ Epidemiol. 1994 Apr-Jun;4(2):133-48.
To understand the short-term health risks to people from air pollution exposure, we investigated time-activity patterns and temporal variation of the respiratory status in 49 asthmatic Los Angeles area residents 18-50 years old. During the summer (May-September) and winter (November-March), subjects measured their lung function two to four times daily at home for one week periods, and every hour recorded their symptoms, medication, and activity hourly in diaries. Almost all subjects recorded heart rates (HR), which were converted to ventilation rate (VR) estimates using individual laboratory exercise data. Most subjects' lung function and symptoms varied diurnally, and were worst in early morning. For subjects with clinically mild asthma, diurnal forced expired volume in 1 sec (FEV1) changes averaged 7%, versus 12% in those with moderate symptoms, and 18% in severely asthmatic subjects. Lung function was similar in summer and winter, but symptoms and medication use decreased in winter. In the aggregate, subjects reported spending 75% of waking hours indoors at self-rated slow activity and 11% in vehicles. HR records usually corroborated reports of medium or fast activity. Mean estimated VR at slow, medium, and fast activity was 19, 37, and 61 L/min for men, and 16, 24, and 32 L/min for women. Outdoor fast activity, representing the greatest vulnerability to outdoor pollution, occupied approximately 0.2% of waking hours (2 min/day on average); outdoor medium activity occupied about 2% of waking hours (19 min/day on average). Estimated cumulative ventilation was higher than that of previous healthy panels because of asthmatics' higher VR at slow activity. If these activity patterns are typical, asthmatics may be especially vulnerable to pollutants with effects dependent on cumulative inhaled dose. Effects dependent on high inhaled dose rates over a short period, e.g., sulfur dioxide effects, would be unlikely, except perhaps for uncommonly active individuals in uncommonly polluted areas.
为了解空气污染对人群的短期健康风险，我们调查了洛杉矶地区49名年龄在18至50岁之间的哮喘患者的时间活动模式以及呼吸状况的时间变化。在夏季（5月至9月）和冬季（11月至3月），受试者在家中每天测量肺功能两至四次，持续一周时间，并每小时在日记中记录症状、用药情况和活动情况。几乎所有受试者都记录了心率（HR），利用个人实验室运动数据将其转换为通气率（VR）估计值。大多数受试者的肺功能和症状呈现昼夜变化，且在清晨时最为严重。对于临床症状较轻的哮喘患者，1秒用力呼气量（FEV1）的昼夜变化平均为7%，中度症状患者为12%，重度哮喘患者为18%。夏季和冬季的肺功能相似，但冬季症状和药物使用有所减少。总体而言，受试者报告称清醒时间的75%是在室内进行自评的缓慢活动，11%是在车内。心率记录通常证实了中等或快速活动的报告。男性在缓慢、中等和快速活动时的平均估计通气率分别为19、37和61升/分钟，女性分别为16、24和32升/分钟。户外快速活动，即对室外污染最易受影响的活动，占清醒时间的约0.2%（平均每天2分钟）；户外中等活动占清醒时间的约2%（平均每天19分钟）。由于哮喘患者在缓慢活动时通气率较高，估计的累积通气量高于之前健康对照组。如果这些活动模式具有代表性，哮喘患者可能对那些作用取决于累积吸入剂量的污染物尤其敏感。依赖于短时间内高吸入剂量率的影响，例如二氧化硫的影响，可能不太可能，除非在污染特别严重地区有异常活跃的个体。
