Schwartz J
Environmental Epidemiology Program, Harvard School of Public Health, 665 Huntington Ave, Boston MA 02115, USA.
Occup Environ Med. 2000 Oct;57(10):692-7. doi: 10.1136/oem.57.10.692.
To assess whether the association between SO(2) and daily deaths in Philadelphia during the years 1974-88 is due to its correlation with airborne particles, and vice versa.
There is a significant variation in the relation between total suspended particulate (TSP) and SO(2) in Philadelphia by year and season. Firstly, 30 separate regressions were fitted for each pollutant in the warm and cold season of each year. These regressions controlled for weather, long term temporal patterns, and day of the week. Then a meta-regression was performed to find whether the effect of SO(2) was due to TSP, or vice versa.
Controlling for TSP, there was no significant association between SO(2) and daily deaths. By contrast, in periods when TSP was less correlated with SO(2), its association with daily deaths was higher. However, all of the association between TSP and daily deaths was explained by its correlation with extinction coefficient, a measurement of the scattering of light by fine particles, which has been shown to be highly correlated with fine combustion particles in Philadelphia.
The association between air pollution and daily deaths in Philadelphia is due to fine combustion particles, and not to SO(2).
评估1974年至1988年期间费城二氧化硫（SO₂）与每日死亡之间的关联是否归因于其与空气中颗粒物的相关性，反之亦然。
费城每年和每个季节总悬浮颗粒物（TSP）与SO₂之间的关系存在显著差异。首先，针对每年温暖和寒冷季节的每种污染物进行30次单独回归分析。这些回归分析对天气、长期时间模式和星期几进行了控制。然后进行元回归分析，以确定SO₂的影响是否归因于TSP，反之亦然。
在控制TSP的情况下，SO₂与每日死亡之间没有显著关联。相比之下，在TSP与SO₂相关性较低的时期，其与每日死亡的关联较高。然而，TSP与每日死亡之间的所有关联都可以通过其与消光系数的相关性来解释，消光系数是衡量细颗粒物对光散射的指标，在费城已被证明与细燃烧颗粒物高度相关。
费城空气污染与每日死亡之间的关联归因于细燃烧颗粒物，而非SO₂。
