Schwartz J, Ballester F, Saez M, Pérez-Hoyos S, Bellido J, Cambra K, Arribas F, Cañada A, Pérez-Boillos M J, Sunyer J
Environmental Epidemiology Program, Harvard School of Public Health, Boston, MA 02115-6021, USA.
Environ Health Perspect. 2001 Oct;109(10):1001-6. doi: 10.1289/ehp.011091001.
Studies on three continents have reported associations between various measures of airborne particles and daily deaths. Sulfur dioxide has also been associated with daily deaths, particularly in Europe. Questions remain about the shape of those associations, particularly whether there are thresholds at low levels. We examined the association of daily concentrations of black smoke and SO(2) with daily deaths in eight Spanish cities (Barcelona, Bilbao, Castellón, Gijón, Oviedo, Valencia, Vitoria, and Zaragoza) with different climates and different environmental and social characteristics. We used nonparametric smoothing to estimate the shape of the concentration-response curve in each city and combined those results using a metasmoothing technique developed by Schwartz and Zanobetti. We extended their method to incorporate random variance components. Black smoke had a nearly linear association with daily deaths, with no evidence of a threshold. A 10 microg/m(3) increase in black smoke was associated with a 0.88% increase in daily deaths (95% confidence interval, 0.56%-1.20%). SO(2) had a less plausible association: Daily deaths increased at very low concentrations, but leveled off and then decreased at higher concentrations. These findings held in both one- and two-pollutant models and held whether we optimized our weather and seasonal model in each city or used the same smoothing parameters in each city. We conclude that the association with particle levels is more convincing than for SO(2), and without a threshold. Linear models provide an adequate estimation of the effect of particulate air pollution on mortality at low to moderate concentrations.
三大洲的研究报告了空气中颗粒物的各种指标与每日死亡人数之间的关联。二氧化硫也与每日死亡人数有关，尤其是在欧洲。关于这些关联的形式仍存在疑问，特别是在低水平时是否存在阈值。我们研究了八个具有不同气候、环境和社会特征的西班牙城市（巴塞罗那、毕尔巴鄂、卡斯特利翁、希洪、奥维耶多、巴伦西亚、维多利亚和萨拉戈萨）中黑烟和二氧化硫的日浓度与每日死亡人数之间的关联。我们使用非参数平滑来估计每个城市浓度 - 反应曲线的形状，并使用施瓦茨和扎诺贝蒂开发的元平滑技术合并这些结果。我们扩展了他们的方法以纳入随机方差成分。黑烟与每日死亡人数有近乎线性的关联，没有阈值的证据。黑烟浓度每增加10微克/立方米，每日死亡人数增加0.88%（95%置信区间，0.56% - 1.20%）。二氧化硫的关联不太合理：每日死亡人数在极低浓度时增加，但在较高浓度时趋于平稳然后下降。这些发现在单污染物模型和双污染物模型中均成立，并且无论我们是在每个城市优化天气和季节模型还是在每个城市使用相同的平滑参数都成立。我们得出结论，与颗粒物水平的关联比与二氧化硫的关联更具说服力，且没有阈值。线性模型能够充分估计低至中等浓度的颗粒物空气污染对死亡率的影响。
