Pennsylvania State University, United States.
CGStat, 3401 Caldwell Drive, Raleigh, NC 27607, United States.
Regul Toxicol Pharmacol. 2018 Jul;96:190-196. doi: 10.1016/j.yrtph.2018.05.012. Epub 2018 May 18.
Since the London Great Smog of 1952 was estimated to have killed over 4000 people, scientists have studied the relationship between air quality and acute mortality. Currently, the association between air quality and acute deaths is usually taken as evidence for causality. As air quality has markedly improved since 1952, do contemporary datasets support this view? We use a large dataset, eight air basins in California for the years 2004-2007, to examine the possible association of ozone and PM with acute deaths after statistically removing seasonal and weather effects. Our analysis dataset is available on request. We conducted a regression-corrected, case-crossover analysis for all non-accidental deaths age 75 and older. We used stepwise regression to examine three causes of death. After seasonal and weather adjustments, there was essentially no predictive power of ozone or PM for acute deaths. The case-crossover analysis produced odds ratio very close to 1.000 (no effect). The very narrow confidence limits indicated good statistical power. We study recent air quality in both time-stratified, symmetric, bidirectional case-crossover and time series regression and both give consistent results. There is no statistically significant association between either ozone or PM and acute human mortality. In the absence of an association, causality is in question.
自 1952 年伦敦大烟雾事件估计造成超过 4000 人死亡以来，科学家们一直在研究空气质量与急性死亡率之间的关系。目前，空气质量与急性死亡之间的关联通常被视为因果关系的证据。由于自 1952 年以来空气质量有了明显改善，当代数据集是否支持这种观点？我们使用了一个大型数据集，即加利福尼亚州的 8 个空气盆地，研究了 2004-2007 年期间臭氧和 PM 与急性死亡之间可能存在的关联，方法是在统计上消除季节性和天气影响后。我们的分析数据集可应要求提供。我们对所有 75 岁及以上的非意外死亡进行了回归校正病例交叉分析。我们使用逐步回归检查了三种死因。经过季节性和天气调整后，臭氧或 PM 对急性死亡几乎没有预测能力。病例交叉分析产生的比值比非常接近 1.000（无影响）。狭窄的置信区间表明具有良好的统计能力。我们在时间分层、对称、双向病例交叉和时间序列回归中研究了最近的空气质量，两者都给出了一致的结果。臭氧或 PM 与急性人类死亡率之间没有统计学上显著的关联。在没有关联的情况下，因果关系值得怀疑。
