National School of Public Health, Carlos III Institute of Health, Madrid, Spain.
Environ Health. 2012 Mar 8;11:11. doi: 10.1186/1476-069X-11-11.
Saharan dust intrusions are a common phenomenon in the Madrid atmosphere, leading induce exceedances of the 50 μg/m(3)--EU 24 h standard for PM10.
We investigated the effects of exposure to PM(10) between January 2003 and December 2005 in Madrid (Spain) on daily case-specific mortality; changes of effects between Saharan and non-Saharan dust days were assessed using a time-stratified case-crossover design.
Saharan dust affected 20% of days in the city of Madrid. Mean concentration of PM(10) was higher during dust days (47.7 μg/m(3)) than non-dust days (31.4 μg/m(3)). The rise of mortality per 10 μg/m(3) PM(10) concentration were always largely for Saharan dust-days. When stratifying by season risks of PM(10), at lag 1, during Saharan dust days were stronger for respiratory causes during cold season (IR% = 3.34% (95% CI: 0.36, 6.41) versus 2.87% (95% CI: 1.30, 4.47)) while for circulatory causes effects were stronger during warm season (IR% = 4.19% (95% CI: 1.34, 7.13) versus 2.65% (95% CI: 0.12, 5.23)). No effects were found for cerebrovascular causes.
We found evidence of strongest effects of particulate matter during Saharan dust days, providing a suggestion of effect modification, even though interaction terms were not statistically significant. Further investigation is needed to understand the mechanism by which Saharan dust increases mortality.
撒哈拉尘埃侵入是马德里大气中的一种常见现象，导致 PM10 的 50μg/m³-EU24 小时标准超标。
我们调查了 2003 年 1 月至 2005 年 12 月期间马德里（西班牙）暴露于 PM（10）对每日特定病例死亡率的影响；使用时间分层病例交叉设计评估撒哈拉和非撒哈拉尘日之间影响变化。
撒哈拉尘埃影响了马德里市 20%的天数。尘埃日的 PM（10）平均浓度（47.7μg/m³）高于非尘埃日（31.4μg/m³）。每 10μg/m³ PM（10）浓度增加 10μg/m³，死亡率的上升幅度在撒哈拉尘日期间始终较大。按季节分层时，PM（10）在撒哈拉尘日期间的滞后 1 天的风险，呼吸道原因的风险更高，寒冷季节（IR%=3.34%（95%CI：0.36，6.41）比 2.87%（95%CI：1.30，4.47），而循环系统原因的影响在温暖季节更强（IR%=4.19%（95%CI：1.34，7.13）比 2.65%（95%CI：0.12，5.23）。对脑血管原因没有发现影响。
我们发现有证据表明，在撒哈拉尘埃日期间，颗粒物的影响最大，这表明存在效应修饰作用，尽管交互项没有统计学意义。需要进一步调查以了解撒哈拉尘埃增加死亡率的机制。
