Background

Evidence on the short-term effects of ultrafine particles (with diameter < 100 nm, UFP) on health is still inconsistent. New particles in ambient urban air are the result of direct emissions and also the formation of secondary UFP from gaseous precursors. We segregated UFP into these two components and investigated their impact on daily mortality in three Spanish cities affected by different sources of air pollution.

Methods

We separated the UFP using a method based on the high correlation between black carbon (BC) and particle number concentration (N). The first component accounts for aerosol constituents emitted by vehicle exhaust (N1) and the second for the photochemical new particle formation enhancements (N2). We applied city-specific Poisson regression models, adjusting for long-term trends, temperature and population dynamics.

Results

Mean BC levels were higher in Barcelona and Tenerife (1.8 and 1.2 μg·m^− 3, respectively) than in Huelva (0.8 μg·m^− 3). While mean UFP concentrations were similar in the three cities, from which N1 was 40% in Barcelona, 46% in Santa Cruz de Tenerife, and 27% in Huelva. We observed an association with N1 and daily mortality in Barcelona, by increasing approximately 1.5% between lags 0 and 2, per an interquartile increase (IQR) of 3277 cm^− 3, but not with N2. A similar pattern was found in Santa Cruz de Tenerife, although none of the associations were significant. Conversely, in the industrial city of Huelva mortality was associated with N2 at lag 0, by increasing 3.9% per an IQR of 12,032·cm^− 3.

Conclusion

The pattern and origin of UFP determines their short-term effect on human health. BC is possibly the better parameter to evaluate the health effects of particulate vehicle exhaust emissions, although in areas influenced by domestic solid fuel combustion this should also be taken into account.

中文翻译：

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西班牙三个城市中超细颗粒对主要车辆尾气与次要污染源的每日死亡率的短期影响

背景

关于超细颗粒（直径<100 nm，UFP）对健康的短期影响的证据仍然不一致。城市大气中的新颗粒是直接排放的结果，也是气态前体形成二次UFP的结果。我们将UFP分为这两个部分，并研究了它们对三个西班牙城市中每日死亡率的影响，这些城市受到不同的空气污染源的影响。

方法

我们使用基于黑碳（BC）和颗粒数浓度（N）之间高度相关的方法分离了UFP。第一个成分解释了汽车尾气排放的气溶胶成分（N1），第二个成分解释了光化学新粒子形成的增强作用（N2）。我们应用了特定于城市的泊松回归模型，针对长期趋势，温度和人口动态进行了调整。

结果

巴塞罗那和特内里费岛的平均BC水平（分别为1.8和1.2μg·m ^-3）高于韦尔瓦（0.8μg·m ^-3）。虽然这三个城市的UFP平均浓度相似，巴塞罗那的N1为40％，特内里费岛的圣克鲁斯为46％，韦尔瓦的为27％。我们观察到与巴塞罗那的N1和每日死亡率相关，在滞后0和滞后2之间每增加3277 cm ^-3的四分位数增加（IQR）大约增加1.5％，但与N2无关。在圣克鲁斯-德特内里费岛也发现了类似的模式，尽管两者之间的关联都不显着。相反，在工业城市韦尔瓦（Huelva），死亡率与滞后0时的N2相关，每IQR为12,032·cm ^-3增加3.9％。

结论

UFP的模式和来源决定了它们对人类健康的短期影响。BC可能是评估微粒车辆尾气排放对健康的影响的更好参数，尽管在受家用固体燃料燃烧影响的地区，也应考虑到这一点。