Andrea Baccarelli  美国哈佛大学公共卫生学院

    <International Circulation>:  How do the personal monitors measure exactly?

  《国际循环》：个人监测器具体是如何操作使用的？

    Prof. Baccarelli:  It is actually a pump that takes samples every three hours and filters particles of a certain diameter， in our case we capture particles with a diameter smaller than 2.5 microns.  At the end of the day the filters can be removed and put them in a bag to control the temperature and humidity， followed by weighing them whenever you are ready.  It is actually referred to a gravimetric method.  We sample the particles and weigh the filter before and after sampling.  This tells us how many total particles we have captured so we can divide the mass by the volume that has been sampled.  We can then tell the concentration of each.

    Baccarelli教授: 它实际上是一个泵，过滤器是由一定直径的粒子组成，每隔3小时采集样品，我们所研究的监测器可以捕捉直径小于2.5微米的微粒。每天结束时，可以将过滤器拆除，放入一个袋中保持恒温恒湿，随时都可以称重。事实上这就是一个称重法。我们采集微粒并称量采样前后过滤器的重量。这样我们可以获知共捕捉多少微粒，并将这些微粒按照体积进行分类，确定每种微粒的浓度。

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