Nano-aerosols of size 100 nm and below are manifested everywhere in various urban micro-environments. In outdoor, the vehicular emission during traffic jam can release nano-aerosols with concentration above 200 million/m³ (200/cm³). Superimposed on vehicular emission are smog particles, around 10–50 nm, generated from the photochemical reaction of hydrocarbon and NOx in the presence of sunlight. These nano-aerosols, by virtue of their small sizes, can be inhaled readily into our bodies leading possibly to various chronic diseases. Air-borne viruses from influenza to epidemic viruses, which can lead to acute sickness and even death, are also in the same size range of 100 nm.

Despite microfibers are being commonly used today in filters, there has been limited studies on filtration of real aerosols using microfiber filters, let alone nanofibrous filters, as most studies used simulated aerosols (e.g. sodium chloride) or test dust. Also, in standard sodium chloride test, only monodispersed aerosol size is allowed to challenge the filter. On the other hand, in reality aerosols of all sizes challenge simultaneously the filter. In this study, for the first time we have used nanofiber filter in a portable test filter set-up to filter polydispersed aerosols from the micro-environment near busy traffic area where aerosols comprise of both vehicular and atmospheric pollutants with size range between 10 and 400 nm. Real-time measurements are carried out with the portable test filter. The test results are compared to the theoretical correlation from Payet with diffusion correction at small Peclet number (Pe). We have found good comparison between test results with theoretical correlations using equivalent aerodynamic diameter for the aerosols with face velocity from 1 to 11 cm/s. A new dimensionless parameter, specific filter resistance (also established independently by Buckingham-π approach), is defined for the first time. It measures the flow drag on fibers to the amount of fibers present in the filter, the lower is the specific filter resistance the better is the filter. For our test condition, it is approximately 1.0–1.2. We have also improved the filtration efficiency of the filter by increasing the fiber basis weight by stacking up two layers of nanofibers. We have demonstrated that the efficiency increases while both the quality factor and specific filter resistance remain constant. We have also investigated the single fiber efficiency due to diffusion and found that at low velocity and low Peclet number (Pe < 10), the test results agree well with the theoretical prediction. On the other hand, at higher face velocity (>0.07 m/s) and large Peclet number (>10), there is small deviation from the theory, which is probably due to the smaller aerosols collecting by the larger aerosols upstream of the filter with an airstream consisting of polydispersed aerosol distribution challenging the filter. This has not been realized previously as tests conducted were mostly using monodispersed aerosol size distribution for which aerosol-aerosol interaction was absent.

在各种城市微环境中到处都可以看到尺寸为100 nm及以下的纳米气溶胶。在室外，交通拥堵期间的车辆排放会释放出浓度超过2亿/ m ³（200 / cm ³）的纳米气溶胶。在有阳光的情况下，碳氢化合物和NOx的光化学反应产生的烟雾颗粒（约10-50 nm）叠加在车辆的排放物上。这些纳米气溶胶由于体积小，可以很容易地吸入我们的体内，可能导致各种慢性疾病。从流感病毒到流行病毒的空气传播病毒（可导致急性疾病甚至死亡）的大小范围也相同，均为100 nm。

尽管今天超滤器中普遍使用超细纤维，但对于使用超细纤维过滤器（更不用说纳米纤维过滤器）过滤实际气溶胶的研究还很少，因为大多数研究都使用模拟气溶胶（例如氯化钠）或测试粉尘。同样，在标准氯化钠测试中，仅允许单分散的气溶胶粒径挑战过滤器。另一方面，实际上，各种尺寸的气雾剂都会同时挑战过滤器。在这项研究中，我们首次在便携式测试过滤器装置中使用了纳米纤维过滤器，以过滤来自交通繁忙区域附近微环境中的多分散气溶胶，其中气溶胶由车辆和大气污染物组成，粒径范围在10到400之间纳米 使用便携式测试滤波器进行实时测量。Pe）。我们发现，当表面速度为1至11 cm / s时，使用等效气动力直径的气溶胶，测试结果与理论相关性之间存在良好的比较。一个新的无量纲参数，特定的滤波器电阻（也是由白金汉-π方法独立建立的），是第一次定义。它测量纤维上的流动阻力与过滤器中存在的纤维量之间的关系，比过滤器阻力越低，过滤器越好。对于我们的测试条件，大约为1.0–1.2。我们还通过堆叠两层纳米纤维来增加纤维的单位面积重量，从而提高了过滤器的过滤效率。我们已经证明，效率提高了，而品质因数和比滤波器的电阻均保持不变。我们还研究了由于扩散引起的单纤维效率，发现在低速和低Peclet数（Pe <10），测试结果与理论预测吻合良好。另一方面，在较高的表面速度（> 0.07 m / s）和大的Peclet数（> 10）时，与理论值的偏差较小，这可能是由于较小的气溶胶被过滤器上游的较大气溶胶收集所致气流由多分散的气溶胶分布组成，对过滤器构成挑战。以前尚未实现这一点，因为所进行的测试主要是使用单分散的气溶胶粒径分布，而这种分布没有气溶胶与气溶胶的相互作用。