Division Regarding the PM2.5 specific inlet:

Currently there are two main inlet designs available and in use for monitoring and research purposes: the impactor type inlet and the sharpcut-cyclone type. Various inlets of both types are currently under testing e.g. within the framework of CEN WG 15. The size fractionation efficiency of the inlet needs to ensure that 50% of the particles with an aerodynamic diameter of 2.5 μm are collected on the filter.