The answer is a qualified yes.
First, you would need to set up the doorway reader properly. The human body absorbs RF energy since it is mostly composed of water, which absorbs RF energy at the frequency that passive ultrahigh-frequency (UHF) systems employ. So the antennas would need to be positioned so that the body was not between the tag and the reader antenna.
Another key issue would be privacy. It might be possible to read the tag, but in certain countries, doing so without a person’s awareness would be deemed a crime. But even in places where it was not considered criminal activity, it would still be important to have people opt into being tracked, rather than monitoring them without their knowledge.
—Mark Roberti, Founder and Editor, RFID Journal
Is RFID Being Used on Public Buses? »