Neither GURPS Ultra-tech (4e) nor Transhuman Space (3e) give a movement rate for the surveillance dust cyberswarm. On the other hand, UT p.106 tells us:
“The swarm is programmed to remain in a particular place, observe for a period of time, and then return; it can also transmit information or be ordered to go to a different location.”
It can be argued that if surveillance dust is not animate it is not really a swarm of microbots, just a collection of sensors. THS 3e p.168 tells us that the dust chassis lacks mobility, not that it is immobile.
It is likely that surveillance dust comes in many varieties, some types being simple sensors, others motile microbots.
Dust mites are 0.2-0.3 mm in length, which indicates that legs may be an adequate form of locomotion for surveillance microbots. Some wasps are only 0.13mm long, so surveillance dust capable of powered flight could potentially be built.
How fast should dust microbots be allowed to move? An inch per second is a reasonable rate, which translates as 5 ft per minute or 3 mph. In terms of body lengths this is actually very fast!
“Surveillance fluff” is my name for a variant of surveillance dust sensors that resemble dandelion seeds. These descend at a rate of approximately 3cm/sec so if released at 2,000ft can gather data on an area below them for around 5½ hours.
Transhuman Space surveillance fluff may be even smaller than that shown above.
Surveillance fluff can be deployed by a variety of mechanisms including mortar bombs, UAVs and small rockets.
Surveillance dust is very difficult to defend against. Not only may you have dust on your clothes, skin and hair but also in your lungs and nasal passages.
An agent could blow dust in through a keyhole or air vent, or send it to be scattered by a millibot or surveillance worm.
If the dust is motile it can be dropped in a neighbouring room and directed to find its own way to the objective.
Secure areas (“Referenftua”) will be literally swept for bugs!
Hooverbots will be a familiar sight, constantly cleaning every available surface and regularly flashing collected dust with an EMP.
“Dust eaters” will constantly circulate and filter the room’s air.
Larger cleaning robots will be supplemented by anti-surveillance cyberswarms.
Before important meetings, the room and its occupants may be flashed with EMP devices, although this may cause complications for implants such as pacemakers and AI companions.
The gangster movie trope of meeting in saunas or bathhouses may take on added relevance in a word where surveillance dust is used!