Dogs don't work very well in urban areas and there's plenty of tricks to throw dogs off your trail.
I'd like to see your tricks for dealing with 100,000 such sensors, one on every street corner.
(also: https://www.canidae.com/blog/2015/10/can-you-throw-off-a-tra...
"In fact, Adam found that it was basically impossible to throw off the scent of a Bloodhound. He crossed a 100 foot wide, waist high river. He changed clothes, poured cologne and coffee on himself, threw smelly fish along the trail and used scent enzyme erasers to try to eliminate his scent.")
May the odds be ever in your favor!
Misdirection and decoys. How much use are those sensors if they're all detecting you at the same time?
If they become prevalent enough, I could imagine the development of "scent bombs" that would spew out so much of your odor that the sensors for miles around would all detect "you."
Cheaper than dog noses, but requires a sample of the target odor and some training time. It is conceivable that the "most wanted" could each have thousands of bees trained on their scents, and then those swarms could be divided up onto plastic cassettes, which would each be loaded onto a lamppost. If the targets go near any lamppost, their bee in it tattles its location in real time. The disadvantage is, of course, that you have to go around swapping out old and dead bees for live, fresh ones all the time.
An electronic nose can just report its odor profile, and a central processing server can attempt to match and track targets. All that needs is a bit more bandwidth. But it is likely slower and lacking specificity. You could likely smell explosives or bomb making residues or gunshots or narcotics, but not specifically track Suspect X across the city. That kind of precision would require that people line up at the lamppost to be swabbed, and their swab vaporized and run through a gas chromatograph for a minute or two, which I don't see happening, even in authoritarian Singapore.
I wanna see someone successfully circumvent scent-based tracking. A dog has a sense of smell a million times more sensitive than a human and can track people over miles, even when a trail is days old. Imagine a network of 100,000 passive scent trackers as sensitive as dog noses, hooked up to the same centralized AI and recognition system.
With a single high-confidence hit, they can localize you. If you're on foot, you're not getting very far in any reasonable time frame.
We don't stand a chance. Sitting ducks, as it were.
You just better hope to God (or the AI, apparently) you're never a target of this system, inadvertently or intentionally, because that race is over, and humans lost.