Therexs an increasing body of research to show they do work. Example:
https://www.bath.ac.uk/announcements/low-emission-zones-improve-air-quality-health-and-peoples-well-being-new-ipr-policy-brief/
Incidentally, back in the bad old days of leaded petrol you could map the inverse correlation between schoolchildren's IQ and distance from the motorways through Birmingham.
The wind may blow at times, it's the days with a temperature inversion over the city that cause most harm.
The ULEZ is just a logical extension of decades of pollution reduction in cities and towns.
Of course, this has no relation to imperfect implementation of sensible legislation, but 'I was caught by a misunderstanding' doesn't invalidate the concept.