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If you feel it was likely that it was shown on a BBC channel, it might be worth searching BBC Genome http://genome.ch.bbc.co.uk
“Children’s BBC” is a search term that might help, as well as any shows which had cartoons shown within them such as “Going Live” and “Parallel 9”. You can narrow down the time period in the advanced section. You could add “cartoon”, “animation” or “animated” to the search terms
Some of the shows have little to no synopsis so it might not be too useful... but if you can think of any words that might be in the show’s title, it might help you find it
Found a reference to a show on Genome called “Toxic Crusaders” which had the “Smogulans” and a monster called “Polluto”, probably not it though
Edited by mla

Details are very fuzzy - bear with me.
Aired in the early 90's, possibly on BBC One or Two. One storyline involved the antagonists (possibly called Plutokians, or Blutokians??) using traffic light to change the moods of people. So red would be angry, amber, happy, and green was sad. I may be confusing this next part with another tv show The protagonist had some special ability in that they could travel to places instantly.
Edited by Loopz