Each turn when that worker comes up, I hit "automate clear damage" shift-D. If there is work to do, the worker zooms off to get started. I wake up the rest of the worker stack, give them all shift-D, and carry on. When they're done with one polluted tile, they will either zoom to the next polluted site or wait for further order. If I'm motivated, I will bring them back and stack them near the core. If I'm lazy, I will create a new stack right there.
The problem with this tactic is that your automated Workers (or more usually Slaves, in my case) will be distributed
evenly rather than
efficiently.
Also, automated Workers/Slaves will not prioritise the more 'important' tiles, e.g. if I don't have sufficient Slaves free to do all the work needed, then fixing SPT-loss in a (Ship-building) core-town takes far higher priority than fixing FPT-loss on a beaker-farm.
First annoyance: the shift-D workers will also go clean up volcano damage, even if I don't really need them to
The real pain here, is that you can't road Volcanoes in the epic-game. So not only will a polluted Volcano attract every free automated Worker on the map —
even when there are sufficient Workers already in place to finish the job in 1T — but any free Mopheads who get their turn to move earlier than the Mopheads-in-place, will arrive this turn, find themselves with nothing to do next next turn, but still need
another IBT to get back onto your road-network. Again, this doesn't matter so much if you've got sufficiently huge numbers of Workers, but
does matter when you've got higher-priority tiles still blotchy, and not enough Workers to clean them.
TLDR:
"Go forth and mop it, guys" automation only works
reliably, if the worker-turns needed to clear all the pollution you've been struck with that turn is
less than the total worker-turns you have available. If not, manually assigning mop-wielders will waste (much) less SPT/FPT.