Are launches permitted when prevailing winds would send liftoff exhaust over populated areas ?
Vulcan is dirtier because of the solid rocket boosters.
But the pollution from either is far less than from a solid fuel engine.
Aside from CO2, methalox engines produce noticeably less soot than kerolox.
Starship uses Methane-Oxygen, which burns way cleaner than Kerosene-Oxygen, which is used by Falcon 9.
The thing people should be concerned about are solid rocket boosters, which SpaceX does not use. Solid boosters have polluted every "untouched" alpine lake on the planet. Those have been used by the new Vulcan, Space Shuttle, and a lot of other rockets.
Tim Dodd has an excellent video and write-up on this topic:
any accident that results in the releasing of that amount of methane unburnt would be horribly damaging.
luckily, rockets rarely DONT go bang and burn when things go wrong.
Basically the equivalent of a herd of 7500 cows burping away for a year.
Bad but I'm not sure that 750ton of methane is horribly damaging compared to a billion cows