[kaybe]

If you don't inject it into the stratosphere, most pollutants such as acids or particles are precipitated out (dry or wet) pretty quickly (on the order of days to weeks/months), so I'd expect a lag of max 2 months due to the transport time to Greenland (and it will be a bit lower due to the distance and loss over time). [1]

(If China did a better job of filtering the SO2 from exhaust, this particular air problem there would be gone within a week.)

[1] http://acmg.seas.harvard.edu/people/faculty/djj/book/bookcha...