Even during times of Southwest winds, it's hard to predict what areas will actually be impacted by the Vog. Geography and changes in elevation play a part and it's just hard to call.
I've been advising my clients who are interested in Volcano to try to keep an eye on weather reports and actually take a drive up that way when the winds are blowing from the south. Going through that process does two things: it makes you aware of how variable the wind patterns really are and also, if you can make the drive up HWY 11 during a time when the trade winds are not blowing, you can see where the Vog is actually present.
I've read some reports that make a distinction between SO2 concentration and the Vog. One I read recently was pointing out that by the time the Vog reaches Kona-side, the actual concentration of SO2 is much less because of other chemical reactions that occur in the atmosphere.
As always, this is a matter for personal research for those who might be considering a move to the Big Island. Some people are more sensitive than others due to pre-existing conditions, so it's not something to take lightly. If the Vog is a major concern, focus your real estate search on the Hamakua coast and Hawi!
