Predicting the vog levels that visitors might experience during a short stay in Hawai`i is as difficult as predicting the weather. Once volcanic emissions are in the atmosphere, they are distributed by prevailing winds. Where and how bad the vog is ultimately depends on several factors including wind direction, wind speed, air temperature, humidity, and rainfall, as well as the location of the source and amount of SO2 being emitted from the volcano.
For normally healthy people, the level of vog typically experienced along the Kona coast on Hawai`i Island—especially for short term exposures such as a week of vacation—can be more annoying than life threatening. However, if you have existing heart and/or respiratory ailments or other conditions that compromise your physical health, or if you are pregnant, you should check with your personal physician for advice about traveling to any location with poor air quality.
If vog reaches levels that are potentially hazardous to human health, Hawai`i County Civil Defense issues advisories via their website and radio broadcasts and, if necessary, calls for voluntary or mandatory evacuations.
Whether or not you should cancel your trip to Hawai`i Island is a personal decision that only you can make.