From the Icelandic Met Office: Today (Thursday) gas pollution from the eruption will affect areas in the northern part of Iceland. Tomorrow (Friday) pollution can be expected in the areas north and east of the eruption.
The Gas Dispersion Forecast can be read on this web link. On the same site, here, you can find a Gas Dispersion Model, which shows the gas dispersion over time. The model has proven to be reliable and can be recommended as a reference for possible gas pollution in Iceland. The model is a new product developed by the scientists at the Met Office as a response to the ongoing volcanic eruption in Holuhraun.
The picture below is taken from the Gas Dispersion Model and shows that gas pollution can be expected today in Mývatn and possibly in Akureyri, Húsavík, Ólafsfjörður and Blönduós.
The page can be found on: http://en.vedur.is/weather/forecasts/gas-model/