My sister and her family live on Oahu, and occasionally will have to deal with Vog. Here is the definition from the computer.
Vog is a form of air pollution that results when sulfur dioxide and other gases and particles emitted by an erupting volcano react with oxygen and moisture in the presence of sunlight. The word is a portmanteau of the words "volcanic", "smog", and "fog". The term is in common use in the Hawaiian islands, where the Kīlauea volcano, on the Island of Hawaiʻi (aka "The Big Island"), has been erupting continuously since 1983. Based on June 2008 measurements, Kīlauea emits 2,000–4,000 tons of sulfur dioxide every day.