Vog

Vog (portmanteau for volcanic smog) forms when sulfur dioxide and other pollutants emitted by an erupting volcano mixes with oxygen and moisture in the presence of sunlight to form a type of smog. Vog can form anytime and anywhere there is an active volcanic eruption, but the term appears to be most closely related to the island of Hawai'i, whose Kilauea volcano has been erupting continuously since 1983.

The health effects of vog are still being studied, but people who have been exposed to vog report headaches, breathing difficulties, flu-like symptoms, and general lethargy.

In Hawaii, vog mostly affects the western coast of the island of Hawai'i, where the prevailing trade winds blow the vog to the southwest and wind patterns then blow it north up the coast. Prolonged periods of southerly winds, however, can cause vog to affect the eastern half of the island, and sometimes the entire state as well.