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.

Vog is created when volcanic gasses react with sunlight, oxygen and moisture. It is made up of a mixture of gasses and aerosols, which makes it hard to study and potentially more dangerous than either on their own. Although vog has not been as extensively studied as it could be, it has been found that most of the aerosols are acidic and of a size where they can remain in the lungs where they can damage and impare their function and degrade the performance of the immune system. People who have been exposed to vog report headaches, breathing difficulties (including inducing asthma attacks), flu-like symptoms, and general lethargy. These effects are especially pronounced with children. Most studies of vog have been in areas where vog is present, and not of the effects of vog itself (in controlled conditions).

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.

External links

• Vog: A Volcanic Hazard