Hawaii Volcanic Gases and Ash

Vog (volcanic smog) is a visible haze comprised of gas and an aerosol of tiny particles and acidic droplets created when sulfur dioxide (SO2) and other gases emitted from Kīlauea Volcano chemically interact with sunlight and atmospheric oxygen, moisture...
Vog pose a health hazard by aggravating preexisting respiratory ailments. SO2 gas can irritate skin and the tissues and mucous membranes of the eyes, nose, and throat, and can penetrate airways, producing respiratory distress in some individuals. Aerosol...
To minimize potential health hazards of SO2 and vog, the Hawai`i State Department of Health and the American Lung Association of Hawai`i recommend the following protective  actions. During times of poor air quality due to SO2 or vog, people—particularly...
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, as illustrated and explained on...
The most critical factors that determine how much vog impacts an area are wind direction and speed. Where and how bad the vog is ultimately depends on several additional factors including air temperature, humidity, and rainfall as well as the location of...
According to June 2008 measurements of gas emissions from the two active vents on Kīlauea—Pu`u `Ō `ō (east rift) and Halema`uma`u (summit)—the combined total ranges from 2,000 to 4,000 tonnes (on average) of SO2 emitted from the volcano each day. These...
The sulfuric acid droplets in vog have the corrosive properties of dilute battery acid. When vog mixes directly with moisture on the leaves of plants it can cause severe chemical burns, which can damage or kill the plants. Sulfur dioxide (SO2) gas can...
USGS Hawaiian Volcano Observatory geochemists use both remote and direct sampling techniques to measure compositions and emission rates of gas from Kīlauea Volcano. Because of the technical challenges posed by Kīlauea 's unique eruptive style, gas...
As part of its mission to monitor eruptions and assess volcanic hazards, the U.S. Geological Survey's Hawaiian Volcano Observatory (HVO) determines the amount and composition of gases emitted by Kīlauea Volcano. Changes in gas emissions can reveal...
Ninety-nine percent of the gas molecules emitted during a volcanic eruption are water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2). The remaining one percent is comprised of small amounts of hydrogen sulfide, carbon monoxide, hydrogen...