Does vog (volcanic smog) impact plants and animals?

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 also diffuse through leaves and dissolve to form acidic conditions within plant tissue. Farmers on Hawai`i Island, particularly in the Ka`u District, have reported losses to agricultural crops and flowers as a result of high SO2 emissions from a gas vent at Kīlauea's summit. The Hawai`i Department of Agriculture has not received any reports of vog-related problems with animals. 

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What gases are emitted by Kīlauea and other active volcanoes?

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 chloride, hydrogen fluoride, and other minor gas species. Learn more at our website for Volcanic...

Who monitors volcanic gases emitted by Kīlauea and how is it done??

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 important clues about the inner workings of a volcano, so they are measured on a regular basis. HVO scientists use both remote and direct sampling techniques to measure...

Where and how do sulfur dioxide and volcanic gases (vog) affect air quality in Hawaii?

The most critical factors that determine how much vog impacts an area are wind direction and speed. Air temperature, humidity, rainfall, location of the source, and the amount of sulfur dioxide (SO2) being emitted are also factors. During prevailing trade (from northeast) wind conditions, any SO2 emitted from Pu`u `Ō `ō is blown out to sea, while...

How much sulfur dioxide (SO2) gas does Kīlauea emit?

Kīlauea typically emits between 500 and 14,000 metric tons of sulfur dioxide gas (SO2) per day during periods of sustained eruption. During the 2018 eruption at Kīlauea’s Lower East Rift Zone, SO2 emissions were over 30,000 metric tons per day, in keeping with the increased vigor of that eruption. Methods for calculating emission rates for SO2 can...

Should I cancel my plans to visit to Hawai`i Island because of sulfur dioxide (SO2) and vog?

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. Where and how bad the vog is ultimately depends on several factors including wind direction, wind speed, air temperature,...

What health hazards are posed by vog (volcanic smog)?

Vog poses a health hazard by aggravating preexisting respiratory ailments. Sulfur dioxide (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 particles in vog can also penetrate deep into human lungs and, at elevated...

What is "vog"? How is it related to sulfur dioxide (SO2) emissions?

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 a volcano chemically interact with sunlight and atmospheric oxygen, moisture, and dust. Volcanic gas emissions can pose environmental and health risks to nearby communities. Vog...

Why is it important to monitor volcanoes?

The United States and its territories contain 169 geologically active volcanoes, of which 54 volcanoes are a high threat or very high threat to public safety. Many of these volcanoes have erupted in the recent past and will erupt again in the foreseeable future. As populations increase, areas near volcanoes are being developed and aviation routes...

Is it dangerous to work on volcanoes? What precautions do scientists take?

Volcanoes are inherently beautiful places where forces of nature combine to produce awesome events and spectacular landscapes. For volcanologists, they're FUN to work on! Safety is, however, always the primary concern, because volcanoes can be dangerous places. USGS scientists try hard to understand the risk inherent in any situation, then train...

What kind of school training do you need to become a volcanologist?

There are many paths to becoming a volcanologist. Most include a college or graduate school education in a scientific or technical field, but the range of specialties is very large. Training in geology, geophysics, geochemistry, biology, biochemistry, mathematics, statistics, engineering, atmospheric science, remote sensing, and related fields can...
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Date published: May 18, 2017


Just like smog and fog, this EarthWord is not what you want to see while driving...

Date published: August 18, 2016

Living with Vog on an Active Volcano: New Resources

New informational products about the health hazards of volcanic air pollution known as “vog,” are available through a new interagency partnership.

Date published: October 5, 2015

EarthWord: Fumarole

Fumaroles are openings in the earth’s surface that emit steam and volcanic gases, such as sulfur dioxide and carbon dioxide. They can occur as holes, cracks, or fissures near active volcanoes or in areas where magma has risen into the earth’s crust without erupting. A fumarole can vent for centuries or quickly go extinct, depending on the longevity of its heat source.

Date published: February 11, 2015

New Study Looks at How People Cope with Vog

A new study to examine how people who live downwind of Kīlauea Volcano cope with volcanic gas emissions, or vog, is currently underway.

Date published: June 20, 2007

Hazardous Sulfur Dioxide Concentrations Measured at Kilauea Volcano

Today, HVO scientists measured concentrations greater than 10 ppm in a broad area adjacent to Halema‘uma‘u crater. Sulfur Dioxide gas is persistently emitted at Kîlauea's summit. Typical concentrations are generally negligible except for areas downwind of Halema‘uma‘u crater, where they can get up to 2.5 ppm (parts-per-million) in narrow zones.

Filter Total Items: 17
scientist with camera and spectrometer at the edge of smoking volcanic crater.
August 16, 2016

USGS HVO geochemist measuring gases released from Kīlauea Volcano

USGS Hawaiian Volcano Observatory geochemist measuring gases released from Kïlauea with a Fourier transform infrared (FTIR) spectrometer, an instrument that detects gas compositions on the basis of absorbed infrared light. The data obtained from FTIR measurements have been useful in identifying the many components of volcanic-gas emissions, which provide information on the

White gas plume rising straight up from Kilauea Volcano summit with distant, bright, full moon.
August 16, 2016

Gas plume from Halemaʻumaʻu Crater, Kilauea Volcano

With stagnant winds present, the plume from Halema`uma`u Crater at the summit of Kilauea Volcano, stands straight up, showing off the distant, but bright, full moon.

Vegetation study, Hawaii
April 15, 2016

Vegetation study, Hawaii

Attribution: Pacific
Fumarole on Kīlauea Volcano, Hawaiʻi. Elemental sulfur vapor escaping from the fumarole has cooled to form yellow-colored crysta
April 14, 2016

Fumarole on Kīlauea Volcano, Hawaiʻi

Fumarole on Kīlauea Volcano, Hawaiʻi. Elemental sulfur vapor escaping from the fumarole has cooled to form yellow-colored crystals around its margins. Credit: Robert L. Christiansen.

Image: Monitoring Volcanic Gases on Kilauea's East Rift Zone
May 31, 2014

Monitoring Volcanic Gases on Kilauea's East Rift Zone

Hawaiian Volcano Observatory Geochemist Jeff Sutton and CSAV international volcanology students visit a continuous gas monitoring site on Kilauea's east rift zone during field studies portion of the summer training course. Instrumentation at this site measures ambient concentration of noxious sulfur dioxide gas released from the volcano's vents, along with meteorological

video thumbnail: Volcano Hazards
July 30, 2012

Volcano Hazards

The United States has 169 active volcanoes. More than half of them could erupt explosively, sending ash up to 20,000 or 30,000 feet where commercial air traffic flies. USGS scientists are working to improve our understanding of volcano hazards to help protect communities and reduce the risks.

Video Sections:

  • Volcanoes: Monitoring Volcanoes
May 9, 2012

Volcano Web Shorts 6: Societal Impacts of Volcanism

USGS geologist, Angie Diefenbach, describes how she uses GIS, (Geographic Information Systems) software to study volcanic eruptions and their impacts on society.

June 30, 2011

The Air We Breathe…It’s a Gas!

We live at the bottom of an ocean of air. Most adults take around 29,000 breaths a day, children breathe a little faster; but what is in this air we breathe? What are the gases in the air? How much of each gas is there? Do these gases have different weights? How cold are liquid nitrogen and dry ice, and where did those names come from? Come join us to explore these

Image: Lava Flows Burning Vegetation
July 27, 2010

Lava Flows Burning Vegetation

The front of this small finger of lava was almost to the sea cliff this morning, and was burning through low brush along the coastline.

Image: Sulfur Crystals
December 17, 2009

Sulfur Crystals

A beautiful example of sulfur crystals that have grown around a small fumarole near the southeast rim of Halema`uma`u crater. The vent is about 0.3 m (1 foot) long.