Watch out for ‘vog,’ Hawaii authorities warn as Mauna Loa erupts. But what is it?

Health officials in Hawaii are warning residents to beware of “vog” amid the volcanic eruption on Mauna Loa — but what is it and what risks does it pose?

Mauna Loa, the world’s largest active volcano, began erupting at about 11:30 p.m. Sunday, Nov. 27, McClatchy News reported. It’s the volcano’s first eruption since 1984.

The eruption is confined to Moku‘āweoweo, the summit caldera of the 13,100-foot volcano, but lava has overflowed the caldera, the Hawaii Volcano Observatory reported.

“Lava flows are not threatening any downslope communities,” said Gov. David Ige, in a news conference, HawaiiNewsNow reported. No mandatory evacuations have been ordered.

But officials have warned residents of vog, and Pele’s Hair, thin glass fibers produced by volcanic eruptions which are named for the volcanic deity Pele.

What is vog?

Vog is hazy air pollution produced by volcanic eruptions, according to the Hawaii Interagency Vog Information Dashboard.

It’s created when sulfur dioxide gas from volcanic vents “reacts in the atmosphere with oxygen, sunlight, moisture, and other gases and particles,” officials said.

Sulfur dioxide is “a colorless, irritating gas that has an acrid odor like fireworks or a burning match,” the site said. It’s also produced by vehicle engines and power plants.

The word ‘vog’ is taken from volcanic smog, the U.S. Geological Survey said.

Why is vog dangerous?

Vog can cause health problems, especially for people with pre-existing respiratory conditions, the USGS reported.

“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,” the agency warned.

Symptoms include “headaches, breathing difficulties, increased susceptibility to respiratory ailments, watery eyes, sore throat, flu-like symptoms, and a general lack of energy.”

Vog also can produce acid rain and reduce visibility.

How can you protect against vog?

Air quality conditions are good in populated areas of Hawaii, the state Department of Health reported. But that may not last.

“Conditions are changing rapidly, and poor air quality may be very localized,” the agency warned.

If vog becomes a problem, the department advised residents to avoid outdoor activities, keep medications available and stay indoors with air conditioners or air purifiers running.

Face masks do not protect against sulfur dioxide and other gases, but can protect against ash and other fine particles, the agency said.

This story was originally published November 29, 2022 at 9:35 AM with the headline "Watch out for ‘vog,’ Hawaii authorities warn as Mauna Loa erupts. But what is it?."