Volcanic fog or volcanic smog, also known as vog, has posed significant health threats to residents of Hawaii for years during Kilauea volcano’s continued activity. Those with pre-existing respiratory issues, including asthma, are especially at risk, although healthy people are also susceptible to vog-related symptoms.

Vog is the hazy air pollution emitted by KÄ«lauea. It’s made up of primarily water vapor, carbon dioxide and sulfur dioxide, which is a colorless gas that smells like fireworks or a struck match, according to the International Volcanic Health Hazard Network.

The volcano’s summit and east rift eruptive vents release sulfur dioxide into the atmosphere, where it reacts with oxygen, moisture, sunlight and other gases and particles. The resulting haze is known as vog.

Lava from the Kilauea Volcano flows into the ocean near Pahoa, Hawaii, on May 20, 2018. (AP Photo/Jae C. Hong)

The International Volcanic Health Hazard Network reports that people living far downwind of the volcano, such as on Hawaii Island’s west side, are mostly affected by fine particles, but areas in close proximity to the volcano’s eruptive vents also face threats from vog exposure.

“There is sulfur dioxide, but also remember that the lava is causing homes [and vegetation] to burn,” said Dr. Elizabeth Tam, a pulmonologist and Chair of Medicine at the University of Hawaii John A. Burns School of Medicine.

“You not only have vog, you have smoke, and when homes burn, there are plastics and all kinds of things,” Tam said. “It’s a toxic mix that is much more than just the volcanic emissions.”

Tam and fellow researchers at the University of Hawaii John A. Burns School of Medicine recently published a 10-year study of about 2,000 Hawaii Island school children between ages 8 and 10 at the time the study began in 2002. Their schools were located at least 20 miles from KÄ«lauea, according to Tam. The children were followed for the full decade or until they graduated.

While vog has been known to trigger asthma symptoms, the vog itself does not result in new asthma cases, experts say. Researchers found that asthma's prevalence is higher in areas where intermittent smoke was present, according to Tam.

“We were surprised to find that vog maybe doesn't cause asthma; we did find that if they already had asthma for a variety of reasons, it was a big factor,” Tam said. “The vog definitely would affect those with [developed] asthma more, and they were more likely to get upper-airway symptoms and cough.”

Vog can trigger additional short-term symptoms including eye, nose, throat or skin irritation, chest tightness, shortness of breath or dizziness and fatigue, according to the International Volcanic Health Hazard Network.

The health of physically active asthma sufferers is most likely to be negatively impacted by inhaling sulfur dioxide, and it only takes a brief exposure to narrow the airways, which exacerbates asthma symptoms. The long-term health effects of vog exposure are not yet known, according to experts.

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The risk extends beyond asthmatics, as vog can harm the health of children, people with chronic lung diseases like COPD, those with cardiovascular issues as well as diabetics, according to the American Lung Association.

“We recommend that people stay indoors or evacuate the area, as is recommend by the protective agencies,” said Janice Nolen, the American Lung Association's assistant vice president of national policy. Experts agree that masks only offer limited protection.

“Aerosols created by volcanic smog are very small particles, and respirator masks do not really prevent them entering the lungs,” said Dr. Yesim Demirdag, assistant professor of pediatrics at Columbia University Medical Center.

Demirdag also recommended using an air purifier at home, and avoiding other asthma triggers such as smoking, burning candles, wood and strong smells.

“[It’s also important to] take controller medications regularly and emergency medications as needed to minimize symptoms,” Demirdag added.

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