VOLCANIC AIR POLLUTION IN OUR BACKYARD: GAS ADVISORY SYSTEM HELPS ALERT PEOPLE OF HAWAI‘I

Kīlauea Volcano, currently in its 20th year of nearly continuous eruption, emits roughly 1500 tons of toxic sulfur dioxide gas (SO₂ ) each day, making it the largest stationary source of SO₂ in the U.S. “Vog”, a locally coined term for volcanic smog, is a visible haze of acid aerosols, unreacted sulfur gases, and fine particulate matter that forms as volcanic SO₂ , other gases, and trace species react and become oxidized in the atmosphere. Depending upon wind conditions, vog can be confined to the south and west sides of Hawai‘i Island, can affect the entire island, or can even reach the island of O‘ahu, 350 km to the northwest. In areas distant from Kīlauea's gas emission-sources, the vog consists largely of acidic or neutral aerosol, but in areas closer to the emission sources, it contains a potentially more irritating mixture of SO₂ and acid aerosol.

Although the health effects of vog exposure are still largely unknown, the major components of vog have been correlated with adverse impacts on human respiratory and pulmonary function, leading to increased emergency room visits, hospitalizations, and total mortality. Since the state of Hawai‘i has one of the highest asthma death rates in the U.S., and the island of Hawai‘i leads the state in asthma death rate, concerns regarding exposure to vog are warranted.

A cooperative project between the USGS and National Park Service (NPS) provides real-time data that show the effects of volcanic emissions on air quality in the populated summit areas of Hawai`i Volcanoes National Park. The Federal Primary Health Standard for SO₂ has been exceeded on more than 85 occasions since 1987 near the Kīlauea Visitor Center, where the majority of the nearly 3 million annual park visitors and park employees spend most of their time.

To address the concerns of park managers and employees, the USGS and NPS recently developed a color-coded advisory system for episodes of poor air quality at the summit of Kīlauea. When SO₂ concentrations reach pre-determined levels, an automated system alerts park personnel, who issue warnings and may close areas, so that visitors and employees can avoid the hazards associated with exposure to volcanic air pollution. Future plans for this system include posting the advisory data on the web so that surrounding communities and local agencies can access the information in near real time.