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Volcano Watch — Sulfur dioxide advisory developed to improve National Park safety during vog episodes

January 25, 2001

With east Hawai'i in the throes of "vog season" over the past several months, the National Park Service (NPS) and U.S. Geological Survey's Hawaiian Volcano Observatory (USGS - HVO) have collaborated on a new initiative designed to better protect the health of visitors and employees in Hawai'i Volcanoes National Park.

"Vog", a local nickname for volcanic smog, occurs as sulfur dioxide gas (SO2) and other irritating and noxious emissions from Kīlauea volcano react with air, moisture and sunlight to form microscopic acid sulfate particles, which can readily be taken into the lungs of those who breathe vog-tainted air.

Health effects caused specifically by vog have not been rigorously proven, but many people report increased breathing difficulties, headaches, itchy and watery eyes, and increased susceptibility to respiratory infection during bad air days. Furthermore, in mainland health studies, SO2 and acid sulfate particles have been linked to decreased lung function, respiratory complaint, hospitalizations, and even mortality.

During the past several months, those of us living, working, and playing in east Hawai'i, from Kīlauea to Kumukahi to Kawainui, and some points in between, have experienced repeated vog episodes caused by seasonal disruptions of the prevailing northeasterly trade winds that usually keep our part of the island vog-free. In the National Park, and especially near gas-emission sources such as Halemaumau and Pu'u 'O'o, these trade wind disruptions can cause rapid deterioration of air quality. And, with over three million visitors each year, many people are potentially affected each time the dreaded southerly "kona" winds blow.

Fortuitously, HVO, in cooperation with Hawai'i Volcanoes National Park, operates an air-quality monitoring station, located behind the Kīlauea Visitor Center. This station measures the concentration of SO2 gas, a major component of vog when close to volcanic emission sources. Recently, the park upgraded its capability to include a second monitor, locating it at HVO, next to the Jaggar Museum.

We science folks are fond of chiding each another that anyone can collect data, but it's what you do with it that really counts. In the case of air-quality monitoring in the national park, the NPS-HVO team will be using the SO2 concentration, and wind speed and direction data in near-real time to help protect visitors and employees in the park from unhealthy levels of SO2.

To do this, SO2 concentrations from the two monitoring sites will be automatically examined on a continuous basis to see whether they have exceeded healthful levels, and, if so, by how much. When exceedences occur, as they frequently did a few weeks ago, the park and HVO will be alerted by the system, and Civil Defense, Health Department and other local groups will be notified as well.

The park will take specific actions based on the SO2 level-these levels being color-coded, somewhat like a traffic light, from green to red. Park actions during poor air quality will include posting information signs at entrance stations and visitor centers; rescheduling or relocating hikes, and, under extreme conditions (Red), closing park entrance stations and relocating employees working out of doors.

So, although we can't turn off the eruption and the accompanying vog, we can take steps to be aware of its severity and minimize our exposure to it. Sometime during the next several months, these data, including gas concentrations and wind conditions at Kīlauea's summit, will also become available to the public over the Internet. Because wind direction and wind speed determine where Kīlauea's noxious emissions go, extended trade wind disruptions or winds from the south generally mean increasingly poor air quality for east Hawai'i. The real-time availability of the air quality and weather data could therefore be helpful to local residents, especially those planning to visit the park, or living in adjacent communities. Watch this space for more information!

Volcano Activity Update

Eruptive activity of Kīlauea Volcano continued unabated at the Pu`u `O`o vent during the past week. Surface flows and burning forest are commonly visible on Pulama pali. Lava began to enter the sea again for the first time since December 15. The new but somewhat sluggish entry was reported on January 21, and is located just west of the previous entry at Kamokuna.

Two earthquakes were reported felt during the week ending January 25. One quake, felt in Leilani Estates and Pahoa occurred at 9:54 a.m. on January 22, was a magnitude-2.5, and located near Pu'ulena crater at a depth of 0.4 km (0.2 mi). The second event, a magnitude-3.2, occurred on January 23, at 9:59 p.m. This quake was located near Honomu at a depth of 19 km (11.4 mi), and was felt in Hilo.