Snow on Mauna Kea’s summit isn’t the only sign of winter in East Hawaii.
Vog levels saw a noticeable increase this week in Hilo as the trade winds died down, shifting movement patterns for the gases and particles emitted by the Kilauea eruption.
“Once the trade winds shut down, we’re sort of in a light southerly flow,” said National Weather Service meteorologist Bob Burke. That moves vog north from its volcanic source.
Emissions from Kilauea vary daily, but have not changed significantly during the past week, according to the Hawaiian Volcano Observatory.
“It’s under these light (wind) conditions … when you’re going to get the worst chances for vog in Hilo,” Burke said.
Under trade wind conditions, vog affects the communities southwest of Kilauea, and often gets hung up on the slopes of South Kona.
On Friday, sulfur dioxide levels measured at the Hawaii Volcanoes National Park visitors center ranged from “moderate” to “unhealthy for sensitive groups.”
Sulfur dioxide is one of the gaseous components of vog.
“There’s a dual nature to vog; it’s gas and particles,” said U.S. Geological Survey geochemist Tamar Elias. Sulfur dioxide gas converts to sulfuric acid particles in the atmosphere. The farther away from Kilauea the vog moves, the more it is comprised of particles.
During the summer, the USGS in cooperation with seven other agencies, including the state Department of Health, created a Vog Dashboard for residents to check air quality and learn more about vog itself.
Sensitivity to vog varies from person to person.
“It affects people differently,” Burke said. “People that have asthmatic-type problems tend to be more susceptible.”
People with cardiovascular disease, keiki and kupuna, and new or pregnant mothers also tend to be more sensitive.
Burke said a northerly flow might appear by Monday that could push the vog away, but the trades are not expected to return in the next week.
For more information about vog, visit the Vog Dashboard at www.ivhhn.org/vog.
Email Ivy Ashe at iashe@hawaiitribune-herald.com.
