Blanket of vog over Oahu finally fading

The vog that obscured views over the long weekend lay in a heavy band over Oahu before largely dissipating Tuesday.

"Usually when we have southerly winds, there is always the threat of vog," said Henry Lau, forecaster for the National Weather Service in Hono­lulu. "The degree of vog tends to vary, and I believe this is one of the thicker episodes. We tend to forget about it because it happens so infrequently."

Tourists who made it to the top of Diamond Head to snap photos on the holiday weekend were disappointed with the hazy outlook as vistas across the island were affected.

The volcanic air pollution blanketed parts of Oahu — far from its source, the ever-active Kilauea on Hawaii island, which has been releasing sulfur dioxide gas for decades.

Vog can cause breathing trouble, headaches and eye irritation.

"Apparently the vog that had been blown south of the islands has been blowing back north and affecting primarily Oahu," Lau said Tuesday morning. "We can see a strip or a band, north- to south-oriented, affecting Oahu and a portion of the Kauai channel."

The state maintains a network of monitoring stations and posts the results online, giving the public ready access to timely information on air quality, noted Lisa Young, environmental health specialist for the Health Department’s Clean Air Branch.

Lorraine Leslie, executive director of the American Lung Association in Hawaii, urged local residents to take precautions when vog conditions hit.

"We always recommend that people stay indoors and drink plenty of warm fluids, have their medication on hand and avoid outdoor activity," Leslie said. "It is not the time to do your gardening or take a jog."

Steven Businger, professor in the department of meteorology at the University of Hawaii, led a Vog Measurement and Prediction project to test the feasibility of forecasting vog, which is made up primarily of sulfur dioxide and sulfate aerosols.

"It was proven to be very successful," Businger said. "We demonstrated skill in forecasting the levels."

Funding for the 18-month project ended a year ago, but the website is still active.

"We are continuing to do the modeling, and we provide those results online," Businger said, adding that there is no money to interpret the results. Still, he predicted more vog may be in the offing.

"This time of year, going into the winter, you tend to have more Kona winds, and so it’s possible to have a repeat of these episodes," Businger said. "I think this one is ending, but looking at the extended forecast, it looks like the middle of next week we could have more Kona winds."

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On the Net:

» weather.hawaii.edu/vmap

» is.gd/zemere

» hawaii.gov/gov/vog