West Hawaii hazy with vog and likely to stay that way

  • Vog obscures a Princess Cruise Lines ship that visited Kailua-Kona on Thursday. (Chelsea Jensen/West Hawaii Today)

  • This photo compilation shows Hualalai on a clear day (left) and Hualalai on Thursday amid heavy vog. (West Hawaii Today

KAILUA-KONA — Vog hung heavy in the skies over Kailua-Kona Thursday — a trend likely to continue, based on all relevant data.

Kilauea’s eruption has kept West Hawaii air murky and thick since it began rumbling two weeks ago. The volcano upped the ante at 4:17 a.m. Thursday, when an explosion at Halema‘uma‘u crater on Kilauea’s summit blew an ash plume stretching 30,000 feet above sea level.


Throughout the day, prevailing winds distributed ash across large swaths of the island. However, officials said risks from sulfur dioxide (SO2), a harmful element of vog, and the ash itself didn’t appear substantial on Hawaii Island’s leeward side.

Levels of SO2 and fine particulate matter, each present in vog, drop as it moves, said Marianne Rossio, manager of the Clean Air Branch of the Hawaii Department of Health (HDOH).

“It depends on how far away you are,” she said. “If you’re all the way across (the island) or on the next island, you won’t have as bad of effects.”

Despite appearances, data available on the vog dashboard element of the HDOH website classified air quality in Kona as “good” throughout the day. The information can be accessed at https://vog.ivhhn.org.

SO2 levels were highest in Kona at noon, registering at 0.0268. Anything below 0.1 is considered “good.”

A different section of the same website projects three-hour air quality averages roughly two days into the future. Kona is expected to see a three-hour SO2 average of 0.02 at 4 p.m. today, jumping to a three-hour average of 0.04 by 7 p.m.

After that, levels are expected to subside.

That’s nothing compared to what Puna is facing in the wake of Thursday morning’s explosion. Air quality in Puna is projected range from “unhealthy” levels to “very unhealthy” and bordering on “hazardous” levels throughout today and into Saturday.

The highest estimate is a three-hour SO2 block average of 4.65 at 4 a.m. Saturday. Anything above a 5.0 level is considered a hazard.

To provide context, Hawaii standards consider a 24-hour block SO2 average of 0.14 acceptable and an annual average level of .03 acceptable.

In response to Thursday’s explosive activity, the U.S. Environmental Protection Agency’s Pacific Southwest Region sent four emergency responders and 12 monitoring stations capable of measuring sulfur dioxide, hydrogen sulfide and particulates in the air to assist HDOA and Hawaii County Civil Defense in monitoring the situation.

HDOH regularly operates seven monitoring stations on the island. Only one is located on the leeward side, situated in Kona.

In the days and weeks to come, West Hawaii may be subject to heightened monitoring. But for now, other areas are a higher priority.

“We are looking at our overall monitoring network and adding capacity to protect communities, so I would expect (West Hawaii) would be included as well,” said Fenix Grange, program manager for HDOH’s Hazard Evaluation Emergency Response Office.

“Our most urgent priorities in the last couple of days where we’ve been adding more monitors are the affected communities around the rift area that are expected to be impacted by drift from the rift zones,” she added.

Beyond the EPA, Grange said the United States Geological Service, the U.S. National Park Service, National Guard Civil Support Teams and the Hawaii County Fire Department are assisting county Civil Defense and HDOH in their response to air quality concerns.

All have inputs, Grange explained, and collating them appropriately is key to Civil Defense’s ability to advise the public and create a monitoring network capable of providing early warning of impending danger.

Grange added she wasn’t in a position to predict whether or not vog would get worse and/or stay worse in West Hawaii or anywhere on the island. But wind patterns are an effective indicator, and according to the National Weather Service, the odds aren’t in Kona’s favor.

“It’s probably going to continue,” said Robert Ballard, science and operations officer with the National Weather Service. “The (trade winds) are going to settle back in over the next 24 hours or so. That doesn’t really help you guys that much because you’re in the shadow of the volcano.”

Trade winds swirl around the southern edge of the island then get pulled back in and recirculate up the West Hawaii coast, which Ballard said has been happening the past few days.

The trades become persistent this time of year, which he added is likely to trap vog in the Kona region. Southwesterly winds tend to carry vog away from West Hawaii, but their time is now past.

“We’re getting out of the time of year where we see those kinds of winds very often, so unless something changes at the volcano, it’s going to be kind of what you see is what you get,” Ballard said.

Interestingly enough, though, that’s not always completely true. Vog can appear worse than it actually is.

Ballard said if the greatest concentration of vog is centered just above the surface of the Earth, that can make the vog appear worse despite relatively low SO2 levels.

Sulfur dioxide also attracts water molecules, so the more humid the air is, the worse the vog aesthetic.

Ballard said the National Weather Service doesn’t have a lot of experience with rain’s impact on vog, but, “Generally, it does seem like when rain storms occur, it does help to wash some of that out of the atmosphere.”

However, it would stand to reason the rain might soak some of the SO2 up, creating acid rain. Ballard said he’s read that’s what happens, but couldn’t confirm it.

Rossio said that there was no immediate risk or danger for Kona involving acid rain, based on current data.

However, anyone who might be concerned and is on a catchment system can access information about safeguarding against acid rain through the University of Hawaii at Manoa’s College of Tropical Agriculture and Human Resources at https://www.ctahr.hawaii.edu/hawaiirain/more-vog.html.

As for those irritated by the vog running thick in Kona and likely to continue that way, experts’ advice was the same as for those immediately adjacent to the rift zones — close your windows and stay indoors.


Grange admitted the multi-agency collaboration isn’t able to monitor every sector of the island and people should remain vigilant, but she added residents of West Hawaii should not assume an elevated health risk in Kona or elsewhere at this point.

“I’m not aware of data that suggests that in that area at this time,” she said.

Leave a Reply

Your email address will not be published. Required fields are marked *


By participating in online discussions you acknowledge that you have agreed to the Star-Advertiser's TERMS OF SERVICE. An insightful discussion of ideas and viewpoints is encouraged, but comments must be civil and in good taste, with no personal attacks. If your comments are inappropriate, you may be banned from posting. To report comments that you believe do not follow our guidelines, email hawaiiwarriorworld@staradvertiser.com.