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What Is This Vog You Speak Of?

January 3, 2010

When the Oahu media is reporting on vog, you know parts of the Big Island are in for a rough couple of days.  For those of us who are sensitive to vog, this can mean a few days of allergy-like symptoms: scratchy throats, itchy eyes, runny noses, sneezing and, possibly, head-aches.

Crater vent at Kilauea Volcano

What is VOG?

VOG is “volcanic smog.” It’s one of the downsides to living near an active volcano.  Thankfully, our normal trade wind pattern usually blows the emissions from the vents of the volcano away from the more populated areas of the Big Island and toward the south.  But, when the winds shift and we have “Kona winds” from the south, vog can move across the island chain, leaving the air hazy and, for some, quite uncomfortable to breathe.

A US Geological Survey Fact Sheet says this about how vog is formed:

Noxious sulfur dioxide gas and other pollutants emitted from Kilauea Volcano on the Island of Hawai`i react with oxygen and atmospheric moisture to produce volcanic smog (vog) and acid rain. Vog poses a health hazard by aggravating preexisting respiratory ailments, and acid rain damages crops and can leach lead into household water supplies….

SO2 is a poisonous gas that irritates skin and the tissues and mucous membranes of the eyes, nose, and throat. During even moderate physical activity, SO2 penetrates deeply into the airway and can produce respiratory distress in some individuals….

Looking toward Kawaihae Harbor

In the photo above, you can see the haze in the distance, obscuring the view of Kawaihae Harbor and the mountains.  (From my experience, people who are unfamiliar with vog end to think that it’s not necessarily “voggy” where they are if they can’t see the haze immediately in front of them or smell the sulfur smell that is characteristic of some areas in the Volcanoes National Park.  Although there are days when the vog does have that distinctive rotten-egg odor, at other times, the composition of the particulates and gases are such that the odor may not be noticeable. )

This is a past photo of the same harbor, from a much greater distance away.  You can even see Maui in the distance:

Kawaihae Harbor from Waikoloa Village

It Comes, It Goes

Vog is a fact of life for those of us who live on the Big Island.  But, just like Hilo’s rainy season,  it comes and goes, and can be quickly forgotten until the next time Kona winds make the skies hazy again.  Even so, visitors and residents alike should be aware of the potential health risks of exposure to vog (and “laze” – the gas release that occurs when lava flows reach the ocean). Taking precautions on voggy days can make another day in Paradise much more enjoyable!

Here’s hoping for a quick return of our trade winds from the north!


USGS Volcano Hazards – Volcanic Gases and Their Effects

Hawaii County Civil Defense Message page

Hawaii Volcanoes National Park – Current Sulfur Dioxide (SO2) Conditions

American Lung Association of Hawaii Vog Brochure

Yesterday, the Hawaii County Civil Defense issued this message:

Persistent light winds are causing consistent poor air quality in Hawai’i Island, especially in the communities surrounding the summit of Kilauea Volcano due to the pooling of emissions. The National Weather Service forecasts light wind conditions to continue until Thursday.

Also, recent flare-ups within the firebreaks at the Hokukano and Kealakekua brush fires are causing smoke problems for Kona residents, especially in the early morning hours…

Because of the fires and the wind forecast the following are issued:

  • Residents affected by smoke and emissions are advised to stay indoors and use an air conditioner if available.
  • Limit physical exertion.
  • Drink plenty of fluids.
  • If you have medications, make sure you have them readily available. For exposure to emissions, the CDC recommends the use of inhalers before symptoms appear.
  • Don’t smoke and avoid second hand smoke.
  • If you are experiencing negative health effects from smoke or emissions it is recommended that you leave the area. Air quality usually improves after a few hours.

Again, volcanic emissions and smoke from fires are having a negative impact on air quality island wide….the National Weather Service forecasts light winds through Thursday. Residents should be prepared for possible exposure to emissions and or smoke.


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