Vog

Kilauea on the Big Island of Hawaii is one of the most active volcanoes in the world. Volcanoes spew ash, a type of particulate matter air pollution, into the air for miles downwind of the eruption. They also produce and release gases mixed with water and tiny particles that form this pollution that we see and call vog. Vog can be harmful, so learn more to take steps to protect yourself and your family.

What Is in Vog?

Vog contains a mix of dangerous components. One of the gases Kilauea releases is sulfur dioxide (SO₂). SO₂ levels in vog are greatest close to the volcano. SO₂ irritates the eyes and causes a range of harmful effects on the lungs, including wheezing, shortness of breath and difficulty breathing.

SO2 reacts with other chemicals in the air to form both liquid and solid particle pollution as it travels downwind. The particles scatter light, making the air appear hazy. Particle pollution can cause asthma attacks, heart attacks and can kill.

Kilauea also produces tons of lava every day. When the lava flows into the ocean, the intense heat evaporates the water, vaporizing salts at the same time. As the water vapor cools, the salts recombine and hydrogen chloride is formed. This reacts with water to form droplets of hydrochloric acid and even tiny glass particles. The droplets scatter light forming a haze called "laze," named for lava and haze.

Wind moves the vog away from Kilauea. The wind direction determines which part of Hawaii will be affected. When the prevailing, northeasterly tradewinds are blowing, Vog collects on the Kona side of the Big Island before being blown out to sea. When southerly (Kona) winds are blowing, Vog affects the Hilo side of the Big Island and may blow up to impact islands farther up the chain.

What To Do

If vog will be heavy in your area, take these extra precautions, especially if you suffer from a chronic breathing problem such as asthma or COPD (which includes chronic bronchitis and emphysema):

• Do not smoke. Avoid secondhand smoke.
• Stay indoors and use an air-conditioner, if possible. Keep the air conditioner on recirculation setting.
• If you have medications, put them in a convenient place. It is important to continue taking your medication.
• Medications you need for an acute episode should be readily available. If you don't have any medications, but feel that you might need them, call your physician. Make sure you have clear instructions from your physician as to what to do if your lung condition suddenly worsens.
• Assume that your lung condition may deteriorate during periods of vog and contact your physician as soon as any problem develops. Do not allow a respiratory condition to linger, especially if there is a high concentration of vog.
• Monitor the wind direction to find out if vog will be blown in your area that day. You can find out the wind direction by watching the television weather report, listening to a weather radio or by checking the weather section of your local newspaper.
• Drink plenty of fluids unless you have a medical condition that requires you to limit your fluid intake.
• Avoid outdoor physical exertion if you have breathing problems.
• Don't count on a dust mask. A paper, gauze surgical, or non-toxic dust mask will not filter out the dangerous smaller particles and masks may not fit well. NOTE: If you find it more difficult to breathe with the mask on, don't use it. A mask is the least important of these suggestions.
• Ask about your oxygen use. People using oxygen should not adjust their levels of intake before consulting a physician. (Call your doctor BEFORE you take any action.)

While these suggestions are focused on people who have chronic lung diseases (such as asthma and COPD, which includes chronic bronchitis and emphysema), they are also useful for normally healthy persons during volcanic haze episodes.

Get More Information on Vog

• Hawaii VOG Information
• Hawai'i Volcanoes National Park
• Hawaii Civil Defense Agency Information
• VMAP—forecasts vog-related SO2 and particulate exposures for Hawaii Island and also provides animated maps of vog direction flow over the island in real time.
• 10 Tips to Prepare for a Disaster