Hawaii Volcano Kilauea: Why High Levels of Sulfur Dioxide Are Dangerous

Hawaii’s Kilauea Volcano has had a busy 12 days. Since it started erupting on May 3, it’s opened up 17 fissures, shot giant rocks into the air, literally screamed, and released copious amounts of toxic sulfur dioxide gas out of its many gaping cracks. It’s spewed so much of the gas into the air that on Monday, County of Hawaii officials released a Condition Red warning to people in the vicinity of the volcano, warning them to get out — and fast. These toxic farts are nothing to be sniffed at, and not only because they smell like rotten eggs.

The warning minced no words in its description of the effects of sulfur dioxide inhalation: “Severe conditions may exist such as choking and inability to breathe.” According to the United States Geological Survey, it can do this because it naturally “irritates skin and the tissues and mucous membranes of the eyes, nose, and throat.” A single exposure to high concentrations of the gas can cause asthma and can even cause pulmonary edema, the accumulation of fluid in the lungs.

Like human gas, sulfur dioxide is produced in the bowels of a volcano as a byproduct of magma creation. Because the pressure is so high underground, the gas stays dissolved in the liquid magma, much like the carbonation in your seltzer stays dissolved until you lower the pressure by opening the bottle. In a volcano, pressure is released as magma pushes through fissures and holes, causing the sulfur dioxide inside it to exsolve — form bubbles — and escape into the atmosphere.

Under the right conditions, having enough sulfur dioxide is in the atmosphere can lead to the formation of “vog” — that’s volcanic fog — and, if it rains, acid rain. Combining with oxygen, water, and nitrogen dioxides, which are released when fossil fuels are burned, sulfur dioxide from the volcano reacts to form sulfuric acid and nitric acid. Droplets of these chemicals falling from the sky is generally not great for humans, vegetation, and life in general.

Because it isn’t clear how long Kilauea will continue erupting, there’s also no telling how much gas will eventually be released into the air. At the time of publishing, fortunately, the government-run Hawai’i Short Term SO2 Advisory website, which tracks sulfur dioxide levels from Kilauea in real time, shows that all the data collection sites have “good” air quality.