What’s Worse: Vog or Smog?

Kilauea volcano at night
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With the Kilauea eruption in the news, some people feel compelled to resurrect the argument that volcanic emissions dwarf human pollution. In view of spectacular demonstrations of nature’s power, it’s a tempting idea. Orders of magnitude separate human-caused from volcanic contributions of greenhouse gases and humans are the primary culprits.

Kilauea

Yes, volcanic eruptions are dangerous. Kilauea, on the Big Island of Hawaii, has technically been erupting continuously since 1983. But on May 3, 2018, the eruption took a dramatic turn when the volcano began spewing lava into residential subdivisions. In the weeks since then, Kilauea has introduced the wider world to a variety of health hazards, including vog, laze, and Pele’s hair.

Volcanic Health Risks

The golden strands of volcanic glass evocatively called Pele’s hair are beautiful. But they can inflame lungs if inhaled and damage the esophagus when ingested in contaminated water. Laze used to be what people did on a Hawaiian vacation, but now laze refers to lava haze, the dense toxic clouds that form along the shoreline when lava contacts ocean water.  

The most dangerous air pollutant produced by Kilauea is vog. Volcanic fog can be invisible or form a smog-like haze. It contains carbon dioxide, sulfur dioxide, hydrogen sulfide, hydrogen fluoride, and carbon monoxide. Vog is similar to smog — the pollution produced by coal power plants and vehicle emissions. People exposed to vog experience eye, nose, throat, and skin irritation; respiratory ailments; fatigue; and dizziness. Those with asthma or emphysema are especially at risk. Sometimes exposure results in long-term damage.

smog over city skyline

Human activities generate 24 billion tons of greenhouse gases annually. Image: stokpic.com

Volcanic Pollution

The local environment is also feeling the effects of Kilauea’s eruption, and not just because of the lava flows. Nitrogen and sulfur deposited from air pollution harms vegetation, soils, and surface waters on the island. They contribute to eutrophication in surface waters and over-enrich soils, encouraging non-native plants. Volcanic eruptions can kill fish and wildlife and disrupt avian migrations.

Volcanoes and Climate Change

But one thing Kilauea, or any volcano, cannot do is cause climate change. The myth that volcanoes cause climate change erupts every time a volcano does. But scientific data is clear: Data shows that human greenhouse gas production continuously drives climate change. Vog is as bad as smog, but there just isn’t enough of it to make a difference. Volcanoes generate about 200 million tons of carbon dioxide annually, while human activities generate 24 billion tons.

This explains why measured atmospheric carbon dioxide levels increase consistently every year, whether or not major volcanic eruptions occur. Scientists have even noted a slight short-term decrease in average temperatures when major eruptions take place — probably as a result of ash reflecting solar energy that would otherwise enter the atmosphere. Don’t ease off your environmental efforts, though — Kilauea doesn’t count as a major eruption, no matter how impressive it looks in the photos.   

Feature image: Kilauea volcano at night. Credit: Adobe Stock

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Gemma Alexander

Gemma Alexander has an M.S. in urban horticulture and a backyard filled with native plants. After working in a genetics laboratory and at a landfill, she now writes about the environment, the arts and family. See more of her writing here.

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