USGS HVO Press Release - Hazardous Sulfur Dioxide Concentrations Measured at Kīlauea Volcano

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Today, HVO scientists measured concentrations greater than 10 ppm in a broad area adjacent to Halema‘uma‘u crater. Sulfur Dioxide gas is persistently emitted at Kīlauea's summit. 

Typical concentrations are generally negligible except for areas downwind of Halema‘uma‘u crater, where they can get up to 2.5 ppm (parts-per-million) in narrow zones.

When sulfur dioxide concentrations greater than 1 ppm (equal to 1,000 parts per billion) are measured at the Jaggar museum or at the Kīlauea Visitor's Center, the buildings are closed and employees and visitors are advised to relocate to areas with cleaner air. See

High sulfur dioxide concentrations have been blamed for several fatalities, many amongst those having a history of asthma. The International Volcanic Health Hazard Network has compiled several studies indicating that 10–15 ppm concentrations of sulfur dioxide is a threshold of toxicity for prolonged exposure (

HVO crews will continue to monitor the situation closely.

HVO will post updates at

Daily updates about ongoing eruptions, recent images and videos of summit and East Rift Zone volcanic activity, maps, and data about recent earthquakes in Hawaii are posted on the HVO website at

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