September 14, 2023 — Kīlauea’s eruption plume

Much of the plume from Kīlauea’s current eruption is sulfur dioxide (SO₂). HVO’s gas monitoring station HRSDH has measured up to 12 ppm of SO₂ at its location, nearly 2 miles (3 km) southwest, downwind of the eruption. According to the International Volcanic Health Hazard Network (IVHHN), prolonged exposure to SO₂ in these concentrations is toxic. Even brief exposure to concentrations less than that will cause a respiratory response (airway resistance) and eye irritation. Concentrations more than that cause paralysis or death with extended exposure. SO₂ mixes with air as it moves away from the vent and is less of a hazard for people keeping a safe distance. While the trade winds transport plume in a southwest direction most of the time, conditions can change rapidly, especially in areas closer to the vent that remain closed to the public. USGS photo by M. Patrick.