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.