Toxic natural pollution at Ijen crater volcano: Environmental characteristics and health risk assessment.

The Ijen crater volcano (ICV) is one of the active volcanoes with unique environmental conditions; it is the largest lake in the world with the most extreme acidity and a blue fire phenomenon and releases toxic volcanic gases, including dangerous sulfur dioxide (SO₂). It has an impact on the environment and ecosystem. This research aimed to investigate the blue fire phenomena and toxic gas SO and characterize the environmental conditions and health effects of the ICV. The method used in this research involved carrying out an SO concentration using an impinger in 32-point sampling around the Inje crater volcano. The environment was characterized based on self-observation, station observation, interviews, and reliable literature data. The health effect was measured based on the threshold level value based on local and global regulations. This research shows that the characteristics of the ICV include a crater lake with a depth of up to 200 m and a diameter of ± 900 m with pH values less than 1. Then, the source of SO comes from the reaction of magma with volcanic gas. the blue fire phenomenon, which occurs in certain situations, frequently adds to the natural wonder of the ICV. In addition, the distribution of SO concentrations ranges from 480 to 6960 ppb. Next, almost the Hazard Quotion (HQ) > 1 every point sampling. This means that the SO concentration and HQ exceed the threshold value affecting human activities.