Hawaii Volcanoes National Park, one of the main attractions on America's outpost in the Pacific, was closed earlier this week due to an eruption of sulfur gas fumes from Mount Kilauea.
Image from Cat Butler on Flickr
Some 2,000 people were evacuated from the scene on Tuesday, and the park remains closed.
Volcanic Fog (Vog, for short) forms when the sulfur dioxide reacts with oxygen, sunlight, dust particles, and the like, to form a highly toxic mix that hangs suspended in the air. It also typically includes such dangerous substances as sulfuric acid. When it's not melting your face, it can cause severe breathing problems especially among those who suffer from asthma, bronchitis, and emphysema.
The dangerous gas has so far forced 6 people into Red Cross shelters, and another 42 into hotels; the park officials are persisting in their hope that the trade winds will resume on Thursday and clear the islands, but are cautioning against any such hope in the citizenry, because, well, that's what officials do in times of natural crisis.