Vog is a volcanic smog caused by the activity from Kilauea on the Big Island. The volcanic vents release gases and acidic aerosols containing hydrogen sulfides and sulfur compounds. Exposure to vog decreases the ability to expel toxins from the body. It can exasperate asthmatic conditions in individuals, especially children. Other symptoms are headaches, sore throat, and watery eyes. The areas of the Big Island mostly affected are Kailua-Kona to Kau and Puna to Hilo. Vog does travel to Maui and Oahu with heavy winds, but only rarely.