VOLCANO, Hawaii (KHNL) - One year ago this March, Halema'uma'u Crater's violent activity on the Island of Hawaii created a towering plume that put scientists on high alert.
Mesmerizing Mother Nature sends a plume from the crater towering into the air. It's a hypnotic sight with a hidden gas, sulfur dioxide.
"Since the beginning of this year this year it has dropped down to 600 tons of SO2 per day," said Jeff Sutton from the Hawaii Volcano Observatory.
This is still dangerously high. To give you some perspective, the Environmental Protection Agency considers it a violation if you emit one quarter of one ton per day.
Once the sulfur gas which is clear and colorless comes out of Halema'uma'u vent, it begins to convert in the oxygen moisture and sunlight becoming sulfuric acid.
This process takes time. That's why the Big Island is hit hardest with the highest concentration of gas. By the time the plume reaches O'ahu, most of the sulfuric dioxide has been converted to sulfuric acid particles. Fewer people higher up the island chain experience the symptoms of the dangerous gas such a difficulty breathing and coughing.
One of the reasons why there is more of a heightened awareness of the affects of sulfur dioxide is because the crater's plume drifts into areas that are highly populated. Whereas the Pu'uo'o lava flow pours into the open ocean.
"Downwind communities or most of those that we think of are those the closest one is only twenty miles away, so you have a concentrated plume of gas and particle that are reaching places like Pahala and Naalehu," said Sutton.