One of the gases ejected from a volcano during in an eruption is sulfur dioxide. (SO2)
If sulfur dioxide is oxidized by certain compounds such as nitrogen dioxide (NO2) then sulfuric acid (H2SO4) is produced. When H2SO4 mixes with airborne moisture it falls to earth as “acid rain” Okmok produced a large cloud of SO2 at the begining of it’s eruption on July 12th. That cloud and addition SO2 produced from subsequent explosions began reaching parts of the pacific northwest on July 17th. See the photos below that track the cloud’s movements from the 13th to the 17th. As of this posting there was no map for the 18th. The red indicates Sulfur Dioxide.
