A description of the attack on April 12 1945 by the 39th BG. It mentions that a major reason for the attack was to stop production of tetraethyl lead (used in high octane aviation gasoline).
Since some of the Japanese launch sites for the FUGO balloons could generate their own hydrogen (possibly using iron filings and dilute sulfuric acid as was done by the Union Army Balloon Corps using portable (horse drawn) wagons during the US Civil War) I wonder how effective attacks on hydrogen producing chemical plants could be.
http://39th.org/39th/history/missions/mission01.html