On March 22, 2012, EPA published the final rule in the Federal Register (77 FR 16679) that revises the manner for applying the threshold planning quantities (TPQs) for those extremely hazardous substances (EHSs) that are non-reactive solid chemicals in solution. The revision allows facilities that have a non-reactive solid EHS in solution to first multiply the amount of the solid chemical in solution on site by 0.2 before determining if this quantity equals or exceeds the lower published TPQ. This rule became effective on April 23, 2012.