If company or organization or state determines that your pay is non-taxable due to working in a state of emergency area, then that amounts should not even be included on W-2.  This much like combat zone pay.  It is not on W-2 to begin with.  Therefore there is nothing for you to do to make it non-taxable.

I am not familiar with what those emergency workers are referring to.  But it could be a state exemption for certain states that you are speaking of.