Petition of the day

The petition of the day is:

Issue: Whether, under a statutory directive to regulate residual public health risks from electric utility steam generating units (EGUs) hazardous air pollutants (HAPs) emissions only as “appropriate and necessary,” the administrator (i) may regulate EGU HAP emissions that pose no hazard to public health, and (ii) may (or must as a Chevron Step One matter) ignore costs in determining “appropriate” regulation because more narrowly drawn decisional standards in the same statute require the administrator to consider (or preclude him from considering) costs.