After serving a notice of intent to sue EPA related to updated emission control requirements associated with “residual risk” air toxics regulations, environmental groups brought suit against the agency on April 8. The plaintiffs in the suit, filed in the U.S. District Court for the District of Columbia, seek to force EPA to reassess requirements imposed on twenty-one industry sectors pertaining to residual health threats and upgrades in pollution control technology. Targeted in the litigation are industry sectors that have not been the subject of previous efforts by advocacy groups. Suits such as this often result in a settlement between the parties whereby EPA agrees to undertake the reassessment by a date certain. Further updates will be provided in subsequent issues of the Air Letter.