The Illinois Environmental Protection Agency says some of the state's largest air polluters are operating without the proper clean air permits.
State officials say limited funding has left the state's administration of the federal permits lagging. Onsite inspections also are infrequent.
The state says 147 of the 733 highest-polluting power plants, factories and other businesses in Illinois don't have approved permits.
The state has through the end of the year to issue them.
The state EPA's Bureau for Air chief Dave Kolaz says they are doing the best they can with what they have.
A coalition of environmental and health organizations says it's not enough.