The Midwest Regional Planning Organization (MRPO) aids in planning to address regional haze in five states, Illinois, Indiana, Michigan, Ohio, and Wisconsin. The group is also responsible for assessing the effects visibility impairment due to regional haze in class 1 areas from sources within and outside of the five states.
In addition to the five states listed above, the organization is made up of tribes located within those states, federal land management agencies, and the U.S. Environmental Protection Agency.
Source:Midwest Regional Planning Organization Principles for Regional Planning March 9, 2001 Available at http://www.frames.gov