MADISON, Wis. -- The key witness for Madison-Kipp Corporation testified Wednesday that air pollution data presented by Kipp critics is overstated.

NEWS 3 I-TEAM News 3's Linda Eggert has been following the Kipp pollution case. Read and watch her special I-Team reports: PART I: Watch It Read It PART II: I-Team: Kipp Contamination, Part II Read It Follow-Up: Kipp Responds More I-Team Reports Contact Linda Eggert Kipp Corp. Statement RESOURCES Madison Health Department EPA: Toxic Air Pollutants

Kipp put chemist and air pollution modeler, Mark Podrez, from Colorado on the stand at a state contested case hearing. The century-old Madison-Kipp Corporation melts aluminum and zinc, creating products and jobs for 600 people.

Clean Air Madison, or CAM, is trying to overturn some DNR permits.

In part, the DNR hiked Kipp's emission limit for particulate matter by 55 percent, or 61 tons a year.

Clean Air Madison claims the DNR did not correctly measure Kipp's pollution impact in the densely packed neighborhood. Residents say pollution from the plant is making them ill.

Podrez disputed that, saying that installing an air quality monitor would probably not work. "It may be difficult to locate -- to implement a monitor to really be able to answer some of these questions given the paritculars at Kipp," Podrez said.

Podrez criticizes the expert for the citizens group, saying the techniques used are so "liberal" that the Kipp pollution numbers are inflated.

The hearing continues Thursday. Check back for more information.