| Polluter | Pollutants | Sources | Emissions |
|---|---|---|---|
| Ag Processing, Inc. - Mason City | 8 | 253 | 887,900.02 |
| Curries Division Of Aadg, Inc. - 12th Street | 12 | 140 | 210,648.43 |
| Curries Division Of Aadg, Inc. - 9th Street | 14 | 302 | 350,320.00 |
| Holcim (Us) Inc. - Mason City | 20 | 38 | 6,466,443.63 |
| Ipl - Lime Creek Combustion Turbines Station | 10 | 34 | 81,410.04 |
| Lehigh Cement Company - Mason City | 32 | 528 | 23,782,327.43 |
| Wellborn Inds. Ltd. | 1 | 1 | 0.10 |
| Woodharbor Molding And Millworks, Inc. | 16 | 286 | 237,748.00 |