| Abbreviation | Definition |
|---|---|
| IHSB | Industrial Hygiene and Safety Branch |
| IIASA | International Institute for Applied Systems Analysis |
| IIED | International Institute for Environment and Development |
| IIES | Integrated International for Environmental Services |
| IIES | International Institute for Environmental Studies |
| IKR | International Koala Rescue |
| ILEC | Ivy League Environmental Coalition |
| ILGBC | Israeli Green Building Council |
| IMAC | Interim Maximum Acceptable Concentration |
| IMEM | International Master in Environmental Management |
| IMEP | international Master of Environmental Policy |
| IMET | Institute of Marine and Environmental Technology |
| IMISWG | Inter-Ministry Invasive Species Working Group |
| IMSW | Integrated Municipal Solid Waste |
| INDCS | Intended Nationally Determined Contributions |
| INEF | International Network of Environmental Forensics |
| INEM | International Network for Environmental Management |
| INEP | Indo Norwegian Environmental Programme |
| INER | Institute of Nuclear Energy Research (Taiwan) |
| INER | Instituto Nacional de Enfermedades Respiratorias |