| Abbreviation | Definition |
|---|---|
| NYEL | New York Environmental Leaders |
| NYSDEC | New York State Department of Environmental Conservation |
| NZCE | Net-Zero Carbon Emission |
| NZE | Net-Zero Emission |
| NZP | NoiZe Pollution |
| NZSG | Net Zero Scrutiny Group |
| OAPC | Ordinance on Air Pollution Control |
| OATS | Open Area Test Site |
| OAW | Ocean acidification and warming |
| OB | Overflow Bucket |
| OBET | Online Bibliography of Environmental Thought |
| OBRC | Oregon Beverage Recycling Collective |
| OBRC | Oregon Beverage Recycling Cooperative |
| OC | organic carbon |
| OCE | Offset Carbonic Emissions |
| OCEB | Oxford Centre for Environmental Biotechnology |
| OCEEA | OSCE Coordinator for Economic and Environmental Activities |
| OCEO | Olympic College Environmental Outreach |
| OCP | Ogranochloride Pesticide |
| OCR | Original Conserved Region |