| Abbreviation | Definition |
|---|---|
| AC | Activated Carbon |
| AC | Air Cleaning |
| AC | Air Contaminant |
| ACAP | Annapurna Conservation Area Project |
| ACCP | Adirondack Communities and Conservation Program |
| ACDP | Air Contaminant Discharge Permit |
| ACEA | Advisory Committee on Environmental Aspects |
| ACEC | Area of Critical Environmental Concern |
| ACECs | Areas of Critical Environmental Concern |
| ACEH | Alameda County Environmental Health |
| ACELA | American Clean Energy Leadership Act |
| ACERT | Advanced Combustion Emissions Reduction Technology |
| ACES | Aspen Center for Environmental Studies |
| ACF | Activated Carbon Filter |
| ACF | Association of Consulting Foresters |
| ACH | air changes per hour |
| ACIA | Air Climate Impact Assessment |
| ACLAR | Alberta Climate Leadership Adjustment Rebate |
| ACME | Assembling Configuration Management Environments |
| ACMP | Alaska Coastal Management Program |