| ASC | Ammonia Slip Catalyst |
| BACT | Best Available Control Technology |
| CARB | California Air Resources Board |
| CH4 | Methane |
| CNG | Compressed Natural Gas |
| CO | Carbon monoxide |
| CO2 | Carbon dioxide |
| CRTÒ | Continuously Regenerating Technology |
| CSR | Corporate Social Responsibility |
| DOC | Diesel oxidation catalyst |
| DPF | Diesel particulate filter |
| ECT | Emission Control Technologies |
| EHS | Environment, health and safety |
| EU | European Union |
| GHG | Greenhouse gas |
| GWP | Global warming potential |
| HAPs | Hazardous Air Pollutants |
| HC | Hydrocarbon |
| HDD | Heavy Duty Diesel |
| HFO | Heavy Fuel Oil |
| ISO 14000 | Internationally recognised series of standards which specify the requirements for an environmental management system |
| ISO 26000 | International standard giving guidelines on social responsibility |
| ISO 9000 | Internationally recognised series of standards which specify the requirements for a quality management system |
| KPI | Key performance indicator |
| LPG | Liquefied Petroleum Gas |
| LSD | Low sulfur diesel |
| MACT | Maximum Achievable Control Technology |
| MATS | Mercury Air and Toxics Standards |
| MDO | Marine diesel oil |
| N2O | Nitrous oxide |
| NG | Natural gas |
| NGO | Non-governmental organisation |
| NMHC | Non-methane hydrocarbon |
| NMNEHC | Non-methane non-ethane hydrocarbon |
| NOx | Oxides of Nitrogen: NO and NO2 |
| PGM | Platinum Group Metal |
| PM | Particulate Mass (diesel soot) composed of solid carbon, ash, SOF and possibly sulfates |
| PTA | Purified Terephthalic Acid |
| R&D | Research and Development |
| REACH | Registration, Evaluation and Authorisation of Chemicals. EU chemical control legislation which came into force in June 2007 |
| RICE NESHAP | Reciprocating Internal Combustion Engine National Emission Standards for Hazardous Air Pollutants |
| SCR | Selective Catalytic Reduction |
| SCRT | SCR + CRT technologies integrated into a single system |
| SEC | Stationary Emissions Control |
| SMR | Steam Methane Reforming |
| SNG | Substitute natural gas |
| SO2 | Sulphur dioxide |
| SOF | Soluble Organic Fraction (of diesel PM) |
| SOx | Oxides of Sulfur |
| Syngas, synthesis gas | A mixture of hydrogen, CO and CO2 |
| TWC | Three-way catalyst |
| ULSD | Ultra Low Sulfur Diesel fuel |
| VOC | Volitile Organic Compound |
| WtE | Waste to Energy |