List of abbreviations and meanings
| ATPD | Ambient temperature, ambient pressure, and dry |
| ATPS | Ambient temperature and pressure saturated with water vapour |
| BTPS | Body temperature (i.e. 37°C), ambient pressure, saturated with water vapour |
| C | Centigrade |
| CFC | Chlorofluorocarbons |
| cm | Centimetres |
| COHb | Carboxyhaemoglobin |
| DL,CO | Diffusing capacity for the lungs measured using carbon monoxide, also known as transfer factor |
| DL,CO/VA | Diffusing capacity for carbon monoxide per unit of alveolar volume, also known as KCO |
| DM | Membrane-diffusing capacity |
| DT | Dwell time of flow >90% of PEF |
| EFL | Expiratory flow limitation |
| ERV | Expiratory reserve volume |
| EV | Back extrapolated volume |
| EVC | Expiratory vital capacity |
| FA,X | Fraction of gas X in the alveolar gas |
| FA,X,t | Alveolar fraction of gas X at time t |
| FEF25–75% | Mean forced expiratory flow between 25% and 75% of FVC |
| FEFX% | Instantaneous forced expiratory flow when X% of the FVC has been expired |
| FEV1 | Forced expiratory volume in one second |
| FEVt | Forced expiratory volume in t seconds |
| FE,X | Fraction of expired gas X |
| FIFX% | Instantaneous forced inspiratory flow at the point where X% of the FVC has been inspired |
| FI,X | Fraction of inspired gas X |
| FIVC | Forced inspiratory vital capacity |
| FRC | Functional residual capacity |
| FVC | Forced vital capacity |
| H2O | Water |
| Hb | Haemoglobin |
| Hg | Mercury |
| Hz | Hertz; cycles per second |
| IC | Inspiratory capacity |
| IRV | Inspiratory reserve volume |
| IVC | Inspiratory vital capacity |
| KCO | Transfer coefficient of the lung (i.e. DL,CO/VA) |
| kg | Kilograms |
| kPa | Kilopascals |
| L | Litres |
| L·min−1 | Litres per minute |
| L·s−1 | Litres per second |
| lb | Pounds |
| MEFX% | Maximal instantaneous forced expiratory flow where X% of the FVC remains to be expired |
| MFVL | Maximum flow–volume loop |
| mg | Milligrams |
| MIF | Maximal inspiratory flow |
| mL | Millilitres |
| mm | Millimetres |
| MMEF | Maximum mid-expiratory flow |
| ms | Milliseconds |
| MVV | Maximum voluntary ventilation |
| PA,O2 | Alveolar oxygen partial pressure |
| PB | Barometric pressure |
| PEF | Peak expiratory flow |
| PH2O | Water vapour partial pressure |
| PI,O2 | Inspired oxygen partial pressure |
| θ (theta) | Specific uptake of CO by the blood |
| RT | Rise time from 10% to 90% of PEF |
| RV | Residual volume |
| s | Seconds |
| STPD | Standard temperature (273 K, 0°C), pressure (101.3 kPa, 760 mmHg) and dry |
| TB | Tuberculosis |
| TGV (or VTG) | Thoracic gas volume |
| tI | Time taken for inspiration |
| TLC | Total lung capacity |
| Tr | Tracer gas |
| ttot | Total time of respiratory cycle |
| TV (or VT) | Tidal volume |
| VA | Alveolar volume |
| VA,eff | Effective alveolar volume |
| VC | Vital capacity |
| Vc | Pulmonary capillary blood volume |
| VD | Dead space volume |
| VI | Inspired volume |
| VS | Volume of the expired sample gas |
| µg | Micrograms |