Some common expressions of gas volume with defined or variable temperature, pressure and humidity inclusion are:
*ATPS: Ambient temperature (variable) and pressure (variable), saturated (humidity depends on temperature)
*ATPD: Ambient temperature (variable) and pressure (variable), dry (no humidity)
*BTPS: Body temperature (37 °C or 310 K) and pressure (generally same as ambient), saturated (47 mmHg or 6.2 kPa)
*STPD: Standard temperature (0 °C or 273 K) and pressure ( or ), dry (no humidity)