Change Date: 10 Feb 2026, 9:07 a.m.
mass_concentration_of_gaseous_OPE_in_air kg m-3 [UKMC] "Mass concentration" means mass per unit volume and is used in the construction "mass_concentration_of_X_in_Y", where X is a material constituent of Y. A chemical species or biological group denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". OPE means organophosphate esters.