. . . . . "SDN:P07::CF12N223" . "" . "mass_concentration_of_atomic_chlorine_in_air"@en . "accepted"@en . "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 denoted by X may be described by a single term such as 'nitrogen' or a phrase such as 'nox_expressed_as_nitrogen'. The chemical symbol for atomic chlorine is Cl."@en . . . . . . .