. . "[ppm]"^^ . . . . "1e-06"^^ . . . "Parts per million"@en . . . "PPM" . "59" . . . . "http://aurora.regenstrief.org/~ucum/ucum.html#section-Derived-Unit-Atoms"^^ . "0112/2///62720#UAD925" . "Dimensionless unit for concentration. Recommended practice is to use specific units such as \\(ug/l\\)."^^ . .