Ppm 11 : Parts Per Million, 1 X 106. A convenient means of expressing very low concentrations of a substance in a mixture, or as a low-level contaminant in a pure product
Grainger, Inc. (Maintenance, Repair and Operating MRO), Glossary of Safety Terms, IL, USA 2012. www.grainger.com/images/GlossaryofSafetyTermsPDF.p df, (IndS/Maint, Repr and Opr - Amer) {79}