Part per million


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Terms & Synonyms

Official WHO Definition

Unit of concentration often used when measuring levels of pollutants in air, water, body fluids, etc. One part per million is 1 part in one million by volume (WHO et al. 2003).A unit equal to 10-6 (Symons et al. 2000).  See ppm 

Other Definitions


Interpretations and Explanations

In water, milligrams per litre (mg/L) is frequently used when referring to parts per million (Symons et al. 2000). 


Symons, J. M., Bradley, L. C. Jr. and Cleveland, T. C.  2000.  The Drinking Water Dictionary. American Water Works Association WHO, WMO and UNEP (2003) Climate change and human health: risks and responses 


WHO Lexicon page (translations and examples)

See also

External Resources


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