- Also PPM, P.P.M., p.p.m. parts per million.
- pulse per minute.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for ppm
Prior to the Industrial Revolution of the late 19th and early 20th centuries, the carbon dioxide level was about 280 ppm.
Today global atmospheric carbon dioxide concentrations are at 395 parts per million (ppm).
Atmospheric carbon-dioxide levels have risen 38% in the industrial era, from 280 to 385 parts per million (ppm).Mother Nature's Nuclear Strike
July 8, 2009
- chem parts per million
- Also: PPM peak programme meter
Word Origin and History for ppm
abbreviation of parts per million, attested by 1913.
Online Etymology Dictionary, © 2010 Douglas Harper
- parts per million
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.