Definition of "ppb" []

• Parts per billion (abbreviation)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "- Methane: Pre-Industrial: 715 ppb; Recent 1774 ppb*, Increase = 148\%"
• "- Nitrous Oxide: Pre-Industrial: 270 ppb; 319 ppb*, Increase = 18\%"
• "In fact the data from the manufacturer [Bayer] has been revised downward in just over two years so that they no longer claim that the NOEC (no observed effects concentration) is 5000 ppb, which is what they claimed at the time this insecticide was registered in Canada for potatoes, but now say it is 4 ppb ...."