ppb

1. abbreviationinitialismInitialism of parts per billion.

   The International Organization for Standardization (ISO)² does not accept the common use of parts per billion (ppb) for two reasons: the meaning of billion is ambiguous, and parts is also ambiguous because it could refer to volume, mass, number, or some other measure.

   2010, Göran Grimvall, “Chapter 1: Numbers”, in Quantify! A Crash Course in Smart Thinking, Johns Hopkins University Press, →ISBN

   1 more example

   . Therefore, Great River Energy expects ozone and NO concentrations associated with the Project to be negligible, and well below all federal standards (nitrogen dioxide (NO2) – 100 parts per billion (ppb) as one-hour average, 53 ppb as annual average; ozone 70 ppb as 8-hour average).

   2024 August 19, “LAKETOWN 115-kV TRANSMISSION LINE PROJECT IN CARVER COUNTY, MN”, in Great River Energy, page 56

1. abbreviationinitialismpluralplural onlyInitialism of parts per billion.

plural PPBs

1. abbreviationinitialismeconomicsInitialism of production-possibility boundary.

   Synonyms: PPC, PPF