Definition

Parts per billion (ppb) is a unit of measurement used to express the concentration of a substance in a mixture, typically in gases or liquids. It signifies the ratio of the quantity of a particular substance to the total quantity of the mixture, with the substance being present at one part per billion.

Mathematically, ppb is defined as:

Ppb = 1 \1,000,000,000parts

In other words, 1 ppb represents one part of the substance in every billion parts of the mixture. This unit is commonly used in environmental science, chemistry, and air quality monitoring to specify very low concentrations of pollutants or trace substances in the atmosphere or other media. It is particularly useful for quantifying substances that are present in extremely small amounts.