Parts Per Million (PPM)

Parts per million (PPM) is a unit of measurement used when expressing a very dilute concentration level of pollutants in the air, water and other fluids. For example, 1 PPM of ink in water means that in a million mass units of water there would be one mass unit of ink. Thus, PPM refers to one item in a million of anything of the same size. Parts Per Million (PPM) is a ratio used to describe the maximum measurement error or resolution of pressure measurement equipment.

PPM is commonly used in measuring air, water and body fluids pollution. PPM is the mass ratio between a component and a solution. It is most often used as an alternative way of expressing very small percentage values for high accuracy measurement standards such as dead weight testers and high resolution digital displays.