Parts per billion

Parts per billion (ppb) is a unit of measurement used in science and engineering to express extremely small concentrations or ratios. It is equivalent to one unit in 1,000,000,000 units of another. This unit is commonly used in environmental science, chemistry, biology, and other fields where minute quantities are significant.

Definition

The term "parts per billion" is defined as the number of units of a given substance (the "part") present in a billion units of a whole. It is a unit of proportion, used to describe the concentration of one substance within another. The term is often used in the context of pollution or other environmental contaminants, where it can describe the concentration of a pollutant in air, water, soil, or other media.

Usage

In environmental science, ppb is often used to measure the concentration of pollutants in the air, water, or soil. For example, the United States Environmental Protection Agency (EPA) might measure the concentration of a pollutant in the air in parts per billion. In chemistry, ppb is used to measure the concentration of a substance in a solution. In medicine, it can be used to measure the concentration of a drug in the bloodstream.

Conversion

One part per billion is equivalent to 1/1,000,000,000, or 0.000000001. This can also be expressed as 1 microgram per kilogram (µg/kg), or 1 nanogram per gram (ng/g). In terms of volume, 1 ppb is equivalent to 1 microliter per liter (µL/L).

See also

• Parts per million
• Parts per trillion
• Concentration (chemistry)
• Environmental science
• Pollution

References

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