What does Parts Per Million (PPM) measure?

Parts Per Million (PPM) is a unit of measurement commonly used to express the concentration of a substance in a solution or mixture. Specifically, it indicates how many parts of a particular material are present in one million parts of the total solution or mixture. This measurement is particularly useful in environmental science and water quality testing, as it allows for precise quantification of contaminants or essential minerals in water.

Using PPM provides a clear understanding of the level of impurities or elements in the water, aiding operators in assessing whether water quality meets safety standards. For example, if a water sample contains 10 PPM of a certain contaminant, this means that in one million parts of that water, there are 10 parts of the contaminant.

In contrast, temperature measures thermal energy, volume quantifies the space occupied by a gas, and pressure measures the force exerted by gas molecules within a given volume. These concepts, while important in other scientific contexts, do not relate directly to the measurement of concentration like PPM does. Thus, the correct understanding of PPM is crucial for monitoring water quality effectively.