Grade 8 Biology Practice Test 2026 - Free Biology Practice Questions and Study Guide

The abbreviation PPM stands for "Parts Per Million," which is a unit of measurement frequently used in environmental science to express the concentration of a substance within a larger mixture or solution. In this context, PPM indicates how many parts of a particular substance are present in one million total parts of the mixture. This measurement is especially important when dealing with pollutants or chemicals in air, water, or soil, allowing scientists and researchers to quantify how much of a contaminant exists in a specific environment.

Using PPM helps in assessing environmental quality, determining regulatory compliance, and studying the impact of pollutants on ecosystems and human health. By expressing concentrations in such a manner, it simplifies the understanding of small quantities, which can be critical in understanding the potential impacts of substances at low levels.