This document discusses various environmental indices used to measure air, water, and noise pollution levels. It describes the Pollutant Standard Index (PSI) which measures levels of 6 air pollutants and indicates their health effects. The Water Quality Index (WQI) is discussed, which uses test results for 6 parameters to determine water quality. Methods for calculating the WQI and interpreting its values are provided. Noise pollution indices and sources of noise pollution along with control measures are also outlined. In the conclusion, the author states that using environmental indices helps characterize existing conditions, collect and summarize data, communicate quality, and provide baseline data for impact assessments.