Publisher Summary This chapter discusses the calculating methods for estimating releases to the environment. Quantities found and reported should reflect the amounts of chemicals released after any onsite treatment and specific to the chemical, metal, or chemical category. These quantities do not reflect the total quantity of waste or constituents of the waste. All sources of wastes should be considered in estimating releases of chemicals from the facility. Accidental or non-routine releases should also account for in the release totals. The quantities that are to be reported should be the total of the releases from the various individual release points of waste streams for each medium. Calculations are complicated when a volatile material is made or used and air emissions must be estimated for leaks, vents, etc., or when no data are available on water releases and the water comes from several points in the process. The emission factor approach relies heavily on determination that the process is analogous to the process for which data were used to derive the factor.