Sources contributing to human exposure to chloroform have been identified in the environment. A general approach has been followed to compare hemispheric background concentrations to those .in a coastal urban environment. Then the available data on exposure‐dose relationships were used to calculate effective personal dosage relative to a standard man. Where specific data were unavailable, national averages were used to conservatively estimate emission rates. Chloroform emissions due to the chlorination of public water supply or cooling waters exceeded that due to its use as a solvent. As a result, human dosage occurs, mainly due to the extensive use of chlorinated water and chloroform's volatility. Urban dwellers receive at least 1.2 times the dose predicted at background levels. Atmospheric exposure proves most important in determining one's total dose.