Abstract This publication presents new correlations and emission factors for estimating total hydrocarbon emissions and evaporative cargo losses for marine vessel loading and ballasting operations. The publication was developed by the American Petroleum Institute's Committee on Evaporation Loss Measurement@ a subcommittee of the Committee on Petroleum Measurement. The correlations and factors are based on recent ship and barge emission tests during typical operations. Correlations are presented for estimating emissions from loading and ballasting of crude oil tankers. To use the crude oil loading correlation@ the Reid vapor pressure and temperature of the crude oil must be known. To use the ballasting correlation@ the arrival ullage of the cargo must also be known. Use of the correlations are recommended whenever the required input data are available. No statistically significant correlation could be developed for gasoline loading. The publication presents several emission factors for gasoline loading that differ according to type of vessel@ prior cargo@ and compartment treatment during the ballast voyage. Similar factors are presented for ctude oil loading. Emission factors for ballasting of crude oil tankers are differentiated by the compartment ullage prior to discharging the cargo. Typical overall emission factors are also provided for use for loading and ballasting operations when the information needed to apply the correlations@ or the more detailed factors@ is not available. The correlations and factors for estimating emissions are applicable to product and crude oil tankers currently calling at U.S. ports. These correlations and factors should not be used for estimating emissions from very large crude carriers or for vessels that employ crude oil washing. The publication does not address crude oil loading into barges@ gasoline tanker ballasting@ or in-transit losses since emission data were not available for these operations. Evaporative cargo loss estimates were also developed from the emission test data (as presented in Appendix E). Evaporative cargo loss is not necessarily equivalent to an atmospheric emission since a cargo loss occurs whenever cargo evaporates@ regardless of whether or not that vapor is displaced from the compartment and emitted into the atmosphere.