Introduction This chapter discusses the sources and typical magnitudes of hydrocarbon emissions from a refinery and described methods of reducing them. While the primary purpose of controlling such emissions is to comply with the applicable regulations on emission rates and on ambient air quality@ conservation of energy through the elimination of losses is an equally valid objective. This discussion is confined to refinery emissions of hydrocarbons to the atmosphere. These hydrocarbons are composed of the various compounds in equilibrium with the individual petroleum fractions. Thus they may contain aliphatic saturates and unsaturates@ naphthenes@ and a variety of substituted aromatics. In additions there may by trace amounts of low molecular weight alcohols@ aldehydes@ organic acids@ and compounds of sulfur and nitrogen. This chapter does no deal with emissions from petrochemical plants.1* *See references on page 7-13.