This text of applied chemistry considers the interface between chemistry and chemical engineering, using examples of some of the important process in­ dustries. Integrated with this is detailed consideration of measures which may be taken for avoidance or control of potential emissions. This new emphasis in applied chemistry has been developed through eight years of experience gained from working in industry in research, development and environment­ al control fields, plus twelve years of teaching here using this approach. It is aimed primarily towards science and engineering students as well as to envi­ ronmentalists and practising professionals with responsibilities or an interest in this interface. By providing the appropriate process information back to back with emis­ sions and control data, the potential for process fine-tuning is improved for both raw material efficiency and emission control objectives. This approach also emphasizes integral process changes rather than add-on units for emis­ sion control. Add-on units have their place, when rapid action on an urgent emission problem is required, or when control simply is not feasible by pro­ cess integral changes alone. Obviously fundamental process changes for emission containment are best conceived at the design stage. However, at whatever stage process modifications are installed, this approach to control should appeal to the industrialist in particular, in that something more sub­ stantial than decreased emissions may be gained.