A review is presented of selected topics related to sampling and evaluation of airborne agents and their control. The need for an air sampling strategy that addresses usage of the results for demonstration of regulatory compliance or for epidemiologic studies is stressed. For sampling particulate matter, the concepts of total and respirable dust are explained and instruments used to obtain these data are described. Postsampling recordkeeping is essential for both regulatory and investigatory survey purposes. Engineering, administrative, and personal protective equipment controls are all options to reduce exposure. Engineering controls are preferred because they do not place day-to-day responsibilities on those potentially exposed. Finally, the approaches described should be applicable to allergic agents in the air, although the bulk of published material is for nonallergic contaminants.