Introduction Air quality standards are established to protect man and his total environment from damage by air pollutants. This goal is attained by enforcing regulations that set limits on the emissions of such pollutants under a mass of federal@ state and local laws. This great body of law is undergoing continual amendment and revision. Thus reliable information as to the regulations in effect at a given time and place can be obtained only from the control agency that has jurisdiction. Accordingly@ this chapter will not attempt to cover in detail the legal requirements embodied in the standards and regulations. Instead emphasis will be placed on the more fundamental aspects of establishing air quality standards@ for example: 1. The rationale for controlling air pollution. 2. Techniques for developing air pollution control strategies. 3. Reasons for controlling the ambient concentrations of individual pollutants. 4. Present federal air quality standards. 5. Possible effects of environmental impact statements.