Abstract
The multi-disciplinary backgrounds and professional competencies within the American Industrial Hygiene Association have been utilized to the fullest in the preparation of a series of ambient air quality guides. These are intended to be concise. To be concise they are offered as single compounds, recognizing that other factors such as potentiation, antagonism, or other effects associated with mixtures, will create special problems from place to place and from time to time, the effects of which must be individually evaluated.