How can this new information be used in a pragmatic way by practicing clinicians? Patients should be advised to minimize outdoor activity during days with high pollution or smog levels. In choosing new residential locations, patients should give preference to sites remote from heavy automobile traffic or chemical manufacturing plants. Finally, as patient advocates, physicians, both individually and as members of large health organizations, should support societal control of air pollution and rally against attempts to weaken science-based regulatory air pollution standards. To this end, the physician should become familiar with current exposure guidelines for compounds considered to be risks for inducing or exacerbating asthma, as determined by the Environmental Protection Agency and nongovernmental agencies, such as the American Conference of Governmental Industrial Hygienists.