Ambient air is the air in the unconfined portion of the atmosphere. This is the open air that we breathe, and the air in which pollutants are emitted.
Source: Terms of Environment. 1998. U.S. Environmental Protection Agency, Office of Communication, Education, and Public Affairs. Available at http://www.epa.gov [2001, Dec] As cited in: Hardy, Colin C., Ottmar, Roger D., Peterson, Janice L., Core, John E., and Seamon, Paula. 2001. Smoke Management Guide for Prescribed and Wildland Fire 2001 Edition. Produced by the National Wildfire coordinating Group Fire Use Working Team.