A concept allied to, but less stringent than, that of zero discharge. Zero risk permits the release to air, water, and land of those pollutants that have a threshold dose below which public health and the environment remain undamaged. Such thresholds are often difficult to determine. They may also involve a time element, as in the case of damage to vegetation by sulfur dioxide in which less severe fumigations over a longer period are equivalent to more severe exposures over a shorter period.

See Also

Air Quality Criteria; Pollution Control; Water Quality Standards