A designation for an area, a metropolitan region, for example, that fails to meet prescribed air quality standards.
The United States Environmental Protection Agency has designated various degrees of air pollution: extreme, severe, serious, moderate, and marginal. The determination of air quality in a particular location is established by taking air samples and subjecting them to evaluation through use of laboratory instruments.
If an area fails to measure up to a prescribed standard, it is said to be a nonattainment area. That is, it is said not to have attained the air quality standard prescribed by the EPA.
When a region is designated a nonattainment area, there are regulatory restrictions placed on activities within the area. For a given location, one of these may be a requirement that motor fuel dispensing facilities within the area install Stage I and Stage II gasoline vapor recovery systems.
See also State Implementation Plan.