Emission limits may not take credit for stack height above good engineering practice or for other dispersion techniques (except stacks and techniques in place by 31 December 1970 and certain pre-1957 coal units). Good engineering practice height is the greater of 65 meters (213.25 feet), the formula height (2.5H for qualifying stacks existing on 12 January 1979, otherwise H plus 1.5L of nearby structures), or a height shown by an approved fluid model or field study to avoid excessive concentrations from downwash, wakes or eddies.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.