Allowance
Definition
An authorization to emit a fixed amount of a pollutant (e.g. one ton of CO2e).
Source
U.S. Environmental Protection Agency. "Allowance Trading Basics." Clean Air Markets. 14 Apr. 2009. 19 September 2010. http://www.epa.gov/airmarkt/trading/basics.html
Alternative definition
An authorisation to emit a fixed amount of a pollutant (e.g. one tonne of CO2e).
Alternative source