"Bubble" means a technique of aggregating certain emissions so as to impose controls that are more stringent than RACT-level on certain emissions units at a particular source, while simultaneously imposing controls that are less stringent than RACT-level on other emissions units, including the option of no controls on such units.
N.H. Admin. Code § Env-A 1202.21
(See Revision Note at chapter heading for Env-A 1200) #9933, eff 6-1-11