high altitude conditions
(1) The Administrator shall promptly establish at least one testing center (in addition to the testing centers existing on November 15, 1990 ) located at a site that represents high altitude conditions, to ascertain in a reasonable manner whether, when in actual use throughout their useful life (as determined under section 7521(d) of this title ), each class or category of vehicle and engines to which regulations under section 7521 of this title apply conforms to the emissions standards established by such regulations. For purposes of this subsection, the term “high altitude conditions” refers to high altitude as defined in regulations of the Administrator in effect as of November 15, 1990 .