"(4) Further information.-If the Administrator determines that
information on the health or environmental effects of a substance
is not sufficient to make a determination required by this
subsection, the Administrator may use any authority available to
the Administrator to acquire such information.
"(5) Test methods.-The Administrator may establish, by rule,
test measures and other analytic procedures for monitoring
and measuring emissions, ambient concentrations, deposition, and
bioaccumulation of hazardous air pollutants.
"(6) Prevention of significant deterioration.-The provisions of
part C (prevention of significant deterioration) shall not apply
to pollutants listed under this section.
"(7) Lead.-The Administrator may not list elemental lead as a
hazardous air pollutant under this subsection.
"(c) List of Source Categories.-
"(1) In general.-Not later than 12 months after the date of
enactment of the Clean Air Act Amendments of 1990, the
Administrator shall publish, and shall from time to time, but no
less often than every 8 years, revise, if appropriate, in
response to public comment or new information, a list of all
categories and subcategories of major sources and area sources
(listed under paragraph (3)) of the air pollutants listed
pursuant to subsection (b). To the extent practicable, the
categories and subcategories listed under this subsection shall
be consistent with the list of source categories established
pursuant to section 111 and part C. Nothing in the preceding
sentence limits the Administrator's authority to establish
subcategories under this section, as appropriate.
"(2) Requirement for emissions standards.-For the categories
and subcategories the Administrator lists, the Administrator
shall establish emissions standards under subsection (d),
according to the schedule in this subsection and subsection (e).
"(3) Area sources.-The Administrator shall list under this
subsection each category or subcategory of area sources which the
Administrator finds presents a threat of adverse effects to human
health or the environment (by such sources individually or in the
aggregate) warranting regulation under this section. The
Administrator shall, not later than 5 years after the date of
enactment of the Clean Air Act Amendments of 1990 and pursuant to
subsection (k)(3)(B), list, based on actual or estimated
aggregate emissions of a listed pollutant or pollutants,
sufficient categories or subcategories of area sources to ensure
that area sources representing 90 percent of the area source
emissions of the 30 hazardous air pollutants that present the
greatest threat to public health in the largest number of urban
areas are subject to regulation under this section. Such
regulations shall be promulgated not later than 10 years after
such date of enactment.
"(4) Previously regulated categories.-The Administrator may, in
the Administrator's discretion, list any category or subcategory
of sources previously regulated under this section as in effect
before the date of enactment of the Clean Air Act Amendments of
"(5) Additional categories.-In addition to those categories and
subcategories of sources listed for regulation pursuant to