Sec. 130. EMISSION FACTORS.
  Within 6 months after enactment of the Clean Air Act Amendments
of 1990, and at least every 3 years thereafter, the Administrator
shall review  and, if  necessary, revise, the  methods ("emission
factors")  used for purposes of this Act to estimate the quantity
of emissions of carbon  monoxide, volatile organic compounds, and
oxides of nitrogen from sources of such air pollutants (including
area sources and mobile  sources). In addition, the Administrator
shall  establish emission factors  for sources for  which no such
methods  have previously been  established by  the Administrator.
The Administrator shall permit any person to demonstrate improved
emissions estimating  techniques, and following  approval of such
techniques,  the Administrator  shall authorize  the use  of such
techniques. Any such technique may be approved only  after appro-
priate   public  participation.   Until  the   Administrator  has
completed
the revision  required by this  section, nothing in  this section
shall  be construed to  affect the  validity of  emission factors
established by the Administrator before the date of the enactment
of the Clean Air Act Amendments of 1990.
[42 U.S.C. 7430]