June 14, 1993





Mr. Charles W. Whitmore
Principal, Whitmore Associates
7315 Frontage Road
Suite 123
Shawnee Mission, Kansas  66204

Dear Mr. Whitmore:

     This is in response to your April 29, 1993 letter in which
you point out that some Environmental Protection Agency (EPA)
documents have incorrectly used the term "total suspended
particulates" (TSP) interchangeably with "particulate emissions"
and "particulate matter emissions" (PM).  As noted in your
letter, TSP is a measure of the particulate content of ambient
air, is not regulated by any of the new source performance
standards (NSPS), and is not a regulated air pollutant as defined
in 40 CFR 70.2.  On the other hand, PM (which is regulated by
NSPS) comes within the definition of regulated air pollutant. We
agree that the terminology related to this definition should be
clarified as guidance and other documents are updated and
revised.

     Your letter contains two incorrect assumptions about EPA
policy.  First, there is the assumption that program
applicability determinations (presumably for major source
thresholds) will be invariably based on particulate emissions.
This is not always the case.  For example, the major source
threshold is based on emissions of PM-10 (particles with an
aerodynamic diameter less than or equal to a nominal 10
micrometers) in PM-10 nonattainment areas classified as
"serious."  

     Second, EPA policy does not require that fees which States
charge sources be based on actual emissions of PM-10.  States
have considerable discretion in designing their fee collection
schedules, including the discretion to collect fees for any set
of pollutants they wish, provided the resulting aggregate fees
are sufficient to fund the permits program.      
     I appreciate the opportunity to be of service and trust that
this information will be helpful to you.  If you have any
questions, please contact Kirt Cox or Candace Carraway of my
staff at (919) 541-5399 and (919) 541-3189, respectively. 

                                   Sincerely,



                                   John S. Seitz /s/
                                     Director
                         Office of Air Quality Planning
                                   and Standards

cc:  W. Spratlin, EPA Region II