Potential To Emit

Rule and Implementation Information for Potential to Emit (PTE)

"Potential to emit” is the maximum capacity of a stationary source to emit under its
physical and operational design. Any physical or operational limitation on the source to
emit an air pollutant, including air pollution control equipment and restrictions on hours of
operation, or on the type or amount of material combusted, stored, or processed, shall
be treated as part of its design if the limitation is enforceable by the (EPA)

PTE Guidance Memoranda

12/30/99 Third Extension of January 30, 1999 Potential to Emit Transition Policy and Clarification of Interim Policy
7/10/98 Second Extension of January 25, 1995 Potential to Emit Transition Policy and Clarification of Interim Policy
4/14/98 Potential to Emit (PTE) Guidance for Specific Source Categories
4/14/98 Attachment: Technical Support Document for PTE Guidance Memo
11/3/97 Discussion paper on Options for the Potential to Emit Rulemaking
06/13/89 Guidance on Limiting Potential to Emit in New Source Permitting

Section 112(a)-Definitions

(a) Definitions: Defines eleven terms found in Section 112: "major source", "area source", "stationary source", "new source", "modification", "hazardous air pollutant", "adverse environmental effect", "electric utility steam generating unit", "owner or operator", "existing source" and "carcinogenic effect".

The definitions as in CAA Section 112(a) follow:


  (a)  Definitions.   -  For  purposes  of  this section,  except
subsection (r) -  
     (1)  Major  source.   - The  term  "major source"  means any
  stationary source or group of stationary sources located within
  a  contiguous area and under  common control that  emits or has
  the potential  to emit considering controls,  in the aggregate,
  10 tons per year or  more of any hazardous air pollutant  or 25
  tons  per  year or  more of  any  combination of  hazardous air
  pollutants. The Administrator may  establish a lesser quantity,
  or in the case of radionuclides different criteria, for a major
  source than  that specified  in the  previous sentence, on  the
  basis  of  the  potency  of  the  air  pollutant,  persistence,
  potential for   bioaccumulation, other characteristics of the
  air pollutant, or   other relevant factors. 
     (2)  Area  source.   -  The  term  "area  source" means  any
  stationary source of  hazardous air  pollutants that  is not  a
  major  source. For  purposes  of this  section, the  term "area
  source" shall  not include  motor vehicles or  nonroad vehicles
  subject to regulation under title II. 
     (3) Stationary source.  - The term "stationary source" shall
  have the same meaning as such term has under section 111(a). 
     (4) New source.  - The term  "new source" means a stationary
  source the construction or reconstruction of which is commenced
  after the Administrator  first proposes regulations under  this
  section establishing  an emission  standard applicable to  such
     (5)  Modification.   -  The  term  "modification" means  any
  physical change in, or change in the method  of operation of, a
  major  source  which  increases  the actual  emissions  of  any
  hazardous air pollutant emitted  by such source by more  than a
  de  minimis  amount or  which results  in  the emission  of any
  hazardous air pollutant not  previously emitted by more than  a
  de minimis amount. 
     (6)  Hazardous  air pollutant.   -  The term  "hazardous air
  pollutant" means  any air pollutant listed  pursuant to subsec-
  tion (b). 
     (7)  Adverse  environmental effect.    -  The term  "adverse
  environmental  effect"  means  any significant  and  widespread
  adverse  effect,   which  may  reasonably  be  anticipated,  to
  wildlife,  aquatic life, or  other natural resources, including
  adverse  impacts on  populations  of  endangered or  threatened
  species or  significant  degradation of  environmental  quality
  over broad areas. 
     (8)  Electric utility  steam  generating unit.   -  The term
  "electric utility steam generating  unit" means any fossil fuel
  fired combustion unit of  more than 25 megawatts that  serves a
  generator  that  produces electricity  for  sale.  A unit  that
  cogenerates  steam  and  electricity  and  supplies  more  than
  one-third of  its potential  electric output capacity  and more
  than  25  megawatts  electrical  output to  any  utility  power
  distribution system  for sale  shall be considered  an electric
  utility steam generating unit. 
     (9) Owner or operator.  - The term "owner or operator" means
  any person who owns,  leases, operates, controls, or supervises
  a stationary source. 
     (10) Existing  source.  -  The term "existing  source" means
  any stationary source other than a new source. 
     (11)  Carcinogenic  effect.    - Unless  revised,  the  term
  "carcinogenic effect"  shall have  the meaning provided  by the
  Administrator under Guidelines for Carcinogenic Risk Assessment
  as  of the  date of  enactment. Any  revisions in  the existing
  Guidelines  shall  be subject  to  notice  and opportunity  for