1. Prevention of Significant Deterioration (PSD) NSR Program
Jessica Montañez
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards ,

2. Agenda 1. PSD Applicability 2. PSD Requirements
3. NSR Applicability Example

3. Prevention of Significant Deterioration (PSD) NSR Program Basics

4. Which sources might be subject to the major PSD program?
Sources locating in areas attaining the National Ambient Air Quality Standards or areas that are unclassifiable
New major sources
Existing major sources making major modifications
Physical or operational changes at the source
Change should show significant net emissions increase

5. How do you know when PSD applies to a source?
Determine source’s potential to emit (PTE)
Assess attainment status of source’s geographic area
Determine applicable source thresholds
Determine if source is major for PSD

6. 1. What is the source’s potential to emit (PTE)?
The maximum capacity of source to emit a pollutant under its physical and operational design
Based on operating 24 hours a day, 365 days a year (8760 hours/year)
Can include effect of emissions controls, if enforceable by permit or:
State Implementation Plan (SIP),
Tribal Implementation Plan (TIP) or
Federal Implementation Plan (FIP) conditions

7. 2. What is the attainment status of source’s geographic area?
Determine if area is in attainment for each National Ambient Air Quality Standard (NAAQS) emitted by the source
To find this information:
Contact the appropriate EPA Regional office or applicable permitting authority
Search an EPA database such as:

8. 3. What is the applicable PSD threshold?
250 tons per year (tpy) for most source categories
100 tpy, if part of the 28 listed source categories

9. 4. How do you determine if a source is major for PSD?
For each pollutant, compare the source’s PTE with applicable threshold
If PTE is equal to or higher than threshold, source is major for PSD
For example:
Source PTE for NO2 is 300 tpy
300 tpy > 250 tpy, source is subject to PSD

10. When might a modification be subject to the PSD program?
Based on significant net emissions increase
Determine if proposed source emissions exceeds significant emissions rate (SER)
Determine net emissions increase (NEI)
Sum of contemporaneous emissions increases and decreases to the proposed modification increase
NEI = PMEI + CEI – CED (ERC) where:
PMEI – Proposed modification emissions increase
CEI – Creditable emissions increase
CED – Creditable emissions decreases
ERC – Emissions reduction credit(s)
Check if NEI is greater than SER, if so, source is major

11. Why might a new or modified source not be subject to PSD?
PTE less than major source thresholds
Source is “grandfathered”
Source opted for “synthetic minor” permit
Major Source Threshold 50
100
150
200
250
300
350
Emissions
(tpy)
Actual
PTE
A synthetic minor source is one with:
PTE greater than or equal to the major source threshold, but has actual emissions below that level
and brings PTE below the major source threshold by accepting enforceable limits on emissions or operating conditions
Synthetic Minor Source Emissions 11

12. In what other circumstances can a source be subject to PSD?
Once it is determined that a source is major for PSD, source also has to review pollutants that are below the thresholds by comparing PTE to Significant Emissions Rate (SER)
Pollutants for which the area is in attainment (NAAQS)
Other pollutants
Emissions equal to or higher than SER make pollutant also subject to PSD
Concept known as “Major for one Major for all”

13. What must a major source subject to PSD do?
Install of Best Available Control Technology (BACT)
Perform air quality analysis
Perform class I area analysis
Perform additional impacts analysis
Allow opportunities for public involvement
Install of Best Available Control Technology (BACT)
Perform air quality analysis to preserve existing clean air
Perform class I area analysis to protect national parks and wilderness areas
Perform additional impacts analysis
Allow opportunities for public involvement

14. NSR Applicability Example

15. Which pollutants are subject to PSD, NA NSR, and minor NSR permitting?
New Kraft Pulp Mill
PTE’s:
PM-10 – 10 tpy
VOC – 80 tpy
SO2 – 185 tpy
Area:
In attainment for PM-10 and VOC
In moderate nonattainment for SO2
Kraft pulp mill’s produce the dark colored wood pulp used in the manufacture of a variety of paper products.

16. Example Solution Evaluate for PSD Determine applicable threshold
Kraft pulp mills part of 28 listed source categories
Major source threshold is 100 tpy, not 250 tpy
Determine if the source is major based on the threshold
185 tpy of SO2 > 100 tpy threshold
Mill is a major source for PSD
Now review all attainment pollutants for PSD applicability
Note that the source is a major source for PSD purposes, even though it has a major emission level only of a nonattainment pollutant.
PTE’s: SO2=185 tpy, VOC=80 tpy, PM-10=10 tpy; Area in: NA for SO2, Att. for VOC and PM-10

17. Example Solution (Continued)
Review the two attainment pollutants based on their SER
VOC:
PTE = 80 tpy, VOC not on SER list
However, VOC is ozone precursor
Ozone on list, SER = 40 tpy
80 tpy of VOC > 40 tpy ozone SER, VOC subject to PSD
PM-10:
PTE = 10 tpy
PM-10 SER = 15tpy
10 tpy of PM-10 < 15 tpy SER, PM-10 not subject to PSD
PTE’s: SO2=185 tpy, VOC=80 tpy, PM-10=10 tpy; Area in: NA for SO2, Att. for VOC and PM-10

18. Example Solution (Continued)
Evaluate for NA NSR
Determine applicable threshold
Major source threshold for moderate NA is 100 tpy
Determine if the source is major based on the threshold
Only NA pollutant is SO2
185 tpy of SO2 > 100 tpy threshold, SO2 subject to NA NSR
Evaluate for Minor NSR
PM-10 PTE = 10 tpy
PM-10 may be subject to minor NSR
Proposed minor Tribal NSR rule, PM-10 Att. threshold = 5 tpy
10 tpy of PM-10 > 5 tpy threshold, PM-10 subject to minor NSR
PTE’s: SO2=185 tpy, VOC=80 tpy, PM-10=10 tpy; Area in: NA for SO2, Att. for VOC and PM-10

19. PSD Requirements Details

20. Agenda 1. PSD Requirements Details
2. Refinements of Increment Modeling Procedures Proposal

21. Review: What must a major source subject to PSD do?
Install of Best Available Control Technology (BACT)
Perform air quality analysis
Perform class I area analysis
Perform additional impacts analysis
Allow opportunities for public involvement
Install of Best Available Control Technology (BACT)
Perform air quality analysis to preserve existing clean air
Perform class I area analysis to protect national parks and wilderness areas
Perform additional impacts analysis
Allow opportunities for public involvement

22. What is Best Available Control Technology (BACT)?
Pollutant specific emissions limit, case-by-case
Takes into account energy, environmental, or economic impacts
Limit must be at least as stringent as applicable:
New Source Performance Standard (NSPS) and/or
National Emission Standard for Hazardous Air Pollutants (NESHAP)
Selected by “Top Down” BACT analysis
NSPS (40 CFR Part 60)
NESHAPS (40 CFR Part 61)
If emission standard infeasible due to technological or economic limitations, a design, equipment, work practice, operational standard, or combination thereof, may be prescribed instead to satisfy the requirement for the application of BACT. 22

23. What are the requirements for the “Top-down” BACT analysis?
Identify all available air pollution control technologies, regardless of cost
Eliminate technical infeasible control options
Rank remaining control technologies according to control effectiveness. For each pollutant, list includes:
Control efficiency (percent of pollutant removed)
Expected emissions reduction (tons/year)
Economic Impacts
Environmental Impacts (i.e. significant impact on surface water)
Energy Impacts
Evaluate most effective controls based on all the factors in step 3 and document results
Select BACT
Identify all available air pollution control technologies, regardless of cost
Eliminate technical infeasible control options
Option can be deemed unfeasible due to physical, chemical or engineering principles
Rank remaining control technologies according to control effectiveness. For each pollutant, ranked list should include:
Control efficiency (percent of pollutant removed)
Expected emissions reduction (tons/year)
Economic Impacts
Environmental Impacts (i.e. significant impact on surface water)
Energy Impacts
Evaluate most effective controls based on all the factors in step 3 and document results
Select BACT
Top down analysis
Step 1 might include pollution prevention alternatives.
Step 2
Rationale for eliminating a control option as technically unfeasible must be presented to the reviewing authority. 23

24. What is an air quality analysis and its purpose?
Analysis that involves:
An assessment of existing air quality
Modeling estimate of ambient concentrations from proposed project and future growth associated with project
Purpose:
Will new plus existing emissions cause or contribute to:
NAAQS and/or
PSD increment violation
Pollutant specific, noncriteria pollutants are also evaluated
Refresh that new emissions consist of a new or modified source.
Explain that NAAQS compliance is based on the comparison of total estimated air quality and the NAAQS
Explain that increment compliance is based on the comparison of the amount of new pollution and the applicable PSD increment.
Generally, the analysis would involve:
An assessment of existing air quality, which may include ambient monitoring data and air quality dispersion modeling results
Predictions, using dispersion modeling, of ambient concentrations that will result from the applicant’s proposed project and future growth associated with the project
Each analysis will be unique, due to the variety of sources and meteorological and topographical conditions that may be involved.
Because of the complex character of the air quality analysis and the site-specific nature of the modeling techniques involved, applicants are advised to review the details of their proposed modeling analysis with the appropriate reviewing agency before a complete PSD application is submitted.
Ambient Monitoring Guidelines for PSD
Appendix W (40 CFR) 24

25. What are the steps of the air quality analysis?
Determine Need for Pre-application Monitoring
Meteorological Data
Model Impact of Proposed and Other Emission Sources
Source Input Data (Pollutants with Significant Emissions)
Ambient Concentrations Above Air Quality Significance Level No
No Further NAAQS or PSD Increment Analysis Performed for Pollutant
Yes
Determine Impact Area
Secondary emissions are part of project emissions.
- Suggest the following modeling information is needed:
* Obtain meteorological data representative of project location.
* Estimates of allowable emissions for project PSD emission sources.
* Determine minor source baseline dates for each modeled pollutant and baseline area within 50 km of each project pollutant’s SIA.
* Develop PSD Emission Inventory
-Identify the PSD affecting sources within the above area.
- Determine recent actual emissions and release conditions (e.g., stack characteristics) for the PSD sources. (Allowable emission can be used if appropriate actual emissions are not available.) Emissions should be appropriate for the modeled averaging periods (e.g., annual, 3-hours, etc.).
* Define appropriate receptor grid(s).
* Obtain topographic information for receptors.
Develop Emissions Inventories of Other Sources
Meteorological Data
Model Impact of Proposed and Other Emission Sources
Source Input Data (Pollutants with Significant Emissions)
Demonstration of Compliance 25

26. What do we require for an increment analysis?
A new source or modification cannot cause or contribute to significant deterioration of air quality in attainment areas
Maximum amount of deterioration allowed is called an increment
Change in air quality measured against a certain baseline
Not all sources consume increment

27. Increment per Area Classification (g/m3)
What is an increment?
Increment
Maximum allowed increase in concentration of a pollutant above baseline (concentration as of baseline date) in an area
Increments exist for:
3 pollutants:
PM-10, SO2, NO2
Variety of averaging periods
3-hour, 24-hour, annual
Variety of area classifications
Class I - national parks and other natural areas
Class II - nearly all other areas in the US
Class III - areas targeted for industrial development
Increment per Area Classification (g/m3)
Averaging Period
Pollutant I II
III
Annual
PM-10 4 17 34
SO2 2 20 40
NO2
2.5 25 50
24-hr 8 30 60 5 91
182
3-hr
512
700

28. How is increment compliance determined?
By using air quality models
Preliminary analysis (significant impact analysis)
Screening type models
Representative meteorology
Only proposed source emissions
Refined receptor grids
Full impact analysis (cumulative impact analysis)
Refined model
All applicable increment affecting sources
More refined receptor grids (smaller grid spacing) 28

29. How is increment compliance determined? (cont.)
Determine Need for Pre-application Monitoring
If existing ambient impact is less than the Significant Monitoring Concentration (SMC), permitting agency can exempt an applicant from monitoring
When applying for a permit you need to determine what the existing air quality is. Pre-application monitoring allows you to do that. The reviewing authority may exempt you from Pre-application monitoring if you are below the SMCs.
Pre-application monitoring data generally must be gathered over a period of at least 1 year and the data are to represent at least the 12-month period immediately preceding receipt of the PSD application.
In the absence of available monitoring data which is representative of the area of concern, this requirement could involve the operation of a site-specific air quality monitoring network by the applicant. Also, the need for meteorological data, for any dispersion modeling that must be performed, could entail the applicant’s operation of a site-specific meteorological network.
If however, either (1) the predicted ambient impact, i.e., the highest modeled concentration for the applicable averaging time, caused by the proposed significant emissions increase (or significant net emission increase), of (2) the existing ambient pollutant concentrations are less that the prescribed significant monitoring value , the permitting agency has discretionary authority to exempt the applicant from this data requirement.

30. How is increment compliance determined? (cont.)
Conduct Significant Impact Analysis
Acquire meteorological and source emissions data (actual emissions)
Model impact of proposed source
If source ambient concentrations are:
Lower than the Significant Impact Levels* (SILs), no further analysis needed
Higher than the SILs, full impact analysis is needed
Meteorological data
These data should be demonstrated to be representative of the location of concern. This is especially of concern for the new AERMOD model.
*EPA’s current PSD regulations do not contain SILs, but they have been widely used as a screening tool. 30

31. How is increment compliance determined? (cont.)
Determine Baseline Area(s)
All portions of the attainment or unclassifiable area in which the PSD applicant proposes to locate (See section 107 of the Act) and/or
Any attainment or unclassifiable area in which the PSD applicant would have a significant ambient impact (i.e. higher than SIL)
Limited to intrastate areas
Baseline areas not triggered across state lines
Once baseline area has been established, subsequent major sources undergoing review have to account for increment consumption in that area.
Sources cannot trigger baseline areas across State lines, but increment is consumed across State lines 31

32. How is increment compliance determined? (cont.)
Determine Baseline Date(s) - when increment consumption starts, pollutant specific
Minor Source Baseline Date
when actual emission changes from all sources affect the available increment
Date of first complete permit application
Trigger Date
when the minor source baseline date may be established
Construction - (i.e., physical changes or changes in the method of operation)
Other changes in actual emissions occurring at any source after the major source baseline date do not affect the increment, but instead (until the minor source baseline date is established) contribute to the baseline concentration.
If the application that established the minor source baseline date is ultimately denied or is voluntarily withdrawn by the applicant, the minor source baseline date remains in effect nevertheless.
The baseline date is pollutant specific and for the emissions of the particular pollutant that are significant. Thus, the minor source baseline dates for different pollutants (for which increments exist) need to be the same for a particular area.
Air quality in a region cannot deteriorate to a level above the NAAQS even when the whole increment has not been consumed.
SO2 and PM – 1977, NOx
Major Source Baseline Date
when actual emissions associated with construction at a major source affect increment
SO2 and PM - Jan. 6, NOx - Feb. 8, 1988
Start 32

33. How is increment compliance determined (cont.)?
Example: Baseline Areas and Dates
New source planned for Iowa county, Wisconsin
Wisconsin lists attainment status by counties
Minor source baseline dates (if already established) for Iowa and surrounding counties listed below
PM-10
SO2
NO2
County
Date
Dane
09/13/1998
Iowa --
Sauk
09/27/2002

34. How is increment compliance determined? (cont.)
Source:
Is major for SO2 and PM-10 (area in attainment for both pollutants)
Submits complete PSD application on November 30, 2007
What is the baseline area?
Dispersion modeling shows impact area covers Iowa, Sauk and Dane counties (e.g., ambient concentrations for SO2 and PM-10 exceed 1g/m3 annual SIL)
What are the baseline dates?
Iowa – November 30, 2007 for SO2 and PM-10
Sauk –November 30, 2007 for SO2: September 27, 2002 for PM-10
Dane –September 13, 1998 for SO2 and PM-10
Significant Impact Area
PM-10
SO2
NO2
County
Date
Dane
09/13/1998
Iowa --
Sauk
09/27/2002

35. How is increment compliance determined? (cont.)
Conduct Cumulative Impact Analysis
Determine Impact Area
Based on impact area determined for preliminary analysis
Circular area with a radius extending from the source to:
Largest area for all the pollutants modeled during preliminary analysis or
Receptor distance of 50 km, whichever is less
Proposed Source
County B
County A
Impact Area calculations for your source include fugitive emissions if you are one of the applicable source categories. 35

36. How is increment compliance determined? (cont.)
Conduct Cumulative Impact Analysis
Develop Emissions Inventory
Includes all increment affecting sources within the impact area and the annular area extending 50 kilometers beyond the impact area.
Includes mobile, area and secondary sources
Based on actual emissions over the 2 years preceding the particular date (i.e., baseline or current)
Other time periods may be used if they are “more representative of normal source operations”
Non-criteria pollutants are not evaluated for the increment analysis because there are no increments for them
As with the NAAQS analysis, applicants are not required to estimate future mobile source emissions growth that could result for the proposed project because they are excluded from the definition of “secondary emissions”
Separate inventories can be developed for the baseline sources and the current date or just one inventory that accounts for the difference in emissions from the baseline date to the current period of time
Proposed Source
County B
County A
50 km 36

37. How is increment compliance determined? (cont.)
Conduct Cumulative Impact Analysis
Model Impact of Proposed and Existing Sources
Uses emission inventory data and meteorology to determine the change (Δ) in concentration from baseline
Determination of Compliance
If model output for each pollutant and averaging period is higher than the increment, the permit:
Is denied or
Granted, if emissions are “offset’ by other sources in the area
Also known as cumulative impact assessment
Rarely are actual emissions on the major/minor source baseline modeled. This is only done when the model will not accept negative emission values (i.e., CALPUFF). PSD Class II area models only model the PSD increment by using negative emissions for PSD expanding sources (i.e., PSD baseline sources that have reduced or shut down) and positive emissions for PSD consuming sources.
The permit cannot be issued until the model violation is corrected. This can be done by obtaining offsets from any source, not just the proposed source, to correct the modeling violation. 37

38. What do we require for the NAAQS analysis?
A new source or modification cannot cause or contribute to a violation of any NAAQS in any area
Compliance with any NAAQS is based on proposed source and all other sources in baseline area
No baseline dates exist
Analysis requirements similar to increment analysis
NAAQS analysis independent from increment analysis

39. What is an class I area impact analysis?
Evaluation of NAAQS, PSD increments and Air Quality Related Values (AQRVs) when a major source’s emissions may affect a Class I area
AQRVs – feature or property of a Class I Area that may be affected by a change in air quality
Differ for each Class I area
Defined by the Federal Land Manager (FLM) for Federal lands, or by the applicable State or Indian Governing body for nonfederal lands
Generally for sources within 100 km of Class I area, not always
FLM must be notified of potential impacts
Determines data and analyses needed
If the FLM is concerned about potential emission impacts of a source:
located at a distance greater than 100 km of a Class I area
Or any other reason,
the reviewing authority should not exclude a major new source or major modification from performing an analysis on potential impact to a Class I area
They differ for each Class I area because they depend on the purpose and characteristics of a particular area and on assessments by the area’s FLM.
These authorities also:
establish the criteria that determines an adverse impact on the AQRVs
Recommend to the permitting authority to either approve or disapprove the PSD permit based on anticipated impacts 39

40. What is an additional impact analysis?
Assesses potential effects of increased pollution from new source and associated growth on:
Soils and Vegetation
Visibility
Pollutant specific
Performed within the impact area of the proposed source
Depends on:
existing air quality
quantity and type of emissions
sensitivity of local soils and vegetation (especially commercial crops)
general visibility concerns
This analysis assesses the impacts of air, ground, and water pollution on soils, vegetation, and visibility caused by any increase in emissions of any regulated pollutant from the source or modification under review, and from associated growth.
Mention that other impact analysis requirements may also be imposed on a permit applicant under, local, State or Federal laws which are outside the PSD permitting process. Examples, ESA, National Historic Preservation Act.
Analysis includes the previous air quality analysis that determined the impacts of the new source and associated growth.
The depth of the analysis generally will depend on existing air quality, the quantity of emissions, and the sensitivity of local soils, vegetation, and visibility in the source’s impact area.
Soils and Vegetation Analysis
Based on an inventory of the soils and vegetation types found in the impact area
This inventory should include all vegetation with any commercial or recreational value.
To find this information:
Consult EPA Air Quality Criteria Documents
Contact US Department of Interior, U.S. Forest Service, U.S. National Park Service
Visibility analysis
Screens emission sources that may cause visibility impairment
Determines the visual quality of the area
More in depth analysis may be required using a plume visibility model if the initial screening indicates the possibility of visibility impairment. 40

41. What is done with the PSD information?
Source submits the analyses in PSD permit application to permitting authority
Permitting authority evaluates analyses/application to determine requirements for PSD permit
Reviewing authority then prepares or provides:
Draft permit
Adequate public notice to affected and general public
30-day public comment period on draft permit
Opportunity for public hearing on draft permit
If all requirements met, permitting authority grants permit

42. Proposed Refinements to Increment Modeling Procedures Rule

43. Refinements of Increment Modeling Procedures Proposal
Purpose:
Clarifies the status of existing PSD increment guidance
Addresses how the emissions and meteorology inventory for increment purposes can be developed
Seeks comment on some of the Western States Air Resources Council (WESTAR) recommendations for improving the PSD program
Addresses the issue of Class I Federal Land Manager (FLM) variances
Proposal:
Published in Federal Register on June 6, 2007
Promulgation:
Scheduled for December 2008

44. What have been some difficulties in increment modeling?
Often don’t have adequate older emissions data
Don’t have direct emissions data for all averaging periods
Don’t have hourly data for any sources other than utilities
Don’t have older meteorological data
Regions and states using different methods

45. Issues Addressed in the Proposal
What is the effect of the 1990 Draft NSR Workshop Manual?
Manual not a binding regulation, not final agency policy
How are emissions estimated for increment purposes?
No prescribed method, reviewing authority discretion allowed
Requested comment on WESTAR’s recommended approaches:
menu of acceptable emissions calculation approaches for both short-term and annual increments
set of guiding principles for selecting the most appropriate option from the menu
Mobile sources emissions should be included
Other time periods may be used to establish actual emissions if they are “more representative of normal source operations”
Unless the Agency has otherwise indicated that it no longer adheres to such policies or interpretations
Example of a policy or interpretation that is still followed is the BACT 5 step, top-down process

46. Issues Addressed in the Proposal (cont.)
How are meteorological data estimated for increment purposes?
Reviewing authorities have discretion for using prognostic meteorological models (models that fill gaps in data)
Years of Data Needed:
Observational data: 5 years and at least 1 year for site specific data
Prognostic data: less than 5, but at least 3 years of data
If proprietary data or software needed, reviewing authority has discretion for:
requiring independent review of the proprietary data and conducting the review, provided that confidential information is protected
determining software acceptability based on the: (1) reproducibility of the data or model simulation and (2) quality assurance procedures used in its development
Unless the Agency has otherwise indicated that it no longer adheres to such policies or interpretations
Example of a policy or interpretation that is still followed is the BACT 5 step, top-down process

47. Issues Addressed in the Proposal (cont.)
How future sources in the area where a variance has been granted treat the emissions from the source who received the variance?
Variances – approval of permit when increment is exceeded, but AQRVs are not impacted
We proposed:
Area now has to comply with two increments: the Class I and Class II increments. The Class II increment can never be exceeded.
Variance source(s) emissions not counted in future Class I increment analyses, counted toward future Class II analyses
Implementation Plans (SIPs) not amended to correct violation
Unless the Agency has otherwise indicated that it no longer adheres to such policies or interpretations
Example of a policy or interpretation that is still followed is the BACT 5 step, top-down process

48. Appendix

49. What are the pollutants regulated by the NSR program?
The National Ambient Air Quality Standards (NAAQS) pollutants
Any NAAQS precursors
Any pollutant regulated under the New Source Performance Standards (CAA, Section 111)
Any pollutant otherwise regulated under the Act, except the National Emission Standards for Hazardous Air Pollutants (CAA Section 112)
Any Class I or Class II substance regulated by Title VI of the Act, Stratospheric Ozone Protection

50. What are the National Ambient Air Quality Standards (NAAQS)?
EPA sets NAAQS for:
Ozone (smog)
Carbon Monoxide (CO)
Particulate Matter (dust/soot)
For each of the NAAQS pollutants, every area of the U.S. is designated into one of the following categories:
Attainment - air quality concentrations equal to or lower than NAAQS
Nonattainment - air quality concentrations higher than NAAQS
Unclassifiable – not enough data on air quality; generally treated as attainment
Nitrogen dioxide (NO2)
Sulfur dioxide (SO2)
Lead (Pb) 50

51. National Ambient Air Quality Standards
Pollutants
Primary Standards
Averaging Times
Secondary Standards
Carbon Monoxide
9 ppm (10 mg/m3)
8-hour
35 ppm (40 mg/m3)
1-hour
Lead
1.5 µg/m3
Quarterly Average
Same as Primary
Nitrogen Dioxide
0.053 ppm (100 µg/m3)
Annual (Arithmetic Mean)
Particulate Matter (PM10)
150 ug/m3
24-hour
Particulate Matter (PM2.5)
15 µg/m3
Annual (Arithmetic Mean)
35 ug/m3
Ozone
0.08 ppm
0.12 ppm
(Only in some areas)
Sulfur Oxides
0.03 ppm
0.14 ppm
3-hour
0.5 ppm (1300 ug/m3)
As of June 19, 2008; changes have been proposed to the Lead NAAQS 51

52. PSD 28 Source Categories with 100 tpy thresholds
1. Coal cleaning plants (with thermal dryers)
15. Coke oven batteries
2. Kraft pulp mills
16. Sulfur recovery plants
3. Portland cement plants
17. Carbon black plants (furnace process)
4. Primary zinc smelters
18. Primary lead smelters
5. Iron and steel mills
19. Fuel conversion plants
6. Primary aluminum ore reduction plants
20. Sintering plants
7. Primary copper smelters
21. Secondary metal production plants
8. Municipal incinerators capable of charging more than 250 tons of refuse per day
22. Chemical process plants
9. Hydrofluoric acid plants
23. Petroleum storage and transfer units with a total storage capacity exceeding 300,000 barrels
10. Sulfuric acid plants
24. Taconite ore processing plants
11. Nitric acid plants
25. Glass fiber processing plants
12. Petroleum refineries
26. Charcoal production plants
13. Lime plants
27. Fossil fuel-fired steam electric plants of more than 250 million British thermal units (BTU)/hour heat input
14. Phosphate rock processing plants
28. Fossil-fuel boilers (or combination thereof) totaling more than 250 million BTU/ hour heat input

53. Significant Emission Rates (SERs)
SER – a rate of emissions that would equal or exceed any of the following rates:
Notwithstanding the above, any emissions rate or any net emissions increase associated with a major stationary source or major modification, which could construct within 10 km of a Class I area, and have an impact on such area equal to or greater than 1 g/m3 (24-hour average)
Pollutant
SER (tpy)
SER (tpy)
Carbon Monoxide
100
Hydrogen sulfide(H2S) 10
Nitrogen Oxides 40
Total reduced sulfur (including H2S)
Sulfur Dioxide
Reduced sulfur compounds (includes H2S)
Particulate Matter (PM10) 15
Municipal waste combustor organics
3.5 x 10-6
Ozone
40 of VOCs or NOx
Municipal waster combustor metals
Lead
0.6
Municipal waste combustor acid gases
Fluorides 3
Municipal solid waste landfills emissions 50
Sulfuric acid mist 7
As of June 19, 2008; SER has been proposed for PM-2.5 53

54. Significant Impact Levels (SILs)
SILs– air quality concentrations below which a full impact analysis may be exempted by the permitting authority
Proposed Significant Impact Levels (µg/m3)
61 Fed. Reg ; July 23, 1996
Pollutant
Averaging Time
Class I
Class II
Class III
Sulfur Dioxide (SO2)
Annual
0.1
1.0
24- hour
0.2
5.0
3-hour
25.0
Particulate Matter (10µm)
0.3
Nitrogen Oxides (NO2)
As of June 19, 2008; SIL has been proposed for PM-2.5 54

55. Significant Monitoring Concentrations (SMCs)
SMCs– air quality concentrations below which monitoring may be exempted by the permitting authority
Pollutant
SMC (µg/m3) and Averaging Time
Carbon Monoxide
575 (8-hour)
Nitrogen Dioxide
14 (Annual)
Sulfur Dioxide
13 (24-hour)
Particulate Matter (PM10)
10 (24-hour)
Lead
0.1 (3-month)
Fluorides
0.25 (24-hour)
Hydrogen sulfide (H2S)
0.2 (1 hour)
Reduced sulfur compounds (includes H2S)
10 (1 hour)
Ozone
Applicants with a net emissions increase of 100 tons/year or more of VOC’s or NOx required to monitor
As of June 19, 2008; SMC has been proposed for PM-2.5 55

56. Air Quality Models Screening Models
Used to determine if a more refined air quality model is needed
Examples: SCREEN3/AERSCREEN
Preferred/Recommended Models (40 CFR Appendix W)
Required for NSR permitting and SIPs. These models include:
AERMOD
source-oriented dispersion model that characterizes atmospheric processes by dispersing a directly emitted pollutant plume to predict concentrations at selected downwind locations
CALPUFF
dispersion model that simulates the effects of time- and space-varying meteorological conditions on pollution transport, transformation, and removal
May be applied for long-range transport and for complex terrain on a case-by-case basis
Alternative Models
Not listed in Appendix W, can be used in regulatory applications with case-by-case justification (See Section 3.2 in 40 CFR Appendix W)
Other required models for other applications exist.