Commonwealth of Pennsylvania

STATE IMPLEMENTATION PLAN REVISION: 

ATTAINMENT DEMONSTRATION AND BASE 

YEAR INVENTORY 

PENNSYLVANIA PORTION OF THE 

PHILADELPHIA-WILMINGTON, PA-NJ-DE

FINE PARTICULATE NONATTAINMENT AREA

APRIL 2010

Bureau of Air Quality

Pennsylvania Department of Environmental Protection

P.O. Box 8468

Harrisburg, PA 17105-8468

717-787-9495

www.depweb.state.pa.us

John Hanger

Secretary

Edward G. Rendell

Governor
blank for two-sided copying
Table of Contents

Executive Summary............................................................................................................. i

I. INTRODUCTION AND OVERVIEW.......................................................................... 1

A. Health and Environmental Effects of Fine Particulate Matter (PM2.5).............. 1

B. Sources of PM2.5 and Implications for Reduction................................................. 1

C. Purpose and Structure of this Document............................................................... 4

D. Public Participation ................................................................................................. 5

II. NATURE OF THE PROBLEM IN THE PHILADELPHIA AREA ............................ 6

A. Background.............................................................................................................. 6

B. Air Quality Monitoring Trends Analysis.............................................................. 7

1. Design Value Trend ............................................................................................... 7

2. NO2 Monitoring Trend........................................................................................... 9

3. SO2 Monitoring Trend ......................................................................................... 10

C. Seasonal Variability .............................................................................................. 10

1. FRM Monitoring Trends...................................................................................... 10

2. Speciation Monitoring Trends ............................................................................. 11

III. EMISSION INVENTORIES ..................................................................................... 12

A. Summary of 2002 Emissions ................................................................................ 12

B. Summary of Inventory Methodologies................................................................ 13

C. Projected Inventories............................................................................................ 16

1. Summary of 2009 Estimated Emissions.............................................................. 16

2. Growth Projection Methodologies....................................................................... 16

D. Reasonable Further Progress (RFP) Requirements .......................................... 20

E. Motor Vehicle Emission Budgets for Transportation Conformity................... 20

IV. CONTROL STRATEGIES ....................................................................................... 23

A. Permanent and Enforceable Control Measures................................................. 23

1. Stationary Point Sources...................................................................................... 23

2. Highway Vehicle Sources.................................................................................... 26

3. Nonroad Sources.................................................................................................. 29

B. Reasonably Available Control Measures/Reasonably Available Control 

Technology Analysis................................................................................................... 29

C. Other Measures - VOC Control Measures......................................................... 31

V. ATTAINMENT DEMONSTRATION AND WEIGHT OF EVIDENCE (WOE)..... 33

A. Attainment Demonstration Background and Objectives.................................. 33

B. Philadelphia Area Conceptual Model Description............................................. 34

C. Modeling Domain and Photochemical Modeling System.................................. 36

D. Model Performance Evaluation........................................................................... 38

1. Daily PM2.5 Mass ................................................................................................. 38

2. PM2.5 Speciation................................................................................................... 40

E. Projected 2009 Design Values for the Philadelphia Nonattainment Area ....... 42

1. Overview............................................................................................................... 42

2. Modeled Attainment Test .................................................................................... 42

3. Determine Baseline Design Values ..................................................................... 43

4. Relative Response Factor Calculations................................................................ 45

5. Annual SMAT Results......................................................................................... 46

6. 24-Hour SMAT Results....................................................................................... 48

F. Unmonitored Area Analysis............................................................................... 49
G. Local Area Analysis.............................................................................................. 50

H. Weight of Evidence and Other Documentation Supporting Attainment ........ 53

I. Conclusions............................................................................................................. 56

VI. CONTINGENCY MEASURES FOR THE ATTAINMENT DEMONSTRATION 57

A. Contingency Measure Requirement.................................................................... 57

B. Identified Contingency Measures........................................................................ 58

ACRONYMS AND ABBREVIATIONS......................................................................... 63

Table of Tables

Table E-1: Summary of the Five-County Philadelphia Area Direct PM and 

Precursor Emissions (Tons per Year)....................................................................iii

Table II-1: Philadelphia Area PM2.5 Annual Average and Design Values (μg/m3) ... 7

Table III-1: 2002 Annual Emissions (Tons per Year) ................................................ 13

Table III-2: 2009 Projected Emissions (Tons per Year)............................................. 16

Table III-3: Five-County Philadelphia Area VMT and Emissions.......................... 18

Table III-4 Comparison of 2009 On-Road Mobile Precursor Emissions to the Total 

Projected 2009 Inventory ....................................................................................... 21

Table III-5: Motor Vehicle Emission Budgets............................................................. 22

Table IV-1: Summary of Emission Reductions 2002-2009 from Control Measures 23

Table V-1: Annual PM2.5 Quarterly RRF Values ........................................................ 47

Table V-2: Annual SMAT Results for the Philadelphia Area 2009 On The Books/On 

The Way Control Measures................................................................................... 47

Table V-3: 24-hour PM2.5 Quarterly RRF Values....................................................... 48

Table V-4: 24-hour SMAT Results for the Philadelphia Area 2009 On The 

Books/On The Way Control Measures................................................................. 49

Table V-5: Summary of Large PM2.5 Sources near the Chester Monitor.................. 51

Table V-6: Summary of PM2.5 Weight of Evidence Guidelines (EPA Guidance)..... 53

Table VI-1: Changes in Design Value and Emissions Expected by 2009.................. 57

Table VI-2: Calculation of Required and Excess Emissions Reductions ................. 58

Table VI-3: Calculation of Required Contingency Plan Reductions........................ 58

Table of Figures

Figure E-1: Map of the Philadelphia-Wilmington, PA-NJ-DE Nonattainment Areaii

Figure 1: PM2.5 Annual Average and Design Value Trends......................................... 8

Figure 2: NO2 Monitoring Trend ................................................................................... 9

Figure 3: SO2 Monitoring Trend.................................................................................. 10

Figure 4: Pennsylvania’s PM2.5 Nonattainment Areas ............................................... 34

Figure 5: Philadelphia Area Percentage of Total Mass.............................................. 36

Figure 6. OTC Modeling Study Domain...................................................................... 37

Figure 7: Mean Fractional Error ................................................................................. 39

Figure 8: Mean Fractional Bias.................................................................................... 40

Figure 9: Time Series of SO4 Mass............................................................................... 41

Figure 10. Wind Rose: Philadelphia Int’l Airport Location (2004-2008)................. 52

Figure 11: Philadelphia Area PM2.5 Trends................................................................ 55
APPENDICES

APPENDIX A: AIR QUALITY MONITORING INFORMATION 

A-1 United States Environmental Protection Agency Air Quality System Quick Look:

Pennsylvania (1999-2008)

A-2 United States Environmental Protection Agency Air Quality System: Quarterly PM2.5 

Data (1999-2008)

APPENDIX B: STATIONARY POINT SOURCES 

B-1 Methodology – Preparation of Pennsylvania Point Source Inventories and Instructions 

for Completing the Annual Emissions Reporting Forms

B-2 Facility Annual Emissions 

B-3 Banked Emissions Reduction Credits

APPENDIX C: STATIONARY AREA SOURCES 

C-1 Pennsylvania 2002 Area Source Criteria Air Pollutant Emission Estimation Methods

(EH Pechan, Feb. 2004)

C-2 Area Source Annual Emissions 

APPENDIX D: EMISSIONS PROJECTIONS 

D-1 Development of Emission Projections for 2009, 2012, and 2018 for NonEGU Point, 

Area and Nonroad Sources in the MANE-VU Region (MACTEC, Feb. 2007)

D-2 Documentation of 2018 Emissions from Electric Generating Units in the Eastern 

United States for MANE-VU’s Regional Haze Modeling (Alpine Geophysics, April 

2008)

D-3 Future Year Electricity Generating Sector Emission Inventory Development Using the 

Integrated Planning Model (IPM®) in Support of Fine Particulate Mass and Visibility 

Modeling in the VISTAS and Midwest RPO Regions (ICF, April 2005)

APPENDIX E: HIGHWAY VEHICLE SOURCES INVENTORY INFORMATION

E-1 Mobile Source Highway Emissions Inventory – An Explanation of Methodology

E-2 Highway Emissions Estimates

E-3 MOBILE6.2 Input Parameter Summary

E-4 MOBILE6.2 Sample Input File

E-5 Traffic Growth Forecasting System Report

APPENDIX F: NONROAD SOURCES 

F-1 Emissions Estimation Methodology

F-2 Nonroad Source Emissions

F-3 Philadelphia International Airport Inventory and Methodology

F-4 Capacity Enhancement Program Construction Period Air Emissions Inventory

APPENDIX G: REASONABLY AVAILABLE CONTROL MEASURES

G-1 Identification and Evaluation of Candidate Control Measures, Final Technical 

Support Document (MACTEC, Feb. 2007)

G-2 OTC Initial List of Measures (Appendix B of Candidate Control Measures TSD)

G-3 Assessment of Reasonable Progress for Regional Haze in MANE-VU Class I Areas

(MACTEC, July 2007)

APPENDIX H: MODELING DEMONSTRATION

H-1 CMAQ Model Performance and Assessment for Base Year 2002 PM2.5 Mass and 

Speciation (NY DEC, Dec. 2007)

H-2 Meteorological Modeling of 2002 Using Penn State/NCAR 5th Generation Mesoscale 

Model (MM5) (NY DEC, Mar. 2006)

H-3 Processing of 2002 Anthropogenic Emissions: OTC Regional and Urban 12km Base 

Year Simulation (NY DEC, Mar. 2007)

H-4 PM2.5 Modeling Using the SMOKE/CMAQ System Over the Ozone Transport Region 

(OTR) (NY DEC, Feb. 2006)

H-5 Processing of 2002 Biogenic Emissions for OTC / MANE-VU Regional and Urban 

Modeling (NY DEC, Sep. 2006)

H-6 Final Air-Quality Modeling Protocol for the Annual PM2.5 NAAQS: PhiladelphiaWilmington, PA-NJ-DE Annual PM2.5 Nonattainment Area (PA DEP, Oct. 2007)

H-7 Sample Calculation of Projected 2009 PM2.5 Annual and 24-hour Concentrations
- i -

Executive Summary

Particulate matter is a mixture of microscopic solids and liquid droplets suspended in air

that include: acids (such as nitrates and sulfates), organic chemicals, metals, soil or dust 

particles and allergens (such as fragments of pollen or mold spores). Fine particle 

pollution or PM2.5 describes particulate matter that is less than or equal to 2.5 micrometer

(μm) in diameter, approximately 1/30th the diameter of a human hair.

Health studies have shown a significant association between exposure to fine particles 

and premature death from heart or lung disease. Fine particles can aggravate heart and 

lung diseases and have been linked to effects such as cardiovascular symptoms, cardiac 

arrhythmias, heart attacks, respiratory symptoms, asthma attacks, and bronchitis. These 

effects can result in increased hospital admissions, emergency room visits, absences from 

school or work, and restricted activity days. Individuals that may be particularly sensitive 

to fine particle exposure include people with heart or lung disease, older adults, and 

children.

The United States Environmental Protection Agency (EPA) issued fine particle (PM2.5) 

national ambient air quality standards (NAAQS) in 1997 after evaluating hundreds of 

health studies and conducting an extensive peer review process. The EPA established an 

annual primary (health-based) and secondary (welfare-based) standard of 15.0 

micrograms per cubic meter (μg/m3), based on the 3-year average of annual mean PM2.5

concentrations. The EPA also established a primary and secondary 24-hour standard of 

65 μg/m3determined by the 3-year average of the 98th percentile of 24-hour 

concentrations. 

On December 17, 2004, the EPA issued air quality designations for the PM2.5 standard

based on air quality monitoring data from 2001-2003. The final designations were 

published in the Federal Register on January 5, 2005 (70 FR 944). The designations 

became effective on April 5, 2005. On April 5, 2005, the EPA issued a supplemental 

notice changing the designation of certain areas from nonattainment to attainment based 

on newly available air quality data (70 FR 19844; published in the Federal Register on 

April 14, 2005). The EPA designated eight areas in Pennsylvania as PM2.5 nonattainment 

areas, comprising all or parts of 21 Pennsylvania counties.

The Philadelphia-Wilmington, PA-NJ-DE Nonattainment Area (Philadelphia Area) is 

comprised of 9 counties in Pennsylvania, New Jersey and Delaware. The Philadelphia 

Area is required to attain the PM2.5 NAAQS no later than five years from the effective 

date of designation, or April 5, 2010. Bucks, Chester, Delaware, Montgomery and 

Philadelphia counties (five-county Philadelphia area) in Pennsylvania are included in the 

Philadelphia Area. Figure E-1 displays a map of the Philadelphia Area.
- ii -

Figure E-1: Map of the Philadelphia-Wilmington, PA-NJ-DE

Nonattainment Area

This State Implementation Plan (SIP) revision contains information on PM2.5 trends and 

emissions and demonstrates that the five-county Philadelphia area meets all requirements 

necessary for an approvable SIP revision. This SIP revision also establishes motor 

vehicle budgets for purposes of transportation conformity. Once the EPA approves the 

budgets for purposes of conformity, the five-county Philadelphia area’s designated 

Metropolitan Planning Organization (MPO), the Delaware Regional Planning 

Commission must use these budgets in its air quality analyses for transportation planning 

purposes.

PM2.5 can be emitted directly or formed secondarily in the atmosphere by chemical 

reactions of gases in the atmosphere. Potential precursors of secondary PM2.5 include 

sulfur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds (VOC), and 

ammonia (NH3).

 

Emissions of the PM2.5 precursors SO2 and NOx are projected to decrease from 2002 to 

2009 in the five-county Philadelphia area, while emissions of direct PM2.5 are projected 

to increase over the same time period. Because sulfates and nitrates are formed from 

atmospheric reactions of SO2 and NOx, the reduction of emissions of SO2 and NOx is 
- iii -

expected to result in attainment of the PM2.5 air quality standard in the Philadelphia Area. 

Based on speciated data from the Chester monitor, sulfates and nitrates account for 46% 

of the PM2.5 mass in the Philadelphia Area. The emission projections take into account 

both growth in economic activity that increases emissions and control measures 

implemented to reduce emissions. 

Table E-1: Summary of the Five-County Philadelphia Area Direct PM and 

Precursor Emissions (Tons per Year)

Pollutant 2002 2009

PM2.5 14727 15219

PM10 61758 66035

SO2 40459 28200

NOx 120248 91651

VOC 122973 101834

NH3 7705 9239

The permanent and enforceable control measures that enable the Pennsylvania portion of 

the Philadelphia Area to demonstrate attainment of the PM2.5 NAAQS include:

The Clean Air Interstate Rule (CAIR) and the NOx “SIP Call” reducing interstate 

pollution transport;

State regulation of smaller sources of NOx, cement kilns and large stationary 

internal combustion engines;

The Pennsylvania and federal new motor vehicle emission control programs for 

passenger and light-duty trucks; 

The Pennsylvania and federal heavy-duty diesel emission control programs;

Federal fuel programs for highway vehicles and nonroad mobile equipment; and

Federal regulation of offroad diesel and gasoline-powered vehicles and 

equipment.

In addition, Pennsylvania’s Diesel-Powered Motor Vehicle Idling Act of 2008 will assist 

the Pennsylvania portion of the Philadelphia Area in attaining and maintaining air 

quality.

Pennsylvania and other member states of the Ozone Transport Commission (OTC) and 

Mid-Atlantic/Northeast Visibility Union (MANE-VU) worked together to analyze 

potential control measures. The Pennsylvania Department of Environmental Protection 

(Department), based on this process that included stakeholders and the other

OTC/MANE-VU states, concluded that there are no additional reasonable cost-effective 

measures that would advance the ability of the area to attain the standard by one year or 

more. 
- iv -

The OTC’s modeling platform, the Community Multi-scale Air Quality (CMAQ) 

photochemical grid model (version 4.5), was used to estimate projected 2009 PM2.5

concentrations within the Philadelphia Area. CMAQ is an Eulerian grid model capable 

of simulating air pollutant concentrations in the atmosphere using mathematical equations 

to characterize chemical and physical properties.

A review of the base case (2002) run indicated the CMAQ model did a reasonable job 

reproducing actual concentrations. Based on this analysis, it is reasonable to assume the 

model can estimate the projected PM2.5 concentrations within the Philadelphia Area for 

2009. The year 2009 will be the last complete year of annual emissions and ambient 

monitoring data that the EPA will use to determine whether the Philadelphia Area attains 

the standard by April 2010.

Projected PM2.5 concentrations from CMAQ indicate the Philadelphia Area will attain the 

annual and 24-hour PM2.5 standards in 2009. Additional evidence supporting this 

conclusion includes recent lower concentrations at monitors within the Philadelphia Area

and the possibility that the model under-predicts the air quality benefits of emission 

reductions.

A number of potential emission control measures were developed during the OTC/

MANE-VU/Mid-Atlantic Regional Air Management Association (MARAMA)

collaborative strategy development process. These measures are outlined in the technical 

support document titled: Development of Emission Projections for 2009, 2012, and 2018 

for NonEGU Point, Area, and Nonroad Sources in the MANE-VU Region, developed by 

MARAMA. This document, which can be found in Appendix D-1, provides details on 

the specific factors, control assumptions, and implementation schedules used in the 

emission projection calculations for each source category.

This SIP revision contains a contingency plan for the five-county Philadelphia area that 

provides assurance that should the Philadelphia Area fail to meet a milestone, fail to 

attain the NAAQS by the attainment date or violate the standard during the maintenance 

period, the area can be brought back into attainment as expeditiously as practicable. 
1

I. INTRODUCTION AND OVERVIEW

A. Health and Environmental Effects of Fine Particulate Matter (PM2.5)

Particulate matter (PM) includes both solid and liquid particles suspended in the air. PM is 

chemically and physically diverse and originates from a variety of human and natural 

activities. PM is composed of particles in a wide range of sizes. Particles less than 10 

micrometers in diameter (PM10) pose a health concern because they can be inhaled into and 

accumulate in the respiratory system. Particles less than 2.5 micrometers in diameter 

(PM2.5) are referred to as fine particles and generally pose the largest health risks. Because 

of their small size, fine particles can penetrate deeply into the lungs.

Many scientific studies have linked exposure to elevated levels of PM2.5 to premature 

death, aggravated respiratory disease, including asthma and chronic bronchitis, 

cardiovascular disease, changes in lung function and increased respiratory problems, such 

as coughing and painful breathing, as well as increased susceptibility to respiratory 

infections. Individuals particularly sensitive to PM2.5 exposure include older adults, people 

with heart and lung disease and children.

The recent article, “Fine-Particulate Air Pollution and Life Expectancy in the United 

States” by C. Arden Pope, III, et al., was published in the New England Journal of 

Medicine on January 22, 2009. The authors of the article were able to demonstrate that 

decreased PM2.5 concentrations contributed to a significant improvement in life 

expectancy. The study used statistical analyses to evaluate the role the PM2.5 reductions

that occurred in the 1980s and 1990s had on the increased life expectancy observed over 

that period. The study found that a reduction of 10 micrograms per cubic meter (μg/m3) of 

PM2.5 was associated with an average increase in life expectancy of 7.3 months. 

PM2.5 has significant environmental impacts, including acid rain and stream 

eutrophication. PM2.5 also affects visibility (regional haze) through the scattering and 

absorption of light. Fine particles, similar in size to the wavelength of light, are most 

efficient, per unit of mass, at reducing visibility. Soiling and materials damage can also be 

caused by PM2.5 in the air. 

B. Sources of PM2.5 and Implications for Reduction

Fine particle pollution can be emitted directly or formed secondarily in the atmosphere. 

PM2.5 emitted directly into the air in a stable solid or liquid chemical form (including PM2.5

that is formed near its source by condensation) is referred to as “primary” PM2.5. PM2.5 

formed by chemical reactions of gases in the atmosphere is considered to be “secondary” 

PM2.5. The chemical composition of PM2.5 in an area depends on the mix of emissions, 

location, time of year, and weather. The chemical composition of PM2.5 can include 

sulfate, nitrate, ammonium, particle-bound water, black (elemental) carbon, a great variety 

of organic compounds, and miscellaneous inorganic material, such as dust and metals.
2

Primary PM2.5 includes soot from diesel engines, condensed organic material from 

incomplete combustion and compounds from condensation during combustion or smelting. 

The atmospheric chemistry of PM2.5 formation is complex. Formation of secondary PM2.5

depends on numerous factors, including the relative concentration of precursors, 

atmospheric conditions and the interactions of precursors with each other and with other 

particles, clouds or fog. The contribution of different precursors will vary by location. 

The principal forms of secondary PM2.5 include:

Sulfates, formed from emissions of sulfur dioxide (SO2) from power plants 

and industrial facilities;

Nitrates, formed from emissions of nitrogen oxides (NOx) from power 

plants, vehicles, and other combustion sources;

Ammonium (NH3), formed primarily from emissions of ammonia from 

animal operations; and

Secondary organic aerosol, formed from emissions of volatile organic 

compounds (VOCs) from incomplete combustion and evaporation from a 

wide diversity of sources. 

To protect public health and the environment, the United States Environmental Protection 

Agency (EPA) is required by the Clean Air Act (CAA) to set and periodically revise 

National Ambient Air Quality Standards (NAAQS) for six criteria pollutants. Particulate 

matter is one of the criteria pollutants. The EPA sets NAAQS based on its review of 

existing scientific knowledge about the adverse health and welfare effects of the pollutant. 

After the EPA sets or revises a NAAQS, states have the responsibility for devising 

strategies to attain and maintain the standard. Previous particulate matter standards were 

set for PM and PM10. In 1997, after evaluating hundreds of health studies and conducting 

an extensive peer review process, the EPA promulgated NAAQS based on the level of 

particles smaller than 2.5 micrometers (PM2.5). In setting the 1997 standards for PM2.5, the 

EPA recognized that the smaller particles were most directly associated with adverse 

health effects. 

The EPA set the annual health-based standard for PM2.5 at 15.0 μg/m3. This is determined 

by the 3-year average of annual mean PM2.5 concentrations. The EPA set the 24-hour 

standard at a level of 65 (μg/m3), as determined by the 3-year average of the 98th 

percentile of 24-hour concentrations. The EPA set levels to protect the environment at the 

same level as it set the health-based standards. The EPA revised the 24-hour standard in 

2006 to be more protective. However, this document addresses attainment of the 1997 

PM2.5 NAAQS. Measures included in this document, or measures as protective, will 

continue to be in place to assist with attaining the more protective standard in the future.

The Philadelphia-Wilmington, PA-NJ-DE Nonattainment Area (Philadelphia Area) is 

comprised of nine counties in Pennsylvania, New Jersey and Delaware. The Philadelphia 

Area is required to attain the PM2.5 NAAQS no later than five years from the effective date 

of designation, or by April 5, 2010. Bucks, Chester, Delaware, Montgomery and 
3

Philadelphia counties (five-county Philadelphia area) in Pennsylvania are included in the 

Philadelphia Area.

The Philadelphia Area was designated as nonattainment because it violated the 1997 

annual standard of 15.0 μg/m3based on 2001-03 monitoring data. The Philadelphia Area

did not violate the 1997 24-hour standard of 65 μg/m3.

Because of the complexity and variability of the process of particulate matter formation,

the EPA recognizes that effective control measures for PM2.5 will vary among

nonattainment areas. In the EPA’s Clean Air Fine Particle Implementation Rule (72 FR 

20586, April 25, 2007) (the implementation rule), the EPA established general 

presumptive policies for assessing which PM2.5 precursors should be evaluated for possible 

controls. The EPA requires states to evaluate control measures for SO2 and primary PM2.5

in all locations. The EPA requires states to evaluate control measures for NOx unless a 

technical demonstration is made to show NOx does not significantly contribute to PM2.5. 

The EPA requires states to evaluate measures for VOC and NH3 only if a technical 

demonstration is made to show they significantly contribute to PM2.5 in that area. While 

this State Implementation Plan (SIP) revision provides emissions information for all 

pollutants (PM10, PM2.5, SO2, NOx, VOC and NH3), as required, it does not provide 

technical demonstrations pertaining to the level of contribution by NOx, VOC, or NH3 to 

PM2.5 concentrations. Therefore, the Commonwealth will consider SO2 and NOx as PM2.5

precursors for purposes of this attainment plan and reasonable further progress.1 The EPA 

has indicated that virtually all nonattainment problems appear to result from a combination 

of local emissions and transported emissions from upwind areas.2

The CAA requires that an area’s attainment date be the date by which attainment can be 

achieved as expeditiously as practicable, but no later than five years from the effective date 

of designation, or no later than April 5, 2010. If appropriate, the EPA could extend the 

attainment date up to but no later than 10 years after the date of designation. States are 

required to propose and justify an attainment date in their attainment plan. This SIP

revision sets an April 2010 attainment date for the Philadelphia Area. The analysis is 

based on modeling of projected emissions for 2009 because 2009 will be the last complete 

year of annual emissions and ambient monitoring data that the EPA will use to determine if

the Philadelphia Area attains the standard by April 2010.

The EPA Administrator is authorized under Section 179(a) of the CAA to impose 

sanctions after making a finding or determination relating to a SIP revision, or after 

disapproving a SIP revision, in whole or in part. Mandatory sanctions would be imposed 

for (1) a state’s failure to submit a plan or plan element, or to make a submission that 

satisfies the minimum criteria of section 110(k) of the CAA in relation to any element of 

the plan; (2) the EPA’s disapproval of a plan in whole or in part; (3) the EPA’s 

determination that a state has failed to make a required submission, including a required 

submission satisfying the minimum criteria of section 110(k); or (4) a state’s failure to 

 

1 The EPA’s definition of PM2.5 attainment plan precursor can be found in 40 CFR Part 51, Subpart Z, 

section 51.1000.

2 Clean Air Fine Particle Implementation Rule, 72 FR 20587.
4

implement any requirement of an approved plan. If the state fails to correct any SIP 

deficiency within 18 months from the Administrator's finding, determination or 

disapproval, mandatory sanctions would be imposed. There are two mandatory sanctions 

for noncomplying states: (1) limitations on certain federal highway funding; and (2) 

"offset" limitations on certain developments in affected areas that require each new 

stationary emission source to be paired with a reduction in area emissions amounting to 

double the amount of increased emissions from the new source. 

In addition, failure to submit a plan, failure to implement a plan, or the EPA 

disapproval of a plan can also affect the ability of transportation planning agencies 

to meet transportation conformity requirements, and thus the ability to implement 

transportation projects. The EPA may also impose discretionary sanctions under 

Section 110 of the CAA. On November 20, 2009, the EPA made a finding that the 

Commonwealth failed to submit a plan with the required elements for the 

Philadelphia Area. The EPA published a Federal Register notice to that effect on 

November 27, 2009. The Department anticipates submitting the SIP revision in 

spring 2010 to provide EPA with ample time for approval before the sanction 

deadlines.

C. Purpose and Structure of this Document 

In December 2004, after consultation with states and receipt of public input, the EPA 

designated eight areas in Pennsylvania comprised of all or parts of 21 Pennsylvania 

counties as PM2.5 nonattainment areas based on air quality monitoring data from 2001-

2003. Under Section 110 of the CAA, states are required to develop a revisions to the SIP

to demonstrate how the area will attain the standard by April 2010, meet emission 

reduction requirements in the CAA and ensure that in the event of a future violation or 

failure to meet emission reduction milestones, the area is brought back to attainment as 

quickly as possible.

This SIP revision is organized as follows:

Section I provides general information about PM2.5 pollution, including information about 

the health and environmental impacts of PM2.5 and sources of PM2.5 and its precursors. 

Section I also provides an overview of the health-based PM2.5 standard and Pennsylvania’s 

responsibility to develop strategies to attain air quality standards.

Section II provides information characterizing the PM2.5 problem in the Philadelphia Area, 

examines current monitoring information, and analyzes trends.
5

Section III describes emission inventories for PM2.5 and its precursors, SO2 and NOx. 

Base year and projected emission inventories are also included as required for PM10, VOC 

and NH3. Section III describes how this SIP revision meets the requirement for 

“reasonable further progress” under Section 172 of the CAA3. Section III also contains the 

highway vehicle emission budgets for purposes of transportation conformity. Technical 

information on methodologies and inputs for point, area, highway and nonroad actual and 

projected emission inventories is contained in the Appendices B through F, relating to: (1) 

stationary point sources; (2) stationary area sources; (3) emissions projections; (4) highway 

vehicle sources inventory information; and (5) nonroad sources. 

Section IV describes the control measures implemented in the Pennsylvania portion of the 

Philadelphia Area that produce emission reductions between 2002 and 2009 in order to 

attain the NAAQS in a timely fashion and how Pennsylvania meets the requirement for 

identifying Reasonably Available Control Measures (RACM) that could advance the 

attainment of the standard by one year or more. Appendix G, relating to Reasonably 

Available Control Measures, includes specific information and recommendations 

developed by the Ozone Transport Commission (OTC) and the Mid-Atlantic/Northeast 

Visibility Union (MANE-VU) states for additional controls to aid in reaching attainment.

Section V discusses the modeling that was done to evaluate attainment by April 2010 and 

the “weight of evidence” analysis. Together, these comprise the attainment demonstration. 

Based on modeling, statistical analyses and other evidence, the attainment demonstration 

indicates the Philadelphia Area will attain the 1997 PM2.5 standards by April 2010. 

Appendix H includes detailed technical information on the Community Multi-scale Air 

Quality (CMAQ) model performance, meteorological data, modeling emission inventories 

and modeling analysis used to project 2009 annual and 24-hour PM2.5 design values.

Section VI is the contingency plan, meeting the requirement that the Commonwealth be 

able to address unanticipated failures to meet emission or air quality requirements in a 

timely fashion. 

D. Public Participation 

Requirements for a public comment process are set forth in Section 110(a)(2) of the CAA,

40 CFR Section 51.102(d) and 35 P.S. Section 4007.5 On February 6, 2010, the 

Pennsylvania Department of Environmental Protection (DEP or Department) published a 

notice of public hearing and commenced a 30-day written comment period on the proposed 

attainment demonstration and base year inventory for the Pennsylvania portion of the

Philadelphia Area. 40 Pa.B. 756. The Department held a public hearing in Norristown on 

the SIP revision on March 11, 2010. The public comment period closed on March 12, 

2010. No one attended the public hearing, and no comments were received during the 

public comment period. Proof of public notice is included in the SIP submittal. 

 

3 Clean Air Fine Particle Implementation Rule, 72 FR 20633.
6

II. NATURE OF THE PROBLEM IN THE PHILADELPHIA AREA

A. Background

The Philadelphia-Wilmington, PA-NJ-DE Nonattainment Area (Philadelphia Area) is 

comprised of nine counties in Pennsylvania, New Jersey and Delaware. Bucks, Chester, 

Delaware, Montgomery and Philadelphia counties (five-county Philadelphia area) in 

Pennsylvania are included in the Philadelphia Area. Other PM2.5 nonattainment areas near 

the Philadelphia Area include the York, Lancaster, Reading, and Harrisburg-LebanonCarlisle nonattainment areas in Pennsylvania, the Baltimore nonattainment area in 

Maryland and the New York-N. New Jersey-Long Island intrastate nonattainment area. 

Topographically, the Philadelphia Nonattainment Area is bounded on the east by higher 

terrain. However, much of the area is situated in the Atlantic Coastal Plain Province, as 

designated by the Pennsylvania Department of Conservation of Natural Resources. This 

area has the lowest elevations (much closer to sea level) within the Commonwealth. 

Therefore, there is little impact of terrain that influences the air quality of many of the 

other areas across the Commonwealth. 

Several types of PM2.5 monitors operate within the five-county Philadelphia area. These 

include eight federal reference method (FRM) monitors. Four of these sites are operated 

by the Department, including Bristol, Chester, New Garden and Norristown. The 

additional four monitors, which include Broad Street, Elmwood, the Philadelphia Air 

Management Service (AMS) Lab and Northeast Airport, are operated by the Philadelphia 

AMS. In addition to the FRMs, four speciation monitors (at Chester, New Garden, the 

Philadelphia AMS Lab and Elmwood) and four continuous monitors (at Chester, 

Norristown, the Philadelphia AMS Lab and Northeast Airport) are maintained within the

region. FRM data has been collected since 1999 on a one in three day frequency (1/3) at 

most of the monitors, except at Elmwood and the Philadelphia AMS Lab (which takes 

samples every day (1/1)). Speciated monitoring on a one in six day frequency (1/6) has 

occurred since April of 2002, while at least one continuous monitor has operated since 

October 2003.
7

B. Air Quality Monitoring Trends Analysis

A short summary of monitoring trends in the Philadelphia Area is provided as follows:

1. Design Value Trend

A monitor’s annual design value is determined by first calculating its quarterly average. 

Quarterly averages are then averaged to calculate the monitor’s average annual PM2.5

concentration. Three consecutive years of average annual PM2.5 concentrations are then 

averaged to determine a monitor’s annual PM2.5 design value. Table II-1 displays PM2.5

annual averages for each monitor and the maximum design value for the Philadelphia 

Area. 

Table II-1: Philadelphia Area PM2.5 Annual Average and Design Values (μg/m3)

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Pennsylvania 

Bristol 12.00 13.64 14.47 14.15 14.42 13.04 14.34 12.15 13.02 12.66

Chester 13.12 15.99 15.86 14.73 15.29 15.02 16.51 13.99 14.45 13.84

New Garden 14.61 15.57 14.25 15.87 12.59 14.07 13.68

Norristown 13.02 13.47 14.88 13.60 13.86 12.00 12.48 12.05 13.09 11.66

AMS Lab 14.64 14.93 16.47 14.38 14.80 13.89 14.21 13.48 13.74 13.01

Broad Street 15.53 17.14 16.98 15.57 16.13 14.39 15.06 15.52 14.37 13.50

Elmwood 14.54 14.81 16.69 13.97 14.03 12.73 14.23 13.14 13.33

NE Airport 12.95 14.66 14.62 13.66 13.19 12.78 12.93 12.40 12.85 11.99

Delaware

Bellefonte 14.26 15.39 15.58 13.97 14.81 13.90 14.30 12.32 13.43 13.76

Lums Pond 13.55 14.20 14.54 13.00 13.26 13.21 13.77 11.43 12.45 12.17

MLK 16.01 16.72 17.50 15.21 15.26 14.92 14.90 14.54 14.09 14.19

Newark 15.42 15.24 15.79 14.56 14.80 14.54 14.42 12.70 13.38 13.03

New Jersey

Camden 13.65 15.02 14.52 14.00 16.25 13.30 14.47 12.17 13.64 12.29

Gibbstown 13.24 15.14 14.53 13.02 13.76 12.38 14.25 9.00 13.30

Pennsauken 14.05 15.48 14.23 14.62 13.92 13.16 14.27 12.36 13.87 12.70

Max Design 

Value

16.74 16.56 16.23 15.36 15.61 15.17 14.98 14.46

Source: Data extracted from the US EPA Air Quality System AMP 450 Report. See 

Appendix A-1 for the AMP 450 Report data for Pennsylvania monitors. 

Note: Monitoring results for 2009 have not yet been quality assured; EPA requires 

certification by June 2010.
8

Figure 1 displays PM2.5 annual averages for each monitor in the Pennsylvania portion of 

the Philadelphia Area. The maximum design value shown is the maximum for the 

interstate Philadelphia area. The 2001 maximum design value was observed at a Delaware 

monitor. The 2002 – 2008 maximum design values were observed at Pennsylvania 

monitors.

Figure 1: PM2.5 Annual Average and Design Value Trends
9

2. NO2 Monitoring Trend

Figure 2 displays the Philadelphia city vs. outside Philadelphia city annual NO2

concentration trend from 1999 to 2008. The Philadelphia city monitor is adequately 

represented by the monitored values at the Philadelphia AMS Lab. The outside 

Philadelphia city monitor is adequately represented by the Chester monitor.

Figure 2: NO2 Monitoring Trend
10

3. SO2 Monitoring Trend

Figure 3 displays the Philadelphia city vs. outside Philadelphia city annual SO2

concentration trend from 1999 to 2008. The Philadelphia city monitor is adequately 

represented by the monitored values at the Philadelphia AMS Lab. The outside 

Philadelphia city monitor is adequately represented by the Chester monitor.

Figure 3: SO2 Monitoring Trend

C. Seasonal Variability

1. FRM Monitoring Trends

Summary of seasonal variability in FRM data: There appears to be little variability in 

quarterly FRM values at monitors located in the Philadelphia Area. Throughout the 

region, the monitors’ 3

rd quarter values (summer) tend to report the highest concentrations 

and the 4th quarter (autumn) tend to report the lowest concentrations. This seasonal 

variability is primarily due to the meteorological conditions that set up in those particular 

seasons. The 3

rd quarter tends to have more stable conditions, and the 4th quarter tends to 

have more volatile conditions.
11

2. Speciation Monitoring Trends

Summary of seasonal variability in speciated data: Raw speciation data for the 

Philadelphia Area indicates some seasonal variability in the primary components. Sulfates 

have the largest variability with 1st quarter concentrations approximately half 

concentrations measured in the 3

rd quarter. Nitrates vary in nearly the opposite direction 

with 1st quarter measurements higher than 2nd, 3

rd and 4th quarter measurements. Organic 

carbon, elemental carbon, ammonium and crustal mass do not appear to show much 

seasonal variability.
12

III. EMISSION INVENTORIES 

Section 51.1008 of 40 CFR Part 51 requires an inventory of pollutants to meet the 

requirements of section 172(c)(3) of the CAA. As specified by the EPA, the pollutants 

inventoried by Pennsylvania include PM10, PM2.5, SO2, NOx, VOC, and NH3. In addition, 

projections of future emissions have been made for the milestone year 2009. Information 

on the manmade sources of direct PM and its potential precursors, SO2, NOx, VOC, and 

NH3 was compiled for:

“Stationary sources” (or “point” sources), which are sources for which the 

Department collects individual emissions-related information. Generally, they 

represent major stationary sources but may be smaller.

“Area sources,” which are industrial, commercial, and residential sources too small 

or too numerous to be handled individually. These include but are not limited to 

commercial and residential open burning, architectural and industrial maintenance 

coatings application and clean-up, consumer product use, and vehicle refueling at 

service stations. Where there is overlap between stationary point sources and 

stationary area sources, the area source values are adjusted to remove any double 

counting.

“Highway vehicles,” which include passenger cars and light-duty trucks, other 

trucks, buses and motorcycles. 

“Nonroad sources,” which encompass a diverse collection of engines, including but 

not limited to outdoor power equipment, recreational vehicles, farm and 

construction machinery, lawn and garden equipment, industrial equipment, 

recreational marine vessels, commercial marine vessels, locomotives, ships, and 

aircraft.

The inventory for the Pennsylvania portion of the Philadelphia Area was compiled for 

Bucks, Chester, Delaware, Montgomery and Philadelphia counties.

A. Summary of 2002 Emissions

An emission inventory is an estimate of the emissions from sources in a particular area. 

The Department developed an emission inventory for 2002, which is the base year for 

attainment planning purposes with respect to 8-hour ozone and PM2.5 SIPs, and for 

planning purposes with respect to the regional haze SIPs. The 2002 base year inventory 

includes the pollutants PM10, PM2.5, SO2, NOx, VOC, and NH3. The inventory consists of

sources in four sectors: stationary point sources, stationary area sources, highway vehicle 

sources and nonroad sources. MANE-VU compiled a regional inventory from the 

emission inventories of the Northeastern and Mid-Atlantic states. This regional inventory 

was used to perform the regional modeling analysis used in Pennsylvania’s air quality 
13

management planning efforts to attain the 8-hour ozone NAAQS and the PM2.5 NAAQS,

and to prepare the regional haze plan. 

An emissions inventory for the base year, 2002, was developed in accordance with EPA 

guidance4. Table III-1 summarizes the emissions for 2002. 

Table III-1: 2002 Annual Emissions (Tons per Year)

Philadelphia Area 2002 PM2.5 PM10 SO2 NOx VOC NH3

Stationary Point Sources 2139 3430 23745 22124 8183 256

Area Sources 10020 55224 13153 13029 59227 4821

Highway Vehicle Sources 1033 1492 1920 63476 33974 2614

Non-Road Sources 1535 1611 1640 21619 21589 14

Totals 14727 61758 40459 120248 122973 7705

B. Summary of Inventory Methodologies

Inventory development methodology is summarized below. 

Stationary Point Sources. The Department requires owners and operators of larger 

facilities to submit annual production figures and emission calculations each year. 

Throughput data are multiplied by emission factors from Factor Information Retrieval 

(FIRE) Data System and the EPA’s publication series AP-42 and are based on Source 

Classification Codes (SCC). Each process has at least one SCC assigned to it. If the 

owners and operators of facilities provide more accurate emission data based upon other 

factors, these more accurate emission estimates supersede those calculated using SCC 

codes. Appendix B-1 includes information on stationary point source emission 

methodology, and Appendix B-2 is the data set for facility 2002 annual emissions. 

Appendix B-3 is a table documenting the banked emissions reduction credits for the fivecounty Philadelphia area in the 2009 emission projection. 

Area Sources. Area source emissions are generally estimated by multiplying an emission 

factor by some known indicator or collective activity for each area source category at the 

county level. Pennsylvania estimates emissions from area sources using emission factors 

and SCC codes in a method similar to that used for Stationary Point Sources. Emission 

factors may also be derived from research and guidance documents if those documents are 

more accurate than FIRE and AP-42 factors. Throughput estimates are derived from 

county-level activity data, by apportioning national or statewide activity data to counties, 

from census numbers, and from county employee numbers. County employee numbers are 

based upon North American Industry Classification System (NAICS) codes to establish 

 

4 Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air 

Quality Standards (NAAQS) and Regional Haze Regulations – EPA-454/R-05-001. August, 2005. Updated 

November, 2005.
14

that those numbers are specific to the industry covered. More specific information on the 

procedure used for each industry type is contained in Pennsylvania 2002 Area Source 

Criteria Air Pollutant Emission Estimation Methods, (E.H. Pechan & Associates, Inc., 

February 2004) which is contained in Appendix C-1. Appendix C-2 is a table containing

stationary area sources emissions data for the five-county Philadelphia area.

Highway Vehicle Sources. The Department employs an emissions estimation 

methodology that uses the current EPA-approved highway vehicle emission model, 

MOBILE 6.2, to estimate highway vehicle emissions. In addition, Pennsylvania uses a 

MOBILE pre- and post-processing software package called PPSUITE to process and 

compile Pennsylvania’s robust highway network and detailed highway vehicle data. The 

Pennsylvania Department of Transportation (PennDOT) provided estimates of vehicle 

miles traveled (VMT) by vehicle type and roadway type. The Pennsylvania methodology 

is consistent with the January 2002 guidance published by the EPA’s Office of 

Transportation and Air Quality (OTAQ) entitled, Technical Guidance on the Use of 

MOBILE6 for Emissions Inventory Preparation. 

More information on highway emission methodology is available in Appendix E. 

Appendix E-1 provides the 2002 base year and 2009 projections of mobile (highway) 

VMT and annual PM2.5 direct and precursor emissions. The document summarizes the

methodology and data inputs used to produce the mobile emissions inventory. Appendix 

E-2 is the table of 2009 five-county Philadelphia area Annual Highway Emissions listed by 

SCC. Appendix E-3 describes the inputs to MOBILE6.2 used to generate emission factors 

for a specific area. Some examples of the inputs described in Appendix E-3 are the type 

and frequency of vehicle emission testing, the fuel types required in the area, temperatures 

by month, and fleet age. The summary in Appendix E-3 indicates when default 

information contained in the model is used rather than specific area information. Finally, 

Appendix E-4 is an electronic file that provides all of the input coding for a sample 

segment and scenario used in Pennsylvania’s MOBILE6.2 modeling system.

Nonroad Sources. The 2002 emissions for the majority of nonroad emission source 

categories and pollutants were estimated using the EPA NONROAD 2005 model. The 

NONROAD model estimates emissions for diesel, gasoline, liquefied petroleum gasoline, 

and compressed natural gas-fueled nonroad equipment types and includes growth factors. 

The National Mobile Inventory Model (NMIM) was used to estimate emissions of 

ammonia from sources contained in the NONROAD model. The NONROAD model does 

not estimate emissions from aircraft, locomotives or commercial marine vessels. 

Emissions from aircraft, locomotives, and commercial marine vessels were estimated using 

EPA guidance and best available information. If specific local operational data was 

available, that data was used to estimate emissions. State and national data was used if 

local data was unavailable.

 

The Department has worked with the staff of the Philadelphia Division of Aviation to 

obtain accurate operational information for emission sources at Philadelphia International 

Airport (PHL). The Division of Aviation operates PHL as well as the Northeast 

Philadelphia Airport. The 2002 PHL Inventory described in Appendix F-3 includes 
15

aircraft and aircraft-related equipment from the EPA-approved model, Emissions and 

Dispersion Modeling System (EDMS), and also additional on-airport highway, stationary 

and area source emissions. In some cases, emissions occurring at PHL are accounted for 

only in the regional inventory; these emissions are identified as such in the Appendix. 

For 2002 aircraft emissions from the Northeast Philadelphia Airport, the Department 

estimated emissions using operations data obtained from the Federal Aviation 

Administration’s (FAA) Terminal Area forecast and modeling the emissions directly with 

the EDMS. 

Emissions produced by aircraft at small airports in the Philadelphia area were estimated by 

using airport operation statistics, which can be found at www.airnav.com and the FAA’s

Terminal Area Forecast Detailed Report. An emissions factor for a typical general aviation 

single engine, multi-engine, and jet engine aircraft were derived by averaging the 

emissions factors from a basket of emission factors for common aircraft of each of the 

three types of aircraft. Emission factors and operational characteristics contained in 

EDMS were used. The proportion of operations among the three groups of aircraft was 

determined by examining the number of each aircraft type based at each airport. For 

military operations at small airports, the type of aircraft and its emission factors are 

sometimes identifiable. If not, emission factors calculated to represent an “average” 

military aircraft are used. Growth was estimated using estimates of future operations at 

Philadelphia airports found in the FAA Terminal Area Forecast Detailed Report. 

For 2002 locomotive emissions, the Department projected emissions from a 1999 survey 

when the Department obtained fuel use statistics from class II and III railroads. For class I 

railroads, which produce most of the locomotive emissions in the Commonwealth, the 

Department conducted a 2002 inventory because the 1999 fuel use data for class I railroads 

was skewed by gridlock caused by the acquisition of Conrail by CSX and Norfolk 

Southern. Emissions were generated using EPA emission factors. Emissions were grown 

using national railroad fuel use trends supplied by the Association of American Railroads. 

The Philadelphia Area contains the Port of Philadelphia. The port is home to several 

refineries where large oil tankers often call and shipping terminals. All air emissions from 

commercial marine vessel (CMV) traffic in the Port of Philadelphia were estimated using 

the methodology outlined in the EPA’s publication Commercial Marine Activity for Deep 

Sea Ports in the United States, Final Report. A comprehensive understanding of the 

methodology can be achieved by reviewing this document. Additional understanding of 

the port’s operations was obtained from conversations with tugboat operators in the port

and ship traffic data provided by the Philadelphia Regional Port Authority. Emission 

estimates were based on port activity data provided by the United States Army Corps of 

Engineers Waterborne Commerce Statistics Center and best available EPA nonroad 

emissions factors. Fuel use and emissions factors for CMV were based on the most current 

data available. 

Appendix F-1 is the technical document providing the methodology and description of the 

procedures used to generate 2002 and 2009 county-level pollutant emission estimates for 
16

nonroad mobile engines included in the EPA’s NONROAD2005 model, locomotive 

engines, and aircraft operations. The table of the specific emissions data used to calculate 

the nonroad emissions sorted by source category is available as Appendix F-2.

C. Projected Inventories

1. Summary of 2009 Estimated Emissions

Table III-2 summarizes the emissions expected in 2009. These emissions take activity and 

emissions growth and/or controls from 2002 into account. Appendix D, relating to 

emissions projections, contains the technical support documents that describe the 

methodologies used to project the 2002 baseline emissions to 2009.

Table III-2: 2009 Projected Emissions (Tons per Year)

Philadelphia Area 2009 PM2.5 PM10 SO2 NOx VOC NH3

Stationary Point Sources 2817 3849 12658 22252 7881 357

Area Sources 10324 59533 13972 13775 55868 5749

Highway Vehicle Sources 699 1193 327 36318 20298 3118

Non-Road Sources 1356 1428 800 18874 15971 16

PHL Capacity 

Enhancement Program 0 0 0 0 254 0

Emission Reduction 

Credits Banked 23 32 442 432 1561 0

Totals 15219 66035 28200 91651 101834 9239

Sulfur and nitrogen are major contributors to the Philadelphia Area’s PM2.5 nonattainment 

problem. Therefore, even though the direct PM2.5 emissions increase in 2009, the 

reductions of PM2.5 precursors, SO2 and NOx, will ensure that the Philadelphia Area attains

the PM2.5 NAAQS by 2010.

2. Growth Projection Methodologies

This section describes the data, methods, and assumptions utilized in developing estimates 

of emissions changes between 2002 and the milestone year 2009. Appendix 

D-1 contains the technical support document entitled, Development of Emission 

Projections for 2009, 2012, and 2018 for Non-EGU Point, Area, and Nonroad Sources in 

the MANE-VU Region, developed by Mid-Atlantic Regional Air Management Association 

(MARAMA). The document provides details on the specific factors, control assumptions, 

and implementation schedules used in the emission projection calculations for each source 

category. 
17

Stationary Point Sources. For electric generating units (EGUs), the Department used the 

EPA’s Integrated Planning Model (IPM) modeling as adjusted by the Visibility 

Improvement State and Tribal Association of the Southeast (VISTAS), specifically 

VISTAS 2.1.9, to predict the results of the EPA’s CAIR at affected facilities throughout 

the CAIR region. The emissions for 2009 resulting from application of the CAIR cap and 

trade program for annual NOx and SO2 emissions, as predicted by IPM, were used. The 

technical support documents that describe the methodologies used to project the emissions 

from EGUs, Documentation of 2018 Emissions from Electric Generating Units in the 

Eastern United States for MANE-VU’s Regional Haze Modeling (Alpine Geophysics, April 

2008) and Future Year Electricity Generating Sector Emission Inventory Development 

Using the Integrated Planning Model (IPM®) in Support of Fine Particulate Mass and 

Visibility Modeling in the VISTAS and Midwest RPO Regions (ICF, April 2005) are 

included as Appendices D-2 and D-3, respectively.

For non-EGU point sources, the methodology for projecting emissions to 2009 is the same 

as the methodology described below for stationary area sources as documented in 

Appendix D-1, Development of Emission Projections for 2009, 2012, and 2018 for NonEGU Point, Area, and Nonroad Sources in the MANE-VU Region. This report was 

prepared for MARAMA as part of an effort to assist states in developing attainment plans 

for ozone and fine particles, and in developing regional haze plans. It describes the data 

sources, methods, and results for emission forecasts for three years, three emission sectors, 

two emission control scenarios, seven pollutants, and 11 states plus the District of 

Columbia. MARAMA developed projections for 2009, 2012, and 2018. 

Area Sources. Area source emissions were projected from the 2002 inventory. 

The factors used for the temporal allocation of projections to 2009 from the 2002 baseline 

inventory were provided by MARAMA, which is coordinating air quality technical 

projects for the Northeast and Mid-Atlantic states. The factors were in the form of Sparse 

Matrix Operator Kernel Emissions (SMOKE) v2.2 input files5. 

A table of growth factors for 2009 was provided by MARAMA. For each state, county 

and SCC, this table includes state growth factors derived from the Energy Information 

Administration (EIA) Annual Energy Outlook, 2005; and/or factors extracted from the 

Economic Growth Analysis System (EGAS). Where more than one factor was available, 

the first choice was the EIA factor followed by the EGAS factor.

MARAMA also supplied tables of control factors, rule effectiveness factors, and rule 

penetration factors for any control measures applicable to these sources. 

For the area sources, these factors were available by SCC and pollutant. There may be 

more than one generic control factor that applies to a given SCC and pollutant. In cases 

 

5 For additional information on the SMOKE file formats, please refer to the SMOKE v2.2 Users Manual, 

available from the Center for Environmental Modeling for Policy Development (CEMPD) at 

http://cf.unc.edu/cep/empd/products/smoke/index.cfm#Documentation.
18

where there was more than one applicable factor, the following formula may have been 

applied recursively to generate reductions that are a composite of those factors.

Emissions Emissions CF RE RP Emissions Controlled

Where

CF is the control factor

RE is the rule effectiveness factor

RP is the rule penetration factor

As described for stationary point sources above, Appendix D includes the MARAMA 

report, Development of Emission Projections for 2009, 2012, and 2018 for NonEGU 

Point, Area, and Nonroad Sources in the MANE-VU Region, which documents the 

methodology for projecting emissions to 2009.

Highway Vehicle Sources. The EPA’s approved highway vehicle emission model, 

MOBILE 6.2, projects highway vehicle average fleet emission factors. State specific 

information was used where available and appropriate. Traffic forecasts were 

compiled using information from PennDOT’s Traffic Information System and 

socioeconomic data. The Pennsylvania methodology for estimating highway vehicle 

emissions is consistent with the January 2002 guidance published by the EPA’s Office 

of Transportation and Air Quality (OTAQ) entitled, Technical Guidance on the Use of 

MOBILE6 for Emissions Inventory Preparation. Appendices E-1 through E-5 include

specific information on the highway emissions inventory methodology, data files of 

emissions estimates, MOBILE6.2 input parameters, a MOBILE6.2 sample input file, 

and the traffic growth forecasting system report.

As shown in Table III-3, VMT for the future analysis year increases 17% from 25.3 billion 

to 29.6 billion VMT within the five-county Philadelphia area. Despite the growth in VMT, 

emissions of the most significant vehicle-related precursors are significantly lower in the 

future analysis year.

Table III-3: Five-County Philadelphia Area VMT and Emissions

Direct PM PM Precursors

YEAR VMT PM2.5 PM10 VOC NOx SO2 NH3

2002 25,315,915,277 1,033 1,492 33,974 63,476 1,920 2,614

2009 29,561,772,617 699 1,193 20,298 36,318 327 3,118

Nonroad Sources. Projected emissions for the majority of nonroad emission source 

categories and pollutants were estimated using the EPA NONROAD 2005 model, which 

contains default assumptions for projected years. The NMIM estimated future NH3

emissions from source categories in the NONROAD model. The NONROAD model and 

NMIM estimate emissions for diesel, gasoline, liquefied petroleum gasoline, and 

compressed natural gas-fueled nonroad equipment types and include growth factors. 
19

The Department worked with the staff of the Philadelphia Division of Aviation to obtain 

accurate operational information for emission sources at Philadelphia International Airport 

(PHL). Emissions from commercial aircraft are estimated using the EPA-approved 

Emissions & Dispersion Modeling System (EDMS). Growth was estimated using estimates 

of future operations at PHL from the Federal Aviation Administration’s (FAA) APO 

Terminal Area Forecast Detailed Report. The complete methodology for determining 

emissions produced from normal airport operations at PHL is described in Appendix F-3. 

Major construction is anticipated at PHL to relieve aircraft congestion, potentially starting 

in 2010. 

Emissions from small aircraft were calculated by using airport operation statistics, which 

can be found at www.airnav.com and the FAA’s APO Terminal Area Forecast Detailed 

Report.

For locomotive emissions, the Department projected emissions from 2002 to 2009, using 

national fuel consumption data obtained from the Association of American Railroads and 

the EPA emission factors developed for the locomotive fleet in future years.

Commercial marine vessel emissions were grown using projected activity, fuel use and 

emission estimates from the EPA document, Final Regulatory Analysis: Control of 

Emissions from Marine Diesel Engines, November 1999.

Additional information about nonroad emission projection methodologies can also be 

found in Appendix F. Appendix F-1 is the technical document providing the methodology 

and description of the procedures used to generate 2002 and 2009 county-level pollutant 

emission estimates for nonroad mobile engines included in the EPA’s NONROAD2005 

model, locomotive engines and aircraft operations. The table of nonroad emissions data

sorted by source category is available as Appendix F-2.

PHL Capacity Enhancement Program. PHL is planning to implement the Capacity 

Enhancement Program (CEP). The CEP will be an effort to reduce ground delays at the 

airport and throughout the nationwide air traffic system. The estimated maximum annual 

emissions of VOC, 254 tons, from the CEP were specifically identified and accounted for 

in the projected inventory in order to provide an emissions budget for the PHL CEP in 

accordance with the General Conformity Regulation in 40 CFR §93.158(a), (relating to 

criteria for determining conformity of general Federal actions). The methodology for 

estimating emissions produced during the CEP is described in Appendix F-4.

The purpose of general conformity is: 1) not to cause or contribute to a new violation of 

the NAAQS, 2) not to increase the frequency or severity of existing violations of the 

NAAQS, and 3) not to delay the timely attainment of any NAAQS or any required interim 

emission reductions or milestones. 

PHL is one of the most congested airports in the nation. The CEP when complete will 

reduce aircraft delays and overall emissions at PHL. As of early 2010, the FAA, the 

agency taking the federal action, was considering two alternatives which were titled 
20

Alternative A and Alternative B. Alternative A would produce fewer emissions than 

Alternative B. Emissions from Alternative A would be produced mostly in the first 5 years 

of the project while maximum emissions from Alternative B would occur at about year 10 

of the project or 2020. Because the Department cannot determine which alternative will 

eventually be built, the maximum level of emissions produced due to aircraft delay and 

construction emissions from Alternative B are included as two line items in the 2009 

inventory. In addition, the airport has implemented many mitigation projects that have 

reduced emissions from aircraft and ground support equipment operations. Mostly these 

emission reductions have addressed PM2.5 and NOx. Not many emission reduction 

projects are possible to reduce emissions of VOC on airport property. Pennsylvania 

proposes to establish budgets for CEP emissions of VOC in order to ensure that the CEP 

emissions do not impede clean air goals established in the SIP. The CEP budgeted 

emissions of VOC will not impede the clean air goals in the SIP because the VOC 

emissions used to model attainment of the fine particulate standard were over 10,000 tons 

in excess of the VOC emissions that were projected in the 2009 emissions inventory.

Once the EPA approves the SIP, including the 2009 projected emissions inventory (Table 

III-2), a general conformity budget for PHL’s CEP project for VOC will be established. 

D. Reasonable Further Progress (RFP) Requirements

Section 172(c)(2) of the CAA requires that plans for nonattainment areas provide 

reasonable further progress. In accordance with 40 CFR 51.1009, if a state submits an 

attainment demonstration for an area which demonstrates that the area will attain the PM2.5

NAAQS within five years of designation, the state is not required to submit a separate RFP 

plan. In that case, compliance with the emission reduction measures in the attainment 

demonstration and SIP will meet the requirements for achieving RFP for the area. This 

attainment demonstration and SIP revision demonstrate that the Philadelphia Area will 

attain the PM2.5 NAAQS by the area’s attainment date of April 2010, which is within five 

years of designation. Therefore, compliance with the emission reduction measures 

described in this plan meets the requirements for achieving RFP for the area. 

E. Motor Vehicle Emission Budgets for Transportation Conformity

Section 176 of the CAA provides a mechanism by which federally funded or approved 

highway and transit plans, programs, and projects are determined not to produce new air 

quality violations, worsen existing violations, or delay timely attainment of the NAAQS. 

EPA regulations issued to implement transportation conformity provide that motor vehicle 

emission “budgets” establish caps of these emissions that cannot be exceeded by the 

predicted transportation system emissions in the future. Transportation agencies in 

Pennsylvania are responsible for making timely transportation conformity determinations. 

The responsible agency in the five-county Philadelphia area is the Delaware Regional 

Planning Commission, the designated Metropolitan Planning Organization (MPO) under 

federal transportation planning requirements.
21

Pennsylvania proposes to establish budgets for highway emissions for direct PM2.5 and 

NOx in order to ensure that transportation emissions do not impede clean air goals in the 

next decade and beyond. The information in Table III-5, once the EPA approves it for 

purposes of conformity, will establish transportation conformity budgets for the fivecounty Philadelphia area.

Amendments to the 40 CFR part 93 transportation conformity regulations to address the 

1997 PM2.5 standard were published in the Federal Register on May 6, 2005 (70 FR 

24280) to account for PM2.5 and its precursors. Section 93.102 requires conformity 

determinations to be applicable to direct emissions of PM2.5 and NOx (unless a 

determination is made that transportation-related emissions are not significant contributors 

to PM2.5), but to emissions of SO2, VOC, and NH3 only if a finding is made that 

transportation-related emissions of these pollutants are significant contributors to PM2.5.

Motor vehicle emissions of SO2, VOC, and NH3 were analyzed to determine if motor 

vehicle budgets should be established for these pollutants. Table III-4 illustrates the onroad mobile source fraction of the total 2009 inventory for each of these pollutants. Motor 

vehicle emissions of VOC and NH3 account for 20% and 34% of the total projected 2009

inventory for VOC and NH3, respectively. Motor vehicle emissions of SO2 account for 1% 

of the total projected 2009 inventory for SO2.

Table III-4 Comparison of 2009 On-Road Mobile Precursor Emissions to the Total 

Projected 2009 Inventory

2009 SO2 VOC NH3

On-Road Mobile Source Projected Inventory (Tons) 327 20298 3118

Total Projected 2009 Inventory (Tons) 28200 101834 9239

Percent of Total Projected 2009 Inventory (%) 1.16 19.93 33.75

Motor vehicle emissions budget for SO2, VOC, and NH3 are needed only if the state air 

agency director or the EPA Regional Administrator makes a finding that motor vehicle 

emissions budgets must be established in order to attain the NAAQS for PM2.5. Because 

the reactions that form particulate matter from emissions of VOC are complex and highly 

variable, there is considerable uncertainty regarding the contribution of VOC to particulate 

formation. Likewise, much uncertainty remains regarding the role of NH3 in particulate 

formation. As discussed earlier in Section I, the Commonwealth is not considering VOC 

or NH3 as PM2.5 precursors for the purpose of the attainment plan because of the 

uncertainty surrounding their role in particulate formation. Therefore, this SIP revision is 

not establishing a motor vehicle emission budget for VOC or NH3. As shown in Table III4, motor vehicle emissions of SO2 are a small percentage of the total inventory. Based on 

these facts and the fact that no applicable finding has been made for these pollutants, this 

SIP revision is only establishing motor vehicle emission budgets for direct PM2.5 and NOx, 

as shown in Table III-5.
22

Table III-5: Motor Vehicle Emission Budgets

2009 PM2.5 NOx

Tons/year 699 36318

The Department has included direct PM2.5 re-entrained road dust emissions from paved 

and unpaved roads in the area source inventory. However, a number of fugitive dust 

studies have indicated that the PM2.5 / PM10 ratios measured by EPA FRM samplers are 

significantly lower than predicted by AP-42 emission factors. As a result, the PM2.5

emission estimates using AP-42 are biased high by as much as a factor of two, compared to 

FRM samplers. The Department believes that the emissions from paved and unpaved 

roads are significantly over-predicted and, therefore, has not included those emissions in 

the motor vehicle emission budgets at this time. Appendix C-2, relating to area source 

annual emissions, contains estimates of the PM2.5 emissions attributable to paved and 

unpaved roads. 

Transportation construction-related fugitive dust emissions are not a significant contributor 

to the air quality problem. At the Philadelphia Area speciation monitor, the crustal 

component was found to be small compared to other components of PM2.5 (see Section V, 

Figure 5). Given that construction-related fugitive dust is one of many source categories 

contributing to the crustal material observed at the monitor, and transportation construction 

is a small subset of all construction, it is safe to conclude that transportation constructionrelated fugitive emissions are insignificant. 
23

IV. CONTROL STRATEGIES

A. Permanent and Enforceable Control Measures

This section describes the federal and state measures that will provide the direct PM2.5, SO2

and NOx emission reductions leading to emission reductions and attainment of the 

standard. 

A summary of the quantity of emission reductions expected from 2002 to 2009 is included 

in Table IV-1. (Positive values indicate emission reductions, negative values indicate an 

increase in emissions.) The emission reduction estimates account for any anticipated 

growth in the activity of sources regulated by the strategy. For some pollutants and 

categories, emissions in 2009 are anticipated to be higher than they were in 2002. In those 

cases, projected growth in emissions is larger than anticipated emission reductions from 

control measures for that pollutant and source category. Each measure is explained in 

greater detail in the following sections.

Table IV-1: Summary of Emission Reductions 2002-2009 from Control Measures

2002-2009 Difference PM2.5 SO2 NOx

Stationary Point Sources -678 11087 -128

Area Sources -304 -819 -745

Highway Vehicle Sources 334 1593 27158

Nonroad Sources 179 841 2745

Total -469 12702 29030

Note: Positive values indicate emission reductions. Negative values indicate an increase 

in emissions.

1. Stationary Point Sources

Clean Air Interstate Rule (CAIR). EPA’s CAIR (70 FR 25162, May 12, 2005) was 

remanded to EPA for revisions by the United States Court of Appeals for the District of 

Columbia on December 23, 2008. The Court ordered the EPA to fix the flaws in CAIR, 

but did not set a deadline. EPA intends to promulgate a replacement rule in 2011. In the 

meantime, CAIR is being implemented. Pennsylvania transitioned from the NOx SIP Call 

to the federal CAIR in 2009. The CAIR is to provide the incentive for large electric 

generation units (EGUs) to reduce emissions below 2002 levels throughout the 28-state 

CAIR region. Pennsylvania and other nearby states were required to adopt a regulation 

implementing the requirements of the CAIR or an equivalent program. On April 28, 2006, 

the EPA promulgated Federal Implementation Plans (FIPs) to reduce the interstate 

transport of NOx and SO2 that contribute significantly to nonattainment and interfere with 

maintenance of the 8-hour ozone and PM2.5 NAAQS. The EGUs in Pennsylvania were

regulated under the FIP until the EPA approved a SIP revision for the implementation of 
24

CAIR for the affected EGUs, at which point the approved CAIR SIP revision superseded

the FIP requirements in Pennsylvania. The Pennsylvania CAIR regulation was published in 

the Pennsylvania Bulletin on April 12, 2008. (38 Pa.B. 1705) On May 23, 2008, the 

Department submitted to the EPA a SIP revision for the Department’s CAIR regulatory 

requirements under §§ 145.201-145.223 (relating to CAIR NOx and SO2 trading 

programs), effective April 12, 2008 (38 Pa.B. 1705), that provide for a CAIR NOx Ozone 

Season Trading Program and a CAIR NOx Annual Trading Program. The EPA approved 

the Department’s CAIR regulation as a SIP revision effective December 10, 2009 (74 FR 

65446).

Interstate Pollution Transport Reduction -- In response to the federal NOx SIP call rule, 

Pennsylvania and other covered states adopted NOx control regulations for large industrial 

boilers and internal combustion engines, EGUs, and cement plants. The regulation 

covering industrial boilers and electric generators required emission reductions to 

commence May 1, 2003, while the regulation covering large internal combustion engines 

and cement plants required emission reductions to commence May 1, 2005. The EPA

approved these regulations, found in 25 Pa. Code Chapter 145, on August 21, 2001 (66 FR 

43795) and September 29, 2006 (71 FR 57428).

Small Sources of NOx, Cement Kilns, and Large Stationary Internal Combustion 

Engines. The Department established additional ozone season requirements for small 

sources of NOx in the counties of Bucks, Chester, Delaware, Montgomery, and 

Philadelphia in regulations that were adopted December 11, 2004. The rules (25 Pa. Code 

Chapter 129) apply to owners and operators of certain boilers, turbines, and stationary 

internal combustion units located in Bucks, Chester, Delaware, Montgomery, and 

Philadelphia Counties. The emission limits are differentiated by fuel type and allow 

alternative compliance mechanisms. By November 1st of each year, owners and operators 

of these sources must surrender NOx allowances if actual emissions exceed allowable 

emissions. The amendments required the NOx emission limits to be implemented by May 

1, 2005. EPA approved this program on September 29, 2006 (71 FR 57428).

New Source Review Programs. The federal New Source Review (NSR) programs are 

preconstruction review and permitting programs applicable to new or modified major 

stationary sources subject to Title I, Parts C and D of the federal CAA. The programs

consist of the Prevention of Significant Deterioration (PSD) requirements, which are 

applicable in areas attaining the NAAQS, and the Nonattainment NSR requirements, which 

are applicable in geographic areas not attaining and maintaining the NAAQS. 

The Department’s PSD regulations, codified in 25 Pa.Code Chapter 127, Subchapter D, 

were approved by the EPA on August 21, 1984 and codified at 40 CFR § 52.2058 (49 FR

33128). The federal PSD regulations codified in 40 CFR Part 52 are incorporated by 

reference in their entirety in 25 Pa. Code § 127.83 (relating to adoption by reference). The 

PSD program requires any new source to implement Best Available Control Technology 

(BACT) and limits a new source's allowable impact on the environment. 
25

The EPA granted “limited” approval of the Department’s revised NSR regulations codified 

in 25 Pa.Code Chapter 127, Subchapter E, and published a final rule on December 7, 1997 

(62 FR 64722). On October 19, 2001, the EPA converted the limited approval to a “full”

approval for all areas of the Commonwealth except the five-county Philadelphia area 

(Bucks, Chester, Delaware, Montgomery, and Philadelphia counties) (66 FR 53904). 

Nonattainment NSR requirements include compliance with the lowest achievable emission 

rate and emission offsets.

These federally enforceable programs, incorporated in the Commonwealth’s SIP, 

will also reduce emissions to provide continued improvements.

Federal Standards for Hazardous Air Pollutants. Federal standards to control 

hazardous air pollutants (HAPs) require Maximum Achievable Control Technology 

(MACT) at units located at major sources of HAPs. The EPA has issued a series of 

regulations that are applicable to sources in Pennsylvania. These MACT standards are 

adopted and incorporated by reference in Section 6.6 of Pennsylvania’s Air Pollution 

Control Act and implementing regulations and are also included in federally enforceable 

permits issued by the Department for affected sources. Controls with a 2002 compliance 

date and earlier are included in the base year inventory for 2002, while controls with a 

compliance date of 2003 and later are included in the projection inventories. A list of the 

categories for which federal MACT standards have been issued is contained in Appendix

D-1.

Source Surveillance. Pursuant to 40 CFR Part 51, Subpart K (relating to source 

surveillance), the SIP revision is required to provide for monitoring of the status of 

compliance with any rules and regulations that set forth any portion of the control strategy. 

These include provisions, as applicable, for:

emissions reports and recordkeeping for stationary sources;

periodic testing and inspection of stationary sources;

enforcement and complaint investigation of visible emission limitations;

enforceable test methods for emission limits; and

continuous emission monitoring for stationary sources.

Subpart K also requires monitoring of the implementation of transportation control 

measures (TCMs). There are no TCMs in this SIP. 

After review, the Department finds that the rules and regulations for stationary sources,

which are part of the control strategy for attaining the PM2.5 standard, as well as the 

Department’s comprehensive permitting program requirements in 25 Pa. Code Chapter 

127 and the Commonwealth’s SIP in 40 CFR 52.2020, meet the requirements of Subpart 

K. 
26

2. Highway Vehicle Sources

Even with increases in VMT that occur from 2002 through 2009, highway vehicle 

emissions will continue to decrease. As more vehicles subject to cleaner new car standards 

replace older vehicles subject to less stringent new vehicle standards, the fleet as a whole 

emits fewer emissions, compensating for the increase in vehicle miles traveled. These 

decreases can be attributed to the programs described below.

Federal Motor Vehicle Control Programs (FMVCP) and Pennsylvania Clean Vehicle 

Program for passenger vehicles and light-duty trucks and cleaner gasoline. 

Tier 1 tailpipe standards established by the CAA Amendments of 1990 include NOx and 

VOC limits for light-duty gasoline vehicles (LDGVs) and light-duty gasoline trucks 

(LDGTs). These standards began to be phased in 1994. Evaporative VOC emissions were 

reduced in gasoline-powered cars starting with Model Year (MY) 1998.

In 1998, under the authority of section 177 of the CAA, the Department adopted the 

Pennsylvania Clean Vehicles Program (28 Pa. B. 5873, Dec. 5, 1998). The Pennsylvania 

Clean Vehicles Program incorporates by reference certain California Low Emission 

Vehicle (CA LEV) emission standards for passenger cars and light-duty trucks. As 

required under Section 177 of the CAA, these provisions are identical to the low emission 

standards adopted by California. The regulation does not incorporate by reference the 

California zero emissions vehicle (ZEV) or emissions control warranty systems statement 

provisions.

In the same rulemaking, the Department adopted the National Low Emission Vehicle 

(NLEV) program as a compliance alternative to the Pennsylvania Clean Vehicles Program. 

The NLEV program became effective in the Ozone Transport Region (OTR) in 1999. 

Pennsylvania’s New Motor Vehicle Emissions Control Program regulations in 25 Pa. 

Code Sections 126.401-126.441 allowed automobile manufacturers to comply with NLEV 

instead of the CA LEV program through MY 2005. These regulations affected vehicles 

6,000 pounds and less and were the regulations in effect for new motor vehicles in the 

baseline year, 2002. 

In 1999, the EPA promulgated regulations more stringent than NLEV (Tier 2), starting 

with MY 2004. In order to participate in NLEV, Pennsylvania had been required to adopt 

language that extended its “commitment” to NLEV until MY 2006. In practical terms, the 

NLEV program was replaced for MY 2004 and later by the more stringent Federal “Tier 2” 

vehicle emissions regulations, 65 FR 6698 (Feb. 10, 2000), and vehicle manufacturers 

operating under the NLEV program became subject to the Tier 2 requirements. 

Pennsylvania amended the former New Motor Vehicle Control Program (which included 

the Pennsylvania Clean Vehicles Program) in 2006. The Clean Vehicles Program 

continues to incorporate the California Low Emission Vehicle Program (CA LEV II) by 

reference. As amended, the program affects MY 2008 and newer passenger cars and lightduty trucks vehicles. 36 Pa. B. 7424 (Dec. 9, 2006). 
27

Emissions for milestone years were estimated based on compliance with the Pennsylvania 

Clean Vehicles Program according to the methodology described in section 7.4.1 of the 

Technical Guidance on the Use of MOBILE6.2 for Emissions Inventory Preparation

published by the EPA’s OTAQ in January 2002. This methodology is further explained in 

Appendix E. The Department is assuming in its MOBILE modeling that the federal Tier 2 

program applies to subject vehicles sold in Pennsylvania from MY 2004 through MY 2007 

and the Pennsylvania Clean Vehicles Program applies to subject vehicles sold in MY 2008 

and beyond.

Reformulated Gasoline. Gasoline sold in the Philadelphia Area is required by the CAA to 

be the cleaner-burning reformulated gasoline meeting standards established in Section 211 

of the CAA. This federally-enforced program has been in place since January 1995. 

Heavy-Duty Diesel Control Programs. The EPA promulgated more stringent national 

regulations for heavy-duty engines and vehicles (over 14,000 pounds) starting with MY

2004. In addition, consent decrees with seven of the largest heavy-duty engine 

manufacturers required, among other terms, that diesel engines made by these companies 

comply with these 2004 standards two model years early, in MY 2002. Pennsylvania 

includes these programs as provided in the MOBILE model. 

In 2002, the Department adopted the Heavy-Duty Diesel Emissions Control Program for 

model years starting after May 2004. The program incorporates California standards by 

reference and requires MY 2005 and subsequent new heavy-duty diesel highway engines 

to be those certified by California. California standards were more stringent than federal 

standards for the two model years between expiration of the consent decrees discussed 

above and the implementation of more stringent federal standards affecting MY 2007 and 

beyond. However, EPA’s MOBILE model already assumes that the engines would 

comply with consent decree standards, even without an enforcement mechanism. The 

Department has used MOBILE defaults to calculate emissions from MY 2005 and 2006 

highway engines.

The EPA adopted new emission standards for heavy-duty engines and vehicles for MY

2007 and subsequent. For diesel engines, the standards will be phased in from 2007 to 

2010 for NOx and VOCs. For gasoline engines, the standards will be phased in during 

MY 2008 and 2009. Federal and California standards are virtually identical for MY 2007. 

For MY 2008, California adopted requirements for idling restriction engine programming

and an optional “clean NOx idle” standard. However, there is no EPA-approved 

methodology to estimate emission reductions from this requirement. Therefore, the 

emission estimates use assumptions of the federal rule for MY 2007 through 2010.

Because the new engine standards are adversely affected by sulfur in fuel, the EPA also 

requires most highway diesel fuel to contain no more than 15 parts per million (ppm) of

sulfur, beginning in the fall of 2006. There is a temporary compliance option allowing 

refiners to continue to produce up to 20 percent of their highway diesel fuel at 500 ppm 
28

fuel until 2010. The Department uses MOBILE defaults to estimate the effects of the 

phase-in provision.

Vehicle Emission Inspection/Maintenance Program. The five-county Philadelphia area 

has had a vehicle emissions inspection program since 1984. In early 2004, Pennsylvania 

revised the implementation of its Vehicle Emission Inspection/Maintenance (I/M) Program 

in the five-county Philadelphia area. The program applies to gasoline-powered vehicles 

9,000 pounds and under, MY 1975 and newer. For vehicles MY 1996 and newer, the 

program consists of an annual on-board diagnostics test and a gas cap pressure test. For 

subject vehicles MY 1995 and older, the program consists of an annual tailpipe test, visual 

inspection of pollution control devices to ensure they are present, connected and the proper 

type for the vehicle and a gas cap pressure test. For vehicles older than 25 years, the 

program is a visual inspection and gas cap test. These regulations can be found in 67 Pa. 

Code Chapter 177. Pennsylvania submitted the revised emissions program as a SIP 

revision on December 1, 2003. The EPA approved the SIP revision on October 6, 2005.

(70 FR 58313).

Low sulfur gasoline. Simultaneously with the Tier 2 program, the EPA published a 

regulation requiring the reduction of sulfur in gasoline beginning in 2004, with full 

implementation in 2006. Sulfur levels are capped at 80 ppm per gallon and annual refinery 

averages must be no more than 30 ppm. The emission reduction analysis uses the default 

assumptions provided in MOBILE6 to account for the implementation of the federal sulfur 

standard rule. 

Diesel Vehicle Idling Restrictions. On October 9, 2008, Governor Rendell signed the 

Diesel-Powered Commercial Motor Vehicle Idling Act (Act 124 of 2008). Act 124 of 

2008 went into effect on February 6, 2009. This Act restricts subject drivers and owners 

statewide from idling a diesel-powered motor vehicle engaged in commerce with a gross 

vehicle weight of 10,001 pounds or more for more than five minutes in any continuous 60-

minute period. Also, no owner or operator of a location where the aforementioned vehicles 

load, unload or park may allow the vehicles to idle for more than 5 minutes in a 60-minute 

continuous period. Act 124 of 2008 specifically excludes some vehicles, such as motor 

homes and farm vehicles used in farm applications. Additional exemptions are allowed for 

certain vehicles being used in specific applications. Truck drivers may idle sleeper-berth 

equipped vehicles for the purposes of long duration travel rest if the temperature is 

extremely hot or cold. In May 2010, this temperature exemption expires. A properly 

labeled “low-NOx idle” engine may idle for an unlimited amount of time. 

Act 124 of 2008 will be enforced by Department personnel, and by state and local law 

enforcement personnel. The law preempts and supersedes local ordinances, although rules 

in Allegheny County and Philadelphia County that are determined by those counties to be 

more stringent than the law may remain in effect. The Department estimates that 50 

percent of all long duration idling for Class 8 trucks will be eliminated in 2010 when the 

temperature exemption for vehicles with sleeper berths expires. Statewide emission 

reductions are estimated to be 1610 tons, 45 tons and 30 tons per year for NOx, VOC, and 

PM2.5, respectively. Emission reductions expected from this strategy are not included in 
29

the projected emissions inventory for 2009 for two reasons: 1) the first year was a period 

of education to the regulated community; and 2) most of the emission reductions from the 

law are expected to come from long-term travel rest idling associated with sleeper berth 

equipped vehicles.

3. Nonroad Sources 

The EPA has adopted a series of regulations affecting new diesel-powered (“compression 

ignition”) and gasoline-powered (“spark ignition”) nonroad engines of various sizes 

(horsepower) and applications. Information on these federal rules, including their 

implementation dates, can be found at www.epa.gov/nonroad. The Department used the 

assumptions built into the nonroad model (NONROAD2005) to estimate emissions for all 

milestone years.

No new national or international regulations are expected to be applicable to aircraft by the 

attainment date. While the EPA has published a notice of proposed rulemaking for more 

stringent standards for locomotives and large commercial marine diesel engines, the 

agency has not finalized any new standards.

The EPA will also require diesel fuel used in most nonroad applications to contain less 

sulfur. The sulfur will prevent damage to the more advanced emission control systems

needed to meet the engine standards; it will also reduce fine particulate emissions from 

diesel engines. In 2007, fuel sulfur levels were limited to 500 ppm for nonroad 

applications other than ocean-going marine vessels. In 2010, fuel sulfur levels will be 

reduced to the same sulfur concentration as in highway fuel, 15 ppm; this requirement 

applies in 2012 to locomotive and marine diesel fuel.

B. Reasonably Available Control Measures/Reasonably Available Control 

Technology Analysis

Section 172(c) of the CAA requires states to “provide for implementation of all reasonably 

available control measures (RACM) as expeditiously as practicable.” The regulatory 

requirement for RACM and reasonably available control technology (RACT) for PM2.5 SIP 

revisions is codified in 40 CFR 51.1010: “For each PM2.5 nonattainment area, the state 

shall submit with the attainment demonstration a SIP revision demonstrating that it has 

adopted all reasonably available control measures (including RACT for stationary sources) 

necessary to demonstrate attainment as expeditiously as practicable and to meet any RFP 

requirements.”

The EPA states in the Clean Air Fine Particle Implementation Rule preamble that it 

encourages states to conduct multi-pollutant analyses for PM2.5 and ozone to cull out 

potential RACM: 

“They can also try to use consistent meteorological fields and emissions inventories so 

that the same control strategies are relatively easy to evaluate for both ozone and PM2.5. 
30

Modeling the same future year(s) for PM2.5 and ozone can also make it easier to evaluate 

the impacts of controls on both pollutants. It should be noted that there are no specific 

modeling requirements other than the recommendation to try to harmonize the ozone, 

PM2.5, and regional haze analyses whenever possible.”6

The Commonwealth participated in two such collaborative processes with other states in 

the region. First, the OTC states formed a workgroup to identify and evaluate candidate 

control measures. Working from a preliminary list of approximately 1,000 potential 

control measures, the workgroup identified and analyzed 30 candidate control measures. 

Appendix G-1 contains the OTC report entitled, Identification and Evaluation of 

Candidate Control Measures, Final Technical Support Document (MACTEC, Feb. 2007).

The initial list of control measures considered is available as Appendix G-2. Based on the 

OTC Workgroup analysis, the Commissioners recommended that States consider emission 

reductions from the following source categories:

• Consumer Products

• Portable Fuel Containers

• Adhesives and Sealants Application

• Diesel Engine Chip Reflash

• Cutback and Emulsified Asphalt Paving

• Asphalt Production Plants

• Cement Kilns

• Glass Furnaces

• Industrial, Commercial, and Institutional (ICI) Boilers

• Regional Fuels

• Electric Generating Units (EGUs)

The final report, included as Appendix G-1, contains more detailed information about the 

process and includes tables summarizing the emission reduction potential of each control 

measure by source category and projection year. There are five subsections discussing the 

control measure and emission reductions for the five source category sectors: non-EGU 

point sources, area sources, EGUs, onroad mobile sources, and nonroad mobile sources. 

The Department also participated in an assessment of control measures for pollutants and 

sources affecting visibility through the MANE-VU regional haze planning process. As 

part of this effort, MANE-VU developed a list of possible control measures for 

consideration. The following categories were selected for analysis:

Coal and oil-fired EGUs

Point and area source industrial, commercial and institutional boilers

Cement kilns

Lime kilns

The use of heating oil

Residential wood combustion and open burning

 

6. 72 FR 20609.
31

Appendix G-3 contains the final report entitled, Assessment of Reasonable Progress for 

Regional Haze in MANE-VU Class I Areas (MACTEC, July 2007) from the MANE-VU 

control measure assessment project. This report presents the results of an analysis of the 

economic and environmental impacts of the potential control scenarios that could be 

implemented by MANE-VU states to reduce emissions from selected source categories in 

order to make reasonable progress toward meeting visibility improvement goals. 

As required under 40 CFR 51.1010, a SIP revision for a PM2.5 nonattainment area must 

demonstrate that all RACM, including RACT for stationary sources, necessary to 

demonstrate attainment as expeditiously as practicable have been adopted. The cumulative 

impact of implementing available measures must be considered in determining whether a 

particular emission reduction measure or set of measures is required to be adopted as 

RACM. Potential measures that are reasonably available considering technical and 

economic feasibility must be adopted as RACM if, considered collectively, they would 

advance the attainment date by one year or more. As discussed earlier in this document,

the Philadelphia Area expects to monitor attainment at the end of 2009. Therefore, any 

RACM measures would need to be in effect in 2008.

The Department determined that there were no additional control measures that could be 

adopted by January 1, 2008. In addition, existing measures and those planned for 

implementation by 2009 are expected to enable the Philadelphia Area to attain the 1997 

PM2.5 NAAQS. Therefore, no further actions on RACM or RACT are warranted.

Although the measures explored by the OTC and MANE-VU workgroups are not required 

as RACM, many are worthwhile measures that Pennsylvania is currently pursuing. Others 

are measures that Pennsylvania may consider for the future.

C. Other Measures - VOC Control Measures

Although VOC is not a regulated PM2.5 precursor for the Philadelphia Area, several VOC 

control measures are discussed in this section because they are included in the modeling 

associated with this attainment demonstration. 

Portable Fuel Containers. The Department adopted a portable fuel container regulation, 

25 Pa. Code Chapter 130, Subchapter A, to address VOC loss resulting from permeation 

through portable gasoline containers, evaporative loss through container openings, and 

spillage during the filling of small tanks on machines such as lawn mowers, chain saws

and jet skis. The regulation was submitted to the EPA as a SIP revision on March 26, 2003 

and approved on December 8, 2004 (69 FR 70893).

Consumer Products. This regulation applies statewide to any person who sells, supplies, 

offers for sale, or manufactures certain consumer products on or after January 1, 2005, for 

use in the Commonwealth. The program is contained in 25 Pa. Code Chapter 130, 

Subchapter B. It was submitted to the EPA as a SIP revision on March 26, 2003 and 

approved on December 8, 2004 (69 FR 70895). Additional regulations were adopted on 

October 11, 2008 and submitted to the EPA as a SIP revision on April 14, 2009.
32

Architectural and Industrial Maintenance (AIM) Coatings. The Pennsylvania AIM 

Coatings regulation applies statewide to any person who supplies, sells, offers for sale, or 

manufactures, blends or repackages an AIM coating for use within the Commonwealth, as 

well as a person who applies or solicits the application of an AIM coating within the 

Commonwealth. The AIM coating program requirements are specified in 25 Pa. Code

Chapter 130, Subchapter C. The regulation was submitted to the EPA as a SIP revision on 

December 3, 2003, with a supplement submitted on October 19, 2004. The EPA approved 

the provisions as an element of the SIP on November 23, 2004 (69 FR 69080).
33

V. ATTAINMENT DEMONSTRATION AND WEIGHT OF EVIDENCE (WOE) 

A. Attainment Demonstration Background and Objectives

The EPA issued fine particle standards in 1997 after evaluating hundreds of health studies 

and conducting an extensive peer review process. The 1997 annual health-based standard 

for PM2.5 is 15.0 μg/m3, based on the 3-year average of annual mean PM2.5 concentrations. 

The EPA also established a 24-hour health-based standard of 65 μg/m3, determined by the 

3-year average of the 98th percentile of 24-hour concentrations. The EPA set levels to

protect the environment at the same levels as it set the health-based standards. Note that 

while the EPA has subsequently revised the 24-hour standard in 2006 to be more 

protective, EPA designated the Philadelphia Area as nonattainment because it violated the 

1997 annual standard of 15.0 μg/m3 based on 2001-03 monitoring data. Therefore, this 

SIP revision compares air quality data to the 1997 24-hour standard (65 μg/m3).

On April 1, 2003, the EPA issued a memorandum, “Designations for the Fine Particle

National Ambient Air Quality Standards” outlining the schedule for designating areas 

under the PM2.5 standard and related guidance on nine factors to consider in identifying 

nonattainment areas. The CAA provides for states and tribes to submit designation

recommendations to the EPA, and it requires the EPA to provide time for consultation in 

cases where the Administrator plans to promulgate a designation that modifies the state or 

tribal recommendation. On December 17, 2004, the EPA published its air quality 

designations and classifications for the 1997 PM2.5 NAAQS. These designations became 

effective on April 5, 2005.

Figure 4 graphically depicts all of the PM2.5 nonattainment areas in Pennsylvania. Based 

on 2006 – 2008 monitoring data, all monitors in the Philadelphia Area meet the EPA’s 

annual PM2.5 standard (15.0 μg/m3). The Philadelphia Area’s maximum 2008 annual 

design value of 14.5 μg/m3 was observed at the Broad Street monitor. Based on 2006 –

2008 monitoring data, all monitors within the Philadelphia Area are monitoring attainment 

of the 1997 24-hour PM2.5 standard (65 μg/m3). The maximum 2008 24-hour design value 

in the Philadelphia Area was 36 μg/m3, observed at the New Garden monitor. The 

Philadelphia Area is required to attain the PM2.5 standard no later than five years from the 

effective date of designation of April 5, 2005 (April, 2010).

The purpose of the attainment demonstration is to ensure, through grid modeling, that 

projected emissions (with controls) will not cause the nonattainment area to exceed the 

1997 PM2.5 NAAQS. A complex grid model was run and processed over the entire 

Northeast to determine if the Philadelphia Area would attain the PM2.5 standard by April 5, 

2010.

The procedures followed in this modeling analysis are in accordance with EPA’s Guidance 

on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality 

Goals for Ozone, PM2.5, and Regional Haze (EPA-454/B-07-002, April 2007). A brief 

summary of the modeling analysis used in this demonstration is included in the following 
34

sections. The Department submitted a modeling protocol to the EPA in May 2006 for the 

Philadelphia Area that includes a more thorough description of the modeling analysis. 

Figure 4: Pennsylvania’s PM2.5 Nonattainment Areas

B. Philadelphia Area Conceptual Model Description

This section provides a brief description of the conceptual model for the Philadelphia Area. 

The conceptual model was based on information from the Northeast States for Coordinated 

Air-Use Management (NESCAUM) final report entitled The Nature of the Fine Particle 

and Regional Haze Air Quality Problems in the MANE-VU Region: A Conceptual 

Description (2006) and the Department’s modeling protocol documentation (October 

2007).
35

Fine particulate formation in the eastern United States is a complex process involving local 

and regional meteorology, topography, chemistry and transport. Since a violation of an 

annual standard potentially involves a large range of conditions throughout the year, it is 

difficult to determine a direct cause-and-effect relationship for such a violation. Violations 

of the annual standard ensure a large range of conditions will contribute to nonattainment 

making direct cause-and-effect relationships difficult to determine. In general, the 

following statements can be used to provide a working conceptual model that describes the 

annual PM2.5 nonattainment problem in the Philadelphia Area:

Secondary fine particulate formation is a major contributor to annual PM2.5 

nonattainment in the Philadelphia Area. Sulfates, organic carbon and nitrates make 

up almost 75% of the annual fine-particulate concentrations (see Figure 5).

Fine-particulate chemistry favors sulfate formation during the warm summer 

months and nitrate formation during the colder winter months.

In the summer time, large high pressure systems create favorable conditions for the 

oxidation of SO2, which eventually forms sulfates. These sulfates then contribute

to episodes of high particulate concentrations.

In the winter time, local temperature inversions concentrate emissions near the 

surface leading to periods of elevated fine-particulate concentrations. This is 

especially apparent if significant terrain features are present.

Continuous measurements in the Philadelphia Area correlate well with the FRM

data. This indicates measurements from the continuous monitor generally reflect

actual concentrations in the nonattainment area.

Average concentrations from the continuous monitor show a general diurnal pattern 

with higher concentrations in the overnight and early morning hours than during 

the day, due to atmospheric conditions and possibly local mobile source emissions

(peaks during rush hour traffic, etc.)

In addition to the diurnal signal noted in the continuous monitoring data, there is a 

strong weekly pattern in the continuous monitoring data with higher PM2.5

concentrations on weekdays than on weekends.

A range of control measures will be necessary to attain the PM2.5 standard in the 

Philadelphia Area due to the complex interaction between local and regional emissions and 

local meteorological conditions. Sulfates and nitrates are formed primarily through 

atmospheric reactions of precursor emissions of SO2, NOx and NH3. Organic carbon is a 

combination of secondary organic particles formed from emissions of VOC and the 

organic portion of primary PM2.5 that is directly emitted or condenses near its source. 

Currently, our understanding of sulfate and nitrate chemistry and its impacts on PM2.5

concentrations far exceeds our understanding of contributions from anthropogenic VOCs. 

This is important because sulfates, nitrates and organic carbon are major contributors to the 

fine particulate problem in the Philadelphia Area. Therefore, it is reasonable to assume

that a mixture of regional and local SO2 and NOx controls in addition to VOC controls 

implemented for attainment of the 8-hour ozone standard will assist in attaining the PM2.5 

standard.
36

Figure 5: Philadelphia Area Percentage of Total Mass

Based on Speciated PM2.5 Data Collected at Chester

Averaged 2005 to 2007 Monitored Values

C. Modeling Domain and Photochemical Modeling System

The modeling demonstration for the Philadelphia Area relies heavily on the OTC SIP 

quality-modeling platform. Ozone modeling was the primary focus of this effort. OTC’s 

interaction with MANE-VU and NESCAUM allowed it, through the regional modeling 

centers, to do additional year-round modeling for PM2.5 and Regional Haze.

EPA’s Guidance on the Use of Models and Other Analyses for Demonstrating Attainment 

of Air Quality Goals for Ozone, PM2.5, and Regional Haze (EPA-454/B-07-002, April 

2007) does not recommend a particular model or models for use in a SIP attainment 

demonstration. The OTC modeling committee used the CMAQ photochemical grid model 

(version 4.5) as part of its SIP modeling platform (OTC Final Modeling Protocol, 2006). 

CMAQ is an Eulerian grid model capable of simulating air pollutant concentrations in the 

atmosphere using mathematical equations to characterize chemical and physical properties.

Meteorological and emission input files must be prepared regardless of which 

photochemical grid model is used. The regional fine particulate modeling analysis 

encompassed an entire year of simulation for the year 2002. This approach provided a 

good variety of episodes to characterize the Philadelphia Area’s PM2.5 nonattainment

problem.
37

Figure 6 shows the modeling domain used by the OTC Modeling Workgroup. A nestedgrid approach was used with the lower resolution outer grid providing boundary conditions 

for a more refined grid covering the area of interest. The modeling domain was chosen to 

be large enough to properly simulate regional transport. The outer domain boundary is far 

enough from the inner grid’s boundary so that clean-boundary condition assumptions along 

the outer domain’s boundary are realistic and probably do not unduly influence 

concentrations within the inner domain.

Figure 6. OTC Modeling Study Domain

Outer grid at 36-kilometer resolution, inner grid at 12-kilometer resolution

The meteorological files used in CMAQ were produced using the Pennsylvania State 

University/National Center for Atmospheric Research (PSU/NCAR) Mesoscale Model 

version 5 (MM5). MM5 is a limited-area, nonhydrostatic, terrain-following sigmacoordinate model designed to simulate or predict mesoscale atmospheric circulation. The 

model is publicly available and has been used for various air quality modeling studies in 

the past.

The OTC Modeling Committee also examined two emissions processors (EMS2001 and 

SMOKE, both using CB4 chemistry) in its prior work and concluded that there are 

differences between them that could be minimized by forcing the models to use a common 

speciation and surrogate database.

For areas with an attainment date of no later than April 5, 2010 for the PM2.5 NAAQS, the 

emission reductions need to be implemented no later than the beginning of 2009. A 

determination of attainment will be based on air quality monitoring data collected in 2007, 

2008, and 2009. Therefore, the year to project future emissions should be no later than the 

last year of the three-year monitoring period, which in this case is 2009.
38

The emissions inventory was developed for 2009 using standard emissions projection 

techniques. The 2009 inventories developed by MANE-VU were used in the attainment 

demonstration. The most recently available inventories from other regional planning 

organizations (RPOs) in the modeling domain were also used.

Emission inventory guidance documents were followed for developing projection year 

inventories for point, area, mobile, and biogenic emissions. These procedures address 

projections of spatial, temporal, and chemical composition change between the base year 

and projection year.

The control strategies developed for evaluation in the attainment demonstration were

selected by the OTC’s Control Strategy Committee. These were selected from groups of 

strategies developed by the technical subcommittees responsible for identifying and 

developing the regulations and/or other control measures.

Consideration was given to maintaining consistency with control measures likely to be 

implemented by other modeling domains that may be involved in region-wide analysis. 

Also, technology-based emission reduction requirements mandated by the CAA are

included in the future year model runs. 

D. Model Performance Evaluation

A critical component of every air quality modeling study is the model performance 

evaluation where modeled estimates for the current year base case are compared against 

observed values to assess the model’s accuracy and provide an indication of its reliability. 

The results presented here serve as an illustration of some of the model evaluation and 

assessment, as outlined in the EPA modeling guidance document entitled, Guidance on the

Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for 

Ozone, PM2.5, and Regional Haze (EPA-454/B-07-002, April 2007), performed on the 

Base Year 2002 CMAQ simulation.

The New York State Department of Environmental Conservation (DEC), Division of Air 

Resources, conducted a performance evaluation of the 2002 base case CMAQ simulation 

on behalf of the OTC member states. Model performance was evaluated over the entire 

year, except for the July 6-9, 2002 period which was excluded from this analysis since the 

observed PM2.5 and organic mass (OM) data at many sites were greatly affected by 

Canadian forest fires. Appendix H, relating to Modeling Demonstration, provides 

comprehensive operational and diagnostic evaluation results. Highlights of this evaluation 

are provided in the following sections. The analysis examines model performance over a 

wide area, including the entire OTR plus the State of Virginia (OTR+).

1. Daily PM2.5 Mass

Model performance over the entire OTR+ region was examined using several statistics. 

These included overall mean fractionalized bias (MFB) and mean fractional error (MFE). 
39

Equations for these diagnostics are summarized below and are included in the EPA

modeling guidance document entitled, Guidance on the Use of Models and Other Analyses 

for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze

(EPA-454/B-07-002, April 2007).

Mean fractionalized bias (MFB), in %:

MFB

N

P O

P O

i i

i i

2

100%

Mean fractional error (MFE), in %:

MFE

N

P O

P O

i i

i i

2

100%

where P = Predicted (modeled) value, O = Observed value, and N = 

Number of observations

Figures 7 and 8 show MFE and MFB over the entire OTC+ region. The figures indicate 

the model is generally doing a reasonable job reproducing PM2.5 across the entire domain 

with the exception of the New York City area and a few monitors in New England. 

Overall, the mean bias (predicted minus observed) was about 3.8 g m

-3

, ranging from -

17.7 g m-3to +24.0 g m-3. The highest over-prediction tended to occur during the colder 

months, quarters 1 and 4, whereas the days on which the model tended to under-predict 

PM2.5 were more likely to occur during the summer months.

Figure 7: Mean Fractional Error

MFE (%) at each FRM location over the entire year: blue, <30%; green, 30-45%; orange, 

45-60%; red, 60-75%; pink, >75% (From NY DEQ report, 2007).
40

Figure 8: Mean Fractional Bias 

MFB (%) at each FRM location over the entire year: gray, <-45%; blue, -45 to -15%; 

green, -15 to 15%; orange, 15-45%; red, 45-75%; pink, >75% (From NY DEQ report, 

2007).

2. PM2.5 Speciation

PM2.5 is composed of several components. The primary components noted in the 

monitoring data include sulfates, nitrates and organic carbon; other components do not 

significantly contribute to PM2.5 concentrations. For proper performance, CMAQ 

predictions for each individual component of PM2.5 must also be examined. 

Data from the various speciation networks in the OTR+ region were compared to model 

predicted values for the base case (2002). Again, data from the July 6-9, 2002 period was 

excluded from this analysis due to the Canadian forest fires.

Sulfates (SO4

-

) are one of the primary contributors to the Philadelphia Area’s PM2.5

nonattainment. Figure 11 depicts modeled and actual sulfate measurements in the OTR+ 

region. The CMAQ model appears to reproduce actual sulfate concentrations quite well 

along with its seasonal variability.

Nitrates (NO3

-

) are another important contributor to the Philadelphia Area’s PM2.5

nonattainment. CMAQ does less well reproducing actual concentrations than it does for 

sulfates. Modeled concentrations appear to be less accurate during the colder months (1st

and 4th quarters) than the warmer months.
41

OM is another important contributor to the Philadelphia Area’s PM2.5 nonattainment. 

CMAQ does not do well reproducing the seasonal variability of OM though it does appear 

to do a better job reproducing observed winter values.

Figure 9: Time Series of SO4 Mass 

Time series of SO4 mass based on the composite average of all 21 Interagency Monitoring 

of Protected Visual Environments (IMPROVE) monitors across the OTR+ region. 

IMPROVE is a long-term monitoring program established in the mid-1980s to provide 

data needed to assess the impacts of new emission sources, identify existing man-made 

visibility impairment, and assess progress toward improving visibility in National Parks 

and Wilderness Areas. The observed values are denoted with the black diamonds, the 

model predictions are denoted with gray squares (From NY DEQ report, 2007).

NY DEQ’s model performance included an analysis of the meteorological model used to 

drive CMAQ, as well as actual PM2.5 values and PM2.5’s speciated components. Appendix 

H-2 is a technical listing of the model inputs, as well as an assessment of the MM5 

simulation to real-world data. The analysis shows that, in general, the performance of the 

MM5 is reasonable both at the surface and in the vertical, thereby providing confidence in 

the use of these data in the CMAQ simulations.

Both the MM5 and CMAQ runs appear to meet performance criteria over the entire OTR+ 

domain. Therefore, it can be assumed the modeling platform provides meaningful 

information in regard to projected 2009 PM2.5 concentrations that will be used to assess the 

Philadelphia Area’s future attainment of the PM2.5 standard.
42

E. Projected 2009 Design Values for the Philadelphia Nonattainment Area

1. Overview

As mentioned previously, the Philadelphia Area has an attainment date of April 5, 2010. 

The PM2.5 NAAQS include an annual standard of 15.0 μg/m3based on the 3-year average 

of annual mean PM2.5 concentrations, and a 24-hour standard of 65 μg/m3based on the 3-

year average of the 98th percentile of 24-hour concentrations.

This section summarizes the procedures that are used to demonstrate attainment of the 

PM2.5 NAAQS. As described in EPA’s Guidance on the Use of Models and Other 

Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and 

Regional Haze (EPA-454/B-07-002, April 2007), an attainment demonstration consists of 

(a) analyses that estimate whether selected emissions reductions will result in ambient 

concentrations that meet the NAAQS, and (b) an identified set of control measures that 

will result in the required emissions reductions. The necessary emission reductions for 

both of these attainment demonstration components may be determined by relying on 

results obtained with air quality models.

EPA’s Guidance on the Use of Models and Other Analyses for Demonstrating Attainment 

of Air Quality Goals for Ozone, PM2.5, and Regional Haze (EPA-454/B-07-002, April 

2007) recommends applying a modeled attainment test to the air quality modeling results 

to determine if the PM2.5 NAAQS will be met. Additional technical or corroboratory 

analyses may also be used as part of a “supplemental analysis” or a more stringent “weight 

of evidence” determination to supplement the modeled attainment test and to further 

support a demonstration of attainment of the NAAQS.

The modeled attainment test and additional corroborative analyses are described in further 

detail in the remaining portions of this section.

2. Modeled Attainment Test

The purpose of a modeling assessment is to determine if control strategies currently being 

implemented “on the books” (OTB) and proposed control strategies (“on the way” or 

OTW) will lead to attainment of the NAAQS for PM2.5 by the attainment year of 2009. 

The modeling is applied in a relative sense, similar to the 8-hour ozone attainment test: 

however, the PM2.5 attainment test is more complicated and reflects the fact that PM2.5 is a 

combination of many different species. In the test, ambient PM2.5 is divided into major 

components. Then, a relative response factor (RRF) and future design value (DVF) is 

calculated for each of the PM2.5 components. Since the attainment test is calculated on a 

per species basis, the attainment test for PM2.5 is referred to as the Speciated Modeled 

Attainment Test (SMAT). The following sections outline the process to determine that 

2009 projections of PM2.5 will meet the NAAQS from regional modeling, as suggested in 

EPA’s modeling guidance.
43

3. Determine Baseline Design Values

The first step in any attainment test process is to determine the baseline design value 

(DVB). The EPA guidance recommends using a DVB that is the average of the three 

design value periods that straddle the baseline inventory year (i.e., the average of the 2000-

2002, 2001-2003, and 2002-2004 design value periods for a 2002 baseline inventory year). 

This results in a 5-year weighted average, with the baseline year having the heaviest 

weight (i.e., {[2000] + 2*[2001] + 3*[2002] + 2*[2003] + [2004]}/9). 

For the SMAT process, a mean PM2.5 DVB is determined, as well as component specific 

DVB, for each quarter. The following section will detail the calculation of baseline design 

values needed for the PM2.5 attainment test.

Mean PM2.5 Baseline Design Values

To begin the SMAT process, a mean PM2.5 DVB is calculated on a quarterly basis for each 

FRM monitor in the PM2.5 nonattainment areas. Concentrations are calculated based on 

calendar quarters (Q1: January - March; Q2: April - June; etc.) as the NAAQS is calculated 

for a calendar year, and the quarters need to fit evenly within a year. Calculating the 

attainment test on a quarterly basis also allows states to examine the differences in PM2.5 

composition that occur during the different seasons.

Speciated Baseline Conditions

The monitored attainment test for PM2.5 utilizes both PM2.5 and individual PM2.5 component 

species. A separate RRF is calculated for each PM2.5 species. In order to perform the 

recommended modeled attainment test, states should divide observed mass concentrations 

of PM2.5 into seven components (plus passive mass):

1. Mass associated with sulfates (SO4)

2. Mass associated with nitrates (NO3)

3. Mass associated with ammonium (NH4)

4. Mass associated with organic carbon (OC)

5. Mass associated with elemental carbon (EC)

6. Mass associated with particle bound water (PBW)

7. Mass associated with “other” primary inorganic particulate matter (Crustal)

8. Passively collected mass or the mass of the blank filter (Passive)

This yields the following formula in order to calculate PM2.5:

PM2.5FRM = [SO4] + [NO3] + [OC] + [EC] + [NH4] + [PBW] + [Crustal] + [Passive]

The second part of the process is to use the quarterly mean PM2.5 DVBs with speciated data 

to calculate the quarterly mean concentrations of these 7 components at the FRM sites. 

This need to speciate the FRM data presents two issues: 
44

1. FRM measurements and speciated PM2.5 measurements do not always measure the 

same mass. 

2. Not all FRM monitoring sites have co-located Speciation Trends Network (STN)

speciation monitors. 

The following sections will explain how these issues are addressed to produce the 

speciated values needed for this attainment demonstration.

SANDWICH

As the EPA’s Guidance on the Use of Models and Other Analyses for Demonstrating 

Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze (EPA-454/B-07-

002, April 2007) notes, recent data analyses have noted that the FRM monitors do not 

measure the same components and do not retain all of the PM2.5 that is measured by STN 

samplers. Therefore, measurements from FRM monitors cannot be directly compared to 

speciation measurements from the STN monitors. By design, the FRM mass measurement 

does not retain all ammonium nitrate and other semi-volatile materials (negative sampling 

artifacts) and includes particle bound water associated with sulfates, nitrates and other 

hygroscopic species (positive sampling artifacts). This results in concentrations (and 

percent contributions to PM2.5 mass) that may be different from the ambient levels of some 

PM2.5 chemical constituents. 

To resolve the differences between FRM and STN total mass, EPA recommends using the 

“sulfate, adjusted nitrate, derived water, inferred carbonaceous” (SANDWICH) material 

balance approach. With the SANDWICH approach, nitrate mass is adjusted to account for 

volatilization based on hourly meteorology parameters. Subsequently, quarterly average 

nitrate, sulfate, elemental carbon, ammonium and crustal mass can be calculated, as well as 

the Degree of Neutralization (DON) of sulfates. Next, the mass of particle bound water 

can be calculated from the previously obtained DON, sulfate, nitrate, and ammonium 

values. (See more details on particle bound water calculations in the Annual SMAT 

Results section, below). Finally, organic carbon is calculated by taking the difference 

between the total PM2.5 mass as measured at the FRM monitor, and the calculated 

component mass (i.e., OC from mass balance ([OCMmb] = PM2.5FRM - {[EC] + [SO4] + 

[NO3] + [NH4] + [PBW] + [Crustal] + [Passive]}), where the Passive (mass) is the FRM 

sampling artifact normally set equal to 0.5). 

EPA Region 3 office provided SANDWICHed data for the Philadelphia Area monitors. 

For a description and use of the SANDWICH method, see the Definition of SANDWICHed 

STN Data (EPA, 2006).

Speciated Profiles

While the SANDWICH method reconciles the differences between FRM and STN, a 

lingering issue is that not all FRM monitoring sites have co-located STN monitors to 

provide speciated data. EPA guidance suggests four measures that can be taken to resolve 

the lack of speciated data: 
45

1. Use of concurrent data from a nearby speciated monitor

2. Use of representative data (from a different time period)

3. Use of interpolation techniques to create a spatial field using ambient speciation 

data

4. Use of interpolation techniques to create spatial fields, and gridded modeling 

outputs to adjust the species concentrations

Of the four methodologies, EPA recommends using one of the spatial interpolation 

techniques to estimate species concentrations at FRM sites that do not have speciation data 

(numbers 3 and 4, above). To assist in this task, EPA began developing a software tool 

called “Modeled Attainment Test Software” (or MATS) that would perform the spatial 

analysis of described options number 3 and 4. However, the MATS tool was not available 

at the time this analysis was completed. In trying to pursue the EPA recommended course 

of action, option 1 (use of concurrent data from a nearby speciated monitor) was utilized.

4. Relative Response Factor Calculations

The calculation of RRFs for this study was performed using the EPA recommended 

method for “nearby” grid cells for a 12-kilometer horizontal grid resolution, with a 3x3 

grid cell array for 12-km resolution modeling. The relative response factor used in the 

modeled attainment test is computed by taking the ratio of the mean of the predictions in 

the future to the mean predictions with baseline emissions, over all relevant days.

For the 24-hour and annual PM2.5 NAAQS, the spatially averaged value of the nearby 

predictions (mean value of the grid cell array) was used. Each component-specific RRF 

was used in the modeled attainment test by taking the ratio of the mean of the spatially 

averaged daily predictions in the future to the mean of the spatially averaged daily 

predictions with current emissions.

The basis for this approach is as follows:

1. Consequence of a control strategy may be “migration” of a predicted peak. If a 

state were to confine its attention only to the cell containing a monitor, it might 

underestimate the RRF (i.e., overestimate the effects of a control strategy).

2. Uncertainty in the formulation of the model and the model inputs is consistent with 

recognizing some leeway in the precision of the predicted location of 

concentrations.

3. Standard practice in defining a gridded modeling domain is to start in the southwest 

corner of the domain and determine grid cell location from there. Considering 

several cells “near” a monitor rather than the single cell containing the monitor 

diminishes the likelihood of inappropriate results that may occur from the geometry 

of the superimposed grid system.

4. The area does not exhibit strong spatial concentration gradients of observed 

primary PM2.5.
46

5. Annual SMAT Results

A difficulty presented in estimating the future design values was missing STN data for 

2000 and 2001at the Philadelphia Area monitors. This limitation restricted the calculation 

of SANDWICH data to the period 2002–2004. Therefore, the 2009 projected design 

values are based on speciation profiles developed using 2002-2004 STN data.

There are four FRM monitors in the Pennsylvania portion of the Philadelphia Area that are

co-located with a speciated sampler: Chester, New Garden, Elmwood, and Philadelphia 

AMS Lab. However, since there are eight FRM monitors within the Philadelphia Area, the 

Department was able to determine that the four speciated monitors (including an additional 

monitor in Camden, NJ) in the nonattainment area were representative of all FRM monitor 

locations in order to complete the SMAT analysis. RRFs were only calculated for the 

sulfates, nitrates, organic carbon, elemental carbon and crustal component of PM2.5. 

Referencing the PM2.5 FRM formula in section 3 above, the only components of PM2.5 that 

were not included in the RRF calculation were ammonium and water. Base and future case 

ammonium was calculated based on the DON value and the following formula presented in 

EPA’s Guidance on the Use of Models and Other Analyses for Demonstrating Attainment 

of Air Quality Goals for Ozone, PM2.5, and Regional Haze: 

NH4 = 0.29 * NO3 + DON * SO4.

The particle bound water was then calculated using the particle bound water formula 

estimated from the Aerosol Inorganic Model. Due to the hygroscopic nature of ammonium 

sulfate and ammonium nitrate, retained sulfate, nitrate and ammonium will all contain 

water. Therefore, the final polynomial equation (seen below and referenced (EPA, 2006 

(2))) contains sulfates, nitrates and ammonium within its calculation. The equation utilized 

was that for low acidity.

PBW = [202049.0 – 391494.6 * S – 390912.1 * N + 442.4 * (S^1.5) – 155.3 * (N^1.5)

- 293406.8 * (A^1.5) + 189277.5 * (S^2) + 377992.6 * N * S + 188636.8 * (N^2)

– 447.1 * (S^2.5) – 507.2 * (S^1.5) * N – 12.8 * (S^3) + 146.2 * (N^1.5) * S 

+ 217.2 * (N^2.5) + 30.0 * (N^1.5) * (S^1.5) – 18.6 * (N^3) + 216267.0 * (A^1.5) * S 

+ 215419.9 * (A^1.5) * N – 621.8 * (A^1.5) * (S^1.5) + 239.1 * (A^1.5) * (N^1.5) 

+ 35413.1 * (A^3)] * (SO4 + NO3+ NH4)

where

S = SO4 / (SO4 + NO3 + NH4)

N = NO3 / (SO4 + NO3 + NH4)

A = NH4 / (SO4 + NO3 + NH4)

Table V-1 displays the calculated quarterly RRFs for the design monitor of the 

Philadelphia Area, Broad Street. Based on the results of the RRF calculations, all PM2.5 

constituents either remain the same or undergo a downward trend, except for the crustal 

portion.
47

Table V-1: Annual PM2.5 Quarterly RRF Values 

Table V-2 presents the results of the annual SMAT results for all of the monitors in the 

Pennsylvania portion of the Philadelphia Area. The SMAT results demonstrate that the 

projected average annual arithmetic mean PM2.5 concentration calculated at each FRM 

monitor attains the annual PM2.5 NAAQS. Specifically, all DVF calculations are less than

15.0 μg/m3. Table V-2 presents the results of the annual SMAT results for a suite of 

regional modeling runs conducted by OTC, with each modeling run representing 

OTB/OTW control measures. All runs demonstrate timely attainment of the annual 

NAAQS.

Table V-2: Annual SMAT Results for the Philadelphia Area 2009 On The Books/On

The Way Control Measures

Source: 2000-2004 DVB quarterly concentrations calculated from data in Appendix A-2. 

Quarter Sulfates Nitrates OC EC Crustal

1

st 0.9429 0.8976 0.9514 0.8171 1.0988

2

nd 0.7272 0.7450 0.9867 0.8083 1.1700

3

rd 0.6619 0.8218 0.9875 0.7927 1.1869

4

th 0.9043 0.9008 0.9848 0.8058 1.1433

AIRS ID

Site 

Name County State

2000-2004 DVB 2009

Q1 Q2 Q3 Q4 DVF

420170012 Bristol Bucks PA 14.14 13.69 14.73 13.85 12.1

420290100 New Garden Chester PA 14.39 14.73 16.36 13.76 12.4

420450002 Chester Delaware PA 15.07 15.96 16.34 13.74 13.3

420910013 Norristown Montgomery PA 12.68 13.62 13.96 12.34 11.3

421010004 AMS Lab Philadelphia PA 15.99 14.01 15.95 13.82 12.9

421010024 NE Airport Philadelphia PA 13.58 13.63 14.95 12.96 11.9

421010047 Broad Street Philadelphia PA 16.59 16.45 15.80 15.37 13.5

421010136 Elmwood Philadelphia PA 15.70 14.20 15.27 12.99 12.7

100031003 Bellefonte New Castle DE 14.87 15.16 15.50 13.13 12.6

100031007 Lums Pond New Castle DE 13.16 14.37 16.05 10.66 11.3

100031012 Newark New Castle DE 15.27 14.91 16.53 13.14 12.6

100032004 MLK New Castle DE 16.41 15.40 17.61 14.04 13.3

340070003 Camden Camden NJ 13.99 14.54 15.76 12.47 12.3

340071007 Pennsauken Camden NJ 13.99 14.00 14.75 13.59 12.3

340155001 Gibbstown Gloucester NJ 13.92 13.43 15.08 11.39 11.7
48

6. 24-Hour SMAT Results

As with obtaining the annual SMAT Results, a difficulty presented in estimating the future 

design values was missing STN data for 2000 and 2001 at all of the Philadelphia area 

monitors. This limitation restricted the calculation of SANDWICH data to the period 

2002–2004. Therefore, the 2009 projected design values are based on speciation profiles 

developed using 2002-2004 STN data.

The RRF calculations were very similar to those that were computed in the annual SMAT 

analysis, except that all modeled RRFs were compared with each monitoring year’s 24-

hour 98th percentile design value. A quarterly analysis was completed consistent with the 

procedure outlined in EPA’s Guidance on the Use of Models and Other Analyses for 

Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze 

(EPA-454/B-07-002, April 2007). 

The procedure that was completed was as follows. The top 25% of the days of the 

speciation and the modeling data were computed on a quarterly basis. The speciation data 

was compared with the quarterly PM2.5 FRM data to compute a speciated composition of 

the FRM data. After the RRFs were calculated (the RRF values for Elmwood, are shown 

below in Table V-3), these RRF values were applied to the speciated composition data to 

compute a 2009 speciated composition data. Once this was completed, a future year 

design value was reconstructed.

Table V-3: 24-hour PM2.5 Quarterly RRF Values 

Quarter Sulfates Nitrates OC EC Crustal

1

st 0.9549 0.9235 0.9211 0.8157 1.0852

2

nd 0.6761 0.7858 0.9841 0.8091 1.1758

3

rd 0.6023 0.8698 0.9947 0.7978 1.2134

4

th 0.9036 0.9237 0.9830 0.8089 1.1514

Table V-4 displays the 24-hour PM2.5 SMAT results for all of the monitors within the 

Philadelphia Area. The SMAT results demonstrate that the projected 24-hour 98th

percentile PM2.5 concentration calculated at the FRM monitor attains the 24-hour PM2.5

NAAQS. Specifically, all DVF calculations are less than 65 μg/m3. Table V-4 presents 

the results of the 24-hour SMAT results for a suite of regional modeling runs conducted by 

OTC each representing OTB/OTW control measures. All runs demonstrate attainment of 

the 24-hour PM2.5 NAAQS.
49

Table V-4: 24-hour SMAT Results for the Philadelphia Area 2009 On The Books/On

The Way Control Measures

AIRS ID

Site 

Name County State

24-Hour 98th Percentile DVB 2009

2000 2001 2002 2003 2004 DVF

420170012 Bristol Bucks PA 38.4 38.5 37.2 39.6 29.9 32.9

420290100 New Garden* Chester PA - - 33.7 38.5 32.7 32.5

420450002 Chester Delaware PA 36.2 39.5 31.9 37.8 30.5 33.7

420910013 Norristown Montgomery PA 31.5 47.6 36.8 37.5 28.8 31.0

421010004 AMS Lab Philadelphia PA 41.2 40.2 39.7 39.9 34.3 35.9

421010024 NE Airport Philadelphia PA 37.5 37.1 33.7 38.7 33.4 31.0

421010047 Broad Street Philadelphia PA 39.0 39.6 36.2 42.3 31.5 33.5

421010136 Elmwood Philadelphia PA 39.0 46.0 37.0 35.6 29.5 33.9

100031003 Bellefonte New Castle DE 38.2 40.7 33.8 35.8 32.5 31.0

100031007 Lums Pond New Castle DE 36.4 35.9 30.6 36.5 30.8 28.4

100031012 Newark New Castle DE 39.8 39.5 41.5 36.4 29.1 31.7

100032004 MLK New Castle DE 39.3 43.2 40.6 37.4 34.1 34.5

340070003 Camden Camden NJ 32.1 41.2 36.8 43.0 35.0 32.0

340071007 Pennsauken Camden NJ 35.7 37.8 36.7 37.8 34.8 33.4

340155001 Gibbstown Gloucester NJ 34.1 40.8 35.7 35.1 29.0 30.0

* The New Garden monitor started operating in 2002.

Source: Data extracted from the US EPA Air Quality System AMP 450 Report. See Appendix A1 for the AMP 450 Report data for Pennsylvania monitors. 

F. Unmonitored Area Analysis

Following EPA’s Guidance on the Use of Models and Other Analyses for Demonstrating 

Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze (EPA-454/B-07-

002, April 2007), an unmonitored area analysis “...is intended to ensure that a control 

strategy leads to reductions in ozone or PM2.5 at other locations which could have baseline 

(and future) design values exceeding the NAAQS were a monitor deployed.”

Projected annual PM2.5 concentrations surrounding the Philadelphia Area indicate most 

areas in the Commonwealth, including the Pennsylvania nonattainment areas immediately 
50

surrounding the Philadelphia Area, are projected to attain the standard by 2009. This 

indicates there should be no areas where concentrations could reasonably be expected to 

exceed the annual PM2.5 NAAQS within the nonattainment area.

The Air Quality Modeling Group (EPA Research Triangle Park) has developed the MATS, 

described on p. 39, above. MATS is a PC-based software tool that can perform the 

modeled attainment tests for PM2.5 and ozone (O3), and perform the uniform rate of 

progress analysis for regional haze (visibility). However, when this analysis was 

conducted, MATS was still in development and therefore was not utilized within this 

analysis. 

G. Local Area Analysis

EPA’s Guidance on the Use of Models and Other Analyses for Demonstrating Attainment 

of Air Quality Goals for Ozone, PM2.5, and Regional Haze (2007) suggests that it may be 

necessary to evaluate the impact of local primary PM sources for contributions to both the 

24-hour and annual NAAQS. Evaluation of local PM sources and their effects on monitor 

concentrations could be evaluated using a near-scale model such as AERMOD or 

CALPUFF.

Since the end of 2008, there are a total of eight (8) FRM monitors within the Philadelphia 

Area; four (4) FRM monitors run by the Department and four (4) FRM monitors run by the 

Philadelphia AMS. In addition, there are four (4) speciation monitors and at least five (5) 

continuous PM2.5 monitors located within the Philadelphia Area.

Pennsylvania has noted local source interference at PA DEP’s Chester monitor (PA DEP, 

September 2004). Chester has the second highest annual PM2.5 design value (14.1 μg/m3) 

and the fifth highest 24-hour design value (33 μg/m3) in the Philadelphia Area in 2008. 

The 24-hour design value is below the (1997) 24-hour standard indicating attainment of the 

NAAQS even with significant local effects. 

A review of the Commonwealth’s, Philadelphia County’s, Delaware’s, Maryland’s and 

New Jersey’s 2002 emissions from the NEI database indicates eighteen (18) large sources 

with greater than 50 tons per year (TPY) of direct PM2.5 emissions within 50 kilometers of 

the Chester PM2.5 monitor. These sources are listed in Table V-5. Each source’s PM2.5

emissions, distance from the Chester monitor, direction from the Chester monitor, county, 

state, and emission to distance ratio (Q/d) are included in the table.
51

Table V-5: Summary of Large PM2.5 Sources near the Chester Monitor

Source Emissions

(TPY)

Distance

(km) Direction County State Q/d

PQ Corp – Chester 54.6 0.54 N Delaware PA 101.5

Kimberly Clark – Chester 97.8 1.35 NE Delaware PA 72.3

Conoco Phillips 89.0 2.53 WSW Delaware PA 35.2

Sunoco – Marcus Hook. 241.4 4.84 WSW Delaware PA 49.9

Exelon – Eddystone 400.9 5.03 ENE Delaware PA 79.8

PG&E Corp – Logan 145.5 5.56 WSW Gloucester NJ 26.1

Valero Refining 128.7 9.50 E Gloucester NJ 13.6

Conectiv Del. – Edge Moor 519.0 15.42 SW New Castle DE 33.7

Sunoco – Philadelphia 212.1 16.62 ENE Philadelphia PA 12.8

PG&E Generating 257.3 18.98 SW Salem NJ 13.6

Sunoco 165.5 19.29 E Gloucester NJ 8.6

Deepwater Gener. Station 107.6 20.82 SW Salem NJ 5.2

Anchor Glass Container 137.2 29.92 SSW Salem NJ 4.6

Sunoco Chemicals 113.9 31.98 ENE Philadelphia PA 3.6

Valero Refining 189.8 35.46 SW New Castle DE 5.4

Exelon – Cromby Gen 160.6 37.67 NW Chester PA 4.3

Hope Creek Generating 53.1 43.23 SSW Salem NJ 1.2

Occidental Chem Corp 64.2 49.01 NW Montgomery PA 1.3

The ratio of emissions to distance (Q/d) is often used as a screening tool to determine if a 

source could cause a significant model concentration. If a source’s Q/d ratio is larger than 

twenty (20) it usually warrants an analysis using a dispersion model. Table V-5 indicates 

seven (7) sources exceed this Q/d ratio and probably warrant an analysis with a dispersion 

model to gauge their effects on the Chester monitor. A quick survey of local wind patterns 

utilizing meteorological data collected from 2004 to 2008 at the Philadelphia International 

Airport meteorological tower indicates the flow is not significantly influenced by any 

terrain features (since the Chester monitor sits in a lowest regional elevation within the 

Commonwealth). Therefore, as shown in Figure 10 below, the Chester area generally 

experiences a strong west, northwest and southwest flow, which is most likely driven by 

the synoptic weather pattern across the continental US. Based on the results from the wind
52

rose analysis, five (5) of the identified sources (Conoco Philips, Sunoco – Marcus Hook, 

PG&E Corp – Logan, Conectiv Del. – Edge Moor, and PQ Corp - Chester) lie upwind of 

the Chester monitor, while the other two (2) sources (Kimberly Clark – Chester and Exelon 

- Eddystone) lie in less favorable wind directions to transport direct PM2.5 emissions to the 

Chester monitor.

Figure 10. Wind Rose: Philadelphia Int’l Airport Location (2004-2008)

As noted earlier, the Department has observed enhancement of PM2.5 concentrations at the 

Chester monitor by local sources. Using emissions to distance ratios (Q/d) and local 

predominant wind directions; seven (7) sources were identified for possible analysis with a 

dispersion model to gauge the effect of local direct PM2.5 emissions on the North Braddock

monitor. A local area analysis using a dispersion model, however, was not conducted 

since the modeled concentrations for the Chester monitor currently would attain the PM2.5

NAAQS. This does not preclude the Department from conducting a dispersion modeling 

analysis as part of a local area analysis in the future for the EPA’s revised 24-hour PM2.5

standard.
53

H. Weight of Evidence and Other Documentation Supporting Attainment

The EPA’s Guidance on the Use of Models and Other Analyses for Demonstrating 

Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze (2007) encourages 

the use of corroboratory analyses to support the modeled attainment demonstration. These 

analyses, collectively referred to as “weight of evidence” (WOE), help bolster the 

assertions that an area will achieve attainment in the allotted time.

Table V-6 outlines the types of supplemental information that EPA suggests will satisfy a 

weight of evidence demonstration. Generally, the analyses become more complicated as 

the projected modeled values increase. The projected 2009 design value for the annual 

standard in the Philadelphia Area, 13.5 μg/m3, is below the lower bounds of the range of 

14.5 μg/m3to 15.5 μg/m3 for which EPA’s Guidance on the Use of Models and Other 

Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and 

Regional Haze (2007) requires a formal weight of evidence demonstration.

According to the EPA’s Guidance on the Use of Models and Other Analyses for 

Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze 

(2007), areas, such as the Philadelphia Area, that have a projected design value lower than 

14.5 μg/m3 are recommended to provide basic supplemental analyses to support the result 

of the modeling demonstration. The basic supplemental analyses can include additional 

modeling, analysis of trends in the monitoring data or emissions and/or observational 

models and diagnostic analyses. The Department’s supporting evidence includes a brief 

summary of the modeling demonstration, recent trends in the Philadelphia Area’s

monitoring data and a brief analysis of some of the largest SO2 sources within the 

nonattainment area.

Table V-6: Summary of PM2.5 Weight of Evidence Guidelines (EPA Guidance)

Results of Modeled Attainment Test Supplemental Analyses

Annual PM2.5 24-Hour PM2.5

Future Design Value 

< 14.5 μg/m3, all sites

Future Design Value 

< 62 μg/m3, all sites

Basic supplemental analyses should be 

completed to confirm the outcome of 

the modeled attainment test

Future Design Value 

14.5 – 15.5 μg/m3, all 

sites

Future Design Value 

62 – 67 μg/m3, all sites

A weight of evidence demonstration 

should be conducted to determine if 

aggregate supplemental analyses 

support the modeled attainment test

Future Design Value 

≥ 15.5 μg/m3, all sites

Future Design Value 

≥ 68 μg/m3, all sites

More qualitative results are less likely 

to support conclusion differing from 

the outcome of the modeled 

attainment test
54

2009 Projected Modeling Concentration: The Department’s attainment demonstration 

relies on results from the OTB/OTW CMAQ runs completed by the Virginia Department 

of Environmental Quality. Emissions for the base case (2002) and projected (2009) time 

frames were developed by MARAMA with input from all jurisdictions that are part of the 

OTR. Base-case and projected emissions within the Philadelphia Area appear to be 

reasonable; therefore, the projected design value for 2009 should reflect what will actually 

be monitored.

Recent analyses of projected CMAQ ozone design values suggest the model may actually 

underestimate the impact of emission reductions on actual concentrations. This modeled 

underestimation of changes in ozone concentrations may be due to the model’s inability to 

adequately reproduce changes in ozone concentrations due to large emission reductions. If

CMAQ has the same shortfall with fine particulate concentrations, then it may also 

overestimate the projected 2009 PM2.5 design values for the Philadelphia Area. Since the 

calculated design value is already well below 15.0 μg/m3, any overestimation of the 

projected 2009 annual PM2.5 design value provides a further cushion bolstering the 

argument that the Philadelphia Area will reach attainment.

PM2.5 and Emission Trends: Many monitors within the region are heavily influenced by 

the mobile source sector. Emissions from the mobile source sector are predicted to be 

significantly lower in 2009 compared to 2002. As more vehicles subject to cleaner new car 

standards replace older vehicles subject to less stringent standards, the fleet as a whole 

emits fewer emissions.

Figure 11 shows the annual and 24-hour PM2.5 concentrations for the Chester monitor from

1999 through 2008. Over the last two years, annual PM2.5 averages appear to have 

declined slightly. In fact, all PM2.5 monitors, excluding the Broad Street monitor, in the 

Philadelphia Area are monitoring attainment of the annual PM2.5 standard, based on 2006 –

2008 monitoring data. This may be due to a combination of weather conditions and 

emission decreases in the mobile source sector and may be indicative of lower future PM2.5

design values allowing the Philadelphia Area to attain the annual PM2.5 standard with a 

comfortable margin.
55

Figure 11: Philadelphia Area PM2.5 Trends
56

I. Conclusions

The Philadelphia Area’s projected 2009 annual PM2.5 concentration was estimated using 

the OTC’s modeling platform. A review of the base case (2002) run indicated the CMAQ

model did a reasonable job reproducing actual concentrations. Based on this analysis, it is 

reasonable to assume the model can estimate the projected PM2.5 concentrations within the 

Philadelphia Area for 2009. The Department understands that the EPA anticipates using 

2009 data to determine whether the Philadelphia Area attains the PM2.5 standard by its 

April 2010 attainment date.

Projected PM2.5 concentrations from CMAQ indicate the Philadelphia Area will attain the 

annual standard by 2009. Additional evidence supporting this conclusion includes lower 

concentrations at all of the PM2.5 monitors within the Philadelphia Area the last couple of

years and possible model under-predictions of the air quality benefits of emission 

reductions.
57

VI. CONTINGENCY MEASURES FOR THE ATTAINMENT DEMONSTRATION

A. Contingency Measure Requirement

Pursuant to 40 CFR 51.1012, the attainment plan for the Philadelphia Area must include a 

contingency plan that contains measures that qualify as contingency measures for the 

attainment demonstration. This section fulfills the contingency measures requirement for 

the attainment demonstration. The contingency plan must provide for one year of 

reductions needed for attainment. 

By 2009, emissions of SO2 and NOx in the Pennsylvania portion of the Philadelphia

Area are projected to decrease by 12,259 tons and 28,597 tons, respectively. Based on 

modeling of the projected 2009 emissions, the Philadelphia Area is predicted to have a 

2009 design value of 13.5 ug/m3. This is lower than the 15 ug/m3required for attainment 

of the PM2.5 standard. Calculations were made to estimate the portion of the emission 

reduction that is necessary to reach the attainment concentration of 15 ug/m3and the 

portion of the emission reduction that reduces the design value below 15 ug/m3and is, 

therefore, excess.

Table VI-1 contains information about the changes in design value and emissions 

expected by 2009 in the five-county Philadelphia area. Table VI-1 displays the 2002

actual and 2009 modeled design values and the 2002 actual and 2009 projected emissions 

of PM2.5, SO2 and NOx. 

Table VI-1: Changes in Design Value and Emissions Expected by 2009

Philadelphia Area

Design 

Value 

(ug/m3)

PM2.5

(tons/year)

SO2

(tons/year)

NOx 

(tons/year)

2002 16.6 14727 40459 120248

2009 (Modeled/Projected) 13.5 15219 28200 91651

Predicted Change from 2002-2009 3.1 -492 12259 28597

As shown in Table VI-2, for each pollutant, the change in pollutant emissions was 

divided by the predicted change in design value to yield the design value reduction rate. 

Next, the change in design value necessary to attain the standard (16.6 ug/m3– 15 ug/m3

= 1.6 ug/m3) was multiplied by the design value reduction rate to estimate the target 

emissions reduction. This represents the portion of emissions reduction necessary to 

attain the standard. The rest of the emissions reduction is beyond what is necessary for 

attainment and is, therefore, considered to be “excess” reduction.
58

Table VI-2: Calculation of Required and Excess Emissions Reductions

Philadelphia Area

Design 

Value 

(ug/m3)

PM2.5

(tons/year)

SO2

(tons/year)

NOx 

(tons/year)

Predicted Change from 2002-2009 3.1 -492 12259 28597

Design Value Reduction Rate (tons/ug/m3) N/A 3955 9225

Target Reductions for Attainment 1.6 N/A 6327 14760

Calculated Excess Reductions 1.5 N/A 5932 13837

The contingency requirement is calculated by dividing the target emissions reduction by 

seven which is the number of years between 2002 and 2009. Table VI-3 shows the 

calculation of the contingency requirement reduction and demonstrates that the 

calculated excess reduction exceeds the amount of reduction necessary for the 

contingency plan.

Table VI-3: Calculation of Required Contingency Plan Reductions

Philadelphia Area PM2.5

(tons/year)

SO2

(tons/year)

NOx 

(tons/year)

Target Reductions for Attainment N/A 6327 14760

Calculated Excess Reductions N/A 5932 13837

Contingency Requirement N/A 904 2109

Excess Reductions Satisfy Contingency 

Requirement N/A Yes Yes

B. Identified Contingency Measures

In addition to the calculated excess reductions shown in Tables VI-2 and VI-3 above, 

the Department has identified additional control measures. EPA guidance encourages 

early implementation of contingency measures to guard against failure either to meet 

a milestone or attain the standard. EPA's guidance on early implementation of 

control measures encourages the early implementation of required control measures 

and of contingency measures as a means of guarding against failures to meet a 
59

milestone or to attain. The EPA states that any implemented measures (that are not 

needed for the rate-of-progress requirements or for the attainment requirements) would 

need to be “backfilled”, meaning replaced with another measure, only to the extent 

they are used to meet a milestone.

7

The reductions from the designated contingency measures are surplus vis-à-vis the 

attainment demonstration contained in this SIP. As a result, the Department will not be 

required to replace any contingency measures that it chooses to implement in advance of 

the contingency plan requirement. 

The following describes specific control measures that are anticipated to be in place in 

order to bring the area back into attainment should a violation occur.

On October 9, 2008, Governor Rendell signed Senate Bill 295, which became Act 124 of 

2008, the Diesel-Powered Commercial Motor Vehicle Idling Act (Act 124). Act 124 went 

into effect on February 6, 2009. The Department estimates that 50 percent of all long 

duration idling for Class 8 trucks will be eliminated in 2010 when the temperature 

exemption for sleeper truck rest expires. Statewide emission reductions are estimated to be 

1610 tons, 45 tons and 30 tons per year for NOx, VOC, and PM2.5, respectively. The 

Department may also utilize enhanced enforcement to obtain additional emission 

reductions.

Significant additional reductions in NOx, direct PM2.5 and, to a limited extent, SO2

emissions will occur in emissions from highway and nonroad mobile sources after 2009. 

NOx emissions from mobile sources are more than one-third of the emissions in 2009.

In addition, the following regulations are in development and are anticipated to be adopted

in the relatively near future:

NOx controls for cement kilns 

NOx controls for glass furnaces 

Sulfur limits for fuel oil (home heating oil and residual fuel oil)

Regulations to reduce VOC emissions are also in development, including controls on the 

manufacture and use of adhesives, primers and sealants and regulations incorporating the 

Control Techniques Guidelines issued by the EPA in 2006, 2007 and 2008.

Once the Department’s Bureau of Air Quality has obtained an approved request to initiate 

a rulemaking, the rulemaking may proceed as follows:

 

7 EPA, "Guidance on the Post-1996 Rate-of-Progress Plan and the Attainment Demonstration," 

Corrected Version as of February 18, 1994, p. 50.
60

Within 2 months: Review by Air Quality Technical Advisory Committee 

(AQTAC), Citizens Advisory Council and other advisory committees,

8

as 

appropriate.

Within 5 months: Environmental Quality Board (EQB) meeting/action. 

Within 7 months: Publication in the Pennsylvania Bulletin for comment as 

proposed rulemaking. 

Within 9 months: Public hearing takes place and comment period on proposed rule 

closes. 

Within 10 months: House and Senate Standing Committees and Independent 

Regulatory Review Commission (IRRC) comment on proposed rule. 

Within 12 months: AQTAC, Citizens Advisory Council and other committees, as 

appropriate, review responses to comments and draft final rulemaking. 

Within 15 months: EQB meeting/action.

Within 16 months: IRRC action on final rulemaking.

Within 17 months: Attorney General review/action. 

Within 18 months: Publication in the Pennsylvania Bulletin as final rulemaking and 

submission to the EPA as a SIP revision. The regulation would become effective 

upon publication in the Pennsylvania Bulletin. 

 

8 Other committees could include the Small Business Compliance Advisory Committee and Agriculture 

Advisory Committee. 
61

REFERENCES

SECTION I

Pope III, C. Arden, M. Ezzati and D. Dockery. “Fine-Particulate Air Pollution and Life 

Expectancy in the United States.” New England Journal of Medicine. 360: 376-386 

January 22, 2009. 

EPA, 2007. Clean Air Fine Particle Implementation Rule. Final Rule. 72 FR 20586 

(April 25, 2007).

SECTION III

EPA, 2005. Emissions Inventory Guidance for Implementation of Ozone and Particulate 

Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations. 

EPA-454/R-05-001. August, 2005. Updated November, 2005

Final Technical Support Document, Development of Emission Projections for 2009, 2012, 

and 2018 for NonEGU Point, Area, and Nonroad Sources in the MANE-VU Region. 

Prepared by MACTEC for MARAMA, February 28, 2007.

Final Regulatory Analysis: Control of Emissions from Marine Diesel Engines, EPA, 

November 1999. 

SECTION V

The Nature of the Fine Particle and Regional Haze Air Quality Problems in the MANE-VU 

Region: A Conceptual Description. Prepared by the Northeast States for Coordinated AirUse Management (NESCAUM), November 2006.

Summary of Pennsylvania’s PM2.5 Nonattainment Analysis, Prepared by the Pennsylvania 

Department of Environmental Protection, October 2007.

Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air 

Quality Goals for Ozone, PM2.5, and Regional Haze. EPA, EPA-454/B-07-002, April 

2007.

Final Air-Quality Modeling Protocol for the Annual PM2.5 NAAQS: PhiladelphiaWilmington PA-NJ-DE Annual PM2.5 Nonattainment Area, prepared by the Pennsylvania 

Department of Environmental Protection, October 2007.

A Modeling Protocol for the OTC SIP Quality Modeling System For Assessment of the 

Ozone National Ambient Air Quality Standard in the Ozone Transport Region, The 

Modeling Committee of the Ozone Transport Commission, March 2006.
62

CMAQ Model Performance and Assessment for Base Year 2002: PM2.5 Mass and 

Speciation, Prepared by the New York State Department of Environmental Conservation, 

December 2007.

Clegg, S.L., P. Brimblecombe, and A. S. Wexler, (1998), “Aerosol Inorganics Model; A

Thermodynamic Model of the System H+ - NH4+ - SO42- - NO3- - H2O at Tropospheric

Temperatures.”, J. Phys. Chem., 102A, 2137-2154.

(http://www.aim.env.uea.ac.uk/aim/project.htm).

EPA, 2004. Procedures for Estimating Future PM2.5 Values for the CAIR Final Rule by 

Application of the (Revised) Speciated Modeled Attainment Test (SMAT). July 26, 2004. 

Available on EPA’S CAIR PDF web page (www.epa.gov/CAIR/pdfs/Revised-SMAT.pdf).

EPA, 2006. Definition of SANDWICHed STN Data. November 1, 2006. Available on 

EPA’s Air Explorer web page (www.epa.gov/mxplorer/sandwich_description.doc).

EPA, 2006 (2). SANDWICH Material Balance Approach for PM 2.5 Data Analysis

(Presented at the 2006 National Air Monitoring Conference). November 6-9, 2006. 

Available on EPA’s AMTIC web page 

(www.epa.gov/ttn/amtic/files/ambient/2006conference/frank.pdf).

SECTION VI

U. S. EPA, "State Implementation Plans; General Preamble for the Implementation of 

Title I of the Clean Air Act Amendments of 1990", Proposed Rule, 57 Federal 

Register 13,498 (April 16, 1992).

EPA, "Guidance on the Post-1996 Rate-of-Progress Plan and the Attainment

Demonstration," Corrected Version as of February 18, 1994, p. 50.

OTC 2007. Identification and Evaluation of Candidate Control Measures: Final 

Technical Support Document. Prepared by MACTEC Federal Programs, Inc., Herndon, 

Virginia for the Ozone Transport Commission. February 28, 2007.
63

ACRONYMS AND ABBREVIATIONS

AIM Architectural and Industrial Maintenance Coatings

AQTAC Air Quality Technical Advisory Committee

BACT Best Available Control Technology

CAA Clean Air Act

CAIR Clean Air Interstate Rule

CA LEV California Low Emission Vehicle (program)

CF Control Factor

CFR Code of Federal Regulations

CMAQ Community Multi-scale Air-Quality Model

CMV Commercial Marine Vessel

DON Degree of Neutralization

DVB Baseline Design Value

DVF Future Design Value

EC Elemental Carbon

EDMS Emissions and Dispersion Modeling System

EGAS Economic Growth Analysis System

EGU Electric Generating Unit

EIA Energy Information Administration

EPA The United States Environmental Protection Agency

EQB Environmental Quality Board

FAA Federal Aviation Administration

FIP Federal Implementation Plan

FIRE Factor Information Retrieval 

FMVCP Federal Motor Vehicle Control Program

FR Federal Register

FRM Federal Reference Method

HAP Hazardous Air Pollutant

ICI Industrial, Commercial, Institutional

I/M Inspection and Maintenance

IPM Integrated Planning Model

IRRC Independent Regulatory Review Commission

LDGV Light Duty Gasoline Vehicles

LDGT Light Duty Gasoline Trucks

MACT Maximum Achievable Control Technology

MANE-VU Mid-Atlantic/Northeast Visibility Union

MARAMA Mid-Atlantic Regional Air Management Association

MATS Modeled Attainment Test Software

MM5 Mesoscale Model Version 5

MPO Metropolitan Planning Organization

MY Model Year

NAAQS National Ambient Air Quality Standard

NAICS North American Industry Classification System

NBP NOx Budget Program

NESCAUM Northeast States for Coordinated Air-Use Management

NH3 Ammonia
64

NH4

+ Ammonium

NLEV National Low Emission Vehicle (program)

NMIM National Mobile Inventory Model

NOx Oxides of Nitrogen

NO2 Nitrogen Dioxide

NO3

- Nitrates

NSR New Source Review

OC Organic Carbon

OM Organic Mass

OTAQ Office of Transportation and Air Quality

OTB On the Books

OTC Ozone Transport Commission

OTW On-the-Way

OTR Ozone Transport Region

PBW Particle Bound Water

PennDOT Pennsylvania Department of Transportation

PHL Philadelphia International Airport

PM Particulate Matter

PM2.5 Particulate Matter less than 2.5 microns in diameter or Fine Particulates 

PM10 Particulate Matter less than 10 microns in diameter

ppm parts per million

PSD Prevention of Significant Deterioration

PSU/NCAR Pennsylvania State University National Center for Atmospheric Research

RACM Reasonably Available Control Measure

RACT Reasonably Available Control Technology

RE Rule Effectiveness

RFP Reasonable Further Progress

RP Rule Penetration

RPO Regional Planning Organization 

RRF Relative Response Factor

RVP Reid Vapor Pressure

SANDWICH Sulfate, Adjusted Nitrate, Derived Water, Inferred Carbonaceous Material 

Balance Approach

SCC Source Classification Code

SCR Selective Catalytic Reduction

SIP State Implementation Plan

SMAT Speciated Modeled Attainment Test

SMOKE Sparse Matrix Operator Kernel Emissions 

SO2 Sulfur Dioxide

SO4

-

Sulfates

STN Speciation Trends Network

TCM Transportation Control Measures

TEOM Tampered Element Oscillating Microbalance Monitor

TSD Technical Support Document 

μg/m3 Microgram per cubic meter

μm Micrometer
65

VISTAS Visibility Improvement State and Tribal Association of the Southeast

VMT Vehicle Miles Traveled

VOC Volatile Organic Compound

WOE Weight of Evidence

ZEV Zero Emissions Vehicle