1

Pennsylvania

Area Designations for the 

2008 Ozone National Ambient Air Quality Standards

The table below identifies the areas and associated counties or parts of counties in Pennsylvania

that EPA intends to designate as nonattainment for the 2008 ozone national ambient air quality 

standards (2008 NAAQS). In accordance with section 107(d) of the Clean Air Act, EPA must 

designate an area “nonattainment” if it is violating the 2008 ozone NAAQS or if it is contributing 

to a violation of the 2008 ozone NAAQS in a nearby area. The technical analyses supporting the 

boundaries for the individual nonattainment areas are provided below.

Intended Nonattainment Areas in Pennsylvania

Area

Pennsylvania Recommended 

Nonattainment Counties

EPA’s Intended 

Nonattainment Counties

Allentown-BethlehemEaston Lehigh Carbon, Lehigh, Northampton

Lancaster Lancaster Lancaster

Philadelphia-WilmingtonAtlantic CityBucks, Montgomery, 

Philadelphia

Bucks, Chester, Delaware, 

Montgomery, Philadelphia

Pittsburgh-Beaver Valley Allegheny

Allegheny, Armstrong, 

Beaver, Butler, Fayette, 

Washington, Westmoreland

Reading Berks Berks

The Philadelphia-Wilmington-Atlantic City Area is a multi-state nonattainment area. Table 1 in 

the Technical Analysis for the Philadelphia-Wilmington-Atlantic City Area, below, identifies the 

counties in the other states that EPA intends to designate as part of the nonattainment area.

EPA intends to designate the remaining counties in Pennsylvania that are not listed in the table 

above as “unclassifiable/attainment” for the 2008 ozone NAAQS. 

The analysis below provides the basis for intended nonattainment area boundaries. It relies on 

our analysis of whether and which monitors are violating the 2008 ozone NAAQS, based on 

certified air quality monitoring data from 2008-2010 and an evaluation of whether nearby areas 

are contributing to such violations. EPA has evaluated contributions from nearby areas based on 

a weight of evidence analysis considering the factors identified below. EPA issued guidance on

December 4, 2008 that identified these factors as ones EPA would consider in determining 

nonattainment area boundaries and recommended that states consider these factors in making 

their designations recommendations to EPA.1 

1. Air quality data (including the design value calculated for each FRM or FEM monitor in 

the area);

 

1 The December 4, 2008 guidance memorandum “Area Designations for the 2008 Revised Ozone National Ambient 

Air Quality Standards” refers to 9 factors. In this technical support document we have grouped the emissionsrelated factors together under the heading of “Emissions and Emissions-Related Data,” which results in 5 categories 

of factors.
2

2. Emissions and emissions-related data (including location of sources and population, 

amount of emissions and emissions controls, and urban growth patterns);

3. Meteorology (weather/transport patterns);

4. Geography and topography (mountain ranges or other basin boundaries);

5. Jurisdictional boundaries (e.g., counties, air districts, existing nonattainment areas, Indian 

country, metropolitan planning organizations (MPOs))

Ground-level ozone is not emitted directly into the air, but is created by chemical reactions 

between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of 

sunlight. Because NOx and VOC emissions from a broad range of sources over a wide area 

typically contribute to violations of the ozone standards, EPA believes it is important to consider 

whether there are contributing emissions from a broad geographic area. Accordingly, EPA chose 

to examine the 5 factors with respect to the larger of the Combined Statistical Area (CSA) or 

Core Based Statistical Area (CBSA) within which is located the violating monitor(s).

2 All data 

and information used by EPA in this evaluation are the latest available to EPA and/or provided to 

EPA by states or tribes.

In EPA’s designations guidance for the 2008 ozone NAAQS3EPA recommended examining 

CSA/CBSAs because certain factors (such as population) used to establish CSAs and CBSAs are 

similar to the factors EPA is using in this technical analysis to determine if a nearby area is 

contributing to a violation of the 2008 ozone NAAQS. EPA used the same basic approach in the 

designation process for the 1997 ozone NAAQS. Where a violating monitor is not located in a 

CSA or CBSA, EPA’s guidance recommended using the boundary of the county containing the 

violating monitor as the starting point for considering the nonattainment area’s boundary.

 

2 Lists of CBSAs and CSAs and their geographic components are provided at 

www.census.gov/population/www/metroareas/metrodef.html . The lists are periodically updated by the Office of 

Management and Budget. EPA used the most recent update, based on 2008 population estimates, issued on 

December 1, 2009 (OMB Bulletin No. 10-02).
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Technical Analysis for the Allentown-Bethlehem-Easton Area

Figure 1 is a map of the Allentown-Bethlehem-Easton intended nonattainment area. The map 

provides other relevant information including the locations and design values of air quality 

monitors, county and other jurisdictional boundaries, census-defined metropolitan statistical area

boundary, existing maintenance area boundary for the 1997 ozone NAAQS, and EPA’s intended 

nonattainment boundary for the 2008 ozone NAAQS. 

Figure 1

For purposes of the 1997 ozone NAAQS, portions of this area were designated nonattainment. The 

boundary for the nonattainment area for the 1997 ozone NAAQS included the entire counties of 

Carbon, Lehigh, and Northampton Counties. Warren County, NJ, which is part of the censusdefined metropolitan statistical area was designated nonattainment for the 1997 ozone NAAQS as 

part of the separate New York-Northern New Jersey-Long Island, NY-NJ-CT nonattainment area.

In March 2009, the Commonwealth of Pennsylvania recommended that the same three counties in 

Pennsylvania be designated as nonattainment in the Allentown-Bethlehem-Easton Area for the 2008 

ozone NAAQS based on air quality data from 2006-2008. Pennsylvania provided an updated
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recommendation on November 22, 2011, based on more recent air quality data from 2009-2011. 

That recommendation was to designate only Lehigh County as nonattainment (as it has a violating 

monitor) and to designate nearby Carbon and Northampton Counties as attainment. The same 

county, Lehigh County, is violating based on the 2008-2010 and 2009-2011 monitoring data. This

data comes from FRM monitors or FEM monitors sited and operated in accordance with 40 CFR 

Part 58. (See the March 17, 2009 and November 22, 2011 letters from the Pennsylvania 

Department of Environmental Protection to EPA.) 

In April 2009, the State of New Jersey recommended the same nonattainment boundary for the 

twelve New Jersey counties (including Warren County) for the 2008 ozone NAAQS as was the case 

for the 1997 ozone NAAQS (i.e., that Warren County be part of the New York-Northern New 

Jersey-Long Island, NY-NJ-CT nonattainment area). These data are from FRM monitors or FEM 

monitors sited and operated in accordance with 40 CFR Part 58. (See the April 1, 2009 letter from 

the New Jersey Department of Environmental Protection to EPA.)

After considering these recommendations and based on EPA's technical analysis described below, 

EPA intends to designate three counties in Pennsylvania as “nonattainment” for the 2008 ozone 

NAAQS as part of the Allentown-Bethlehem-Easton nonattainment area. 

Table 1. States’ Recommended and EPA’s Intended Designated Nonattainment Counties for 

Allentown-Bethlehem-Easton.

Allentown-BethlehemEastonState-Recommended 

Nonattainment Counties

EPA Intended

Nonattainment Counties

Pennsylvania Lehigh Carbon, Lehigh, 

Northampton

New Jersey None None

Factor Assessment

EPA has determined that it is appropriate to place the nearby counties of Berks, Montgomery, and 

Bucks in Pennsylvania and Hunterdon and Morris in New Jersey, in separate nonattainment areas 

for the 2008 ozone NAAQS from the Allentown-Bethlehem-Easton Metropolitan Statistical Area. 

See EPA’s respective technical analyses for these adjacent nonattainment areas for EPA’s rationale 

for our intended nonattainment designation for these counties. To the extent that emissions from 

those counties may contribute to ozone concentrations in the Allentown-Bethlehem-Easton 

nonattainment area, that contribution will be lessened by emission controls put in place in those 

separate nonattainment areas. Therefore, EPA is not including Berks, Montgomery, and Bucks, 

Hunterdon and Morris in this analysis for the Allentown-Bethlehem-Easton nonattainment area.

Factor 1: Air Quality Data 

For this factor, we considered 8-hour ozone design values (in parts per billion (ppb)) for air quality 

monitors in counties in the Allentown-Bethlehem-Easton area based on data for the 2008-2010

period (i.e., the 2010 design value, or DV), which are the most recent years with fully-certified air 

quality data. A monitor’s DV is the metric or statistic that indicates whether that monitor attains a 

specified air quality standard. The 2008 ozone NAAQS are met when the annual fourth-highest 
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daily maximum 8-hour average concentration, averaged over 3 years is 0.075 ppm or less. A DV is 

only valid if minimum data completeness criteria are met. See 40 CFR part 50 Appendix P. Where 

several monitors are located in a county (or a designated nonattainment area or maintenance area), 

the DV for the county or area is determined by the monitor with the highest level.

The 2010 DVs for the ozone NAAQS for counties in the Allentown-Bethlehem-Easton and nearby 

surrounding area are shown in Table 2. We did not include neighboring counties to the south of the 

area, which have been recommended as intended nonattainment as part of separate areas from this 

area. 

Table 2. Air Quality Data.

County

State 

Recommended 

Nonattainment?

EPA 

Recommended 

Nonattainment?

2010 8-hour 

Ozone DV (ppb)

Preliminary 2011 

8-hour Ozone DV 

(ppb)

Carbon, PA No Yes -- --

Lehigh, PA Yes Yes 76 76

Northampton, PA No Yes 75 75

Warren, NJ Yes, other area Yes, other area -- --

Schuylkill, PA No No -- --

Luzerne, PA No No 69 65

Lackawanna, PA No No 72 71

Monroe, PA No No 70 70

 Note: Counties with no ozone monitor are identified with “--“ in the 2010 and 2011 8-hour Ozone DV columns.

In accordance with section 107(d) of the Clean Air Act, EPA must designate an area 

“nonattainment” if it is violating the 2008 ozone NAAQS. Lehigh County shows a violation of the 

2008 ozone NAAQS, therefore this county must be included in a nonattainment area. A county (or 

partial county) must also be designated nonattainment if it contributes to a violation in a nearby 

area. Each county without a violating monitor that is located near a county with a violating monitor 

has been evaluated based on the weight of evidence of the five factors and other relevant 

information to determine whether it contributes to the nearby violation. 

Factor 2: Emissions and Emissions-Related Data

EPA evaluated emissions of ozone precursors (NOx and VOC) and other emissions-related data that 

provide information on areas contributing to violating monitors.

Emissions Data

EPA evaluated county-level emission data for NOx and VOC derived from the 2008 National 

Emissions Inventory (NEI), version 1.5. This is the most recently available NEI. (See 

http://www.epa.gov/ttn/chief/net/2008inventory.html) Significant emissions levels in a nearby area 

indicate the potential for the area to contribute to monitored violations. We will also consider any 

additional information we receive on changes to emissions levels that are not reflected in recent 

inventories. These changes include emissions reductions due to permanent and enforceable 

emissions controls that will be in place before final designations are issued and emissions increases 

due to new sources.
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Table 3 shows emissions of NOx and VOC (given in tons per year) for violating and potentially 

contributing counties in the Allentown-Bethlehem-Easton area. 

Table 3. Total 2008 NOx and VOC Emissions.

County

State 

Recommended

Nonattainment?

EPA Recommended 

Nonattainment? NOx (tpy) VOC (tpy)

Carbon, PA No Yes 3,302 3,452 

Lehigh, PA Yes Yes 11,160 12,147 

Northampton, PA No Yes 17,082 8,499 

Warren, NJ Yes, other area Yes, other area 4,483 3,925 

Schuylkill, PA No No 6,554 5,922

Luzerne, PA No No 12,045 13,183

Lackawanna, PA No No 7,118 7,233

Monroe, PA No No 5,761 8,017

Of the counties in the Allentown-Bethlehem-Easton Metropolitan Statistical Area, Northampton has 

the highest total NOx emissions, and Lehigh has the highest total VOC emissions. Lehigh also has 

high NOx emissions, and Northampton has relatively high VOC emissions. Carbon County and 

Warren County, by comparison, have much lower NOX and VOC emissions. Of the nearby 

counties outside this metropolitan statistical area, Luzerne has the highest NOx and VOC emissions. 

Monroe, Lackawanna, and Schuylkill have lower emissions by comparison, than Lehigh and 

Northampton, however, they are similar to Carbon County.

Population density and degree of urbanization

EPA evaluated the population and vehicle use characteristics and trends of the area as indicators of 

the probable location and magnitude of non-point source emissions. These include ozone-creating 

emissions from on-road and off-road vehicles and engines, consumer products, residential fuel 

combustion, and consumer services. Areas of dense population or commercial development are an 

indicator of area source and mobile source NOx and VOC emissions that may contribute to ozone 

formation. Rapid population or VMT growth (see below) in a county on the urban perimeter 

signifies increasing integration with the core urban area, and indicates that the associated area

source and mobile source emissions may be appropriate to include in the nonattainment area. Table 

4 shows the population, population density, and population growth information for each county in 

the area.

Of the counties that are part of the Allentown-Bethlehem-Easton Metropolitan Statistical Area, 

Lehigh and Northampton have the highest populations, with Carbon having the lowest population 

and population density (followed closely by Warren County). Lehigh is also the fastest growing 

county and has the largest population change. Carbon, Lehigh, and Northampton all experienced 

double digit population growth in the prior decade, but by comparison, are fairly sparsely populated. 

Of the counties nearby to, but outside of this, metropolitan statistical area, Luzerne has the highest 

population, very nearly as large as Lehigh, distantly followed by Lackawanna County. 
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Table 4. Population and Growth

County

State Recommended 

Nonattainment?

EPA 

Recommended 

Nonattainment?

2010 

Population

2010 

Population 

Density 

(1000 

pop/sq mi)

Absolute 

change in 

population 

(2000-2010)

Population 

% change 

(2000-2010)

Carbon, PA No Yes 65,249 0.17 6,417 +11%

Lehigh, PA Yes Yes 349,497 1.00 36,843 +12%

Northampton, PA No Yes 297,735 0.79 30,295 +11%

Warren, NJ Yes, other area No 108,692 0.30 5,745 +6%

Schuylkill, PA No No 148,289 0.19 -1,798 -1.2%

Luzerne, PA No No 320,918 0.35 2,363 +0.7%

Lackawanna, PA No No 214,437 0.46 1,524 +0.7%

Monroe, PA No No 169,842 0.28 30,077 +22%

Sources: U.S. Census Bureau population estimates for 2010 as of August 4, 2011 

(http://factfinder2.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=DEC_10_PL_GCTPL2.STO5&prod

Type=table) 

Figure 2. Population Distribution of Allentown-Bethlehem-Easton.

Source: US Census (http://2010.census.gov/2010census/popmap/)

The counties neighboring the Allentown-Bethlehem-Easton Metropolitan Statistical Area, have 

comparatively low population growth, with the exception of Monroe County. Monroe County has a 

population that is more than four times larger than Carbon County, with a population growth rate 
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twice that of Carbon County. These adjacent counties are comparatively sparsely populated, with 

population densities ranging from a high of 460 to a low of 190 persons per square mile. Figure 2 

illustrates how the population centers of this area are clustered primarily in the urban centers, with 

very sparse populations in the surrounding communities.

Traffic and VMT data 

EPA evaluated the total Vehicle Miles Traveled (VMT) and the commuting patterns of residents for 

each county in the area of analysis. In combination with the population/population density data and 

the location of main transportation arteries (see Figure 1 above), this information helps identify the 

probable location of non-point source emissions. A county with high VMT and/or a high number of 

commuters is generally an integral part of an urban area and indicates the presence of motor vehicle 

emissions that may contribute to ozone formation. Rapid population or VMT growth in a county on 

the urban perimeter signifies increasing integration with the core urban area, and indicates that the 

associated area source and mobile source emissions may be appropriate to include in the 

nonattainment area. Table 5 shows traffic and commuting pattern data, including total 2008 VMT 

and 10-year VMT growth. Table 6 shows the number of commuters in each county who travel 

within that county or to another county in the area of analysis. 

Table 5. Traffic and VMT Data.

County

State 

Recommended 

Nonattainment?

EPA Recommended 

Nonattainment?

2008 VMT 

(million miles)

Percent VMT 

Growth 

(2002-2008)

Carbon, PA No Yes 740 0.8%

Lehigh, PA Yes Yes 2,893 2.9%

Northampton, PA No Yes 1,997 0.7%

Warren, NJ No No 1,530 1.1%

Luzerne, PA No No 2,963 4.2%

Lackawanna, PA No No 1,994 5.9%

Monroe, PA No No 1,621 2.5%

Schuylkill, PA No No 1,394 -3.4%

* MOBILE model VMTs are those inputs into the NEI version 1.5. 

Table 6. County to County Worker Flow

Residence County Carbon, 

PA

Lehigh, PA Northampton, 

PA

Warren, 

NJ

Monroe, 

PA

Lackawanna, 

PA

Luzerne, 

PA

Schuylkill, 

PA

Workplace County 

Carbon, PA 12,341 550 390 8 614 38 634 1,014

Lehigh, PA 4,663 110,302 30,180 602 1618 193 678 1,742

Northampton, PA 1,975 18,040 68,449 1,803 3,467 46 142 258

Warren, NJ 88 682 7,192 21,034 1,359 4 7 15

Monroe, PA 1,185 410 2,137 200 39,829 2,536 1,664 98

Lackawanna, PA 100 80 92 0 579 79,507 8,105 72

Luzerne, PA 2,224 207 97 12 639 6,847 120,645 3,588

Schuylkill, PA 1,435 268 61 0 31 76 1,179 43,979

Source: U.S. Census Bureau estimates for 2000 County-to-County Worker Flow 

(http://www.census.gov/hhes/commuting/data/commuting.html)
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Of the counties in the Allentown-Bethlehem-Easton Metropolitan Statistical Area, Lehigh County 

has the highest overall VMT, and the highest proportion commuting to violating counties, with most 

of that commuting occurring within Lehigh County (see Table 6). Northampton County has 

significant VMT, with a sizable portion commuting to Lehigh County (the location of the violating 

monitor). Warren County has lower overall VMT, and comparatively lower commuting 

contribution to Lehigh County (or any of the nearby counties). Carbon County has extremely low 

VMT and commuting levels to a violating county. Of the counties in the area of analysis, Luzerne 

and Lackawanna have comparatively high overall VMT, and Lackawanna has the highest recent 

VMT growth. Table 6 illustrates how little commuting contribution these (or any of the 

neighboring counties) contribute to the Allentown-Bethlehem-Easton area. 

Factor 3: Meteorology (weather/transport patterns)

EPA evaluated any available meteorological data to help determine how meteorological conditions, 

such as weather, transport patterns and stagnation conditions, would affect the fate and transport of 

precursor emissions contributing to ozone formation. 

The prevailing winds during the summer ozone season for Lehigh County come predominately from 

the southwest, and to a lesser degree the west and south direction. The violating monitor for this 

area is located near the center of Lehigh County, close to the eastern edge of the county. On this 

basis, the neighboring Scranton-Wilkes-Barre area to the northeast is less likely to contribute to a 

violation of the Lehigh County monitor, particularly in light of the topography separation between 

the areas (i.e., the Blue Mountain Ridge). Based solely on historical prevailing winds, the violating 

monitor in Lehigh County is unlikely to be impacted by downwind contribution from Monroe 

County and Warren County. However, the prevailing historical wind data analyzed is not specific 

to the violating monitor or the meteorological episodes when the ozone exceedances actually 

occurred.

Figure 3. Prevailing Wind Direction for Lehigh County.
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Factor 4: Geography/topography (mountain ranges or other air basin boundaries)

The geography/topography analysis evaluates the physical features of the land that might affect the 

airshed and, therefore, the distribution of ozone over the area.

The Allentown-Bethlehem-Easton area does have several geographical and topographical barriers 

that impact air pollution generation and transport within its air shed. The region is bounded on the 

north by Pocono Mountains, and in particular by the Blue Mountain Ridge that runs west-southwest 

to north-northeast, creating a significant physical barrier to air movement from north to south and 

south to north. The Lehigh River crosses the area, with a broad valley that runs from east to west 

connecting both Lehigh and Northampton Counties. The Delaware River divides Northampton and 

Warren Counties. Elevation changes run from lows of just over 100 feet above sea level to nearly 

1600 feet on the Blue Ridge Mountain Ridge, with the elevation at the Lehigh Valley Airport near 

Allentown falling at approximately 300 feet. The area lies approximately 80 miles west of the 

Atlantic Ocean. Warren County is mountainous, with the Kittatinny Ridge bounding the county on 

the west. Warren County is also part of the Lehigh Valley on its southern edge, and the Kittatinny 

Valley in the northern part of the county.

Figure 4. Allentown-Bethlehem-Easton Topography (Northampton and Lehigh Counties).

Source: Lehigh Valley Planning Commission
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Factor 5: Jurisdictional boundaries

Once the general areas to be included in the nonattainment area were determined, EPA considered

existing jurisdictional boundaries for the purposes of providing a clearly defined legal boundary and 

carrying out the air quality planning and enforcement functions for nonattainment areas. Examples 

of jurisdictional boundaries include existing/prior nonattainment areas for ozone or other urbanscale pollutants, counties, air districts, townships, metropolitan planning organizations, state lines, 

Reservations, urban growth boundary, etc. Where existing jurisdictional boundaries are not 

adequate to describe the nonattainment area, other clearly defined and permanent landmarks or 

geographic coordinates are considered.

The Allentown-Bethlehem-Easton area has previously established nonattainment boundaries 

associated with the 1997 ozone NAAQS, with Carbon, Lehigh, and Northampton Counties forming 

the Allentown-Bethlehem-Easton nonattainment area. The Commonwealth initially recommended 

the same nonattainment area boundary for the 2008 ozone NAAQS in March 2009, but 

subsequently recommended that only Lehigh County be nonattainment in a November 2011 revised 

recommendation to EPA. Warren County, New Jersey was part of the separate New York-Northern 

New Jersey-Long Island, NY-NJ-CT nonattainment area under the 1997 ozone NAAQS, and New 

Jersey has recommended the same nonattainment boundary for the 2008 ozone NAAQS.

The counties comprising the Allentown-Bethlehem-Easton area historically have strong planning 

and economic ties. Maintaining the 1997 ozone NAAQS boundary promotes continuity of 

planning. Lehigh and Northampton counties comprise the metropolitan transportation planning 

organization, while Carbon County is part of a five-county rural planning organization. However,

the Pennsylvania Department of Transportation supports Carbon County with respect to air qualityrelated technical work, and Pennsylvania concedes that past inclusion of Carbon County in the 

nonattainment area has not proven problematic from a jurisdictional perspective. 

Warren County, NJ is part of the Allentown-Bethlehem-Easton census-defined metropolitan 

statistical area, but is covered by a separate transportation planning organization, and has 

historically been part of a separate nonattainment area for ozone, as well as for particulate matter 

NAAQS. New Jersey has recommended it for inclusion under the 2008 NAAQS as part of the 

nearby New York-Northern New Jersey-Long Island, NY-NJ-CT area, which has a higher overall 

design value than it would if included in the Allentown-Bethlehem-Easton nonattainment area.

Luzerne and Lackawanna Counties have are part of the Scranton-Wilkes-Barre, PA Metropolitan 

Statistical Area, and have social and economic times associated with that area. They also have a 

separate transportation planning agency from the Allentown-Bethlehem-Easton area. Scranton was 

nonattainment under the 1997 ozone NAAQS, but the area is currently monitoring attainment of the 

2008 ozone NAAQS. The topography of the region separates Allentown-Bethlehem-Easton from 

this and other nearby areas to the west and north of the area. 

Monroe County is part of the East Stroudsburg Micropolitan Statistical Area. Schuylkill County is 

part of the one-county Pottsville Micropolitan Statistical Area. Neither of these two counties has 

strong economic or social ties to the Allentown-Bethlehem-Easton area.

The Allentown-Bethlehem-Easton Air Basin defined in 25 Pa. Code §121.1 covers portions of 

Lehigh and Northampton Counties (see Figure 5). These basins were developed for purposes of the 
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sulfur compound controls outlined in 25 Pa. Code § 123.22, yet they represent existing local 

boundaries for emission controls in the areas of the Commonwealth where they exist. 

Figure 5. Pennsylvania Air Basins.

Conclusion

Based on the assessment of factors described above, EPA has preliminarily concluded that the 

following counties meet the CAA criteria for inclusion in the Allentown-Bethlehem-Easton 

nonattainment area: Carbon, Lehigh, and Northampton. These are the same counties that are 

included in the Allentown-Bethlehem-Easton nonattainment area for the 1997 ozone NAAQS. 

The air quality monitor in Lehigh County indicates a violation of the 2008 ozone NAAQS based on 

the 2010 DV, therefore this county is included in the nonattainment area. Carbon and Northampton 

are nearby counties that do not have violating monitors, but EPA has concluded that these areas 

contribute to the ozone concentrations in violation of the 2008 ozone NAAQS through ozone 

precursor emissions. Northampton and Lehigh Counties have among the highest NOx and VOC 

emissions in the area. Lehigh and Northampton Counties contain the cities of Allentown, 

Bethlehem, and Easton, where the highest population concentrations in the area are located. 
13

Vehicle miles of travel are highest in Lehigh and Northampton Counties, and Lehigh County also 

has the highest percentage of commuters travelling to a county with a violating monitor. Prevailing 

winds and topography support exclusion of the Scranton-Wilkes-Barre area counties of Luzerne and 

Lackawanna, as well as the downwind counties of Monroe and Warren. 

In 2009, Pennsylvania recommended that the Allentown-Bethlehem-Easton nonattainment area 

maintain the same boundaries as were in place for the 1997 ozone NAAQS. In November 2011, 

Pennsylvania revised its recommendation to shrink the area to only Lehigh County (the location of 

the violating monitor), setting aside past jurisdictional factors for inclusion of Carbon and 

Northampton counties as part of the nonattainment area. EPA’s believes this jurisdictional 

argument is a prominent reason for recommending the same intended nonattainment area boundary 

for the 2008 ozone NAAQS. New Jersey recommends inclusion of Warren County in the New 

York-Northern New Jersey-Long Island nonattainment area, as it was under the 1997 ozone 

NAAQS, rather than including Warren County in the Allentown-Bethlehem-Easton area. Although 

Warren County lies in the Allentown-Bethlehem-Easton CSA, there are strong jurisdictional 

arguments for maintaining the nonattainment boundaries of the 1997 ozone standard for the 2008 

ozone standard. EPA there recommends that Warren County not be part of the AllentownBethlehem-Easton nonattainment area.

The adjacent counties to the Allentown-Bethlehem-Easton area eastern and southern boundary are 

being recommended by EPA (and the states) as part of separate nonattainment areas with equal or 

higher classification as EPA recommends for this area. Finally, past ozone NAAQS boundaries and 

jurisdictional ties support keeping the prior nonattainment boundaries for Allentown-BethlehemEaston, to include Carbon, Lehigh, and Northampton Counties. 
14

Technical Analysis for the Lancaster Area

Figure 1 is a map of the Lancaster intended nonattainment area. The map provides other relevant 

information including the locations and design values of air quality monitors, county and other 

jurisdictional boundaries, metropolitan statistical area boundary, existing maintenance area boundary for 

the 1997 ozone NAAQS, and EPA’s intended nonattainment area boundary for the 2008 ozone NAAQS. 

Figure 1

For purposes of the 1997 8-hour ozone NAAQS, this area was designated nonattainment. The boundary 

for the nonattainment area for the 1997 ozone NAAQS included the entire county of Lancaster.

In March 2009, the Commonwealth of Pennsylvania recommended that Lancaster County be designated 

as nonattainment as the Lancaster Area for the 2008 ozone NAAQS based on air quality data from 2006-

2008, keeping the same boundaries as the 1997 ozone NAAQS nonattainment area. Pennsylvania 

provided an update to the original recommendation in November 2011 based on air quality data from 

2009-2011. Based on this updated information, the Commonwealth once more recommended that 

Lancaster County be designated nonattainment under the 2008 ozone NAAQS. The 2008-2010 and 

preliminary 2009-2011 monitoring data both show that the same county (Lancaster) is violating the 2008 

ozone NAAQS. The recommendations are based on monitoring data from FRM monitors or FEM 

monitors sited and operated in accordance with 40 CFR Part 58. (See the March 17, 2009 and 

November 22, 2011 letters from the Pennsylvania Department of Environmental Protection to EPA.) 
15

After considering these recommendations and based on EPA's technical analysis described below, EPA 

intends to designate Lancaster County, Pennsylvania (identified in Table 1 below) as “nonattainment”

for the 2008 ozone NAAQS as a single-county nonattainment area. 

Table 1. State's Recommended and EPA’s Intended Designated Nonattainment Counties for Lancaster.

Lancaster State-Recommended 

Nonattainment Counties

EPA Intended

Nonattainment Counties

Pennsylvania Lancaster Lancaster

Factor Assessment

EPA intends to include the nearby counties of Berks, Chester, Cecil, and Harford as part of separate 

nonattainment areas for the 2008 ozone NAAQS from Lancaster County. Based on EPA's five-factor 

analyses, EPA has preliminarily concluded that Berks County should be designated nonattainment as the 

Reading Area, Chester, and Cecil Counties should be designated nonattainment in the PhiladelphiaWilmington-Atlantic City Area, and Harford County should be designated nonattainment as part of the 

Baltimore Area. See EPA’s respective technical analyses for these adjacent nonattainment areas for 

EPA’s rationale for our intended nonattainment designation for these counties. To the extent that 

emissions from those counties may contribute ozone concentrations in the Lancaster nonattainment area, 

that contribution will be lessened by emission controls put in place in those separate nonattainment 

areas. Therefore, EPA is not including Berks, Chester, Cecil, and Harford Counties in this analysis for 

the Lancaster nonattainment area.

Factor 1: Air Quality Data 

For this factor, we considered 8-hour ozone design values (in parts per billion (ppb)) for air quality 

monitors in counties in the Lancaster area based on data for the 2008-2010 period (i.e., the 2010 design 

value, or DV), which are the most recent years with fully-certified air quality data. A monitor’s DV is 

the metric or statistic that indicates whether that monitor attains a specified air quality standard. The 

2008 ozone NAAQS are met when the annual fourth-highest daily maximum 8-hour average 

concentration, averaged over 3 years is 0.075 ppm or less. A DV is only valid if minimum data 

completeness criteria are met. See 40 CFR part 50 Appendix P. Where several monitors are located in a 

county (or a designated nonattainment area or maintenance area), the DV for the county or area is 

determined by the monitor with the highest level.

The 2010 DVs and preliminary 2011 DVs for the ozone NAAQS for counties in the Lancaster area and 

certain nearby surrounding counties are shown in Table 2.

Table 2. Air Quality Data.

County

State 

Recommended 

Nonattainment?

EPA 

Recommended 

Nonattainment?

2008-2010

Design Value 

(ppb)

2009-2011 

Preliminary 

Design Value 

(ppb)

Lancaster, PA Yes Yes 77 77

York, PA No No 74 72

Lebanon, PA No No -- --

Dauphin, PA No No 73 73

Note: Counties with no ozone monitor are identified with “--“ in the 2010 and 2011 8-hour Ozone DV columns.
16

In accordance with section 107(d) of the Clean Air Act, EPA must designate an area “nonattainment” if 

it is violating the 2008 ozone NAAQS. Lancaster County shows a violation of the 2008 ozone NAAQS, 

therefore this county must be included in a nonattainment area. A county (or partial county) must also 

be designated nonattainment if it contributes to a violation in a nearby area. Each county without a 

violating monitor that is located near a county with a violating monitor has been evaluated based on the 

weight of evidence of the five factors to determine whether it contributes to the nearby violation. 

Factor 2: Emissions and Emissions-Related Data

EPA evaluated emissions of ozone precursors (NOx and VOC) and other emissions-related data that 

provide information on areas contributing to violating monitors.

Emissions Data

EPA evaluated county-level emission data for NOx and VOC derived from the 2008 National Emissions 

Inventory (NEI), version 1.5. This is the most recently available NEI. (See 

http://www.epa.gov/ttn/chief/net/2008inventory.html) Significant emissions levels in a nearby area 

indicate the potential for the area to contribute to observed violations. We will also consider any 

additional information we receive on changes to emissions levels that are not reflected in recent 

inventories. These changes include emissions reductions due to permanent and enforceable emissions 

controls that will be in place before final designations are issued and emissions increases due to new 

sources.

Table 3 shows emissions of NOx and VOC (given in tons per year) for violating and nearby potentially 

contributing counties in the Lancaster area. 

Table 3. Total 2008 NOx and VOC Emissions.

County State Recommended

Nonattainment?

EPA Recommended 

Nonattainment? NOx (tpy) VOC (tpy)

Lancaster, PA Yes Yes 18,217 22,877

York, PA No No 35,616 15,723

Lebanon, PA No No 6,166 5,367

Dauphin, PA No No 10,848 11,760

York County has much higher NOx emissions than the other nearby counties, having nearly as much 

total NOx emissions as all the other counties listed in Table 3. Lancaster has the highest VOC 

emissions, followed closely by York. Lebanon and Dauphin have comparatively lower emissions of 

both NOx and VOCs. 

Population density and degree of urbanization

EPA evaluated the population and vehicle use characteristics and trends of the area as indicators of the

probable location and magnitude of non-point source emissions. These include ozone-creating 

emissions from on-road and off-road vehicles and engines, consumer products, residential fuel 

combustion, and consumer services. Areas of dense population or commercial development are an 

indicator of area source and mobile source NOx and VOC emissions that may contribute to ozone 
17

formation. Table 4 shows the population, population density, and population growth information for 

each county in the area.

Table 4. Population and Growth.

County State 

Recommended 

Nonattainment?

EPA 

Recommended 

Nonattainment?

2010

Population

2010 Population 

Density

(1000 pop/sq mi)

Absolute 

change in 

population

(2000-2010)

Population 

% change

(2000-

2010)

Lancaster, PA Yes Yes 519,445 0.53 47,669 +10% 

York, PA No No 434,972 0.48 52,263 +14%

Lebanon, PA No No 133,568 0.37 13,151 +11%

Dauphin, PA No No 268,100 0.48 16,303 +6%

Sources: U.S. Census Bureau population estimates for 2010 as of August 4, 2011 

(http://factfinder2.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=DEC_10_PL_GCTPL2.STO5&prodType

=table)

Figure 2. Population Distribution for Lancaster, York, Harrisburg, and Reading

Source: US Census Bureau (http://2010.census.gov/2010census/popmap/)

Lancaster County has the highest population of any of the counties in the Lancaster and surrounding 

areas, followed by York County. Dauphin and Lebanon have much lower populations. All of these 

counties have similar population densities, ranging from 370 to 530 persons per square mile, however, 

these populations of the cities and towns are distributed unevenly between small, dense urban cores and 

outlying towns and rural areas. As can be seen in the Census map in Figure 2, the Cities of Lancaster, 
18

York (and to a lesser extent Reading and Harrisburg) all have small dense urban centers surrounded by 

sparsely populated areas with smaller towns interspersed. 

Nearly all of the counties in Table 4 have experienced double digit growth between 2000 and 2010, but 

the overall population growth numbers for all four counties total just over a hundred thousand persons

over the past decade. 

Traffic and commuting patterns

EPA evaluated the total Vehicle Miles Traveled (VMT) in the area and VMT growth, as well as 

commuter movement within and between counties. This information, in combination with the 

population/population density data and the location of main transportation arteries (see Figure 1, above), 

helps in identifying the probable location of non-point source emissions. A county with high VMT 

and/or a high number of commuters is generally an integral part of an urban area and indicates the 

presence of motor vehicle emissions that may contribute to ozone formation. Rapid population or VMT 

growth in a county on the urban perimeter signifies increasing integration with the core urban area, and 

indicates that the associated area source and mobile source emissions may be appropriate to include in 

the nonattainment area. Table 5 shows traffic and commuting pattern data, including total 2005 VMT, 

growth in VMT for the period between 2002-2008, and the total vehicle miles traveled (VMT) for each 

county. Table 6 shows the number of commuters traveling within and between the counties in the area 

of analysis.

Table 5. Traffic and VMT data.

County

State 

Recommended 

Nonattainment?

EPA 

Recommended 

Nonattainment?

2008 VMT*

(million miles)

Percent VMT Growth 

2002-2008

Lancaster, PA Yes Yes 4,245 9.0%

York, PA No No 3,275 6.1%

Lebanon, PA No No 1,210 4.5%

Dauphin, PA No No 3,062 2.0%

* MOBILE model VMTs are those inputs into the NEI version 1.5. 

Table 6. County to County Worker Flow.

Residence County Lancaster, PA York, PA Lebanon, PA Dauphin, PA

Workplace County 

Lancaster, PA 201,608 5,485 3,770 2,585

York, PA 4,018 142,104 266 2,365

Lebanon, PA 1,952 332 36,677 2,508

Dauphin, PA 6,927 9,848 12,853 93,958

Source: U.S. Census Bureau estimates for 2000 County-to-County Worker Flow 

(http://www.census.gov/hhes/commuting/data/commuting.html

Lancaster County has the highest overall VMT and historical growth in VMT of the counties in the area 

of analysis, followed by York and Dauphin Counties. Table 6 shows the county to county commuter 

worker flow. Lancaster has the highest number of commuters, most of whom travel within Lancaster 

County, which has the only violating monitor in the area of analysis. Similarly, York County 

commuters travel predominantly inside York County, with only 10% travelling to any county with a 
19

violating monitor. Dauphin and Lebanon Counties also contribute very few commuters to Lancaster 

County, with most commuting inside their home county. 

Factor 3: Meteorology (weather/transport patterns)

EPA evaluated any available meteorological data to help determine how meteorological conditions, such 

as weather, transport patterns and stagnation conditions, would affect the fate and transport of precursor 

emissions contributing to ozone formation. 

Figure 3. Prevailing Summertime Wind Direction for Lancaster.

The prevailing winds during the ozone season predominate from the west-northwest, indicating that 

emissions from the Harrisburg-Lebanon-Carlisle metropolitan area counties of Lebanon and Dauphin 

may have an impact on the Lancaster violating monitor. To a lesser extent, York County emissions may 

also contribute to the violating monitor, dependent upon the wind direction during an ozone episode. 

The emissions impact from Berks, Chester, Cecil, and even Harford Counties appear to be lower, on the 

basis of prevalent wind direction alone, than the counties to the west of Lancaster. Note that the 

counties of Chester, Berks, and Harford, MD are downwind (based on prevalent wind direction) of 

Lancaster and have higher 2010 DVs than the monitors in York, Cumberland, and Dauphin Counties, 
20

which are are upwind of Lancaster. Wind data alone is inconclusive, but it is possible the upwind 

counties are contributing emissions affecting Lancaster, and also that pollution is transported as it moves 

downwind along the MSAs in the Northeast Corridor. There may be local as well as long range impacts, 

but further meteorological modeling or source apportionment would be necessary to prove the impact

between these nearby areas. 

Factor 4: Geography/topography (mountain ranges or other air basin boundaries)

The geography/topography analysis evaluates the physical features of the land that might affect the 

airshed and, therefore, the distribution of ozone over the area.

Figure 4. Topographic Map of Lancaster.

Source: US Geologic Society (www.usgs.gov)
21

The Lancaster area does not have any geographical or topographical barriers significantly limiting air

pollution transport within its air shed. Therefore, this factor did not play a significant role in this 

evaluation.

Factor 5: Jurisdictional boundaries

Once the general areas to be included in the nonattainment area were determined, EPA considered

existing jurisdictional boundaries for the purposes of providing a clearly defined legal boundary and 

carrying out the air quality planning and enforcement functions for nonattainment areas. Examples of 

jurisdictional boundaries include existing/prior nonattainment areas for ozone or other urban-scale 

pollutants, counties, air districts, townships, metropolitan planning organizations, state lines, 

Reservations, urban growth boundary, etc. Where existing jurisdictional boundaries are not adequate to 

describe the nonattainment area, other clearly defined and permanent landmarks or geographic 

coordinates are used.

The single-county Lancaster MSA area has previously established nonattainment boundaries associated 

with the 1997 8-hour ozone NAAQS. 

The Commonwealth has recommended the same boundary for the 2008 ozone NAAQS, with Lancaster 

County to be designated nonattainment as a single-county area for the 2008 ozone NAAQS. Lancaster 

County is a single-county metropolitan statistical area based on economic, political and commuting 

patterns. This area is served by a single-county transportation-planning agency. 

Figure 5. Pennsylvania Air Basins
22

The Lancaster Air Basin defined in 25 Pa. Code §121.1 covers portions of Lancaster County (see Figure 

5). These basins were developed for purposes of the sulfur compound controls outlined in 25 Pa. Code 

§ 123.22, yet they represent existing local boundaries for emission controls in the areas of the 

Commonwealth where they exist. 

Conclusion

Based on the assessment of factors described above, EPA has preliminarily concluded that the following 

counties meet the CAA criteria for inclusion in the Lancaster nonattainment area: Lancaster.

This is the same county that is included in the Lancaster nonattainment area for the 1997 ozone 

NAAQS. The air quality monitor in Lancaster County indicates violations of the 2008 ozone NAAQS 

based on the 2010 DVs, therefore this county must be included in the nonattainment area. 

Chester, Harford, Cecil, and Berks are nearby counties that have violating monitors, but are part of 

nearby CSAs and are being recommended for nonattainment as part of separate areas. York, 

Cumberland, Dauphin, and Lebanon Counties do not have violating monitors, but EPA has concluded 

that these areas do not contribute to the ozone concentrations in violation of the 2008 ozone NAAQS of 

Lancaster County enough to warrant their inclusion in the Lancaster nonattainment area. 

York County has the highest NOx emissions of the counties evaluated and has the second highest VOC 

emissions. York County has the second highest population and the largest population growth over the 

past decade. York County has the second highest VMT, but most York County commuters remain 

within York County and do not travel to Lancaster County (where the violating monitor is located). 

Meteorology indicates that emissions from York County may contribute little to violations of the ozone 

standard as prevalent wind patterns come predominantly from the west and northwest, and York County 

is to the west/southwest of Lancaster County and its violating monitor. Meteorology indicates that 

Lebanon and Dauphin may contribute to violations in Lancaster, because prevalent wind patterns come 

from the west and northwest, and those counties lie in that direction. However, the magnitude of NOx 

and VOCs from those counties is comparatively smaller than Lancaster or York Counties. 

Lancaster has the highest VMT of all the counties being compared here (followed by York), and has by 

far the highest number of commuters, most of whom commute within Lancaster County, where the 

violating monitor is located. 

There are strong jurisdictional arguments for making Lancaster a single county nonattainment area. 

The county has is a single-county metropolitan statistical area based on economic, political and 

commuting patterns. Lancaster County was a single county nonattainment area under the 1997 ozone 

NAAQS, and the prior 1-hour ozone NAAQS. The area is served by a single-county transportationplanning agency, and has a unique political and cultural identity of its own. 

The Commonwealth has recommended the same single-county boundary for the 2008 ozone NAAQS, 

with Lancaster County to be designated nonattainment for the 2008 ozone NAAQS. This area is served 

by a single-county transportation-planning agency. Designating it as a single-county nonattainment area 

maintains continuity of planning since the county has an approved maintenance plan for the 1997 ozone 

NAAQS.
23

Technical Analysis for the Philadelphia-Wilmington-Atlantic City Area

Figure 1 is a map of the Philadelphia-Wilmington-Atlantic City intended nonattainment area (the 

Philadelphia Area). The map provides other relevant information including the locations and design 

values of air quality monitors, county and other jurisdictional boundaries. The map shows the 

boundaries of the Philadelphia-Camden-Vineland CSA, the existing nonattainment area boundary for the 

1997 ozone NAAQS, and EPA’s intended nonattainment boundary for the 2008 ozone NAAQS.

Figure 1.

For purposes of the 1997 8-hour ozone NAAQS, this area was designated nonattainment. The 

Philadelphia-Wilmington-Atlantic City nonattainment area included the entire counties of Kent, New 

Castle, and Sussex in Delaware; Cecil in Maryland; Atlantic, Burlington, Camden, Cape May,

Cumberland, Gloucester, Mercer, Ocean, and Salem in New Jersey; and Bucks, Chester, Delaware, 

Montgomery, and Philadelphia in Pennsylvania.

In March 2009, the State of Delaware recommended that no counties in Delaware be included in the 

Philadelphia Area for the 2008 ozone NAAQS based on air quality data from 2006-2008. Instead, 

Delaware recommend a large, multi-state nonattainment area, covering the entire States of Delaware, 

Maryland, Michigan, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Virginia, and West 

Virginia, and the District of Columbia. Alternatively, Delaware recommended that the entire State of 

Delaware be designated as a stand-alone nonattainment area. In October 2011, Delaware updated its 

recommendations. In that letter, Delaware expanded its recommended large multi-state nonattainment 
24

area to include the States of Kentucky, Indiana, Illinois, Missouri, Tennessee, and Wisconsin. In 

addition, in its October 2011 letter, the State of Delaware specified that if EPA did not accept either of its 

designation options, then Kent County should not be designated nonattainment. This recommendation is 

based on 2008-2010 data and preliminary 2009-2011 data. The recommendations were based on data from

Federal Reference Method (FRM) monitors or Federal Equivalent Method (FEM) monitors sited and 

operated in accordance with 40 CFR Part 58. (See the March 18, 2009 letter from Governor Jack A. 

Markell to EPA, received on April 3, 2009; and the October 28, 2011 letter from the Delaware

Department of Natural Resources and Environmental Control.)

In March 2009, the State of Maryland recommended that Cecil County be designated as nonattainment 

as part of the Philadelphia Area for the 2008 ozone NAAQS based on air quality data from 2006-2008. 

This is the same Maryland County that was included in the Philadelphia-Wilmington-Atlantic City

nonattainment area for the 1997 ozone NAAQS. This recommendation was based on data from FRM 

monitors or FEM monitors sited and operated in accordance with 40 CFR Part 58. (See the March 10,

2009 letter from Governor Martin O’Malley to EPA, received on March 16, 2009.)

In April 2009, the State of New Jersey recommended that the same nine counties in New Jersey that 

were included in the Philadelphia-Wilmington-Atlantic City nonattainment area for the 1997 ozone 

NAAQS be designated as nonattainment in the Philadelphia Area for the 2008 ozone NAAQS based on 

air quality data from 2006-2008. This recommendation was based on data from FRM monitors or FEM 

monitors sited and operated in accordance with 40 CFR Part 58. (See the April 1, 2009 letter from the 

New Jersey Department of Environmental Protection to EPA.)

In March 2009, the Commonwealth of Pennsylvania recommended that the same five counties in 

Pennsylvania that were included in the Philadelphia-Wilmington-Atlantic City nonattainment area for 

the 1997 ozone NAAQS be designated as nonattainment in the Philadelphia Area for the 2008 ozone 

NAAQS based on air quality data from 2006-2008. Pennsylvania provided an update to the original 

recommendation in November 2011 based on air quality data from 2009-2011. That recommendation 

was to remove Chester and Delaware Counties from the Philadelphia Area, and designate those counties 

as attainment. This recommendation was based on data from FRM monitors or FEM monitors sited and 

operated in accordance with 40 CFR Part 58. (See the March 17, 2009 and November 22, 2011 letters

from the Pennsylvania Department of Environmental Protection to EPA.) 

After considering these recommendations and based on EPA's technical analysis described below, EPA 

intends to designate 16 counties in Delaware, Maryland, New Jersey, and Pennsylvania (identified in 

Table 1 below) as “nonattainment” for the 2008 ozone NAAQS as the Philadelphia Area nonattainment 

area. 

Table 1. State's Recommended and EPA’s Intended Designated Nonattainment Counties for the 

Philadelphia Area.

Philadelphia State-Recommended 

Nonattainment Counties

EPA Intended

Nonattainment Counties

Delaware None New Castle

Maryland Cecil Cecil

New Jersey

Atlantic, Burlington, Camden, Cape 

May, Cumberland, Gloucester, 

Mercer, Ocean, and Salem

Atlantic, Burlington, Camden, Cape 

May, Cumberland, Gloucester, 

Mercer, Ocean, and Salem

Pennsylvania Bucks, Montgomery, and 

Philadelphia

Bucks, Chester, Delaware, 

Montgomery, and Philadelphia
25

Factor Assessment

The counties evaluated in this analysis include all counties in the Philadelphia-Camden-Vineland CSA 

plus the counties outside the CSA that were included in the Philadelphia-Wilmington-Atlantic City 

nonattainment area for the 1997 ozone NAAQS.

Factor 1: Air Quality Data 

For this factor, we considered 8-hour ozone design values (in parts per billion (ppb)) for air quality 

monitors in counties in the Philadelphia Area based on data for the 2008-2010 period (i.e., the 2010 

design value, or DV), which are the most recent years with fully-certified air quality data. A monitor’s 

DV is the metric or statistic that indicates whether that monitor attains a specified air quality standard. 

The 2008 ozone NAAQS are met when the annual fourth-highest daily maximum 8-hour average 

concentration, averaged over 3 years is 0.075 ppm or less. A DV is only valid if minimum data 

completeness criteria are met. See 40 CFR part 50 Appendix P. Where several monitors are located in a 

county (or a designated nonattainment area or maintenance area), the DV for the county or area is 

determined by the monitor with the highest level.

Note: Monitors that are eligible for providing design value data generally include State and Local Air 

Monitoring Stations (SLAMS) that are sited in accordance with 40 CFR Part 58, Appendix D (Section 

4.1) and operating with a federal reference method (FRM) or federal equivalent method (FEM) monitor 

that meets the requirements of 40 CFR part 58, appendix A. All data from a special purpose monitor 

(SPM) using an FRM or FEM which has operated for more than 24 months is eligible for comparison to 

the NAAQS unless the monitoring agency demonstrates that the data came from a particular period 

during which the requirements of appendix A (quality assurance requirements) or appendix E (probe and 

monitoring path siting criteria) were not met.

The 2010 DVs for the ozone NAAQS for counties in the Philadelphia-Camden-Vineland CBSA and 

several nearby surrounding area are shown in Table 2. 

Table 2. Air Quality Data.

County

State Recommended 

Nonattainment?

2010 8-hour Ozone 

DV (ppb)

Atlantic, NJ Yes 74

Berks, PA Yes, other area 79

Bucks, PA Yes 83

Burlington, NJ Yes --

Camden, NJ Yes 80

Cape May, NJ Yes --

Cecil, MD Yes 80

Chester, PA No 76

Cumberland, NJ Yes 76

Delaware, PA No 74

Gloucester, NJ Yes 81

Kent, DE No 74

Mercer, NJ Yes 78

Montgomery, PA Yes 78
26

New Castle, DE Yes, other area 76

Ocean, NJ Yes 81

Philadelphia, PA Yes 82

Salem, NJ Yes --

Sussex, DE Yes, other area 77

Note: Counties with no ozone monitor are identified with “--“ in the 2010 8-hour Ozone DV column.

In accordance with section 107(d) of the Clean Air Act, EPA must designate an area nonattainment if it 

is violating the 2008 ozone NAAQS. New Castle and Sussex Counties in Delaware, Cecil County, 

Maryland; Berks, Bucks, Montgomery, and Philadelphia Counties in Pennsylvania; and several counties 

in New Jersey show violations of the 2008 ozone NAAQS. Therefore, these counties must be included 

in a nonattainment area. A county (or partial county) must also be designated nonattainment if it 

contributes to a violation in a nearby area. Each county without a violating monitor that is located near a 

county with a violating monitor has been evaluated based on the weight of evidence of the five factors 

and other relevant information to determine whether it contributes to the nearby violation. 

Factor 2: Emissions and Emissions-Related Data

EPA evaluated emissions of ozone precursors (NOx and VOC) and other emissions-related data that 

provide information on areas contributing to violating monitors.

Emissions Data

EPA evaluated county-level emission data for NOx and VOC derived from the 2008 National Emissions 

Inventory (NEI), version 1.5. This is the most recently available NEI. (See 

http://www.epa.gov/ttn/chief/net/2008inventory.html) Significant emissions levels in a nearby area 

indicate the potential for the area to contribute to observed violations. We will also consider any 

additional information we receive on changes to emissions levels that are not reflected in recent 

inventories. These changes include emissions reductions due to permanent and enforceable emissions 

controls that will be in place before final designations are issued and emissions increases due to new 

sources.

Table 3 shows emissions of NOx and VOC (given in tons per year) for violating and potentially 

contributing counties in the Philadelphia Area. 

Table 3. Total 2008 NOx and VOC Emissions.

County

State Recommended 

Nonattainment? NOx (tpy) VOC (tpy)

Atlantic, NJ Yes 6,143 10,713

Berks, PA Yes, other area 18,908 15,918

Bucks, PA Yes 17,736 21,160

Burlington, NJ Yes 10,919 12,909

Camden, NJ Yes 12,725 10,731

Cape May, NJ Yes 6,407 7,774

Cecil, MD Yes 4,763 3,715

Chester, PA No 16,806 16,351

Cumberland, NJ Yes 4,916 5,727
27

Delaware, PA No 28,118 15,881

Gloucester, NJ Yes 18,335 11,756

Kent, DE No 7,667 5,381

Mercer, NJ Yes 9,909 8,160

Montgomery, PA Yes 22,741 26,372

New Castle, DE Yes, other area 22,633 14,133

Ocean, NJ Yes 9,909 19,572

Philadelphia, PA Yes 33,176 32,021

Salem, NJ Yes 6,106 3,308

Sussex, DE Yes, other area 14,870 9,972

Philadelphia County, PA has the highest NOx and VOC emissions in the area of analysis. Other 

counties with comparatively high emissions are New Castle County in Delaware; and Delaware and 

Montgomery Counties in Pennsylvania. Counties with comparatively low emissions are Kent County, 

Delaware; Cecil County, Maryland; and several counties in New Jersey.

Population density and degree of urbanization

EPA evaluated the population and vehicle use characteristics and trends of the area as indicators of the 

probable location and magnitude of non-point source emissions. These include ozone-creating 

emissions from on-road and off-road vehicles and engines, consumer products, residential fuel 

combustion, and consumer services. Areas of dense population or commercial development are an 

indicator of area source and mobile source NOx and VOC emissions that may contribute to ozone 

formation. Table 4 shows the population, population density, and population growth information for 

each county in the area.

Table 4. Population and Growth.

County

State 

Recommended 

Nonattainment?

2010 

Population

2010 Population 

Density (1000 

pop/sq mi)

Absolute change 

in population 

(2000-2010)

Population % 

change 

(2000-2010)

Atlantic, NJ Yes 274,549 0.45 21,569 +9% 

Berks, PA Yes, other area 411,442 0.48 36,945 +10% 

Bucks, PA Yes 625,249 1.01 25,841 +4% 

Burlington, NJ Yes 448,734 0.55 24,255 +6% 

Camden, NJ Yes 513,657 2.26 6,064 +1% 

Cape May, NJ Yes 97,265 0.34 (5,043) -5% 

Cecil, MD Yes 101,108 0.27 14,643 +17% 

Chester, PA No 498,886 0.66 63,107 +14% 

Cumberland, NJ Yes 156,898 0.31 10,547 +7% 

Delaware, PA No 558,979 2.93 6,938 +1% 

Gloucester, NJ Yes 288,288 0.86 31,962 +12% 

Kent, DE No 162,310 0.27 35,200 +28% 

Mercer, NJ Yes 366,513 1.60 14,979 +4% 

Montgomery, PA Yes 799,874 1.64 48,936 +7% 

New Castle, DE Yes, other area 538,479 1.11 36,620 +7% 

Ocean, NJ Yes 576,567 0.76 62,913 +12% 

Philadelphia, PA Yes 1,526,006 10.71 12,194 +1% 
28

Salem, NJ Yes 66,083 0.19 1,867 +3% 

Sussex, DE Yes, other area 197,145 0.20 39,710 +25% 

Sources: U.S. Census Bureau population estimates for 2010 as of August 4, 2011. 

(http://factfinder2.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=DEC_10_PL_GCTPL2.STO5&prodType

=table)

Philadelphia County, Pennsylvania has the highest population and population density in the area of 

analysis. Bucks, Chester, Montgomery, and Delaware Counties, in Pennsylvania and New Castle 

County in Delaware also have comparatively large populations compared to Kent County, Delaware and 

several counties in New Jersey with comparatively small populations and population densities. Most 

counties in the analysis have experienced some population growth.

Traffic and commuting patterns

EPA evaluated the total Vehicle Miles Traveled (VMT) for each county in the area. In combination 

with the population/population density data and the location of main transportation arteries (see Figure 

1, above), this information helps identify the probable location of non-point source emissions. A county 

with high VMT is generally an integral part of an urban area and indicates the presence of motor vehicle 

emissions that may contribute to ozone formation. Rapid population or VMT growth in a county on the 

urban perimeter signifies increasing integration with the core urban area, and indicates that the 

associated area source and mobile source emissions may be appropriate to include in the nonattainment 

area. Table 5 shows total 2008 VMT for each county.

Table 5. Traffic (VMT) Data.

County State Recommended 

Nonattainment?

2008 VMT*

(million miles)

Atlantic, NJ Yes 2,863

Berks, PA Yes, other area 3,335

Bucks, PA Yes 5,021

Burlington, NJ Yes 4,524

Camden, NJ Yes 3,923

Cape May, NJ Yes 1,040

Cecil, MD Yes 1,350

Chester, PA No 4,410

Cumberland, NJ Yes 1,163

Delaware, PA No 3,782

Gloucester, NJ Yes 2,645

Kent, DE No 1,565

Mercer, NJ Yes 3,306

Montgomery, PA Yes 6,883

New Castle, DE Yes, other area 5,266

Ocean, NJ Yes 3,834

Philadelphia, PA Yes 5,955

Salem, NJ Yes 992

Sussex, DE Yes, other area 2,122

* MOBILE model VMT are those inputs into the NEI version 1.5. 
29

New Castle County, Delaware; and Bucks, Montgomery, and Philadelphia Counties in Pennsylvania 

have the highest VMT in the area of analysis. Kent County, Delaware; Cecil County, Maryland; and 

several counties in New Jersey have relatively low VMT.

Table 6. County to County Worker Flow.

Residence County Kent, 

DE

New Castle, 

DE

Sussex, 

DE

Cecil, 

MD

Berks, 

PA

Bucks, 

PA

Chester, 

PA

Delaware, 

PA

Montgomery,

PA

Philadelphia,

PA

Workplace County 

Kent, DE 47,455 3,927 5,704 186 157 18 131 112 41 65

New Castle, DE 6,058 209,742 1,119 14,059 493 12,976 9,002 1,201 1,856

Sussex, DE 3,779 319 52,073 33 29 15 6 39

Cecil, MD 243 3,379 42 18,446 18 557 192 52

Atlantic, NJ 11 142 31 4 172 73 231 181 831

Burlington, NJ 40 475 25 27 40 4,250 426 1,306 1,559 5,087

Camden, NJ 55 434 10 72 27 2,039 539 2,287 1,844 7,196

Cape May, NJ 27 20 13 54 81 118 95 324

Cumberland, NJ 26 164 5 19 42 24 103 66 140

Gloucester, NJ 750 19 82 16 362 411 1,251 405 1,502

Mercer, NJ 10 78 12 7 37 20,812 222 345 1,298 1,676

Ocean, NJ 13 30 8 5 220 23 10 13 86

Salem, NJ 32 1,841 11 139 37 155 245 59 84

Berks, PA 4 48 5 140,819 410 1,916 187 4,231 243

Bucks, PA 12 261 12 22 675 168,090 1,133 2,060 23,722 23,248

Chester, PA 37 4,738 33 941 5,596 3,036 137,678 18,504 25,006 7,810

Delaware, PA 125 8,150 61 373 505 2,754 17,870 137,988 11,758 21,802

Montgomery, PA 27 1,851 53 176 12,727 48,414 25,673 28,144 245,619 59,970

Philadelphia, PA 83 5,386 131 254 702 31,892 10,568 48,151 54,576 429,667

Source: US Census Bureau County-To-County Worker Flow Files 

http://www.census.gov/population/www/cen2000/commuting/index.html

Bucks, Chester, Delaware, Montgomery, and Philadelphia Counties in Pennsylvania have the highest 

numbers of commuters to other counties in the Philadelphia-Camden-Vineland CSA. New Castle 

County, Delaware, Cecil County, Maryland, and Berks County, Pennsylvania have moderate numbers of 

commuters into other counties in the CSA. Sussex and Kent Counties in Delaware, which are not in the 

Philadelphia-Camden-Vineland CSA, have the fewest commuters into the CSA.

Factor 3: Meteorology (weather/transport patterns)

EPA evaluated available meteorological data, consisting of 30-year average summertime wind directions

from the National Weather Service, to help determine how meteorological conditions, such as weather, 

transport patterns and stagnation conditions, would affect the fate and transport of precursor emissions 

contributing to ozone formation. 

The highest ozone design values, over 80 ppb, are in Bucks and Philadelphia Counties, in Pennsylvania, 

and Ocean County in New Jersey. The winds during the ozone season come predominantly from the 

southwest. This indicates that emissions from Chester and Delaware Counties in Pennsylvania; New 

Castle County, Delaware; Cecil County, Maryland; and counties in southwest New Jersey contribute to 

the downwind violations in Bucks and Philadelphia Counties during most of the ozone season. 

Considering prevailing wind patterns and the location of the highest violating monitors, Berks County, 

Pennsylvania and Kent and Sussex Counties in Delaware are unlikely to contribute to downwind 

violations during most of the ozone season.
30

Factor 4: Geography/topography (mountain ranges or other air basin boundaries)

The geography/topography analysis evaluates the physical features of the land that might affect the 

airshed and, therefore, the distribution of ozone over the area.

The Philadelphia Area does not have any geographical or topographical barriers significantly limiting air

pollution transport within its air shed. Therefore, there are no barriers to contribution from upwind 

areas.

Factor 5: Jurisdictional boundaries

EPA considers existing jurisdictional boundaries for the purposes of providing a clearly defined legal 

boundary and so that areas designated nonattainment have the legal authority and cooperative planning 

necessary to carrying out the air quality planning and enforcement functions for nonattainment areas. 

Examples of jurisdictional boundaries include existing/prior nonattainment areas for ozone or other 

urban-scale pollutants, counties, air districts, townships, metropolitan planning organizations, state lines, 

Reservations, urban growth boundary, etc. Where existing jurisdictional boundaries are not adequate to 

describe the nonattainment area, other clearly defined and permanent landmarks or geographic 

coordinates are used.

The major jurisdictional boundaries in the Philadelphia-Wilmington-Atlantic area are the state lines 

between Pennsylvania, Delaware, and New Jersey. Air-quality monitors that violate the 2008 8-hour 

ozone NAAQS in the Philadelphia Area are located in Delaware, Maryland, New Jersey, and 

Pennsylvania. 

The Philadelphia-Camden-Vineland CSA consists of New Castle County, Delaware; Cecil County, 

Maryland; Burlington, Camden, Cumberland, Gloucester, and Salem Counties in New Jersey, and 

Berks, Bucks, Chester, Delaware, Montgomery, and Philadelphia Counties in Pennsylvania. All those 

counties, except for Berks County, Pennsylvania are included in the Philadelphia-Wilmington-Atlantic 

City nonattainment area for the 1997 8-hour ozone NAAQS. The nonattainment area also includes Kent 

and Sussex Counties, Delaware and Atlantic, Cape May, Mercer, and Ocean Counties, New Jersey. 

Mercer and Ocean Counties, New Jersey are part of the New York-Newark-Bridgeport, NY-NJ-CT-PA 

CSA. Atlantic County makes up the Atlantic City-Hammonton, NJ MSA. Cape May County makes up 

the Ocean City, NJ MSA. In Delaware, Kent County, Delaware makes up the Dover MSA and Sussex 

County makes up the Seaford Micropolitan Statistical Area. 

The Delaware Valley Regional Planning Commission (DVRPC), the metropolitan planning organization 

(MPO) in the Philadelphia Area, serves Bucks, Chester, Delaware, Montgomery, and Philadelphia 

Counties in Pennsylvania, and Burlington, Camden, Gloucester, and Mercer Counties in New Jersey. 

New Castle County, DE and Cecil County, Maryland are in a separate MPO, the Wilmington Area 

Planning Council (WILMAPCO). 

Delaware

New Castle County has historically been part of the Philadelphia nonattainment area for ozone (1-hour 

and 8-hour) and fine particulate matter (PM2.5). New Castle County is part of the Wilmington, DE-MD-
31

NJ Metropolitan Division of the Philadelphia-Camden-Wilmington Metropolitan Statistical Area (MSA)

in the Philadelphia-Camden-Vineland CSA. Being part of a statistical area indicates that counties are 

linked through employment and commuting. According to the Office of Management and Budget’s 

“Standards for Defining Metropolitan and Micropolitan Statistical Areas,” published in the Federal 

Register on December 27, 2000 (65 FR 82228), the “general concept of a Metropolitan Statistical Area 

or a Micropolitan Statistical Area is that of an area containing a recognized population nucleus and 

adjacent communities that have a high degree of integration with that nucleus.” Delaware, 

Pennsylvania, Maryland and New Jersey have a long history of working cooperatively through the 

Ozone Transport Commission (OTC) and the Mid-Atlantic Northeast Visibility Union (MANE-VU) 

with ozone attainment planning. Furthermore, the two local MPOs, DVRPC and WILMAPCO, have 

worked together for decades.

Kent and Sussex Counties are less connected to the Philadelphia Area. They are not part of the 

Philadelphia-Camden-Vineland CSA. Kent County makes up the Dover MSA, and Sussex County 

makes up the Seaford Micropolitan Statistical Area. The Dover/Kent County MPO is the planning 

organization for Kent County, Delaware. This MPO covers 20 municipalities including all of Smyrna, 

which is also in New Castle County and all of Milford, which is also in Sussex County. Planning for 

Sussex County is done by the Sussex County Planning and Zoning Commission While Kent County was 

part of the Philadelphia-Wilmington-Trenton nonattainment area for the 1-hour ozone NAAQS, Sussex 

County was a separate nonattainment area. 

Maryland

Cecil County has historically been part of the Philadelphia nonattainment area for ozone (1-hour and 8-

hour) and PM2.5. Cecil County is part of the Wilmington, DE-MD-NJ Metropolitan Division of the 

Philadelphia-Camden-Wilmington MSA in the Philadelphia-Camden-Vineland CSA. Maryland, 

Delaware, Pennsylvania, and New Jersey have a long history of working cooperatively through the OTC 

and MANE-VU and with ozone attainment planning. Furthermore, the two local MPOs, DVRPC and 

WILMAPCO, have worked together for decades. 

Pennsylvania

Bucks, Chester, Delaware, Montgomery, and Philadelphia Counties have historically been part of the 

Philadelphia nonattainment area for ozone (1-hour and 8-hour) and PM2.5. These five counties are part 

of the Philadelphia, PA Metropolitan Division of the Philadelphia-Camden-Wilmington MSA in the 

Philadelphia-Camden-Vineland CSA. These counties are part of DVRPC, the main MPO for the 

Philadelphia Area.

Berks County is less connected to Philadelphia. While it was added to the Philadelphia-CamdenVineland CSA in December 2005, it’s in a separate MSA, the Reading, PA MSA. Berks County has 

historically not been part of the Philadelphia nonattainment area for 8-hour ozone and PM2.5, but has 

been designated separately as the Reading area. Berks County was designated attainment/unclassifiable 

for 1-hour ozone. In addition, Berks County is covered by a separate MPO, the Berks County Planning 

Commission. 

Conclusion

Based on the assessment of factors described above, EPA has preliminarily concluded that the following 

counties meet the CAA criteria for inclusion in the Philadelphia-Camden-Atlantic City nonattainment 

area: New Castle County, Delaware; Cecil County, Maryland; Atlantic, Burlington, Camden, Cape 
32

May, Cumberland, Gloucester, Mercer, Ocean, and Salem Counties in New Jersey; and Bucks, Chester, 

Delaware, Montgomery, and Philadelphia Counties in Pennsylvania. The Philadelphia-WilmingtonAtlantic City nonattainment area for the 1997 8-hour ozone NAAQS included these same counties, plus 

Kent and Sussex Counties in Delaware. New Castle County in Delaware; Cecil County in Maryland; and 

Berks, Bucks, Montgomery, and Philadelphia Counties in Pennsylvania show violations of the 2008 

ozone NAAQS.4 Maryland and Pennsylvania have requested that these violating counties in their 

respective States be included as part of the Philadelphia nonattainment area, which is consistent with 

their inclusion of that area for the 1-hour and 1997 8-hour NAAQS and the PM2.5 NAAQS. 

Additionally, we think the factors above support inclusion of these counties in that nonattainment area. 

Therefore, we intend to include them as part of the Philadelphia nonattainment area for the 2008 ozone 

NAAQS. 

New Castle County, Delaware has relatively high emissions, high population, and high VMT. 

Considering prevailing winds from the southwest, this county likely contributes to downwind violations 

of the ozone NAAQS in the Philadelphia Area. Furthermore, New Castle County is part of the 

Philadelphia-Wilmington-Atlantic City 8-hour ozone nonattainment area and the Philadelphia-CamdenVineland CSA. New Castle County has a moderate degree of commuting into the other counties in the 

CSA, including over 24,000 commuters into Cecil, Chester, Delaware, Montgomery, and Philadelphia 

Counties. Therefore, EPA intends to designate New Castle County as nonattainment as part of the 

Philadelphia Area.

Chester and Delaware Counties in Pennsylvania are part of the Philadelphia, PA Metropolitan Division 

of the Philadelphia-Camden-Wilmington MSA in the Philadelphia-Camden-Vineland CSA. These 

counties have been historically part of the Philadelphia nonattainment areas for ozone (8-hour and 1-

hour) and PM2.5 and are linked together with significant commuting throughout the 5 counties. These 

counties have relatively high populations and population densities. Delaware County has the second 

highest NOx emissions in the areas of analysis and among the highest VOC emissions. Taking into 

account the prevailing winds during the ozone season are predominantly from the southwest, emissions 

from Chester and Delaware Counties likely contribute to downwind violations in Bucks and 

Philadelphia Counties during most of the ozone season. Considering all these factors, EPA has 

concluded that Chester and Delaware Counties should be included in the Philadelphia Area.

In addition, monitors in Sussex County, Delaware and Berks County, Pennsylvania show violations of 

the 2008 ozone NAAQS and must be designated nonattainment. We believe that Sussex County, 

Delaware and Berks County, Pennsylvania should be designated as in separate nonattainment areas, and 

explained below.

Berks County, Pennsylvania has a violating monitor, but relatively moderate emissions, population, and 

VMT. There is some commuting from Berks County to the other counties in the Philadelphia Area, and 

Berks County is part of the Philadelphia-Camden-Vineland CSA. However, Berks County has 

historically been a separate ozone and PM2.5 nonattainment area. The County’s MPO, the Berks 

County Planning Commission, is separate from the Philadelphia Area’s MPO, DVRPC. Furthermore, 

meteorology indicates that on typical summer days when the violating monitors are experiencing 

exceedances of the ozone NAAQS, emissions from Berks County are not upwind of those monitors in 

the Philadelphia Area and thus we believe emissions from Berks County do not significantly contribute 

to nonattainment at those monitors. Therefore, EPA has preliminarily concluded that Berks County 

 

4 We discuss our conclusions as to the New Jersey counties in a Technical Analysis for the Philadelphia-Wilmington-Atlantic 

City Area sent to the State of New Jersey from EPA Region II.
33

should not be included in the Philadelphia Area, and should be designated as nonattainment in a separate 

area5.

Sussex County, Delaware has a monitor that is violating the 2008 ozone NAAQS. It has moderate

emissions and population in the area as compared with the other counties in the area of analysis. It is 

not part of the Philadelphia-Camden-Vineland CSA. Furthermore, considering prevailing winds from 

the southwest and the location of the highest violating monitors in the Philadelphia Area, it is not likely 

that Sussex County is contributing significantly to the Philadelphia Area. Therefore, EPA has 

preliminarily concluded that Sussex County should not be included in the Philadelphia Area, and should 

be designated as nonattainment in a separate area6.

Kent County, Delaware has a monitor that meets the 2008 8-hour ozone NAAQS. This county has 

comparatively low emissions, population and VMT, and is not part of the Philadelphia-CamdenVineland CSA. Therefore, EPA has preliminarily concluded that Kent County should not be included in 

the Philadelphia Area, and should be designated as unclassifiable/attainment.

 

5

See EPA’s Technical Analysis for the Reading Area, sent to the Commonwealth of Pennsylvania by EPA Region III.

6

See EPA’s Technical Analysis for the Seaford Area, sent to the State of Delaware by EPA Region III.
34

Technical Analysis for the Pittsburgh-Beaver Valley Area

Figure 1 is a map of the Pittsburgh-Beaver Valley EPA intended nonattainment area. The map provides 

other relevant information including the locations and design values of air quality monitors, county and 

other jurisdictional boundaries, CSA/CBSA boundary, existing nonattainment or maintenance boundary 

for 1997 ozone NAAQS, and EPA’s recommended boundaries.

Figure 1

For purposes of the 1997 8-hour ozone NAAQS, the Pittsburgh-Beaver Valley area was designated 

nonattainment. The boundary for the nonattainment area for the 1997 ozone NAAQS included the entire 

counties of Allegheny, Armstrong, Beaver, Butler, Fayette, Washington, and Westmoreland. 

In March 2009, Pennsylvania recommended that the same counties be designated as “nonattainment” for 

the 2008 ozone NAAQS based on air quality data from 2006-2008. Pennsylvania provided an update to 

the original recommendation on November 22, 2011 based on updated certified air quality data from 

2009-2011. Pennsylvania’s 2011 updated recommendation also revised the recommendation to limit the 

nonattainment area (for all areas in the Commonwealth) to only the county with the violating monitor. 

In the case of Pittsburgh, the Commonwealth recommends nonattainment for only Allegheny County, 

which continues to violate the 2008 ozone NAAQS based on 2009-2011 preliminary monitoring data. 

The preliminary data for 2009-2011 shows that Armstrong County is no longer violating the 2008 

NAAQS. 
35

This monitoring data is from Federal Reference Method (FRM) monitors or Federal Equivalent Method 

(FEM) monitors sited and operated in accordance with 40 CFR Part 58 (see the March 17, 2009 and 

November 22, 2011 letters from the Pennsylvania Department of Environmental Protection to EPA.)

After considering these recommendations and based on EPA's technical analysis described below, EPA 

intends to designate seven counties in Pennsylvania (identified in Table 1 below) as “nonattainment” for 

the 2008 ozone NAAQS as part of the Pittsburgh-Beaver Valley nonattainment area. 

Table 1. State's Recommended and EPA’s Intended Designated Nonattainment Counties for PittsburghBeaver Valley.

Pittsburgh-Beaver Valley State-Recommended 

Nonattainment Counties

EPA Intended

Nonattainment Counties

Pennsylvania Allegheny Allegheny, Armstrong, Beaver

Butler, Fayette, Washington, and

Westmoreland

Factor Assessment

Factor 1: Air Quality Data 

For this factor, we considered 8-hour ozone design values (in parts per billion (ppb)) for air quality 

monitors in counties in the Pittsburgh-New Castle area based on data for the 2008-2010 period (i.e., the 

2010 design value, or DV), which are the most recent years with fully-certified air quality data. A 

monitor’s DV is the metric or statistic that indicates whether that monitor attains a specified air quality 

standard. The 2008 ozone NAAQS are met when the annual fourth-highest daily maximum 8-hour 

average concentration, averaged over 3 years is 0.075 ppm or less. A DV is only valid if minimum data 

completeness criteria are met. See 40 CFR part 50 Appendix P. Where several monitors are located in a 

county (or a designated nonattainment area or maintenance area), the DV for the county or area is 

determined by the monitor with the highest level.

The 2010 and 2011 DVs for the ozone NAAQS for counties in the Pittsburgh-New Castle CSA are 

shown in Table 2. Pennsylvania submitted a letter to revise its nonattainment area recommendations 

based on updated certified monitoring data for the three-year period 2009-2011. Based on the 

preliminary 2009-2011 monitoring data provided by Pennsylvania in its November 2011 revised 

recommendation, two of the three monitors that violated based on 2008-2010 data are attaining the 2008 

NAAQS (one of the monitors in Allegheny County and the monitor in Armstrong County)

Table 2. Air Quality Data.

County

State 

Recommended 

Nonattainment?

EPA 

Recommended 

Nonattainment?

2010 8-hour Ozone 

DV (ppb)

Preliminary 2011 

8-hour Ozone DV 

(ppb)

Allegheny, PA Yes Yes 81 79

Armstrong, PA No Yes 76 73

Beaver, PA No Yes 73 72

Butler, PA No Yes -- --

Fayette, PA No Yes -- --

Lawrence, PA No No 66 66
36

Washington, PA No Yes 71 69

Westmoreland, PA No Yes 72 69

Note: Counties with no ozone monitor are identified with “--“ in the 2010 and 2011 8-hour Ozone DV columns.

One monitor in Allegheny County and one monitor in Armstrong County showed a violation of the 2008

ozone NAAQS based on 2008-2010 data. Pennsylvania updated its recommendations using 2009-2011 

monitoring data via a letter to EPA dated November 22, 2011. Based on this more recent data, only the 

Harrison monitor in Allegheny County shows a violation of the 2008 ozone NAAQS. Therefore

Allegheny County must be included in the nonattainment area. However, a county (or partial county) 

must also be designated nonattainment if it contributes to a violation in a nearby area. Each county 

without a violating monitor that is located nearby a county with a violating monitor has been evaluated 

based on the weight of evidence of the five factors and other relevant information to determine whether 

it contributes to the nearby violation. 

Factor 2: Emissions and Emissions-Related Data

EPA evaluated emissions of ozone precursors (NOx and VOC) and other emissions-related data that 

provide information on areas contributing to violating monitors.

Emissions Data

EPA evaluated county-level emission data for NOx and VOC derived from the 2008 National Emissions 

Inventory (NEI), version 1.5. This is the most recently available NEI. (See 

http://www.epa.gov/ttn/chief/net/2008inventory.html) Significant emissions levels in a nearby area 

indicate the potential for the area to contribute to observed violations. We will also consider any 

additional information we receive on changes to emissions levels that are not reflected in recent 

inventories. These changes include emissions reductions due to permanent and enforceable emissions 

controls that will be in place before final designations are issued and emissions increases due to new 

sources.

Table 3 shows emissions of NOx and VOC (given in tons per year) for violating and potentially 

contributing counties in the Pittsburgh-New Castle CSA. 

Table 3. Total 2008 NOx and VOC Emissions

County

State 

Recommended 

Nonattainment?

EPA 

Recommended 

Nonattainment? NOx (tpy) VOC (tpy)

Allegheny, PA Yes Yes 52,399 37,506 

Armstrong, PA No Yes 21,140 3,253 

Beaver, PA No Yes 35,714 6,030 

Butler, PA No Yes 7,789 7,856 

Fayette, PA No Yes 4,639 6,149 

Lawrence, PA No No 8,960 3,814 

Washington, PA No Yes 14,304 7,256 

Westmoreland, PA No Yes 14,827 13,548 
37

Allegheny County has the highest NOx and VOC emissions in the area. Beaver and Armstrong 

Counties NOx emissions are somewhat higher than the remaining counties in the area, although Beaver 

County has fairly low VOC emissions. Westmoreland County has higher emissions than the remaining 

counties. Lawrence and Fayette Counties have relatively low emissions of NOx and VOC, by 

comparison to the other counties. 

Population density and degree of urbanization

EPA evaluated the population and vehicle use characteristics and trends of the area as indicators of the 

probable location and magnitude of non-point source emissions. These include ozone-creating 

emissions from mobile sources, such as on-road and off-road vehicles and engines, and area sources, 

such as consumer products, residential fuel combustion, and consumer services. Areas of dense 

population or commercial development are an indicator of area source and mobile source NOx and VOC 

emissions that may contribute to ozone formation. Rapid population or vehicle miles travelled (VMT)

growth (see below) in a county on the urban perimeter signifies increasing integration with the core 

urban area, and indicates that the associated area source and mobile source emissions may be 

appropriate to include in the nonattainment area. Table 4 shows the population, population density, and 

population growth information for each county in the area.

Table 4. Population and Growth.

County

State 

Recommended 

Nonattainment?

EPA 

Recommended 

Nonattainment?

2010 

Population

2010 

Population 

Density 

(1000 pop 

/sq mi)

Absolute 

change in 

population 

(2000-2010)

Population 

% change 

(2000-

2010)

Allegheny, PA Yes Yes 1,223,348 1.64 (56,566) -4% 

Armstrong, PA No Yes 68,941 0.10 (3,374) -5% 

Beaver, PA No Yes 170,539 0.38 (10,576) -6% 

Butler, PA No Yes 183,862 0.23 9,343 +5% 

Fayette, PA No Yes 136,606 0.17 (11,908) -8% 

Lawrence, PA No No 91,108 0.25 (3,514) -4% 

Washington, PA No Yes 207,820 0.24 4,873 +2% 

Westmoreland, PA No Yes 365,169 0.35 (4,521) -1% 

Sources: U.S. Census Bureau population estimates for 2010 as of August 4, 2011 

(http://factfinder2.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=DEC_10_PL_GCTPL2.STO5&prodType

=table) and U.S. Census Bureau GIS files for the county boundaries

Allegheny County has by far the largest overall 2010 population (and population density), with its 

population nearly totaling the combined population of the other seven counties in the CSA. All of the 

counties are relatively sparsely populated in comparison to Allegheny County, with Armstrong, Fayette, 

Butler, Washington, and Lawrence being the most sparsely populated (having population densities of 

less than 250 persons per square mile). In terms of population change, only Butler and Washington 

Counties have exhibited any population growth since 2000, with all remaining area counties exhibiting 

declining population. 
38

Traffic and VMT data

EPA evaluated the total Vehicle Miles Traveled (VMT) for each county, as well as VMT growth. In 

combination with the population/population density data and the location of main transportation arteries 

(see above), this information helps identify the probable location of non-point source emissions. A 

county with high VMT and/or a high number of commuters is generally an integral part of an urban area 

and indicates the presence of motor vehicle emissions that may contribute to ozone formation. Rapid 

population or VMT growth in a county on the urban perimeter signifies increasing integration with the 

core urban area, and indicates that the associated area source and mobile source emissions may be 

appropriate to include in the nonattainment area. Table 5 shows total 2008 VMT and 2002-2008 VMT 

growth for each county. 

Table 5. Traffic and Commuting Patterns

County

EPA Recommended 

Nonattainment?

2008 VMT 

(million miles)

Percent VMT Growth 

(2002-2008)

Allegheny, PA Yes 9,227 -0.6

Armstrong, PA Yes 621 -1.0

Beaver, PA Yes 1,434 -2.6

Butler, PA Yes 1,747 2.8

Fayette, PA Yes 1,062 5.7

Lawrence, PA No 781 -0.6

Washington, PA Yes 2,114 -7.2

Westmoreland, PA Yes 3,430 -4.4

* MOBILE model VMTs are those inputs into the NEI version 1.5. 

Table 6. County to County Worker Flow

Residence County Allegheny Armstrong Beaver Butler Fayette Washington Westmoreland Lawrence

Workplace County 

Allegheny 536,655 4,582 23,946 21,403 5,151 27,645 43,536 2,043

Armstrong 635 16,279 14 1,013 25 22 2,197 12

Beaver 5,235 106 47,074 1,372 136 556 561 2,717

Butler 7,868 2,609 4,885 51,572 168 370 1,231 2,366

Fayette 732 12 28 35 35,915 1,317 2,391 25

Washington 9,211 68 467 267 25 53,268 3,473 53

Westmoreland 12,049 2,719 291 831 3,051 2,718 106,015 103

Lawrence 736 44 2,003 1013 8,985 69 165 27,536

Source: U.S. Census Bureau estimates for 2000 County-to-County Worker Flow 

(http://www.census.gov/hhes/commuting/data/commuting.html

Allegheny County has by far the highest VMT, totaling nearly the combined VMT of the next five 

highest counties VMT. Allegheny County also has by far the largest number of commuters travelling to 

or within violating counties, as of 2008. Fayette and Butler are the only counties in the area with 

appreciable VMT growth. Table 6 depicts commuter flow within and between the respective counties. 
39

It is clear from Table 6 that Allegheny County draws the greatest number of commuters from all 

counties, but also that most of the counties have at least some contribution to each other. Lawrence 

County is a notable exception, as very few commuters travel to Allegheny County, or to any county in 

the Pittsburgh MSA.

Figure 2 is a map depicting the arterial highway network for the Pittsburgh CSA. Figure 3 depicts the 

key interstate and arterial highways, focusing on Allegheny County, where the preponderance of the 

total area VMT and commuter traffic flow.

Figure 2

Figures 2 and 3 depict the arterial highway network for Pittsburgh, with figure 3 focusing on Allegheny 

County and the City of Pittsburgh downtown area. The main interstates for the region are: Interstate 376 

(the main east-west route), Interstate 279 (the main north-south artery extending from downtown 

Pittsburgh north to meet with I-79), and Interstate 579 (a short freeway spur from Interstate 279 south).

I-79 skirts the Pittsburgh downtown district to the west (passing north-south through Butler, Allegheny, 

and Washington Counties before leaving Pittsburgh to West Virginia). The Pennsylvania Turnpike 

(Interstate 76) skirts the Pittsburgh downtown district to the North and East (passing through 

Westmoreland, Allegheny, Beaver, and Lawrence Counties before passing into Ohio).

With most of these interstates looping outside the Pittsburgh downtown, Pittsburgh relies on an inner 

beltway system of smaller highways within Allegheny County. Figure 4 depicts the Beltway system of 

six color-coded loops surround the City of Pittsburgh and link the city and surrounding communities, 

highways, and airports.
40

Figure 3

Source: AA Roads (www.aaroads.com)

Figure 4

Source: Highway Route Markers of the United States (www.routemarkers.com) 

From Table 5, it is clear that much of the total commuting for the area consists of Allegheny commuters 

commuting within Allegheny County. The commuting totals from the remaining counties are much 

smaller in comparison (in spite of some of the large percentages of commuters), due to their lower VMT 
41

totals and lower population densities. The high percentage of commuters in Armstrong County traveling 

to a county with a violating monitor is a function of that county having been in violation of the 2008 

ozone NAAQS prior to the 2009-2011 period. It is clear that the remaining Pittsburgh CSA counties 

have lower total commuters and smaller total VMT, and likely have a higher proportion of their VMT 

associated with the regional interstate highway network depicted in Figures 2 and 3 (although some of 

those may be regional commuters that are moving to the inner ring highways depicted in Figure 4).

Of all the CSA counties, Lawrence and Armstrong have the lowest overall 2008 VMT, and Lawrence 

has the lowest number of commuters to a violating county, based on 2008 data. 

Factor 3: Meteorology (weather/transport patterns)

EPA evaluated any available meteorological data to help determine how meteorological conditions, such 

as weather, transport patterns and stagnation conditions, would affect the fate and transport of precursor 

emissions contributing to ozone formation. 

The highest ozone design value for the period 2008-2010 is 81 ppb in Allegheny County, followed by 76 

ppb in Armstrong County. For the period 2009-2011, the highest ozone design value was 79 ppb in 

Allegheny County. The prevailing winds during the ozone season have strong westerly and 

southwesterly components. This indicates the potential contribution to violations from western Counties 

in the CSA and potentially from transport from areas in Ohio and West Virginia. However, a number of 

monitors in counties on both sides of the Pennsylvania-Ohio and Pennsylvania-West Virginia border are 

currently measuring attainment of the ozone standard. 

Further analysis of backward trajectories could prove helpful in resolving the affect of meteorology on 

this area. Pennsylvania’s March 2009 ozone recommendation did contain some NOAA HYSPLIT 

model backward trajectory information, but not for monitors in the Pittsburgh area. The supplied 

information for a monitor in eastern Pennsylvania indicated that HYSPLIT 24-hour period back 

trajectories were highly variable based upon the episode in question. Therefore, this information was 

not useful in determining the impact of meteorology on the Pittsburgh-New Castle CSA.

Factor 4: Geography/topography (mountain ranges or other air basin boundaries)

The geography/topography analysis evaluates the physical features of the land that might affect the 

airshed and, therefore, the distribution of ozone over the area.

Pittsburgh lies on the Appalachian Plateau extending westward from the Allegheny Front, which is an 

escarpment that makes the western part of Pennsylvania higher than the eastern part of the 

Commonwealth. The City of Pittsburgh itself is defined by the river valleys of the Allegheny, the 

Monongahela, and the Ohio. 

Elevations in the Pittsburgh region range from around 700 feet above sea level where the rivers meet, to 

1,200 to 1,300 feet at the highest points, with dramatic hills and valleys often separating neighborhoods 

and communities. The highest land is at the prevailing level of the Appalachian Plateau, with the river 

valleys forming the low points, and varying slopes connecting it together. 
42

Figure 5

Source: US Geologic Society, National Historic Map, Eastern United States

While this topography may not form a geographic or topographic barrier significantly limiting air 

pollution within the airshed, the topography may impact weather patterns in the area, result in 

atmospheric inversions or other conditions that affect local emissions transport or monitored ozone 

levels. Pennsylvania did not submit data as part of its recommendation indicating that topography plays 

a significant role in distribution of ozone across the Pittsburgh-Beaver Valley area.

Factor 5: Jurisdictional boundaries

Once the general areas to be included in the nonattainment area were determined, EPA considered

existing jurisdictional boundaries for the purposes of providing a clearly defined legal boundary and 

carrying out the air quality planning and enforcement functions for nonattainment areas. Examples of 

jurisdictional boundaries include existing/prior nonattainment areas for ozone or other urban-scale 

pollutants, counties, air districts, townships, metropolitan planning organizations, state lines, 

Reservations, urban growth boundary, etc. Where existing jurisdictional boundaries are not adequate to 

describe the nonattainment area, other clearly defined and permanent landmarks or geographic 

coordinates were considered.
43

The Pittsburgh-Beaver Valley area has previously established nonattainment boundaries associated with 

both the 1-hour and 1997 8-hour ozone NAAQS. In its March 2009 recommendation to EPA, the 

Commonwealth recommended the same nonattainment area boundary for the 2008 ozone NAAQS. 

However, in a letter sent to EPA on November 22, 2011, Pennsylvania revised its recommendation to 

include as nonattainment only those counties having monitored violations of the 2008 ozone standard. 

In the case of the Pittsburgh-Beaver Valley area, Pennsylvania is now recommending that only 

Allegheny County be designated as nonattainment. 

EPA relied on the Pittsburgh-New Castle CSA as its analytical starting point for determining 

nonattainment area boundaries. The Pittsburgh-New Castle CSA includes the 7-county Pittsburgh 

Metropolitan Statistical Area, as well as the one-county New Castle Micropolitan Statistical Area 

(comprised of Lawrence County). 

Figure 6

As Pennsylvania indicated in its March 2009 recommendation to EPA, the counties in the Pittsburgh 

Metropolitan Statistical Area are part of one single transportation-planning agency as designated by the 

U.S. Department of Transportation (U.S. DOT) based on economic and commuting patterns. Retaining 

the existing boundary for this nonattainment area will allow the area to benefit from continuity of

planning for the 1997 8-hour standard. Also, the 1997 Pittsburgh ozone nonattainment area has two 

emission control programs that pertain only to this area and not to surrounding counties: a requirement 

for cleaner gasoline during the ozone season and a requirement for gasoline pumps to control

fumes when vehicles are refueling. Finally, the recommended nonattainment area includes three air 

basins (as defined in 25 Pa.Code § 121.1): the Lower Beaver Valley Air Basin, the Allegheny County 

Air Basin and the Monongahela Valley Air Basin. These basins were developed for purposes of the

sulfur compound controls outlined in 25 Pa. Code § 123.22, yet they represent existing
44

local boundaries for emission controls in the areas of the Commonwealth where they exist. 

In November 2011, Pennsylvania submitted a revised recommendation letter to EPA to alter its March

2009 recommendation to reflect only the county violating the 2008 ozone NAAQS (i.e. Allegheny 

County), dismissing its jurisdiction-based arguments set forth in the Commonwealth’s prior March 2009 

recommendation. 

Pennsylvania did not recommend inclusion of Lawrence County in its March 2009 or November 2011 

area recommendation letters to EPA. The Commonwealth’s rationale in the March 2009 letter was that 

Lawrence County has a monitor that is monitoring well below the 2008 ozone NAAQS, that the area has 

traditionally been a stand-alone planning area, and that the county’s micropolitan statistical area status 

indicates a lower level of social and economic ties to the Pittsburgh metropolitan area counties than 

counties within the Pittsburgh metropolitan statistical area. 

Conclusion

Based on the assessment of factors described above, EPA has preliminarily concluded that the following 

counties meet the CAA criteria for inclusion in the Pittsburgh-Beaver Valley nonattainment area:

Allegheny, Armstrong, Beaver, Butler, Fayette, Washington, and Westmoreland

On the basis of the factor discussion above, there is cause to extend the nonattainment boundary beyond 

the county having a violating monitor, i.e., Allegheny County. With respect to emissions and emissionsrelated data, Armstrong, Beaver, Washington, and Westmoreland Counties have relatively high 

emissions. Although the area is facing low to negative population growth (with the exception of Butler 

and Washington Counties) and many of the counties are sparsely populated, Washington, 

Westmoreland, Beaver, Butler, and Fayette Counties continue to have populations over 100,000 persons. 

Westmoreland, Washington, Beaver, and Butler Counties have high VMT, even relative to more densely 

populated Allegheny County. 

With respect to jurisdictional boundaries, it is clear that the counties in the Pittsburgh Metropolitan 

Statistical Area are socially and economically intertwined. The Pittsburgh metropolitan area counties 

utilize a single transportation-planning agency, and have emission control programs unique from 

neighboring counties and metropolitan areas. Historically, this Pittsburgh metropolitan area has been 

the ozone nonattainment boundary. 

Based on this factor assessment, EPA contends that the Pittsburgh Metropolitan Statistical Area be the 

boundary for the 2008 nonattainment area, as it was for the 1997 ozone NAAQS nonattainment area. 

Based on the most recent 2009-2011 monitoring data, Allegheny County is the only county monitoring a 

violation of the 2008 NAAQS, and under the Clean Air Act must be designated nonattainment. 

However, we disagree with Pennsylvania’s recommendation to exclude the remaining Pittsburgh area 

counties from the nonattainment area and believe the nearby counties in the Pittsburgh Metropolitan 

Statistical Area contribute to nonattainment of the 2008 ozone NAAQS. Therefore, these nearby 

counties must also be designated nonattainment. EPA agrees with Pennsylvania that there is sufficient 

evidence on the basis of the above factor assessment to exclude Lawrence County from the EPA 

intended nonattainment area. Therefore, EPA recommends that the intended nonattainment area for 

2008 ozone NAAQS for the Pittsburgh-Beaver Valley area be the same as the 7-county nonattainment 

area boundary under the prior 1997 ozone NAAQS.
45

Technical Analysis for the Reading Area

Figure 1 is a map of the Reading intended nonattainment area, Berks County, Pennsylvania. The map 

provides other relevant information including the locations and design values of air quality monitors, 

major transportation arteries, and county and other jurisdictional boundaries. This map shows the 

former Reading nonattainment area for the 1997 ozone NAAQS, now a maintenance area, which 

consists of Berks County, Pennsylvania. It also shows the Philadelphia-Camden-Vineland CSA.

Figure 1.

For purposes of the 1997 8-hour ozone NAAQS, the Reading Area was designated nonattainment. The 

boundary for the nonattainment area for the 1997 ozone NAAQS included the entire county of Berks in 

Pennsylvania.

In March 2009, the Commonwealth of Pennsylvania recommended that the same county, Berks, be 

designated as nonattainment in the Reading Area for the 2008 ozone NAAQS based on air quality data 

from 2006-2008. Pennsylvania provided an update to the original recommendation in November 2011 

based on air quality data from 2009-2011. That recommendation update did not make any modification 

to the Reading area boundary. The recommendations are based on data from Federal Reference Method 

(FRM) monitors or Federal Equivalent Method (FEM) monitors sited and operated in accordance with 

40 CFR Part 58. (See the March 17, 2009 and November 22, 2011 letters from the Pennsylvania 

Department of Environmental Protection to EPA.)
46

After considering these recommendations and based on EPA's technical analysis described below, EPA 

intends to designate Berks County, Pennsylvania as “nonattainment” for the 2008 ozone NAAQS as the 

Reading nonattainment area. 

Table 1. State's Recommended and EPA’s Intended Designated Nonattainment Counties for Reading 

Area.

Reading State-Recommended 

Nonattainment Counties

EPA Intended

Nonattainment Counties

Pennsylvania Berks Berks

Factor Assessment

EPA has determined that it is appropriate to include Bucks, Chester, Montgomery, Lancaster, and 

Lehigh Counties in other separate nonattainment areas for the 2008 ozone NAAQS. Based on EPA’s 

five-factor analyses, EPA has preliminary; determined that Bucks, Chester, and Montgomery Counties 

should be designated as nonattainment in the Philadelphia-Wilmington-Atlantic City Area, Lancaster 

County should be designated as nonattainment in the Lancaster Area, and Lehigh County should be 

designated nonattainment as part of the Allentown-Bethlehem-Easton Area. See EPA’s respective 

technical analyses for these adjacent nonattainment areas for EPA’s rationale for our intended 

nonattainment designation for these counties. To the extent that emissions from the Bucks, Chester, 

Montgomery, Lancaster, and Lehigh Counties may contribute ozone concentrations in the Reading

nonattainment area, that contribution will be lessened by emission controls put in place in those separate 

nonattainment areas. Therefore, EPA is not including Bucks, Chester, Montgomery, Lancaster, and 

Lehigh Counties in this analysis for the Reading nonattainment area.

Factor 1: Air Quality Data 

For this factor, we considered 8-hour ozone design values (in parts per billion (ppb)) for air quality 

monitors in counties in the Reading area based on data for the 2008-2010 period (i.e., the 2010 design 

value, or DV), which are the most recent years with fully-certified air quality data. A monitor’s DV is 

the metric or statistic that indicates whether that monitor attains a specified air quality standard. The 

2008 ozone NAAQS are met when the annual fourth-highest daily maximum 8-hour average 

concentration, averaged over 3 years is 0.075 ppm or less. A DV is only valid if minimum data 

completeness criteria are met. See 40 CFR part 50 Appendix P. Where several monitors are located in a 

county (or a designated nonattainment area or maintenance area), the DV for the county or area is 

determined by the monitor with the highest DV.

Note: Monitors that are eligible for providing design value data generally include State and Local Air 

Monitoring Stations (SLAMS) that are sited in accordance with 40 CFR Part 58, Appendix D (Section 

4.1) and operating with a federal reference method (FRM) or federal equivalent method (FEM) monitor 

that meets the requirements of 40 CFR part 58, appendix A. All data from a special purpose monitor 

(SPM) using an FRM or FEM which has operated for more than 24 months is eligible for comparison to 

the NAAQS unless the monitoring agency demonstrates that the data came from a particular period 

during which the requirements of appendix A (quality assurance requirements) or appendix E (probe and 

monitoring path siting criteria) were not met.
47

The 2010 DVs for the ozone NAAQS for Berks County and nearby surrounding counties are shown in 

Table 2. 

Table 2. Air Quality Data.

County State Recommended 

Nonattainment?

2008-2010 Design Value

(ppb)

Berks, PA Yes 79

Lebanon, PA No --

Schuylkill, PA No --

Note: Counties with no ozone monitor are identified with “--“ in the 2010 8-hour Ozone DV column.

In accordance with section 107(d) of the Clean Air Act, EPA must designate an area nonattainment if it 

is violating the 2008 ozone NAAQS. Berks County shows a violation of the 2008 ozone NAAQS, 

therefore this county must be included in a nonattainment area. Note that the absence of a violating 

monitor is not a sufficient reason to eliminate nearby counties as candidates for nonattainment status

based upon contribution to violations in other nearby areas. Each county is being evaluated based on the 

weight of evidence of the five factors.

Factor 2: Emissions and Emissions-Related Data

EPA evaluated emissions of ozone precursors (NOx and VOC) and other emissions-related data that 

provide information on areas potentially contributing to violating monitors.

Emissions Data

EPA evaluated county-level emission data for NOx and VOC derived from the 2008 National Emissions 

Inventory (NEI), version 1.5. This is the most recently available NEI. (See 

http://www.epa.gov/ttn/chief/net/2008inventory.html) Significant emissions levels in a nearby area 

indicate the potential for the area to contribute to observed violations. We will also consider any 

additional information we receive on changes to emissions levels that are not reflected in recent 

inventories. These changes include emissions reductions due to permanent and enforceable emissions 

controls that will be in place before final designations are issued and emissions increases due to new 

sources.

Table 3 shows emissions of NOx and VOC (given in tons per year) potentially contributing counties in 

the Reading Area.

Table 3. Total 2008 NOx and VOC Emissions.

County State Recommended

Nonattainment? NOx (tpy) VOC (tpy)

Berks, PA Yes 18,908 15,918

Lebanon, PA No 6,166 5,367

Schuylkill, PA No 6,554 5,922

Berks County has the highest NOx and VOC emissions in the area of analysis. In fact, the emissions 

from Berks County are nearly three times higher than the emissions in Lebanon and Schuylkill Counties. 

This indicates that emissions from Lebanon and Schuylkill Counties are not likely to contribute to ozone

violations in Berks County.
48

Population density and degree of urbanization

EPA evaluated the population and vehicle use characteristics and trends of the area as indicators of the 

probable location and magnitude of non-point source emissions. These include ozone-creating 

emissions from on-road and off-road vehicles and engines, consumer products, residential fuel 

combustion, and consumer services. Areas of dense population or commercial development are an 

indicator of area source and mobile source NOx and VOC emissions that may contribute to ozone 

formation. Table 4 shows the population, population density, and population growth information for 

each county in the area of analysis.

Table 4. Population and Growth.

County

State 

Recommended 

Nonattainment?

2010 Population

2010 Population 

Density

(1000 pop/sq mi)

Absolute change

in population

(2000-2010)

Population % 

change

(2000-2010)

Berks, PA Yes 411,442 0.48 36,945 +10% 

Lebanon, PA No 133,568 0.37 13,151 +11%

Schuylkill, PA No 148,289 0.19 -1,798 -1.2%

Sources: U.S. Census Bureau population estimates for 2010 as of August 4, 2011 

(http://factfinder2.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=DEC_10_PL_GCTP

L2.STO5&prodType=table).

Berks County has the highest population in the area of analysis. In fact, the population in Berks County

is nearly three times higher than the populations of Lebanon and Schuylkill Counties. This indicates 

that non-point source emissions from Lebanon or Schuylkill Counties are not likely to contribute to 

ozone violations in Berks County.

Traffic and commuting patterns

EPA evaluated the commuting patterns of residents in the area, as well as the total Vehicle Miles 

Traveled (VMT) for each county. In combination with the population/population density data and the 

location of main transportation arteries (see Figure 1, above), this information helps identify the 

probable location of non-point source emissions. A county with high VMT and/or a high number of 

commuters is generally an integral part of an urban area and indicates the presence of motor vehicle 

emissions that may contribute to ozone formation. Rapid population or VMT growth in a county on the 

urban perimeter signifies increasing integration with the core urban area, and indicates that the 

associated area source and mobile source emissions may be appropriate to include in the nonattainment 

area. Table 5 shows the total vehicle miles traveled (VMT) for each county in 2008.

Table 5. Traffic (VMT) Data..

County State Recommended 

Nonattainment?

2008 VMT*

(million miles)

Berks, PA Yes 3,335

Lebanon, PA No 1,210

Schuylkill, PA No 1,394

* MOBILE model VMTs are those inputs into the NEI version 1.5. 

VMT in Berks County is more than twice as high as VMT in Lebanon and Schuylkill Counties. 

However, as shown in Table 6, below, Lebanon and Schuylkill Counties do have commuters into Berks 

County. Therefore, there is come contribution of VMT and mobile source emissions from Lebanon and 

Schuylkill Counties to Berks County.
49

Table 6. County to County Worker Flow.

Residence County Berks, PA Lebanon, PA Schuylkill, PA

Workplace County 

Berks, PA 140,819 2,799 5,790

Lebanon, PA 2,053 36,677 1,482

Schuylkill, PA 619 188 43,979

Source: US Census Bureau County-To-County Worker Flow Files 

http://www.census.gov/population/www/cen2000/commuting/index.html

Factor 3: Meteorology (weather/transport patterns)

EPA evaluated available meteorological data, consisting of 30-year average summertime wind directions

from the National Weather Service, to help determine how meteorological conditions, such as weather, 

transport patterns and stagnation conditions, would affect the fate and transport of precursor emissions 

contributing to ozone formation.

In the summertime, the predominant winds in Berks County come from the west, with the largest 

components from the west-southwest (20%) and west-northwest (20%). There is also a high frequency 

of winds from the south-southwest (15%). As shown in Figure 2, below, this indicates that Lebanon 

County is upwind of the violating monitor in Berks County. Therefore, emissions from Lebanon County 

likely contribute to ozone concentrations in Berks County. However, since emissions in Lebanon 

County are relatively low, the contribution to ozone concentrations in Berks County is also relatively 

low.

Figure 2. 30-Year Average Summertime Wind Directions in Berks County, Pennsylvania
50

Factor 4: Geography/topography (mountain ranges or other air basin boundaries)

The geography/topography analysis evaluates the physical features of the land that might affect the 

airshed and, therefore, the distribution of ozone over the area.

The Reading area does not have any geographical or topographical barriers significantly limiting air

pollution transport within its air shed. Therefore, there are no barriers to contribution from upwind 

areas.

Factor 5: Jurisdictional boundaries

EPA considers existing jurisdictional boundaries for the purposes of providing a clearly defined legal 

boundary and carrying out the air quality planning and enforcement functions for nonattainment areas. 

Examples of jurisdictional boundaries include existing/prior nonattainment areas for ozone or other 

urban-scale pollutants, counties, air districts, townships, metropolitan planning organizations, state lines, 

Reservations, urban growth boundary, etc. Where existing jurisdictional boundaries are not adequate to 

describe the nonattainment area, other clearly defined and permanent landmarks or geographic 

coordinates are used.

The three counties in the area of analysis are in the same state, but otherwise are not connected 

jurisdictionally. They are served by different metropolitan planning organizations (MPOs); the Berks 

County Planning Commission, the Lebanon County MPO, and the Schuylkill County Planning and 

Zoning Commission. They are historically in separate nonattainment areas for ozone and fine 

particulate matter (PM2.5). Finally, they are in separate statistical areas, as defined by the US Census 

Bureau.

The Reading area has a previously-established nonattainment boundary associated with the 1997 8-hour

ozone NAAQS, which is the single county of Berks. Pennsylvania has recommended the same 

boundary for the 2008 ozone NAAQS. The Reading area for the 1997 PM2.5.NAAQS also consists of 

the single county of Berks. Lebanon and Schuylkill Counties have historically been included in 

nonattainment areas other than the Reading area for ozone and/or PM2.5. Lebanon County is part of the 

Harrisburg area for ozone (1-hour and 8-hour) and PM2.5. Schuylkill County was a single-county 

nonattainment area for the 1-hour ozone NAAQS, and was designated attainment/unclassifiable for the 

1997 8-hour NAAQS and PM2.5.

According to the Office of Management and Budget’s “Standards for Defining Metropolitan and 

Micropolitan Statistical Areas,” published in the Federal Register on December 27, 2000 (65 FR 82228), 

the “general concept of a Metropolitan Statistical Area or a Micropolitan Statistical Area is that of an 

area containing a recognized population nucleus and adjacent communities that have a high degree of 

integration with that nucleus.” Being part of a statistical area indicates that counties are linked through 

employment and commuting. Conversely, being in separate statistical areas implies little 

interconnection. As stated above, Berks, Lebanon, and Schuylkill Counties are in separate statistical 

areas. Lebanon County makes up the Lebanon MSA, which is part of the Harrisburg-Carlisle-Lebanon,

CSA. Schuylkill County makes up the Pottsville Micropolitan Statistical Area. Berks County makes up 

the Reading MSA, which is part of the Philadelphia-Camden-Vineland CSA. However, EPA’s 
51

preliminary recommendation is to not include Berks County in the Philadelphia-Wilmington-Atlantic 

City Area for the 2008 ozone NAAQS, as supported by EPA’s five-factor analysis for that area7. 

Conclusion

Based on the assessment of factors described above, EPA has preliminarily concluded that the following 

counties meet the CAA criteria for inclusion in the Reading nonattainment area: Berks County. This is 

the same county that was included in the Reading nonattainment area for the 1997 ozone NAAQS (now 

the Reading maintenance area). An air quality monitor in Berks County is violating the 2008 ozone 

NAAQS based on the 2010 DV, therefore this county must be included in a nonattainment area. EPA 

has preliminary concluded that Berks County should be included in the Reading Area.

EPA has concluded that the other counties in this analysis, Lebanon and Schuylkill Counties, do not 

contribute to ozone violations in Berks County. These counties do not have ozone monitors. These 

counties have relatively low emissions, populations, and VMT. Dominant ozone season winds in Berks 

County come from the west and west-southwest. Therefore, Lebanon County is upwind of the violating 

monitor in Berks County. However, since emissions in Lebanon County are relatively low, the 

contribution to ozone concentrations in Berks County from upwind emissions in Lebanon County is also 

relatively low. Furthermore, Lebanon and Schuylkill Counties are not linked jurisdictionally to the 

Reading area. They are served by different MPOs and they are in separate statistical areas. Therefore, 

Lebanon and Schuylkill Counties should not be included in the Reading nonattainment area.

 

7

See EPA’s Technical Analysis for the Philadelphia-Wilmington-Atlantic City nonattainment area.